blob: 97cfdf970806bd28d6e48b6f21cd3cd4c54e62c8 [file] [log] [blame]
------------------------------------------------------------------------------
-- --
-- GNAT LIBRARY COMPONENTS --
-- --
-- G N A T . S P I T B O L . P A T T E R N S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1998-2021, AdaCore --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- Note: the data structures and general approach used in this implementation
-- are derived from the original MINIMAL sources for SPITBOL. The code is not
-- a direct translation, but the approach is followed closely. In particular,
-- we use the one stack approach developed in the SPITBOL implementation.
with Ada.Strings.Unbounded.Aux; use Ada.Strings.Unbounded.Aux;
with GNAT.Debug_Utilities; use GNAT.Debug_Utilities;
with System; use System;
with Ada.Unchecked_Conversion;
with Ada.Unchecked_Deallocation;
package body GNAT.Spitbol.Patterns is
------------------------
-- Internal Debugging --
------------------------
Internal_Debug : constant Boolean := False;
-- Set this flag to True to activate some built-in debugging traceback
-- These are all lines output with PutD and Put_LineD.
procedure New_LineD;
pragma Inline (New_LineD);
-- Output new blank line with New_Line if Internal_Debug is True
procedure PutD (Str : String);
pragma Inline (PutD);
-- Output string with Put if Internal_Debug is True
procedure Put_LineD (Str : String);
pragma Inline (Put_LineD);
-- Output string with Put_Line if Internal_Debug is True
-----------------------------
-- Local Type Declarations --
-----------------------------
subtype String_Ptr is Ada.Strings.Unbounded.String_Access;
subtype File_Ptr is Ada.Text_IO.File_Access;
function To_Address is new Ada.Unchecked_Conversion (PE_Ptr, Address);
-- Used only for debugging output purposes
subtype AFC is Ada.Finalization.Controlled;
N : constant PE_Ptr := null;
-- Shorthand used to initialize Copy fields to null
type Natural_Ptr is access all Natural;
type Pattern_Ptr is access all Pattern;
--------------------------------------------------
-- Description of Algorithm and Data Structures --
--------------------------------------------------
-- A pattern structure is represented as a linked graph of nodes
-- with the following structure:
-- +------------------------------------+
-- I Pcode I
-- +------------------------------------+
-- I Index I
-- +------------------------------------+
-- I Pthen I
-- +------------------------------------+
-- I parameter(s) I
-- +------------------------------------+
-- Pcode is a code value indicating the type of the pattern node. This
-- code is used both as the discriminant value for the record, and as
-- the case index in the main match routine that branches to the proper
-- match code for the given element.
-- Index is a serial index number. The use of these serial index
-- numbers is described in a separate section.
-- Pthen is a pointer to the successor node, i.e the node to be matched
-- if the attempt to match the node succeeds. If this is the last node
-- of the pattern to be matched, then Pthen points to a dummy node
-- of kind PC_EOP (end of pattern), which initializes pattern exit.
-- The parameter or parameters are present for certain node types,
-- and the type varies with the pattern code.
type Pattern_Code is (
PC_Arb_Y,
PC_Assign,
PC_Bal,
PC_BreakX_X,
PC_Cancel,
PC_EOP,
PC_Fail,
PC_Fence,
PC_Fence_X,
PC_Fence_Y,
PC_R_Enter,
PC_R_Remove,
PC_R_Restore,
PC_Rest,
PC_Succeed,
PC_Unanchored,
PC_Alt,
PC_Arb_X,
PC_Arbno_S,
PC_Arbno_X,
PC_Rpat,
PC_Pred_Func,
PC_Assign_Imm,
PC_Assign_OnM,
PC_Any_VP,
PC_Break_VP,
PC_BreakX_VP,
PC_NotAny_VP,
PC_NSpan_VP,
PC_Span_VP,
PC_String_VP,
PC_Write_Imm,
PC_Write_OnM,
PC_Null,
PC_String,
PC_String_2,
PC_String_3,
PC_String_4,
PC_String_5,
PC_String_6,
PC_Setcur,
PC_Any_CH,
PC_Break_CH,
PC_BreakX_CH,
PC_Char,
PC_NotAny_CH,
PC_NSpan_CH,
PC_Span_CH,
PC_Any_CS,
PC_Break_CS,
PC_BreakX_CS,
PC_NotAny_CS,
PC_NSpan_CS,
PC_Span_CS,
PC_Arbno_Y,
PC_Len_Nat,
PC_Pos_Nat,
PC_RPos_Nat,
PC_RTab_Nat,
PC_Tab_Nat,
PC_Pos_NF,
PC_Len_NF,
PC_RPos_NF,
PC_RTab_NF,
PC_Tab_NF,
PC_Pos_NP,
PC_Len_NP,
PC_RPos_NP,
PC_RTab_NP,
PC_Tab_NP,
PC_Any_VF,
PC_Break_VF,
PC_BreakX_VF,
PC_NotAny_VF,
PC_NSpan_VF,
PC_Span_VF,
PC_String_VF);
type IndexT is range 0 .. +(2 **15 - 1);
type PE (Pcode : Pattern_Code) is record
Index : IndexT;
-- Serial index number of pattern element within pattern
Pthen : PE_Ptr;
-- Successor element, to be matched after this one
case Pcode is
when PC_Arb_Y
| PC_Assign
| PC_Bal
| PC_BreakX_X
| PC_Cancel
| PC_EOP
| PC_Fail
| PC_Fence
| PC_Fence_X
| PC_Fence_Y
| PC_Null
| PC_R_Enter
| PC_R_Remove
| PC_R_Restore
| PC_Rest
| PC_Succeed
| PC_Unanchored
=>
null;
when PC_Alt
| PC_Arb_X
| PC_Arbno_S
| PC_Arbno_X
=>
Alt : PE_Ptr;
when PC_Rpat =>
PP : Pattern_Ptr;
when PC_Pred_Func =>
BF : Boolean_Func;
when PC_Assign_Imm
| PC_Assign_OnM
| PC_Any_VP
| PC_Break_VP
| PC_BreakX_VP
| PC_NotAny_VP
| PC_NSpan_VP
| PC_Span_VP
| PC_String_VP
=>
VP : VString_Ptr;
when PC_Write_Imm
| PC_Write_OnM
=>
FP : File_Ptr;
when PC_String =>
Str : String_Ptr;
when PC_String_2 =>
Str2 : String (1 .. 2);
when PC_String_3 =>
Str3 : String (1 .. 3);
when PC_String_4 =>
Str4 : String (1 .. 4);
when PC_String_5 =>
Str5 : String (1 .. 5);
when PC_String_6 =>
Str6 : String (1 .. 6);
when PC_Setcur =>
Var : Natural_Ptr;
when PC_Any_CH
| PC_Break_CH
| PC_BreakX_CH
| PC_Char
| PC_NotAny_CH
| PC_NSpan_CH
| PC_Span_CH
=>
Char : Character;
when PC_Any_CS
| PC_Break_CS
| PC_BreakX_CS
| PC_NotAny_CS
| PC_NSpan_CS
| PC_Span_CS
=>
CS : Character_Set;
when PC_Arbno_Y
| PC_Len_Nat
| PC_Pos_Nat
| PC_RPos_Nat
| PC_RTab_Nat
| PC_Tab_Nat
=>
Nat : Natural;
when PC_Pos_NF
| PC_Len_NF
| PC_RPos_NF
| PC_RTab_NF
| PC_Tab_NF
=>
NF : Natural_Func;
when PC_Pos_NP
| PC_Len_NP
| PC_RPos_NP
| PC_RTab_NP
| PC_Tab_NP
=>
NP : Natural_Ptr;
when PC_Any_VF
| PC_Break_VF
| PC_BreakX_VF
| PC_NotAny_VF
| PC_NSpan_VF
| PC_Span_VF
| PC_String_VF
=>
VF : VString_Func;
end case;
end record;
subtype PC_Has_Alt is Pattern_Code range PC_Alt .. PC_Arbno_X;
-- Range of pattern codes that has an Alt field. This is used in the
-- recursive traversals, since these links must be followed.
EOP_Element : aliased constant PE := (PC_EOP, 0, N);
-- This is the end of pattern element, and is thus the representation of
-- a null pattern. It has a zero index element since it is never placed
-- inside a pattern. Furthermore it does not need a successor, since it
-- marks the end of the pattern, so that no more successors are needed.
EOP : constant PE_Ptr := EOP_Element'Unrestricted_Access;
-- This is the end of pattern pointer, that is used in the Pthen pointer
-- of other nodes to signal end of pattern.
-- The following array is used to determine if a pattern used as an
-- argument for Arbno is eligible for treatment using the simple Arbno
-- structure (i.e. it is a pattern that is guaranteed to match at least
-- one character on success, and not to make any entries on the stack.
OK_For_Simple_Arbno : constant array (Pattern_Code) of Boolean :=
(PC_Any_CS |
PC_Any_CH |
PC_Any_VF |
PC_Any_VP |
PC_Char |
PC_Len_Nat |
PC_NotAny_CS |
PC_NotAny_CH |
PC_NotAny_VF |
PC_NotAny_VP |
PC_Span_CS |
PC_Span_CH |
PC_Span_VF |
PC_Span_VP |
PC_String |
PC_String_2 |
PC_String_3 |
PC_String_4 |
PC_String_5 |
PC_String_6 => True,
others => False);
-------------------------------
-- The Pattern History Stack --
-------------------------------
-- The pattern history stack is used for controlling backtracking when
-- a match fails. The idea is to stack entries that give a cursor value
-- to be restored, and a node to be reestablished as the current node to
-- attempt an appropriate rematch operation. The processing for a pattern
-- element that has rematch alternatives pushes an appropriate entry or
-- entry on to the stack, and the proceeds. If a match fails at any point,
-- the top element of the stack is popped off, resetting the cursor and
-- the match continues by accessing the node stored with this entry.
type Stack_Entry is record
Cursor : Integer;
-- Saved cursor value that is restored when this entry is popped
-- from the stack if a match attempt fails. Occasionally, this
-- field is used to store a history stack pointer instead of a
-- cursor. Such cases are noted in the documentation and the value
-- stored is negative since stack pointer values are always negative.
Node : PE_Ptr;
-- This pattern element reference is reestablished as the current
-- Node to be matched (which will attempt an appropriate rematch).
end record;
subtype Stack_Range is Integer range -Stack_Size .. -1;
type Stack_Type is array (Stack_Range) of Stack_Entry;
-- The type used for a history stack. The actual instance of the stack
-- is declared as a local variable in the Match routine, to properly
-- handle recursive calls to Match. All stack pointer values are negative
-- to distinguish them from normal cursor values.
-- Note: the pattern matching stack is used only to handle backtracking.
-- If no backtracking occurs, its entries are never accessed, and never
-- popped off, and in particular it is normal for a successful match
-- to terminate with entries on the stack that are simply discarded.
-- Note: in subsequent diagrams of the stack, we always place element
-- zero (the deepest element) at the top of the page, then build the
-- stack down on the page with the most recent (top of stack) element
-- being the bottom-most entry on the page.
-- Stack checking is handled by labeling every pattern with the maximum
-- number of stack entries that are required, so a single check at the
-- start of matching the pattern suffices. There are two exceptions.
-- First, the count does not include entries for recursive pattern
-- references. Such recursions must therefore perform a specific
-- stack check with respect to the number of stack entries required
-- by the recursive pattern that is accessed and the amount of stack
-- that remains unused.
-- Second, the count includes only one iteration of an Arbno pattern,
-- so a specific check must be made on subsequent iterations that there
-- is still enough stack space left. The Arbno node has a field that
-- records the number of stack entries required by its argument for
-- this purpose.
---------------------------------------------------
-- Use of Serial Index Field in Pattern Elements --
---------------------------------------------------
-- The serial index numbers for the pattern elements are assigned as
-- a pattern is constructed from its constituent elements. Note that there
-- is never any sharing of pattern elements between patterns (copies are
-- always made), so the serial index numbers are unique to a particular
-- pattern as referenced from the P field of a value of type Pattern.
