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-- --
-- --
-- P A R --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2003 Free Software Foundation, Inc. --
-- --
-- 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 2, 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. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
with Atree; use Atree;
with Casing; use Casing;
with Debug; use Debug;
with Elists; use Elists;
with Errout; use Errout;
with Fname; use Fname;
with Lib; use Lib;
with Namet; use Namet;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
with Output; use Output;
with Scans; use Scans;
with Scn; use Scn;
with Sinput; use Sinput;
with Sinput.L; use Sinput.L;
with Sinfo; use Sinfo;
with Snames; use Snames;
with Style;
with Table;
with Tbuild; use Tbuild;
function Par (Configuration_Pragmas : Boolean) return List_Id is
Num_Library_Units : Natural := 0;
-- Count number of units parsed (relevant only in syntax check only mode,
-- since in semantics check mode only a single unit is permitted anyway)
Save_Config_Switches : Config_Switches_Type;
-- Variable used to save values of config switches while we parse the
-- new unit, to be restored on exit for proper recursive behavior.
Loop_Block_Count : Nat := 0;
-- Counter used for constructing loop/block names (see the routine
-- Par.Ch5.Get_Loop_Block_Name)
-- Error Recovery --
-- When an error is encountered, a call is made to one of the Error_Msg
-- routines to record the error. If the syntax scan is not derailed by the
-- error (e.g. a complaint that logical operators are inconsistent in an
-- EXPRESSION), then control returns from the Error_Msg call, and the
-- parse continues unimpeded.
-- If on the other hand, the Error_Msg represents a situation from which
-- the parser cannot recover locally, the exception Error_Resync is raised
-- immediately after the call to Error_Msg. Handlers for Error_Resync
-- are located at strategic points to resynchronize the parse. For example,
-- when an error occurs in a statement, the handler skips to the next
-- semicolon and continues the scan from there.
-- Each parsing procedure contains a note with the heading "Error recovery"
-- which shows if it can propagate the Error_Resync exception. In order
-- not to propagate the exception, a procedure must either contain its own
-- handler for this exception, or it must not call any other routines which
-- propagate the exception.
-- Note: the arrangement of Error_Resync handlers is such that it should
-- never be possible to transfer control through a procedure which made
-- an entry in the scope stack, invalidating the contents of the stack.
Error_Resync : exception;
-- Exception raised on error that is not handled locally, see above.
Last_Resync_Point : Source_Ptr;
-- The resynchronization routines in Par.Sync run a risk of getting
-- stuck in an infinite loop if they do not skip a token, and the caller
-- keeps repeating the same resync call. On the other hand, if they skip
-- a token unconditionally, some recovery opportunities are missed. The
-- variable Last_Resync_Point records the token location previously set
-- by a Resync call, and if a subsequent Resync call occurs at the same
-- location, then the Resync routine does guarantee to skip a token.
-- Handling Semicolon Used in Place of IS --
-- The following global variables are used in handling the error situation
-- of using a semicolon in place of IS in a subprogram declaration as in:
-- procedure X (Y : Integer);
-- Q : Integer;
-- begin
-- ...
-- end;
-- The two contexts in which this can appear are at the outer level, and
-- within a declarative region. At the outer level, we know something is
-- wrong as soon as we see the Q (or begin, if there are no declarations),
-- and we can immediately decide that the semicolon should have been IS.
-- The situation in a declarative region is more complex. The declaration
-- of Q could belong to the outer region, and we do not know that we have
-- an error until we hit the begin. It is still not clear at this point
-- from a syntactic point of view that something is wrong, because the
-- begin could belong to the enclosing subprogram or package. However, we
-- can incorporate a bit of semantic knowledge and note that the body of
-- X is missing, so we definitely DO have an error. We diagnose this error
-- as semicolon in place of IS on the subprogram line.
-- There are two styles for this diagnostic. If the begin immediately
-- follows the semicolon, then we can place a flag (IS expected) right
-- on the semicolon. Otherwise we do not detect the error until we hit
-- the begin which refers back to the line with the semicolon.
-- To control the process in the second case, the following global
-- variables are set to indicate that we have a subprogram declaration
-- whose body is required and has not yet been found. The prefix SIS
-- stands for "Subprogram IS" handling.
SIS_Entry_Active : Boolean;
-- Set True to indicate that an entry is active (i.e. that a subprogram
-- declaration has been encountered, and no body for this subprogram has
-- been encountered). The remaining fields are valid only if this is True.
SIS_Labl : Node_Id;
-- Subprogram designator
SIS_Sloc : Source_Ptr;
-- Source location of FUNCTION/PROCEDURE keyword
SIS_Ecol : Column_Number;
-- Column number of FUNCTION/PROCEDURE keyword
SIS_Semicolon_Sloc : Source_Ptr;
-- Source location of semicolon at end of subprogram declaration
SIS_Declaration_Node : Node_Id;
-- Pointer to tree node for subprogram declaration
SIS_Missing_Semicolon_Message : Error_Msg_Id;
-- Used to save message ID of missing semicolon message (which will be
-- modified to missing IS if necessary). Set to No_Error_Msg in the
-- normal (non-error) case.