-- The index numbers meet three separate invariants, which are used for
-- various purposes as described in this section.
-- First, the numbers uniquely identify the pattern elements within a
-- pattern. If Num is the number of elements in a given pattern, then
-- the serial index numbers for the elements of this pattern will range
-- from 1 .. Num, so that each element has a separate value.
-- The purpose of this assignment is to provide a convenient auxiliary
-- data structure mechanism during operations which must traverse a
-- pattern (e.g. copy and finalization processing). Once constructed
-- patterns are strictly read only. This is necessary to allow sharing
-- of patterns between tasks. This means that we cannot go marking the
-- pattern (e.g. with a visited bit). Instead we construct a separate
-- vector that contains the necessary information indexed by the Index
-- values in the pattern elements. For this purpose the only requirement
-- is that they be uniquely assigned.
-- Second, the pattern element referenced directly, i.e. the leading
-- pattern element, is always the maximum numbered element and therefore
-- indicates the total number of elements in the pattern. More precisely,
-- the element referenced by the P field of a pattern value, or the
-- element returned by any of the internal pattern construction routines
-- in the body (that return a value of type PE_Ptr) always is this
-- maximum element,
-- The purpose of this requirement is to allow an immediate determination
-- of the number of pattern elements within a pattern. This is used to
-- properly size the vectors used to contain auxiliary information for
-- traversal as described above.
-- Third, as compound pattern structures are constructed, the way in which
-- constituent parts of the pattern are constructed is stylized. This is
-- an automatic consequence of the way that these compound structures
-- are constructed, and basically what we are doing is simply documenting
-- and specifying the natural result of the pattern construction. The
-- section describing compound pattern structures gives details of the
-- numbering of each compound pattern structure.
-- The purpose of specifying the stylized numbering structures for the
-- compound patterns is to help simplify the processing in the Image
-- function, since it eases the task of retrieving the original recursive
-- structure of the pattern from the flat graph structure of elements.
-- This use in the Image function is the only point at which the code
-- makes use of the stylized structures.
type Ref_Array is array (IndexT range <>) of PE_Ptr;
-- This type is used to build an array whose N'th entry references the
-- element in a pattern whose Index value is N. See Build_Ref_Array.
procedure Build_Ref_Array (E : PE_Ptr; RA : out Ref_Array);
-- Given a pattern element which is the leading element of a pattern
-- structure, and a Ref_Array with bounds 1 .. E.Index, fills in the
-- Ref_Array so that its N'th entry references the element of the
-- referenced pattern whose Index value is N.
-------------------------------
-- Recursive Pattern Matches --
-------------------------------
-- The pattern primitive (+P) where P is a Pattern_Ptr or Pattern_Func
-- causes a recursive pattern match. This cannot be handled by an actual
-- recursive call to the outer level Match routine, since this would not
-- allow for possible backtracking into the region matched by the inner
-- pattern. Indeed this is the classical clash between recursion and
-- backtracking, and a simple recursive stack structure does not suffice.
-- This section describes how this recursion and the possible associated
-- backtracking is handled. We still use a single stack, but we establish
-- the concept of nested regions on this stack, each of which has a stack
-- base value pointing to the deepest stack entry of the region. The base
-- value for the outer level is zero.
-- When a recursive match is established, two special stack entries are
-- made. The first entry is used to save the original node that starts
-- the recursive match. This is saved so that the successor field of
-- this node is accessible at the end of the match, but it is never
-- popped and executed.
-- The second entry corresponds to a standard new region action. A
-- PC_R_Remove node is stacked, whose cursor field is used to store
-- the outer stack base, and the stack base is reset to point to
-- this PC_R_Remove node. Then the recursive pattern is matched and
-- it can make history stack entries in the normal matter, so now
-- the stack looks like:
-- (stack entries made by outer level)
-- (Special entry, node is (+P) successor
-- cursor entry is not used)
-- (PC_R_Remove entry, "cursor" value is (negative) <-- Stack base
-- saved base value for the enclosing region)
-- (stack entries made by inner level)
-- If a subsequent failure occurs and pops the PC_R_Remove node, it
-- removes itself and the special entry immediately underneath it,
-- restores the stack base value for the enclosing region, and then
-- again signals failure to look for alternatives that were stacked
-- before the recursion was initiated.
-- Now we need to consider what happens if the inner pattern succeeds, as
-- signalled by accessing the special PC_EOP pattern primitive. First we
-- recognize the nested case by looking at the Base value. If this Base
-- value is Stack'First, then the entire match has succeeded, but if the
-- base value is greater than Stack'First, then we have successfully
-- matched an inner pattern, and processing continues at the outer level.
-- There are two cases. The simple case is when the inner pattern has made
-- no stack entries, as recognized by the fact that the current stack
-- pointer is equal to the current base value. In this case it is fine to
-- remove all trace of the recursion by restoring the outer base value and
-- using the special entry to find the appropriate successor node.
-- The more complex case arises when the inner match does make stack
-- entries. In this case, the PC_EOP processing stacks a special entry
-- whose cursor value saves the saved inner base value (the one that
-- references the corresponding PC_R_Remove value), and whose node
-- pointer references a PC_R_Restore node, so the stack looks like:
-- (stack entries made by outer level)
-- (Special entry, node is (+P) successor,
-- cursor entry is not used)
-- (PC_R_Remove entry, "cursor" value is (negative)
-- saved base value for the enclosing region)
-- (stack entries made by inner level)
-- (PC_Region_Replace entry, "cursor" value is (negative)
-- stack pointer value referencing the PC_R_Remove entry).
-- If the entire match succeeds, then these stack entries are, as usual,
-- ignored and abandoned. If on the other hand a subsequent failure
-- causes the PC_Region_Replace entry to be popped, it restores the
-- inner base value from its saved "cursor" value and then fails again.
-- Note that it is OK that the cursor is temporarily clobbered by this
-- pop, since the second failure will reestablish a proper cursor value.
---------------------------------
-- Compound Pattern Structures --
---------------------------------
-- This section discusses the compound structures used to represent
-- constructed patterns. It shows the graph structures of pattern
-- elements that are constructed, and in the case of patterns that
-- provide backtracking possibilities, describes how the history
-- stack is used to control the backtracking. Finally, it notes the
-- way in which the Index numbers are assigned to the structure.
-- In all diagrams, solid lines (built with minus signs or vertical
-- bars, represent successor pointers (Pthen fields) with > or V used
-- to indicate the direction of the pointer. The initial node of the
-- structure is in the upper left of the diagram. A dotted line is an
-- alternative pointer from the element above it to the element below
-- it. See individual sections for details on how alternatives are used.
-------------------
-- Concatenation --
-------------------
-- In the pattern structures listed in this section, a line that looks
-- like ----> with nothing to the right indicates an end of pattern
-- (EOP) pointer that represents the end of the match.
-- When a pattern concatenation (L & R) occurs, the resulting structure
-- is obtained by finding all such EOP pointers in L, and replacing
-- them to point to R. This is the most important flattening that
-- occurs in constructing a pattern, and it means that the pattern
-- matching circuitry does not have to keep track of the structure
-- of a pattern with respect to concatenation, since the appropriate
-- successor is always at hand.
-- Concatenation itself generates no additional possibilities for
-- backtracking, but the constituent patterns of the concatenated
-- structure will make stack entries as usual. The maximum amount
-- of stack required by the structure is thus simply the sum of the
-- maximums required by L and R.
-- The index numbering of a concatenation structure works by leaving
-- the numbering of the right hand pattern, R, unchanged and adjusting
-- the numbers in the left hand pattern, L up by the count of elements
-- in R. This ensures that the maximum numbered element is the leading
-- element as required (given that it was the leading element in L).
-----------------
-- Alternation --
-----------------
-- A pattern (L or R) constructs the structure:
-- +---+ +---+
-- | A |---->| L |---->
-- +---+ +---+
-- .
-- .
-- +---+
-- | R |---->
-- +---+
-- The A element here is a PC_Alt node, and the dotted line represents
-- the contents of the Alt field. When the PC_Alt element is matched,
-- it stacks a pointer to the leading element of R on the history stack
-- so that on subsequent failure, a match of R is attempted.
-- The A node is the highest numbered element in the pattern. The
-- original index numbers of R are unchanged, but the index numbers
-- of the L pattern are adjusted up by the count of elements in R.
-- Note that the difference between the index of the L leading element
-- the index of the R leading element (after building the alt structure)
-- indicates the number of nodes in L, and this is true even after the
-- structure is incorporated into some larger structure. For example,
-- if the A node has index 16, and L has index 15 and R has index
-- 5, then we know that L has 10 (15-5) elements in it.
-- Suppose that we now concatenate this structure to another pattern
-- with 9 elements in it. We will now have the A node with an index
-- of 25, L with an index of 24 and R with an index of 14. We still
-- know that L has 10 (24-14) elements in it, numbered 15-24, and
-- consequently the successor of the alternation structure has an
-- index with a value less than 15. This is used in Image to figure
-- out the original recursive structure of a pattern.
-- To clarify the interaction of the alternation and concatenation
-- structures, here is a more complex example of the structure built
-- for the pattern:
-- (V or W or X) (Y or Z)
-- where A,B,C,D,E are all single element patterns:
-- +---+ +---+ +---+ +---+
-- I A I---->I V I---+-->I A I---->I Y I---->
-- +---+ +---+ I +---+ +---+
-- . I .
-- . I .
-- +---+ +---+ I +---+
-- I A I---->I W I-->I I Z I---->
-- +---+ +---+ I +---+
-- . I
-- . I
-- +---+ I
-- I X I------------>+
-- +---+
-- The numbering of the nodes would be as follows:
-- +---+ +---+ +---+ +---+
-- I 8 I---->I 7 I---+-->I 3 I---->I 2 I---->
-- +---+ +---+ I +---+ +---+
-- . I .
-- . I .
-- +---+ +---+ I +---+
-- I 6 I---->I 5 I-->I I 1 I---->
-- +---+ +---+ I +---+
-- . I
-- . I
-- +---+ I
-- I 4 I------------>+
-- +---+
-- Note: The above structure actually corresponds to
-- (A or (B or C)) (D or E)
-- rather than
-- ((A or B) or C) (D or E)
-- which is the more natural interpretation, but in fact alternation
-- is associative, and the construction of an alternative changes the
-- left grouped pattern to the right grouped pattern in any case, so
-- that the Image function produces a more natural looking output.
---------
-- Arb --
---------
-- An Arb pattern builds the structure
-- +---+
-- | X |---->
-- +---+
-- .
-- .
-- +---+
-- | Y |---->
-- +---+
-- The X node is a PC_Arb_X node, which matches null, and stacks a
-- pointer to Y node, which is the PC_Arb_Y node that matches one
-- extra character and restacks itself.
-- The PC_Arb_X node is numbered 2, and the PC_Arb_Y node is 1
-------------------------
-- Arbno (simple case) --
-------------------------
-- The simple form of Arbno can be used where the pattern always
-- matches at least one character if it succeeds, and it is known
-- not to make any history stack entries. In this case, Arbno (P)
-- can construct the following structure:
-- +-------------+
-- | ^
-- V |
-- +---+ |
-- | S |----> |
-- +---+ |
-- . |
-- . |
-- +---+ |
-- | P |---------->+
-- +---+
-- The S (PC_Arbno_S) node matches null stacking a pointer to the
-- pattern P. If a subsequent failure causes P to be matched and
-- this match succeeds, then node A gets restacked to try another
-- instance if needed by a subsequent failure.
-- The node numbering of the constituent pattern P is not affected.
-- The S node has a node number of P.Index + 1.
--------------------------
-- Arbno (complex case) --
--------------------------
-- A call to Arbno (P), where P can match null (or at least is not
-- known to require a non-null string) and/or P requires pattern stack
-- entries, constructs the following structure:
-- +--------------------------+
-- | ^
-- V |
-- +---+ |
-- | X |----> |
-- +---+ |
-- . |
-- . |
-- +---+ +---+ +---+ |
-- | E |---->| P |---->| Y |--->+
-- +---+ +---+ +---+
-- The node X (PC_Arbno_X) matches null, stacking a pointer to the
-- E-P-X structure used to match one Arbno instance.
-- Here E is the PC_R_Enter node which matches null and creates two
-- stack entries. The first is a special entry whose node field is
-- not used at all, and whose cursor field has the initial cursor.
-- The second entry corresponds to a standard new region action. A
-- PC_R_Remove node is stacked, whose cursor field is used to store
-- the outer stack base, and the stack base is reset to point to
-- this PC_R_Remove node. Then the pattern P is matched, and it can
-- make history stack entries in the normal manner, so now the stack
-- looks like:
-- (stack entries made before assign pattern)
-- (Special entry, node field not used,
-- used only to save initial cursor)
-- (PC_R_Remove entry, "cursor" value is (negative) <-- Stack Base
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- If the match of P fails, then the PC_R_Remove entry is popped and
-- it removes both itself and the special entry underneath it,
-- restores the outer stack base, and signals failure.
-- If the match of P succeeds, then node Y, the PC_Arbno_Y node, pops
-- the inner region. There are two possibilities. If matching P left
-- no stack entries, then all traces of the inner region can be removed.
-- If there are stack entries, then we push an PC_Region_Replace stack
-- entry whose "cursor" value is the inner stack base value, and then
-- restore the outer stack base value, so the stack looks like:
-- (stack entries made before assign pattern)
-- (Special entry, node field not used,
-- used only to save initial cursor)
-- (PC_R_Remove entry, "cursor" value is (negative)
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- (PC_Region_Replace entry, "cursor" value is (negative)
-- stack pointer value referencing the PC_R_Remove entry).
-- Now that we have matched another instance of the Arbno pattern,
-- we need to move to the successor. There are two cases. If the
-- Arbno pattern matched null, then there is no point in seeking
-- alternatives, since we would just match a whole bunch of nulls.
-- In this case we look through the alternative node, and move
-- directly to its successor (i.e. the successor of the Arbno
-- pattern). If on the other hand a non-null string was matched,
-- we simply follow the successor to the alternative node, which
-- sets up for another possible match of the Arbno pattern.
-- As noted in the section on stack checking, the stack count (and
-- hence the stack check) for a pattern includes only one iteration
-- of the Arbno pattern. To make sure that multiple iterations do not
-- overflow the stack, the Arbno node saves the stack count required
-- by a single iteration, and the Concat function increments this to
-- include stack entries required by any successor. The PC_Arbno_Y
-- node uses this count to ensure that sufficient stack remains
-- before proceeding after matching each new instance.
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the Y node is numbered N + 1,
-- the E node is N + 2, and the X node is N + 3.
----------------------
-- Assign Immediate --
----------------------
-- Immediate assignment (P * V) constructs the following structure
-- +---+ +---+ +---+
-- | E |---->| P |---->| A |---->
-- +---+ +---+ +---+
-- Here E is the PC_R_Enter node which matches null and creates two
-- stack entries. The first is a special entry whose node field is
-- not used at all, and whose cursor field has the initial cursor.
-- The second entry corresponds to a standard new region action. A
-- PC_R_Remove node is stacked, whose cursor field is used to store
-- the outer stack base, and the stack base is reset to point to
-- this PC_R_Remove node. Then the pattern P is matched, and it can
-- make history stack entries in the normal manner, so now the stack
-- looks like:
-- (stack entries made before assign pattern)
-- (Special entry, node field not used,
-- used only to save initial cursor)
-- (PC_R_Remove entry, "cursor" value is (negative) <-- Stack Base
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- If the match of P fails, then the PC_R_Remove entry is popped
-- and it removes both itself and the special entry underneath it,
-- restores the outer stack base, and signals failure.
-- If the match of P succeeds, then node A, which is the actual
-- PC_Assign_Imm node, executes the assignment (using the stack
-- base to locate the entry with the saved starting cursor value),
-- and the pops the inner region. There are two possibilities, if
-- matching P left no stack entries, then all traces of the inner
-- region can be removed. If there are stack entries, then we push
-- an PC_Region_Replace stack entry whose "cursor" value is the
-- inner stack base value, and then restore the outer stack base
-- value, so the stack looks like:
-- (stack entries made before assign pattern)
-- (Special entry, node field not used,
-- used only to save initial cursor)
-- (PC_R_Remove entry, "cursor" value is (negative)
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- (PC_Region_Replace entry, "cursor" value is the (negative)
-- stack pointer value referencing the PC_R_Remove entry).
-- If a subsequent failure occurs, the PC_Region_Replace node restores
-- the inner stack base value and signals failure to explore rematches
-- of the pattern P.
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the A node is numbered N + 1,
-- and the E node is N + 2.
---------------------
-- Assign On Match --
---------------------
-- The assign on match (**) pattern is quite similar to the assign
-- immediate pattern, except that the actual assignment has to be
-- delayed. The following structure is constructed:
-- +---+ +---+ +---+
-- | E |---->| P |---->| A |---->
-- +---+ +---+ +---+
-- The operation of this pattern is identical to that described above
-- for deferred assignment, up to the point where P has been matched.
-- The A node, which is the PC_Assign_OnM node first pushes a
-- PC_Assign node onto the history stack. This node saves the ending
-- cursor and acts as a flag for the final assignment, as further
-- described below.
-- It then stores a pointer to itself in the special entry node field.
-- This was otherwise unused, and is now used to retrieve the address
-- of the variable to be assigned at the end of the pattern.
-- After that the inner region is terminated in the usual manner,
-- by stacking a PC_R_Restore entry as described for the assign
-- immediate case. Note that the optimization of completely
-- removing the inner region does not happen in this case, since
-- we have at least one stack entry (the PC_Assign one we just made).
-- The stack now looks like:
-- (stack entries made before assign pattern)
-- (Special entry, node points to copy of
-- the PC_Assign_OnM node, and the
-- cursor field saves the initial cursor).
-- (PC_R_Remove entry, "cursor" value is (negative)
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- (PC_Assign entry, saves final cursor)
-- (PC_Region_Replace entry, "cursor" value is (negative)
-- stack pointer value referencing the PC_R_Remove entry).
-- If a subsequent failure causes the PC_Assign node to execute it
-- simply removes itself and propagates the failure.
-- If the match succeeds, then the history stack is scanned for
-- PC_Assign nodes, and the assignments are executed (examination
-- of the above diagram will show that all the necessary data is
-- at hand for the assignment).
-- To optimize the common case where no assign-on-match operations
-- are present, a global flag Assign_OnM is maintained which is
-- initialize to False, and gets set True as part of the execution
-- of the PC_Assign_OnM node. The scan of the history stack for
-- PC_Assign entries is done only if this flag is set.
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the A node is numbered N + 1,
-- and the E node is N + 2.
---------
-- Bal --
---------
-- Bal builds a single node:
-- +---+
-- | B |---->
-- +---+
-- The node B is the PC_Bal node which matches a parentheses balanced
-- string, starting at the current cursor position. It then updates
-- the cursor past this matched string, and stacks a pointer to itself
-- with this updated cursor value on the history stack, to extend the
-- matched string on a subsequent failure.
-- Since this is a single node it is numbered 1 (the reason we include
-- it in the compound patterns section is that it backtracks).
------------
-- BreakX --
------------
-- BreakX builds the structure
-- +---+ +---+
-- | B |---->| A |---->
-- +---+ +---+
-- ^ .
-- | .
-- | +---+
-- +<------| X |
-- +---+
-- Here the B node is the BreakX_xx node that performs a normal Break
-- function. The A node is an alternative (PC_Alt) node that matches
-- null, but stacks a pointer to node X (the PC_BreakX_X node) which
-- extends the match one character (to eat up the previously detected
-- break character), and then rematches the break.
-- The B node is numbered 3, the alternative node is 1, and the X
-- node is 2.
-----------
-- Fence --
-----------
-- Fence builds a single node:
-- +---+
-- | F |---->
-- +---+
-- The element F, PC_Fence, matches null, and stacks a pointer to a
-- PC_Cancel element which will abort the match on a subsequent failure.
-- Since this is a single element it is numbered 1 (the reason we
-- include it in the compound patterns section is that it backtracks).
--------------------
-- Fence Function --
--------------------
-- A call to the Fence function builds the structure:
-- +---+ +---+ +---+
-- | E |---->| P |---->| X |---->
-- +---+ +---+ +---+
-- Here E is the PC_R_Enter node which matches null and creates two
-- stack entries. The first is a special entry which is not used at
-- all in the fence case (it is present merely for uniformity with
-- other cases of region enter operations).
-- The second entry corresponds to a standard new region action. A
-- PC_R_Remove node is stacked, whose cursor field is used to store
-- the outer stack base, and the stack base is reset to point to
-- this PC_R_Remove node. Then the pattern P is matched, and it can
-- make history stack entries in the normal manner, so now the stack
-- looks like:
-- (stack entries made before fence pattern)
-- (Special entry, not used at all)
-- (PC_R_Remove entry, "cursor" value is (negative) <-- Stack Base
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- If the match of P fails, then the PC_R_Remove entry is popped
-- and it removes both itself and the special entry underneath it,
-- restores the outer stack base, and signals failure.
-- If the match of P succeeds, then node X, the PC_Fence_X node, gets
-- control. One might be tempted to think that at this point, the
-- history stack entries made by matching P can just be removed since
-- they certainly are not going to be used for rematching (that is
-- whole point of Fence after all). However, this is wrong, because
-- it would result in the loss of possible assign-on-match entries
-- for deferred pattern assignments.
-- Instead what we do is to make a special entry whose node references
-- PC_Fence_Y, and whose cursor saves the inner stack base value, i.e.
-- the pointer to the PC_R_Remove entry. Then the outer stack base
-- pointer is restored, so the stack looks like:
-- (stack entries made before assign pattern)
-- (Special entry, not used at all)
-- (PC_R_Remove entry, "cursor" value is (negative)
-- saved base value for the enclosing region)
-- (stack entries made by matching P)
-- (PC_Fence_Y entry, "cursor" value is (negative) stack
-- pointer value referencing the PC_R_Remove entry).
-- If a subsequent failure occurs, then the PC_Fence_Y entry removes
-- the entire inner region, including all entries made by matching P,
-- and alternatives prior to the Fence pattern are sought.
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the X node is numbered N + 1,
-- and the E node is N + 2.
-------------
-- Succeed --
-------------
-- Succeed builds a single node:
-- +---+
-- | S |---->
-- +---+
-- The node S is the PC_Succeed node which matches null, and stacks
-- a pointer to itself on the history stack, so that a subsequent
-- failure repeats the same match.
-- Since this is a single node it is numbered 1 (the reason we include
-- it in the compound patterns section is that it backtracks).
---------------------
-- Write Immediate --
---------------------
-- The structure built for a write immediate operation (P * F, where
-- F is a file access value) is:
-- +---+ +---+ +---+
-- | E |---->| P |---->| W |---->
-- +---+ +---+ +---+
-- Here E is the PC_R_Enter node and W is the PC_Write_Imm node. The
-- handling is identical to that described above for Assign Immediate,
-- except that at the point where a successful match occurs, the matched
-- substring is written to the referenced file.
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the W node is numbered N + 1,
-- and the E node is N + 2.
--------------------
-- Write On Match --
--------------------
-- The structure built for a write on match operation (P ** F, where
-- F is a file access value) is:
-- +---+ +---+ +---+
-- | E |---->| P |---->| W |---->
-- +---+ +---+ +---+
-- Here E is the PC_R_Enter node and W is the PC_Write_OnM node. The
-- handling is identical to that described above for Assign On Match,
-- except that at the point where a successful match has completed,
-- the matched substring is written to the referenced file.
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the W node is numbered N + 1,
-- and the E node is N + 2.