-- Five things can happen to an active SIS entry
-- 1. If a BEGIN is encountered with an SIS entry active, then we have
-- exactly the situation in which we know the body of the subprogram is
-- missing. After posting an error message, we change the spec to a body,
-- rechaining the declarations that intervened between the spec and BEGIN.
-- 2. Another subprogram declaration or body is encountered. In this
-- case the entry gets overwritten with the information for the new
-- subprogram declaration. We don't catch some nested cases this way,
-- but it doesn't seem worth the effort.
-- 3. A nested declarative region (e.g. package declaration or package
-- body) is encountered. The SIS active indication is reset at the start
-- of such a nested region. Again, like case 2, this causes us to miss
-- some nested cases, but it doesn't seen worth the effort to stack and
-- unstack the SIS information. Maybe we will reconsider this if we ever
-- get a complaint about a missed case :-)
-- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively
-- supplies the missing body. In this case we reset the entry.
-- 5. We encounter the end of the declarative region without encoutering
-- a BEGIN first. In this situation we simply reset the entry. We know
-- that there is a missing body, but it seems more reasonable to let the
-- later semantic checking discover this.
-- Handling of Reserved Words Used as Identifiers --
-- Note: throughout the parser, the terms reserved word and keyword
-- are used interchangably to refer to the same set of reserved
-- keywords (including until, protected, etc).
-- If a reserved word is used in place of an identifier, the parser
-- where possible tries to recover gracefully. In particular, if the
-- keyword is clearly spelled using identifier casing, e.g. Until in
-- a source program using mixed case identifiers and lower case keywords,
-- then the keyword is treated as an identifier if it appears in a place
-- where an identifier is required.
-- The situation is more complex if the keyword is spelled with normal
-- keyword casing. In this case, the parser is more reluctant to
-- consider it to be intended as an identifier, unless it has some
-- further confirmation.
-- In the case of an identifier appearing in the identifier list of a
-- declaration, the appearence of a comma or colon right after the
-- keyword on the same line is taken as confirmation. For an enumeration
-- literal, a comma or right paren right after the identifier is also
-- treated as adequate confirmation.
-- The following type is used in calls to Is_Reserved_Identifier and
-- also to P_Defining_Identifier and P_Identifier. The default for all
-- these functins is that reserved words in reserved word case are not
-- considered to be reserved identifiers. The Id_Check value indicates
-- tokens, which if they appear immediately after the identifier, are
-- taken as confirming that the use of an identifier was expected
type Id_Check is
-- Default, no special token test
-- Consider as identifier if followed by comma or right paren
-- Consider as identifier if followed by comma or colon
-- Consider as identifier if followed by DO
-- Consider as identifier if followed by period
-- Consider as identifier if followed by >>
-- Consider as identifier if followed by IN
-- Consider as identifier if followed by IS
-- Consider as identifier if followed by left paren or semicolon
-- Consider as identifier if followed by USE
-- Consider as identifier if followed by | or =>
-- Handling IS Used in Place of Semicolon --
-- This is a somewhat trickier situation, and we can't catch it in all
-- cases, but we do our best to detect common situations resulting from
-- a "cut and paste" operation which forgets to change the IS to semicolon.
-- Consider the following example:
-- package body X is
-- procedure A;
-- procedure B is
-- procedure C;
-- ...
-- procedure D is
-- begin
-- ...
-- end;
-- begin
-- ...
-- end;
-- The trouble is that the section of text from PROCEDURE B through END;
-- consitutes a valid procedure body, and the danger is that we find out
-- far too late that something is wrong (indeed most compilers will behave
-- uncomfortably on the above example).
-- We have two approaches to helping to control this situation. First we
-- make every attempt to avoid swallowing the last END; if we can be
-- sure that some error will result from doing so. In particular, we won't
-- accept the END; unless it is exactly correct (in particular it must not
-- have incorrect name tokens), and we won't accept it if it is immediately
-- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably
-- signal the start of a compilation unit, and which therefore allow us to
-- reserve the END; for the outer level.) For more details on this aspect
-- of the handling, see package Par.Endh.
-- If we can avoid eating up the END; then the result in the absense of
-- any additional steps would be to post a missing END referring back to
-- the subprogram with the bogus IS. Similarly, if the enclosing package
-- has no BEGIN, then the result is a missing BEGIN message, which again
-- refers back to the subprogram header.
-- Such an error message is not too bad (it's already a big improvement
-- over what many parsers do), but it's not ideal, because the declarations
-- following the IS have been absorbed into the wrong scope. In the above
-- case, this could result for example in a bogus complaint that the body
-- of D was missing from the package.