-----------------------
-- Constant Patterns --
-----------------------
-- The following pattern elements are referenced only from the pattern
-- history stack. In each case the processing for the pattern element
-- results in pattern match abort, or further failure, so there is no
-- need for a successor and no need for a node number
CP_Assign : aliased PE := (PC_Assign, 0, N);
CP_Cancel : aliased PE := (PC_Cancel, 0, N);
CP_Fence_Y : aliased PE := (PC_Fence_Y, 0, N);
CP_R_Remove : aliased PE := (PC_R_Remove, 0, N);
CP_R_Restore : aliased PE := (PC_R_Restore, 0, N);
-----------------------
-- Local Subprograms --
-----------------------
function Alternate (L, R : PE_Ptr) return PE_Ptr;
function "or" (L, R : PE_Ptr) return PE_Ptr renames Alternate;
-- Build pattern structure corresponding to the alternation of L, R.
-- (i.e. try to match L, and if that fails, try to match R).
function Arbno_Simple (P : PE_Ptr) return PE_Ptr;
-- Build simple Arbno pattern, P is a pattern that is guaranteed to
-- match at least one character if it succeeds and to require no
-- stack entries under all circumstances. The result returned is
-- a simple Arbno structure as previously described.
function Bracket (E, P, A : PE_Ptr) return PE_Ptr;
-- Given two single node pattern elements E and A, and a (possible
-- complex) pattern P, construct the concatenation E-->P-->A and
-- return a pointer to E. The concatenation does not affect the
-- node numbering in P. A has a number one higher than the maximum
-- number in P, and E has a number two higher than the maximum
-- number in P (see for example the Assign_Immediate structure to
-- understand a typical use of this function).
function BreakX_Make (B : PE_Ptr) return Pattern;
-- Given a pattern element for a Break pattern, returns the
-- corresponding BreakX compound pattern structure.
function Concat (L, R : PE_Ptr; Incr : Natural) return PE_Ptr;
-- Creates a pattern element that represents a concatenation of the
-- two given pattern elements (i.e. the pattern L followed by R).
-- The result returned is always the same as L, but the pattern
-- referenced by L is modified to have R as a successor. This
-- procedure does not copy L or R, so if a copy is required, it
-- is the responsibility of the caller. The Incr parameter is an
-- amount to be added to the Nat field of any P_Arbno_Y node that is
-- in the left operand, it represents the additional stack space
-- required by the right operand.
function C_To_PE (C : PChar) return PE_Ptr;
-- Given a character, constructs a pattern element that matches
-- the single character.
function Copy (P : PE_Ptr) return PE_Ptr;
-- Creates a copy of the pattern element referenced by the given
-- pattern element reference. This is a deep copy, which means that
-- it follows the Next and Alt pointers.
function Image (P : PE_Ptr) return String;
-- Returns the image of the address of the referenced pattern element.
-- This is equivalent to Image (To_Address (P));
function Is_In (C : Character; Str : String) return Boolean;
pragma Inline (Is_In);
-- Determines if the character C is in string Str
procedure Logic_Error;
-- Called to raise Program_Error with an appropriate message if an
-- internal logic error is detected.
function Str_BF (A : Boolean_Func) return String;
function Str_FP (A : File_Ptr) return String;
function Str_NF (A : Natural_Func) return String;
function Str_NP (A : Natural_Ptr) return String;
function Str_PP (A : Pattern_Ptr) return String;
function Str_VF (A : VString_Func) return String;
function Str_VP (A : VString_Ptr) return String;
-- These are debugging routines, which return a representation of the
-- given access value (they are called only by Image and Dump)
procedure Set_Successor (Pat : PE_Ptr; Succ : PE_Ptr);
-- Adjusts all EOP pointers in Pat to point to Succ. No other changes
-- are made. In particular, Succ is unchanged, and no index numbers
-- are modified. Note that Pat may not be equal to EOP on entry.
function S_To_PE (Str : PString) return PE_Ptr;
-- Given a string, constructs a pattern element that matches the string
procedure Uninitialized_Pattern;
pragma No_Return (Uninitialized_Pattern);
-- Called to raise Program_Error with an appropriate error message if
-- an uninitialized pattern is used in any pattern construction or
-- pattern matching operation.
procedure XMatch
(Subject : String;
Pat_P : PE_Ptr;
Pat_S : Natural;
Start : out Natural;
Stop : out Natural);
-- This is the common pattern match routine. It is passed a string and
-- a pattern, and it indicates success or failure, and on success the
-- section of the string matched. It does not perform any assignments
-- to the subject string, so pattern replacement is for the caller.
--
-- Subject The subject string. The lower bound is always one. In the
-- Match procedures, it is fine to use strings whose lower bound
-- is not one, but we perform a one time conversion before the
-- call to XMatch, so that XMatch does not have to be bothered
-- with strange lower bounds.
--
-- Pat_P Points to initial pattern element of pattern to be matched
--
-- Pat_S Maximum required stack entries for pattern to be matched
--
-- Start If match is successful, starting index of matched section.
-- This value is always non-zero. A value of zero is used to
-- indicate a failed match.
--
-- Stop If match is successful, ending index of matched section.
-- This can be zero if we match the null string at the start,
-- in which case Start is set to zero, and Stop to one. If the
-- Match fails, then the contents of Stop is undefined.
procedure XMatchD
(Subject : String;
Pat_P : PE_Ptr;
Pat_S : Natural;
Start : out Natural;
Stop : out Natural);
-- Identical in all respects to XMatch, except that trace information is
-- output on Standard_Output during execution of the match. This is the
-- version that is called if the original Match call has Debug => True.
---------
-- "&" --
---------
function "&" (L : PString; R : Pattern) return Pattern is
begin
return (AFC with R.Stk, Concat (S_To_PE (L), Copy (R.P), R.Stk));
end "&";
function "&" (L : Pattern; R : PString) return Pattern is
begin
return (AFC with L.Stk, Concat (Copy (L.P), S_To_PE (R), 0));
end "&";
function "&" (L : PChar; R : Pattern) return Pattern is
begin
return (AFC with R.Stk, Concat (C_To_PE (L), Copy (R.P), R.Stk));
end "&";
function "&" (L : Pattern; R : PChar) return Pattern is
begin
return (AFC with L.Stk, Concat (Copy (L.P), C_To_PE (R), 0));
end "&";
function "&" (L : Pattern; R : Pattern) return Pattern is
begin
return (AFC with L.Stk + R.Stk, Concat (Copy (L.P), Copy (R.P), R.Stk));
end "&";
---------
-- "*" --
---------
-- Assign immediate
-- +---+ +---+ +---+
-- | E |---->| P |---->| A |---->
-- +---+ +---+ +---+
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the A node is numbered N + 1,
-- and the E node is N + 2.
function "*" (P : Pattern; Var : VString_Var) return Pattern is
Pat : constant PE_Ptr := Copy (P.P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
A : constant PE_Ptr :=
new PE'(PC_Assign_Imm, 0, EOP, Var'Unrestricted_Access);
begin
return (AFC with P.Stk + 3, Bracket (E, Pat, A));
end "*";
function "*" (P : PString; Var : VString_Var) return Pattern is
Pat : constant PE_Ptr := S_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
A : constant PE_Ptr :=
new PE'(PC_Assign_Imm, 0, EOP, Var'Unrestricted_Access);
begin
return (AFC with 3, Bracket (E, Pat, A));
end "*";
function "*" (P : PChar; Var : VString_Var) return Pattern is
Pat : constant PE_Ptr := C_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
A : constant PE_Ptr :=
new PE'(PC_Assign_Imm, 0, EOP, Var'Unrestricted_Access);
begin
return (AFC with 3, Bracket (E, Pat, A));
end "*";
-- Write immediate
-- +---+ +---+ +---+
-- | E |---->| P |---->| W |---->
-- +---+ +---+ +---+
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the W node is numbered N + 1,
-- and the E node is N + 2.
function "*" (P : Pattern; Fil : File_Access) return Pattern is
Pat : constant PE_Ptr := Copy (P.P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
W : constant PE_Ptr := new PE'(PC_Write_Imm, 0, EOP, Fil);
begin
return (AFC with 3, Bracket (E, Pat, W));
end "*";
function "*" (P : PString; Fil : File_Access) return Pattern is
Pat : constant PE_Ptr := S_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
W : constant PE_Ptr := new PE'(PC_Write_Imm, 0, EOP, Fil);
begin
return (AFC with 3, Bracket (E, Pat, W));
end "*";
function "*" (P : PChar; Fil : File_Access) return Pattern is
Pat : constant PE_Ptr := C_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
W : constant PE_Ptr := new PE'(PC_Write_Imm, 0, EOP, Fil);
begin
return (AFC with 3, Bracket (E, Pat, W));
end "*";
----------
-- "**" --
----------
-- Assign on match
-- +---+ +---+ +---+
-- | E |---->| P |---->| A |---->
-- +---+ +---+ +---+
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the A node is numbered N + 1,
-- and the E node is N + 2.
function "**" (P : Pattern; Var : VString_Var) return Pattern is
Pat : constant PE_Ptr := Copy (P.P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
A : constant PE_Ptr :=
new PE'(PC_Assign_OnM, 0, EOP, Var'Unrestricted_Access);
begin
return (AFC with P.Stk + 3, Bracket (E, Pat, A));
end "**";
function "**" (P : PString; Var : VString_Var) return Pattern is
Pat : constant PE_Ptr := S_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
A : constant PE_Ptr :=
new PE'(PC_Assign_OnM, 0, EOP, Var'Unrestricted_Access);
begin
return (AFC with 3, Bracket (E, Pat, A));
end "**";
function "**" (P : PChar; Var : VString_Var) return Pattern is
Pat : constant PE_Ptr := C_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
A : constant PE_Ptr :=
new PE'(PC_Assign_OnM, 0, EOP, Var'Unrestricted_Access);
begin
return (AFC with 3, Bracket (E, Pat, A));
end "**";
-- Write on match
-- +---+ +---+ +---+
-- | E |---->| P |---->| W |---->
-- +---+ +---+ +---+
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the W node is numbered N + 1,
-- and the E node is N + 2.
function "**" (P : Pattern; Fil : File_Access) return Pattern is
Pat : constant PE_Ptr := Copy (P.P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
W : constant PE_Ptr := new PE'(PC_Write_OnM, 0, EOP, Fil);
begin
return (AFC with P.Stk + 3, Bracket (E, Pat, W));
end "**";
function "**" (P : PString; Fil : File_Access) return Pattern is
Pat : constant PE_Ptr := S_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
W : constant PE_Ptr := new PE'(PC_Write_OnM, 0, EOP, Fil);
begin
return (AFC with 3, Bracket (E, Pat, W));
end "**";
function "**" (P : PChar; Fil : File_Access) return Pattern is
Pat : constant PE_Ptr := C_To_PE (P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
W : constant PE_Ptr := new PE'(PC_Write_OnM, 0, EOP, Fil);
begin
return (AFC with 3, Bracket (E, Pat, W));
end "**";
---------
-- "+" --
---------
function "+" (Str : VString_Var) return Pattern is
begin
return
(AFC with 0,
new PE'(PC_String_VP, 1, EOP, Str'Unrestricted_Access));
end "+";
function "+" (Str : VString_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_String_VF, 1, EOP, Str));
end "+";
function "+" (P : Pattern_Var) return Pattern is
begin
return
(AFC with 3,
new PE'(PC_Rpat, 1, EOP, P'Unrestricted_Access));
end "+";
function "+" (P : Boolean_Func) return Pattern is
begin
return (AFC with 3, new PE'(PC_Pred_Func, 1, EOP, P));
end "+";
----------
-- "or" --
----------
function "or" (L : PString; R : Pattern) return Pattern is
begin
return (AFC with R.Stk + 1, S_To_PE (L) or Copy (R.P));
end "or";
function "or" (L : Pattern; R : PString) return Pattern is
begin
return (AFC with L.Stk + 1, Copy (L.P) or S_To_PE (R));
end "or";
function "or" (L : PString; R : PString) return Pattern is
begin
return (AFC with 1, S_To_PE (L) or S_To_PE (R));
end "or";
function "or" (L : Pattern; R : Pattern) return Pattern is
begin
return (AFC with
Natural'Max (L.Stk, R.Stk) + 1, Copy (L.P) or Copy (R.P));
end "or";
function "or" (L : PChar; R : Pattern) return Pattern is
begin
return (AFC with 1, C_To_PE (L) or Copy (R.P));
end "or";
function "or" (L : Pattern; R : PChar) return Pattern is
begin
return (AFC with 1, Copy (L.P) or C_To_PE (R));
end "or";
function "or" (L : PChar; R : PChar) return Pattern is
begin
return (AFC with 1, C_To_PE (L) or C_To_PE (R));
end "or";
function "or" (L : PString; R : PChar) return Pattern is
begin
return (AFC with 1, S_To_PE (L) or C_To_PE (R));
end "or";
function "or" (L : PChar; R : PString) return Pattern is
begin
return (AFC with 1, C_To_PE (L) or S_To_PE (R));
end "or";
------------
-- Adjust --
------------
-- No two patterns share the same pattern elements, so the adjust
-- procedure for a Pattern assignment must do a deep copy of the
-- pattern element structure.
procedure Adjust (Object : in out Pattern) is
begin
Object.P := Copy (Object.P);
end Adjust;
---------------
-- Alternate --
---------------
function Alternate (L, R : PE_Ptr) return PE_Ptr is
begin
-- If the left pattern is null, then we just add the alternation
-- node with an index one greater than the right hand pattern.
if L = EOP then
return new PE'(PC_Alt, R.Index + 1, EOP, R);
-- If the left pattern is non-null, then build a reference vector
-- for its elements, and adjust their index values to accommodate
-- the right hand elements. Then add the alternation node.
else
declare
Refs : Ref_Array (1 .. L.Index);
begin
Build_Ref_Array (L, Refs);
for J in Refs'Range loop
Refs (J).Index := Refs (J).Index + R.Index;
end loop;
end;
return new PE'(PC_Alt, L.Index + 1, L, R);
end if;
end Alternate;
---------
-- Any --
---------
function Any (Str : String) return Pattern is
begin
return (AFC with 0, new PE'(PC_Any_CS, 1, EOP, To_Set (Str)));
end Any;
function Any (Str : VString) return Pattern is
begin
return Any (S (Str));
end Any;
function Any (Str : Character) return Pattern is
begin
return (AFC with 0, new PE'(PC_Any_CH, 1, EOP, Str));
end Any;
function Any (Str : Character_Set) return Pattern is
begin
return (AFC with 0, new PE'(PC_Any_CS, 1, EOP, Str));
end Any;
function Any (Str : not null access VString) return Pattern is
begin
return (AFC with 0, new PE'(PC_Any_VP, 1, EOP, VString_Ptr (Str)));
end Any;
function Any (Str : VString_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_Any_VF, 1, EOP, Str));
end Any;
---------
-- Arb --
---------
-- +---+
-- | X |---->
-- +---+
-- .
-- .
-- +---+
-- | Y |---->
-- +---+
-- The PC_Arb_X element is numbered 2, and the PC_Arb_Y element is 1
function Arb return Pattern is
Y : constant PE_Ptr := new PE'(PC_Arb_Y, 1, EOP);
X : constant PE_Ptr := new PE'(PC_Arb_X, 2, EOP, Y);
begin
return (AFC with 1, X);
end Arb;
-----------
-- Arbno --
-----------
function Arbno (P : PString) return Pattern is
begin
if P'Length = 0 then
return (AFC with 0, EOP);
else
return (AFC with 0, Arbno_Simple (S_To_PE (P)));
end if;
end Arbno;
function Arbno (P : PChar) return Pattern is
begin
return (AFC with 0, Arbno_Simple (C_To_PE (P)));
end Arbno;
function Arbno (P : Pattern) return Pattern is
Pat : constant PE_Ptr := Copy (P.P);
begin
if P.Stk = 0
and then OK_For_Simple_Arbno (Pat.Pcode)
then
return (AFC with 0, Arbno_Simple (Pat));
end if;
-- This is the complex case, either the pattern makes stack entries
-- or it is possible for the pattern to match the null string (more
-- accurately, we don't know that this is not the case).
-- +--------------------------+
-- | ^
-- V |
-- +---+ |
-- | X |----> |
-- +---+ |
-- . |
-- . |
-- +---+ +---+ +---+ |
-- | E |---->| P |---->| Y |--->+
-- +---+ +---+ +---+
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the Y node is numbered N + 1,
-- the E node is N + 2, and the X node is N + 3.
declare
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
X : constant PE_Ptr := new PE'(PC_Arbno_X, 0, EOP, E);
Y : constant PE_Ptr := new PE'(PC_Arbno_Y, 0, X, P.Stk + 3);
EPY : constant PE_Ptr := Bracket (E, Pat, Y);
begin
X.Alt := EPY;
X.Index := EPY.Index + 1;
return (AFC with P.Stk + 3, X);
end;
end Arbno;
------------------
-- Arbno_Simple --
------------------
-- +-------------+
-- | ^
-- V |
-- +---+ |
-- | S |----> |
-- +---+ |
-- . |
-- . |
-- +---+ |
-- | P |---------->+
-- +---+
-- The node numbering of the constituent pattern P is not affected.
-- The S node has a node number of P.Index + 1.
-- Note that we know that P cannot be EOP, because a null pattern
-- does not meet the requirements for simple Arbno.
function Arbno_Simple (P : PE_Ptr) return PE_Ptr is
S : constant PE_Ptr := new PE'(PC_Arbno_S, P.Index + 1, EOP, P);
begin
Set_Successor (P, S);
return S;
end Arbno_Simple;
---------
-- Bal --
---------
function Bal return Pattern is
begin
return (AFC with 1, new PE'(PC_Bal, 1, EOP));
end Bal;
-------------
-- Bracket --
-------------
function Bracket (E, P, A : PE_Ptr) return PE_Ptr is
begin
if P = EOP then
E.Pthen := A;
E.Index := 2;
A.Index := 1;
else
E.Pthen := P;
Set_Successor (P, A);
E.Index := P.Index + 2;
A.Index := P.Index + 1;
end if;
return E;
end Bracket;
-----------
-- Break --
-----------
function Break (Str : String) return Pattern is
begin
return (AFC with 0, new PE'(PC_Break_CS, 1, EOP, To_Set (Str)));
end Break;
function Break (Str : VString) return Pattern is
begin
return Break (S (Str));
end Break;
function Break (Str : Character) return Pattern is
begin
return (AFC with 0, new PE'(PC_Break_CH, 1, EOP, Str));
end Break;
function Break (Str : Character_Set) return Pattern is
begin
return (AFC with 0, new PE'(PC_Break_CS, 1, EOP, Str));
end Break;
function Break (Str : not null access VString) return Pattern is
begin
return (AFC with 0,
new PE'(PC_Break_VP, 1, EOP, Str.all'Unchecked_Access));
end Break;
function Break (Str : VString_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_Break_VF, 1, EOP, Str));
end Break;
------------
-- BreakX --
------------
function BreakX (Str : String) return Pattern is
begin
return BreakX_Make (new PE'(PC_BreakX_CS, 3, N, To_Set (Str)));
end BreakX;
function BreakX (Str : VString) return Pattern is
begin
return BreakX (S (Str));
end BreakX;
function BreakX (Str : Character) return Pattern is
begin
return BreakX_Make (new PE'(PC_BreakX_CH, 3, N, Str));
end BreakX;
function BreakX (Str : Character_Set) return Pattern is
begin
return BreakX_Make (new PE'(PC_BreakX_CS, 3, N, Str));
end BreakX;
function BreakX (Str : not null access VString) return Pattern is
begin
return BreakX_Make (new PE'(PC_BreakX_VP, 3, N, VString_Ptr (Str)));
end BreakX;
function BreakX (Str : VString_Func) return Pattern is
begin
return BreakX_Make (new PE'(PC_BreakX_VF, 3, N, Str));
end BreakX;
-----------------
-- BreakX_Make --
-----------------
-- +---+ +---+
-- | B |---->| A |---->
-- +---+ +---+
-- ^ .
-- | .
-- | +---+
-- +<------| X |
-- +---+
-- The B node is numbered 3, the alternative node is 1, and the X
-- node is 2.
function BreakX_Make (B : PE_Ptr) return Pattern is
X : constant PE_Ptr := new PE'(PC_BreakX_X, 2, B);
A : constant PE_Ptr := new PE'(PC_Alt, 1, EOP, X);
begin
B.Pthen := A;
return (AFC with 2, B);
end BreakX_Make;
---------------------
-- Build_Ref_Array --
---------------------
procedure Build_Ref_Array (E : PE_Ptr; RA : out Ref_Array) is
procedure Record_PE (E : PE_Ptr);
-- Record given pattern element if not already recorded in RA,
-- and also record any referenced pattern elements recursively.
---------------
-- Record_PE --
---------------
procedure Record_PE (E : PE_Ptr) is
begin
PutD (" Record_PE called with PE_Ptr = " & Image (E));
if E = EOP or else RA (E.Index) /= null then
Put_LineD (", nothing to do");
return;
else
Put_LineD (", recording" & IndexT'Image (E.Index));
RA (E.Index) := E;
Record_PE (E.Pthen);
if E.Pcode in PC_Has_Alt then
Record_PE (E.Alt);
end if;
end if;
end Record_PE;
-- Start of processing for Build_Ref_Array
begin
New_LineD;
Put_LineD ("Entering Build_Ref_Array");
Record_PE (E);
New_LineD;
end Build_Ref_Array;
-------------
-- C_To_PE --
-------------
function C_To_PE (C : PChar) return PE_Ptr is
begin
return new PE'(PC_Char, 1, EOP, C);
end C_To_PE;
------------
-- Cancel --
------------
function Cancel return Pattern is
begin
return (AFC with 0, new PE'(PC_Cancel, 1, EOP));
end Cancel;
------------
-- Concat --
------------
-- Concat needs to traverse the left operand performing the following
-- set of fixups:
-- a) Any successor pointers (Pthen fields) that are set to EOP are
-- reset to point to the second operand.
-- b) Any PC_Arbno_Y node has its stack count field incremented
-- by the parameter Incr provided for this purpose.
-- d) Num fields of all pattern elements in the left operand are
-- adjusted to include the elements of the right operand.
-- Note: we do not use Set_Successor in the processing for Concat, since
-- there is no point in doing two traversals, we may as well do everything
-- at the same time.
function Concat (L, R : PE_Ptr; Incr : Natural) return PE_Ptr is
begin
if L = EOP then
return R;
elsif R = EOP then
return L;
else
declare
Refs : Ref_Array (1 .. L.Index);
-- We build a reference array for L whose N'th element points to
-- the pattern element of L whose original Index value is N.
P : PE_Ptr;
begin
Build_Ref_Array (L, Refs);
for J in Refs'Range loop
P := Refs (J);
P.Index := P.Index + R.Index;
if P.Pcode = PC_Arbno_Y then
P.Nat := P.Nat + Incr;
end if;
if P.Pthen = EOP then
P.Pthen := R;
end if;
if P.Pcode in PC_Has_Alt and then P.Alt = EOP then
P.Alt := R;
end if;
end loop;
end;
return L;
end if;
end Concat;
----------
-- Copy --
----------
function Copy (P : PE_Ptr) return PE_Ptr is
begin
if P = null then
Uninitialized_Pattern;
else
declare
Refs : Ref_Array (1 .. P.Index);
-- References to elements in P, indexed by Index field
Copy : Ref_Array (1 .. P.Index);
-- Holds copies of elements of P, indexed by Index field
E : PE_Ptr;
begin
Build_Ref_Array (P, Refs);
-- Now copy all nodes
for J in Refs'Range loop
Copy (J) := new PE'(Refs (J).all);
end loop;
-- Adjust all internal references
for J in Copy'Range loop
E := Copy (J);
-- Adjust successor pointer to point to copy
if E.Pthen /= EOP then
E.Pthen := Copy (E.Pthen.Index);
end if;
-- Adjust Alt pointer if there is one to point to copy
if E.Pcode in PC_Has_Alt and then E.Alt /= EOP then
E.Alt := Copy (E.Alt.Index);
end if;
-- Copy referenced string
if E.Pcode = PC_String then
E.Str := new String'(E.Str.all);
end if;
end loop;
return Copy (P.Index);
end;
end if;
end Copy;
----------
-- Dump --
----------
procedure Dump (P : Pattern) is
procedure Write_Node_Id (E : PE_Ptr; Cols : Natural);
-- Writes out a string identifying the given pattern element. Cols is
-- the column indentation level.
-------------------
-- Write_Node_Id --
-------------------
procedure Write_Node_Id (E : PE_Ptr; Cols : Natural) is
begin
if E = EOP then
Put ("EOP");
for J in 4 .. Cols loop
Put (' ');
end loop;
else
declare
Str : String (1 .. Cols);
N : Natural := Natural (E.Index);
begin
Put ("#");
for J in reverse Str'Range loop
Str (J) := Character'Val (48 + N mod 10);
N := N / 10;
end loop;
Put (Str);
end;
end if;
end Write_Node_Id;
-- Local variables
Cols : Natural := 2;
-- Number of columns used for pattern numbers, minimum is 2
E : PE_Ptr;
subtype Count is Ada.Text_IO.Count;
Scol : Count;
-- Used to keep track of column in dump output
-- Start of processing for Dump
begin
New_Line;
Put
("Pattern Dump Output (pattern at "
& Image (P'Address)
& ", S = "
& Natural'Image (P.Stk) & ')');
New_Line;
Scol := Col;
while Col < Scol loop
Put ('-');
end loop;
New_Line;
-- If uninitialized pattern, dump line and we are done
if P.P = null then
Put_Line ("Uninitialized pattern value");
return;
end if;
-- If null pattern, just dump it and we are all done
if P.P = EOP then
Put_Line ("EOP (null pattern)");
return;
end if;
declare
Refs : Ref_Array (1 .. P.P.Index);
-- We build a reference array whose N'th element points to the
-- pattern element whose Index value is N.
begin
Build_Ref_Array (P.P, Refs);
-- Set number of columns required for node numbers
while 10 ** Cols - 1 < Integer (P.P.Index) loop
Cols := Cols + 1;
end loop;
-- Now dump the nodes in reverse sequence. We output them in reverse
-- sequence since this corresponds to the natural order used to
-- construct the patterns.
for J in reverse Refs'Range loop
E := Refs (J);
Write_Node_Id (E, Cols);
Set_Col (Count (Cols) + 4);
Put (Image (E));
Put (" ");
Put (Pattern_Code'Image (E.Pcode));
Put (" ");
Set_Col (21 + Count (Cols) + Address_Image_Length);
Write_Node_Id (E.Pthen, Cols);
Set_Col (24 + 2 * Count (Cols) + Address_Image_Length);
case E.Pcode is
when PC_Alt
| PC_Arb_X
| PC_Arbno_S
| PC_Arbno_X
=>
Write_Node_Id (E.Alt, Cols);
when PC_Rpat =>
Put (Str_PP (E.PP));
when PC_Pred_Func =>
Put (Str_BF (E.BF));
when PC_Assign_Imm
| PC_Assign_OnM
| PC_Any_VP
| PC_Break_VP
| PC_BreakX_VP
| PC_NotAny_VP
| PC_NSpan_VP
| PC_Span_VP
| PC_String_VP
=>
Put (Str_VP (E.VP));
when PC_Write_Imm
| PC_Write_OnM
=>
Put (Str_FP (E.FP));
when PC_String =>
Put (Image (E.Str.all));
when PC_String_2 =>
Put (Image (E.Str2));
when PC_String_3 =>
Put (Image (E.Str3));
when PC_String_4 =>
Put (Image (E.Str4));
when PC_String_5 =>
Put (Image (E.Str5));
when PC_String_6 =>
Put (Image (E.Str6));
when PC_Setcur =>
Put (Str_NP (E.Var));
when PC_Any_CH
| PC_Break_CH
| PC_BreakX_CH
| PC_Char
| PC_NotAny_CH
| PC_NSpan_CH
| PC_Span_CH
=>
Put (''' & E.Char & ''');
when PC_Any_CS
| PC_Break_CS
| PC_BreakX_CS
| PC_NotAny_CS
| PC_NSpan_CS
| PC_Span_CS
=>
Put ('"' & To_Sequence (E.CS) & '"');
when PC_Arbno_Y
| PC_Len_Nat
| PC_Pos_Nat
| PC_RPos_Nat
| PC_RTab_Nat
| PC_Tab_Nat
=>
Put (S (E.Nat));
when PC_Pos_NF
| PC_Len_NF
| PC_RPos_NF
| PC_RTab_NF
| PC_Tab_NF
=>
Put (Str_NF (E.NF));
when PC_Pos_NP
| PC_Len_NP
| PC_RPos_NP
| PC_RTab_NP
| PC_Tab_NP
=>
Put (Str_NP (E.NP));
when PC_Any_VF
| PC_Break_VF
| PC_BreakX_VF
| PC_NotAny_VF
| PC_NSpan_VF
| PC_Span_VF
| PC_String_VF
=>
Put (Str_VF (E.VF));
when others =>
null;
end case;
New_Line;
end loop;
New_Line;
end;
end Dump;
----------
-- Fail --
----------
function Fail return Pattern is
begin
return (AFC with 0, new PE'(PC_Fail, 1, EOP));
end Fail;
-----------
-- Fence --
-----------
-- Simple case
function Fence return Pattern is
begin
return (AFC with 1, new PE'(PC_Fence, 1, EOP));
end Fence;
-- Function case
-- +---+ +---+ +---+
-- | E |---->| P |---->| X |---->
-- +---+ +---+ +---+
-- The node numbering of the constituent pattern P is not affected.
-- Where N is the number of nodes in P, the X node is numbered N + 1,
-- and the E node is N + 2.
function Fence (P : Pattern) return Pattern is
Pat : constant PE_Ptr := Copy (P.P);
E : constant PE_Ptr := new PE'(PC_R_Enter, 0, EOP);
X : constant PE_Ptr := new PE'(PC_Fence_X, 0, EOP);
begin
return (AFC with P.Stk + 1, Bracket (E, Pat, X));
end Fence;
--------------
-- Finalize --
--------------
procedure Finalize (Object : in out Pattern) is
procedure Free is new Ada.Unchecked_Deallocation (PE, PE_Ptr);
procedure Free is new Ada.Unchecked_Deallocation (String, String_Ptr);
begin
-- Nothing to do if already freed
if Object.P = null then
return;
-- Otherwise we must free all elements
else
declare
Refs : Ref_Array (1 .. Object.P.Index);
-- References to elements in pattern to be finalized
begin
Build_Ref_Array (Object.P, Refs);
for J in Refs'Range loop
if Refs (J).Pcode = PC_String then
Free (Refs (J).Str);
end if;
Free (Refs (J));
end loop;
Object.P := null;
end;
end if;
end Finalize;
-----------
-- Image --
-----------
function Image (P : PE_Ptr) return String is
begin
return Image (To_Address (P));
end Image;
function Image (P : Pattern) return String is
begin
return S (Image (P));
end Image;
function Image (P : Pattern) return VString is
Kill_Ampersand : Boolean := False;
-- Set True to delete next & to be output to Result
Result : VString := Nul;
-- The result is accumulated here, using Append
Refs : Ref_Array (1 .. P.P.Index);
-- We build a reference array whose N'th element points to the
-- pattern element whose Index value is N.
procedure Delete_Ampersand;
-- Deletes the ampersand at the end of Result
procedure Image_Seq (E : PE_Ptr; Succ : PE_Ptr; Paren : Boolean);
-- E refers to a pattern structure whose successor is given by Succ.
-- This procedure appends to Result a representation of this pattern.
-- The Paren parameter indicates whether parentheses are required if
-- the output is more than one element.
procedure Image_One (E : in out PE_Ptr);
-- E refers to a pattern structure. This procedure appends to Result
-- a representation of the single simple or compound pattern structure
-- at the start of E and updates E to point to its successor.
----------------------
-- Delete_Ampersand --
----------------------
procedure Delete_Ampersand is
L : constant Natural := Length (Result);
begin
if L > 2 then
Delete (Result, L - 1, L);
end if;
end Delete_Ampersand;
---------------
-- Image_One --
---------------
procedure Image_One (E : in out PE_Ptr) is
ER : PE_Ptr := E.Pthen;
-- Successor set as result in E unless reset
begin
case E.Pcode is
when PC_Cancel =>
Append (Result, "Cancel");
when PC_Alt => Alt : declare
Elmts_In_L : constant IndexT := E.Pthen.Index - E.Alt.Index;
-- Number of elements in left pattern of alternation
Lowest_In_L : constant IndexT := E.Index - Elmts_In_L;
-- Number of lowest index in elements of left pattern
E1 : PE_Ptr;
begin
-- The successor of the alternation node must have a lower
-- index than any node that is in the left pattern or a
-- higher index than the alternation node itself.
while ER /= EOP
and then ER.Index >= Lowest_In_L
and then ER.Index < E.Index
loop
ER := ER.Pthen;
end loop;
Append (Result, '(');
E1 := E;
loop
Image_Seq (E1.Pthen, ER, False);
Append (Result, " or ");
E1 := E1.Alt;
exit when E1.Pcode /= PC_Alt;
end loop;
Image_Seq (E1, ER, False);
Append (Result, ')');
end Alt;
when PC_Any_CS =>
Append (Result, "Any (" & Image (To_Sequence (E.CS)) & ')');
when PC_Any_VF =>
Append (Result, "Any (" & Str_VF (E.VF) & ')');
when PC_Any_VP =>
Append (Result, "Any (" & Str_VP (E.VP) & ')');
when PC_Arb_X =>
Append (Result, "Arb");
when PC_Arbno_S =>
Append (Result, "Arbno (");
Image_Seq (E.Alt, E, False);
Append (Result, ')');
when PC_Arbno_X =>
Append (Result, "Arbno (");
Image_Seq (E.Alt.Pthen, Refs (E.Index - 2), False);
Append (Result, ')');
when PC_Assign_Imm =>
Delete_Ampersand;
Append (Result, "* " & Str_VP (Refs (E.Index).VP));
when PC_Assign_OnM =>
Delete_Ampersand;
Append (Result, "** " & Str_VP (Refs (E.Index).VP));
when PC_Any_CH =>
Append (Result, "Any ('" & E.Char & "')");
when PC_Bal =>
Append (Result, "Bal");
when PC_Break_CH =>
Append (Result, "Break ('" & E.Char & "')");
when PC_Break_CS =>
Append (Result, "Break (" & Image (To_Sequence (E.CS)) & ')');
when PC_Break_VF =>
Append (Result, "Break (" & Str_VF (E.VF) & ')');
when PC_Break_VP =>
Append (Result, "Break (" & Str_VP (E.VP) & ')');
when PC_BreakX_CH =>
Append (Result, "BreakX ('" & E.Char & "')");
ER := ER.Pthen;
when PC_BreakX_CS =>
Append (Result, "BreakX (" & Image (To_Sequence (E.CS)) & ')');
ER := ER.Pthen;
when PC_BreakX_VF =>
Append (Result, "BreakX (" & Str_VF (E.VF) & ')');
ER := ER.Pthen;
when PC_BreakX_VP =>
Append (Result, "BreakX (" & Str_VP (E.VP) & ')');
ER := ER.Pthen;
when PC_Char =>
Append (Result, ''' & E.Char & ''');
when PC_Fail =>
Append (Result, "Fail");
when PC_Fence =>
Append (Result, "Fence");
when PC_Fence_X =>
Append (Result, "Fence (");
Image_Seq (E.Pthen, Refs (E.Index - 1), False);
Append (Result, ")");
ER := Refs (E.Index - 1).Pthen;
when PC_Len_Nat =>
Append (Result, "Len (" & E.Nat & ')');
when PC_Len_NF =>
Append (Result, "Len (" & Str_NF (E.NF) & ')');
when PC_Len_NP =>
Append (Result, "Len (" & Str_NP (E.NP) & ')');
when PC_NotAny_CH =>
Append (Result, "NotAny ('" & E.Char & "')");
when PC_NotAny_CS =>
Append (Result, "NotAny (" & Image (To_Sequence (E.CS)) & ')');
when PC_NotAny_VF =>
Append (Result, "NotAny (" & Str_VF (E.VF) & ')');
when PC_NotAny_VP =>
Append (Result, "NotAny (" & Str_VP (E.VP) & ')');
when PC_NSpan_CH =>
Append (Result, "NSpan ('" & E.Char & "')");
when PC_NSpan_CS =>
Append (Result, "NSpan (" & Image (To_Sequence (E.CS)) & ')');
when PC_NSpan_VF =>
Append (Result, "NSpan (" & Str_VF (E.VF) & ')');
when PC_NSpan_VP =>
Append (Result, "NSpan (" & Str_VP (E.VP) & ')');
when PC_Null =>
Append (Result, """""");
when PC_Pos_Nat =>
Append (Result, "Pos (" & E.Nat & ')');
when PC_Pos_NF =>
Append (Result, "Pos (" & Str_NF (E.NF) & ')');
when PC_Pos_NP =>
Append (Result, "Pos (" & Str_NP (E.NP) & ')');
when PC_R_Enter =>
Kill_Ampersand := True;
when PC_Rest =>
Append (Result, "Rest");
when PC_Rpat =>
Append (Result, "(+ " & Str_PP (E.PP) & ')');
when PC_Pred_Func =>
Append (Result, "(+ " & Str_BF (E.BF) & ')');
when PC_RPos_Nat =>
Append (Result, "RPos (" & E.Nat & ')');
when PC_RPos_NF =>
Append (Result, "RPos (" & Str_NF (E.NF) & ')');
when PC_RPos_NP =>
Append (Result, "RPos (" & Str_NP (E.NP) & ')');
when PC_RTab_Nat =>
Append (Result, "RTab (" & E.Nat & ')');
when PC_RTab_NF =>
Append (Result, "RTab (" & Str_NF (E.NF) & ')');
when PC_RTab_NP =>
Append (Result, "RTab (" & Str_NP (E.NP) & ')');
when PC_Setcur =>
Append (Result, "Setcur (" & Str_NP (E.Var) & ')');
when PC_Span_CH =>
Append (Result, "Span ('" & E.Char & "')");
when PC_Span_CS =>
Append (Result, "Span (" & Image (To_Sequence (E.CS)) & ')');
when PC_Span_VF =>
Append (Result, "Span (" & Str_VF (E.VF) & ')');
when PC_Span_VP =>
Append (Result, "Span (" & Str_VP (E.VP) & ')');
when PC_String =>
Append (Result, Image (E.Str.all));
when PC_String_2 =>
Append (Result, Image (E.Str2));
when PC_String_3 =>
Append (Result, Image (E.Str3));
when PC_String_4 =>
Append (Result, Image (E.Str4));
when PC_String_5 =>
Append (Result, Image (E.Str5));
when PC_String_6 =>
Append (Result, Image (E.Str6));
when PC_String_VF =>
Append (Result, "(+" & Str_VF (E.VF) & ')');
when PC_String_VP =>
Append (Result, "(+" & Str_VP (E.VP) & ')');
when PC_Succeed =>
Append (Result, "Succeed");
when PC_Tab_Nat =>
Append (Result, "Tab (" & E.Nat & ')');
when PC_Tab_NF =>
Append (Result, "Tab (" & Str_NF (E.NF) & ')');
when PC_Tab_NP =>
Append (Result, "Tab (" & Str_NP (E.NP) & ')');
when PC_Write_Imm =>
Append (Result, '(');
Image_Seq (E, Refs (E.Index - 1), True);
Append (Result, " * " & Str_FP (Refs (E.Index - 1).FP));
ER := Refs (E.Index - 1).Pthen;
when PC_Write_OnM =>
Append (Result, '(');
Image_Seq (E.Pthen, Refs (E.Index - 1), True);
Append (Result, " ** " & Str_FP (Refs (E.Index - 1).FP));
ER := Refs (E.Index - 1).Pthen;
-- Other pattern codes should not appear as leading elements
when PC_Arb_Y
| PC_Arbno_Y
| PC_Assign
| PC_BreakX_X
| PC_EOP
| PC_Fence_Y
| PC_R_Remove
| PC_R_Restore
| PC_Unanchored
=>
Append (Result, "???");
end case;
E := ER;
end Image_One;
---------------
-- Image_Seq --
---------------
procedure Image_Seq (E : PE_Ptr; Succ : PE_Ptr; Paren : Boolean) is
Indx : constant Natural := Length (Result);
E1 : PE_Ptr := E;
Mult : Boolean := False;
begin
-- The image of EOP is "" (the null string)
if E = EOP then
Append (Result, """""");
-- Else generate appropriate concatenation sequence
else
loop
Image_One (E1);
exit when E1 = Succ;
exit when E1 = EOP;
Mult := True;
if Kill_Ampersand then
Kill_Ampersand := False;
else
Append (Result, " & ");
end if;
end loop;
end if;
if Mult and Paren then
Insert (Result, Indx + 1, "(");
Append (Result, ")");
end if;
end Image_Seq;
-- Start of processing for Image
begin
Build_Ref_Array (P.P, Refs);
Image_Seq (P.P, EOP, False);
return Result;
end Image;
-----------
-- Is_In --
-----------
function Is_In (C : Character; Str : String) return Boolean is
begin
for J in Str'Range loop
if Str (J) = C then
return True;
end if;
end loop;
return False;
end Is_In;
---------
-- Len --
---------
function Len (Count : Natural) return Pattern is
begin
-- Note, the following is not just an optimization, it is needed
-- to ensure that Arbno (Len (0)) does not generate an infinite
-- matching loop (since PC_Len_Nat is OK_For_Simple_Arbno).
if Count = 0 then
return (AFC with 0, new PE'(PC_Null, 1, EOP));
else
return (AFC with 0, new PE'(PC_Len_Nat, 1, EOP, Count));
end if;
end Len;
function Len (Count : Natural_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_Len_NF, 1, EOP, Count));
end Len;
function Len (Count : not null access Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_Len_NP, 1, EOP, Natural_Ptr (Count)));
end Len;
-----------------
-- Logic_Error --
-----------------
procedure Logic_Error is
begin
raise Program_Error with
"Internal logic error in GNAT.Spitbol.Patterns";
end Logic_Error;
-----------
-- Match --
-----------
function Match
(Subject : VString;
Pat : Pattern) return Boolean
is
S : Big_String_Access;
L : Natural;
Start : Natural;
Stop : Natural;
pragma Unreferenced (Stop);
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
return Start /= 0;
end Match;
function Match
(Subject : String;
Pat : Pattern) return Boolean
is
Start, Stop : Natural;
pragma Unreferenced (Stop);
subtype String1 is String (1 .. Subject'Length);
begin
if Debug_Mode then
XMatchD (String1 (Subject), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (String1 (Subject), Pat.P, Pat.Stk, Start, Stop);
end if;
return Start /= 0;
end Match;
function Match
(Subject : VString_Var;
Pat : Pattern;
Replace : VString) return Boolean
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
if Start = 0 then
return False;
else
Get_String (Replace, S, L);
Replace_Slice
(Subject'Unrestricted_Access.all, Start, Stop, S (1 .. L));
return True;
end if;
end Match;
function Match
(Subject : VString_Var;
Pat : Pattern;
Replace : String) return Boolean
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
if Start = 0 then
return False;
else
Replace_Slice
(Subject'Unrestricted_Access.all, Start, Stop, Replace);
return True;
end if;
end Match;
procedure Match
(Subject : VString;
Pat : Pattern)
is
S : Big_String_Access;
L : Natural;
Start : Natural;
Stop : Natural;
pragma Unreferenced (Start, Stop);
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
end Match;
procedure Match
(Subject : String;
Pat : Pattern)
is
Start, Stop : Natural;
pragma Unreferenced (Start, Stop);
subtype String1 is String (1 .. Subject'Length);
begin
if Debug_Mode then
XMatchD (String1 (Subject), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (String1 (Subject), Pat.P, Pat.Stk, Start, Stop);
end if;
end Match;
procedure Match
(Subject : in out VString;
Pat : Pattern;
Replace : VString)
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
if Start /= 0 then
Get_String (Replace, S, L);
Replace_Slice (Subject, Start, Stop, S (1 .. L));
end if;
end Match;
procedure Match
(Subject : in out VString;
Pat : Pattern;
Replace : String)
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
if Start /= 0 then
Replace_Slice (Subject, Start, Stop, Replace);
end if;
end Match;
function Match
(Subject : VString;
Pat : PString) return Boolean
is
Pat_Len : constant Natural := Pat'Length;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Anchored_Mode then
if Pat_Len > L then
return False;
else
return Pat = S (1 .. Pat_Len);
end if;
else
for J in 1 .. L - Pat_Len + 1 loop
if Pat = S (J .. J + (Pat_Len - 1)) then
return True;
end if;
end loop;
return False;
end if;
end Match;
function Match
(Subject : String;
Pat : PString) return Boolean
is
Pat_Len : constant Natural := Pat'Length;
Sub_Len : constant Natural := Subject'Length;
SFirst : constant Natural := Subject'First;
begin
if Anchored_Mode then
if Pat_Len > Sub_Len then
return False;
else
return Pat = Subject (SFirst .. SFirst + Pat_Len - 1);
end if;
else
for J in SFirst .. SFirst + Sub_Len - Pat_Len loop
if Pat = Subject (J .. J + (Pat_Len - 1)) then
return True;
end if;
end loop;
return False;
end if;
end Match;
function Match
(Subject : VString_Var;
Pat : PString;
Replace : VString) return Boolean
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
else
XMatch (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
end if;
if Start = 0 then
return False;
else
Get_String (Replace, S, L);
Replace_Slice
(Subject'Unrestricted_Access.all, Start, Stop, S (1 .. L));
return True;
end if;
end Match;
function Match
(Subject : VString_Var;
Pat : PString;
Replace : String) return Boolean
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
else
XMatch (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
end if;
if Start = 0 then
return False;
else
Replace_Slice
(Subject'Unrestricted_Access.all, Start, Stop, Replace);
return True;
end if;
end Match;
procedure Match
(Subject : VString;
Pat : PString)
is
S : Big_String_Access;
L : Natural;
Start : Natural;
Stop : Natural;
pragma Unreferenced (Start, Stop);
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
else
XMatch (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
end if;
end Match;
procedure Match
(Subject : String;
Pat : PString)
is
Start, Stop : Natural;
pragma Unreferenced (Start, Stop);
subtype String1 is String (1 .. Subject'Length);
begin
if Debug_Mode then
XMatchD (String1 (Subject), S_To_PE (Pat), 0, Start, Stop);
else
XMatch (String1 (Subject), S_To_PE (Pat), 0, Start, Stop);
end if;
end Match;
procedure Match
(Subject : in out VString;
Pat : PString;
Replace : VString)
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
else
XMatch (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
end if;
if Start /= 0 then
Get_String (Replace, S, L);
Replace_Slice (Subject, Start, Stop, S (1 .. L));
end if;
end Match;
procedure Match
(Subject : in out VString;
Pat : PString;
Replace : String)
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
else
XMatch (S (1 .. L), S_To_PE (Pat), 0, Start, Stop);
end if;
if Start /= 0 then
Replace_Slice (Subject, Start, Stop, Replace);
end if;
end Match;
function Match
(Subject : VString_Var;
Pat : Pattern;
Result : Match_Result_Var) return Boolean
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
if Start = 0 then
Result'Unrestricted_Access.all.Var := null;
return False;
else
Result'Unrestricted_Access.all.Var := Subject'Unrestricted_Access;
Result'Unrestricted_Access.all.Start := Start;
Result'Unrestricted_Access.all.Stop := Stop;
return True;
end if;
end Match;
procedure Match
(Subject : in out VString;
Pat : Pattern;
Result : out Match_Result)
is
Start : Natural;
Stop : Natural;
S : Big_String_Access;
L : Natural;
begin
Get_String (Subject, S, L);
if Debug_Mode then
XMatchD (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
else
XMatch (S (1 .. L), Pat.P, Pat.Stk, Start, Stop);
end if;
if Start = 0 then
Result.Var := null;
else
Result.Var := Subject'Unrestricted_Access;
Result.Start := Start;
Result.Stop := Stop;
end if;
end Match;
---------------
-- New_LineD --
---------------
procedure New_LineD is
begin
if Internal_Debug then
New_Line;
end if;
end New_LineD;
------------
-- NotAny --
------------
function NotAny (Str : String) return Pattern is
begin
return (AFC with 0, new PE'(PC_NotAny_CS, 1, EOP, To_Set (Str)));
end NotAny;
function NotAny (Str : VString) return Pattern is
begin
return NotAny (S (Str));
end NotAny;
function NotAny (Str : Character) return Pattern is
begin
return (AFC with 0, new PE'(PC_NotAny_CH, 1, EOP, Str));
end NotAny;
function NotAny (Str : Character_Set) return Pattern is
begin
return (AFC with 0, new PE'(PC_NotAny_CS, 1, EOP, Str));
end NotAny;
function NotAny (Str : not null access VString) return Pattern is
begin
return (AFC with 0, new PE'(PC_NotAny_VP, 1, EOP, VString_Ptr (Str)));
end NotAny;
function NotAny (Str : VString_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_NotAny_VF, 1, EOP, Str));
end NotAny;
-----------
-- NSpan --
-----------
function NSpan (Str : String) return Pattern is
begin
return (AFC with 0, new PE'(PC_NSpan_CS, 1, EOP, To_Set (Str)));
end NSpan;
function NSpan (Str : VString) return Pattern is
begin
return NSpan (S (Str));
end NSpan;
function NSpan (Str : Character) return Pattern is
begin
return (AFC with 0, new PE'(PC_NSpan_CH, 1, EOP, Str));
end NSpan;
function NSpan (Str : Character_Set) return Pattern is
begin
return (AFC with 0, new PE'(PC_NSpan_CS, 1, EOP, Str));
end NSpan;
function NSpan (Str : not null access VString) return Pattern is
begin
return (AFC with 0, new PE'(PC_NSpan_VP, 1, EOP, VString_Ptr (Str)));
end NSpan;
function NSpan (Str : VString_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_NSpan_VF, 1, EOP, Str));
end NSpan;
---------
-- Pos --
---------
function Pos (Count : Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_Pos_Nat, 1, EOP, Count));
end Pos;
function Pos (Count : Natural_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_Pos_NF, 1, EOP, Count));
end Pos;
function Pos (Count : not null access Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_Pos_NP, 1, EOP, Natural_Ptr (Count)));
end Pos;
----------
-- PutD --
----------
procedure PutD (Str : String) is
begin
if Internal_Debug then
Put (Str);
end if;
end PutD;
---------------
-- Put_LineD --
---------------
procedure Put_LineD (Str : String) is
begin
if Internal_Debug then
Put_Line (Str);
end if;
end Put_LineD;
-------------
-- Replace --
-------------
procedure Replace
(Result : in out Match_Result;
Replace : VString)
is
S : Big_String_Access;
L : Natural;
begin
Get_String (Replace, S, L);
if Result.Var /= null then
Replace_Slice (Result.Var.all, Result.Start, Result.Stop, S (1 .. L));
Result.Var := null;
end if;
end Replace;
----------
-- Rest --
----------
function Rest return Pattern is
begin
return (AFC with 0, new PE'(PC_Rest, 1, EOP));
end Rest;
----------
-- Rpos --
----------
function Rpos (Count : Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_RPos_Nat, 1, EOP, Count));
end Rpos;
function Rpos (Count : Natural_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_RPos_NF, 1, EOP, Count));
end Rpos;
function Rpos (Count : not null access Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_RPos_NP, 1, EOP, Natural_Ptr (Count)));
end Rpos;
----------
-- Rtab --
----------
function Rtab (Count : Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_RTab_Nat, 1, EOP, Count));
end Rtab;
function Rtab (Count : Natural_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_RTab_NF, 1, EOP, Count));
end Rtab;
function Rtab (Count : not null access Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_RTab_NP, 1, EOP, Natural_Ptr (Count)));
end Rtab;
-------------
-- S_To_PE --
-------------
function S_To_PE (Str : PString) return PE_Ptr is
Len : constant Natural := Str'Length;
begin
case Len is
when 0 =>
return new PE'(PC_Null, 1, EOP);
when 1 =>
return new PE'(PC_Char, 1, EOP, Str (Str'First));
when 2 =>
return new PE'(PC_String_2, 1, EOP, Str);
when 3 =>
return new PE'(PC_String_3, 1, EOP, Str);
when 4 =>
return new PE'(PC_String_4, 1, EOP, Str);
when 5 =>
return new PE'(PC_String_5, 1, EOP, Str);
when 6 =>
return new PE'(PC_String_6, 1, EOP, Str);
when others =>
return new PE'(PC_String, 1, EOP, new String'(Str));
end case;
end S_To_PE;
-------------------
-- Set_Successor --
-------------------
-- Note: this procedure is not used by the normal concatenation circuit,
-- since other fixups are required on the left operand in this case, and
-- they might as well be done all together.
procedure Set_Successor (Pat : PE_Ptr; Succ : PE_Ptr) is
begin
if Pat = null then
Uninitialized_Pattern;
elsif Pat = EOP then
Logic_Error;
else
declare
Refs : Ref_Array (1 .. Pat.Index);
-- We build a reference array for L whose N'th element points to
-- the pattern element of L whose original Index value is N.
P : PE_Ptr;
begin
Build_Ref_Array (Pat, Refs);
for J in Refs'Range loop
P := Refs (J);
if P.Pthen = EOP then
P.Pthen := Succ;
end if;
if P.Pcode in PC_Has_Alt and then P.Alt = EOP then
P.Alt := Succ;
end if;
end loop;
end;
end if;
end Set_Successor;
------------
-- Setcur --
------------
function Setcur (Var : not null access Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_Setcur, 1, EOP, Natural_Ptr (Var)));
end Setcur;
----------
-- Span --
----------
function Span (Str : String) return Pattern is
begin
return (AFC with 0, new PE'(PC_Span_CS, 1, EOP, To_Set (Str)));
end Span;
function Span (Str : VString) return Pattern is
begin
return Span (S (Str));
end Span;
function Span (Str : Character) return Pattern is
begin
return (AFC with 0, new PE'(PC_Span_CH, 1, EOP, Str));
end Span;
function Span (Str : Character_Set) return Pattern is
begin
return (AFC with 0, new PE'(PC_Span_CS, 1, EOP, Str));
end Span;
function Span (Str : not null access VString) return Pattern is
begin
return (AFC with 0, new PE'(PC_Span_VP, 1, EOP, VString_Ptr (Str)));
end Span;
function Span (Str : VString_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_Span_VF, 1, EOP, Str));
end Span;
------------
-- Str_BF --
------------
function Str_BF (A : Boolean_Func) return String is
function To_A is new Ada.Unchecked_Conversion (Boolean_Func, Address);
begin
return "BF(" & Image (To_A (A)) & ')';
end Str_BF;
------------
-- Str_FP --
------------
function Str_FP (A : File_Ptr) return String is
begin
return "FP(" & Image (A.all'Address) & ')';
end Str_FP;
------------
-- Str_NF --
------------
function Str_NF (A : Natural_Func) return String is
function To_A is new Ada.Unchecked_Conversion (Natural_Func, Address);
begin
return "NF(" & Image (To_A (A)) & ')';
end Str_NF;
------------
-- Str_NP --
------------
function Str_NP (A : Natural_Ptr) return String is
begin
return "NP(" & Image (A.all'Address) & ')';
end Str_NP;
------------
-- Str_PP --
------------
function Str_PP (A : Pattern_Ptr) return String is
begin
return "PP(" & Image (A.all'Address) & ')';
end Str_PP;
------------
-- Str_VF --
------------
function Str_VF (A : VString_Func) return String is
function To_A is new Ada.Unchecked_Conversion (VString_Func, Address);
begin
return "VF(" & Image (To_A (A)) & ')';
end Str_VF;
------------
-- Str_VP --
------------
function Str_VP (A : VString_Ptr) return String is
begin
return "VP(" & Image (A.all'Address) & ')';
end Str_VP;
-------------
-- Succeed --
-------------
function Succeed return Pattern is
begin
return (AFC with 1, new PE'(PC_Succeed, 1, EOP));
end Succeed;
---------
-- Tab --
---------
function Tab (Count : Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_Tab_Nat, 1, EOP, Count));
end Tab;
function Tab (Count : Natural_Func) return Pattern is
begin
return (AFC with 0, new PE'(PC_Tab_NF, 1, EOP, Count));
end Tab;
function Tab (Count : not null access Natural) return Pattern is
begin
return (AFC with 0, new PE'(PC_Tab_NP, 1, EOP, Natural_Ptr (Count)));
end Tab;
---------------------------
-- Uninitialized_Pattern --
---------------------------
procedure Uninitialized_Pattern is
begin
raise Program_Error with
"uninitialized value of type GNAT.Spitbol.Patterns.Pattern";
end Uninitialized_Pattern;
------------
-- XMatch --
------------
procedure XMatch
(Subject : String;
Pat_P : PE_Ptr;
Pat_S : Natural;
Start : out Natural;
Stop : out Natural)
is
Node : PE_Ptr;
-- Pointer to current pattern node. Initialized from Pat_P, and then
-- updated as the match proceeds through its constituent elements.
Length : constant Natural := Subject'Length;
-- Length of string (= Subject'Last, since Subject'First is always 1)
Cursor : Integer := 0;
-- If the value is non-negative, then this value is the index showing
-- the current position of the match in the subject string. The next
-- character to be matched is at Subject (Cursor + 1). Note that since
-- our view of the subject string in XMatch always has a lower bound
-- of one, regardless of original bounds, that this definition exactly
-- corresponds to the cursor value as referenced by functions like Pos.
--
-- If the value is negative, then this is a saved stack pointer,
-- typically a base pointer of an inner or outer region. Cursor
-- temporarily holds such a value when it is popped from the stack
-- by Fail. In all cases, Cursor is reset to a proper non-negative
-- cursor value before the match proceeds (e.g. by propagating the
-- failure and popping a "real" cursor value from the stack.
PE_Unanchored : aliased PE := (PC_Unanchored, 0, Pat_P);
-- Dummy pattern element used in the unanchored case
Stack : Stack_Type;
-- The pattern matching failure stack for this call to Match
Stack_Ptr : Stack_Range;
-- Current stack pointer. This points to the top element of the stack
-- that is currently in use. At the outer level this is the special
-- entry placed on the stack according to the anchor mode.
Stack_Init : constant Stack_Range := Stack'First + 1;
-- This is the initial value of the Stack_Ptr and Stack_Base. The
-- initial (Stack'First) element of the stack is not used so that
-- when we pop the last element off, Stack_Ptr is still in range.
Stack_Base : Stack_Range;
-- This value is the stack base value, i.e. the stack pointer for the
-- first history stack entry in the current stack region. See separate
-- section on handling of recursive pattern matches.
Assign_OnM : Boolean := False;
-- Set True if assign-on-match or write-on-match operations may be
-- present in the history stack, which must then be scanned on a
-- successful match.
procedure Pop_Region;
pragma Inline (Pop_Region);
-- Used at the end of processing of an inner region. If the inner
-- region left no stack entries, then all trace of it is removed.
-- Otherwise a PC_Restore_Region entry is pushed to ensure proper
-- handling of alternatives in the inner region.
procedure Push (Node : PE_Ptr);
pragma Inline (Push);