-- To catch at least some of these cases, we take the following additional
-- steps. First, a subprogram body is marked as having a suspicious IS if
-- the declaration line is followed by a line which starts with a symbol
-- that can start a declaration in the same column, or to the left of the
-- column in which the FUNCTION or PROCEDURE starts (normal style is to
-- indent any declarations which really belong a subprogram). If such a
-- subprogram encounters a missing BEGIN or missing END, then we decide
-- that the IS should have been a semicolon, and the subprogram body node
-- is marked (by setting the Bad_Is_Detected flag true. Note that we do
-- not do this for library level procedures, only for nested procedures,
-- since for library level procedures, we must have a body.
-- The processing for a declarative part checks to see if the last
-- declaration scanned is marked in this way, and if it is, the tree
-- is modified to reflect the IS being interpreted as a semicolon.
-- Parser Type Definitions and Control Variables --
-- The following variable and associated type declaration are used by the
-- expression parsing routines to return more detailed information about
-- the categorization of a parsed expression.
type Expr_Form_Type is (
EF_Simple_Name, -- Simple name, i.e. possibly qualified identifier
EF_Name, -- Simple expression which could also be a name
EF_Simple, -- Simple expression which is not call or name
EF_Range_Attr, -- Range attribute reference
EF_Non_Simple); -- Expression that is not a simple expression
Expr_Form : Expr_Form_Type;
-- The following type is used for calls to P_Subprogram, P_Package, P_Task,
-- P_Protected to indicate which of several possibilities is acceptable.
type Pf_Rec is record
Spcn : Boolean; -- True if specification OK
Decl : Boolean; -- True if declaration OK
Gins : Boolean; -- True if generic instantiation OK
Pbod : Boolean; -- True if proper body OK
Rnam : Boolean; -- True if renaming declaration OK
Stub : Boolean; -- True if body stub OK
Fil1 : Boolean; -- Filler to fill to 8 bits
Fil2 : Boolean; -- Filler to fill to 8 bits
end record;
pragma Pack (Pf_Rec);
function T return Boolean renames True;
function F return Boolean renames False;
Pf_Decl_Gins_Pbod_Rnam_Stub : constant Pf_Rec :=
Pf_Rec'(F, T, T, T, T, T, F, F);
Pf_Decl : constant Pf_Rec :=
Pf_Rec'(F, T, F, F, F, F, F, F);
Pf_Decl_Gins_Pbod_Rnam : constant Pf_Rec :=
Pf_Rec'(F, T, T, T, T, F, F, F);
Pf_Decl_Pbod : constant Pf_Rec :=
Pf_Rec'(F, T, F, T, F, F, F, F);
Pf_Pbod : constant Pf_Rec :=
Pf_Rec'(F, F, F, T, F, F, F, F);
Pf_Spcn : constant Pf_Rec :=
Pf_Rec'(T, F, F, F, F, F, F, F);
-- The above are the only allowed values of Pf_Rec arguments
type SS_Rec is record
Eftm : Boolean; -- ELSIF can terminate sequence
Eltm : Boolean; -- ELSE can terminate sequence
Extm : Boolean; -- EXCEPTION can terminate sequence
Ortm : Boolean; -- OR can terminate sequence
Sreq : Boolean; -- at least one statement required
Tatm : Boolean; -- THEN ABORT can terminate sequence
Whtm : Boolean; -- WHEN can terminate sequence
Unco : Boolean; -- Unconditional terminate after one statement
end record;
pragma Pack (SS_Rec);
SS_Eftm_Eltm_Sreq : constant SS_Rec := SS_Rec'(T, T, F, F, T, F, F, F);
SS_Eltm_Ortm_Tatm : constant SS_Rec := SS_Rec'(F, T, F, T, F, T, F, F);
SS_Extm_Sreq : constant SS_Rec := SS_Rec'(F, F, T, F, T, F, F, F);
SS_None : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, F);
SS_Ortm_Sreq : constant SS_Rec := SS_Rec'(F, F, F, T, T, F, F, F);
SS_Sreq : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, F, F);
SS_Sreq_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, T, F);
SS_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, T, F);
SS_Unco : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, T);
Label_List : Elist_Id;
-- List of label nodes for labels appearing in the current compilation.
-- Used by Par.Labl to construct the corresponding implicit declarations.
-- Scope Table --
-- The scope table, also referred to as the scope stack, is used to
-- record the current scope context. It is organized as a stack, with
-- inner nested entries corresponding to higher entries on the stack.
-- An entry is made when the parser encounters the opening of a nested
-- construct (such as a record, task, package etc.), and then package
-- Par.Endh uses this stack to deal with END lines (including properly
-- dealing with END nesting errors).
type SS_End_Type is
-- Type of end entry required for this scope. The last two entries are
-- used only in the subprogram body case to mark the case of a suspicious
-- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END).
-- See separate section on dealing with IS used in place of semicolon.
-- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are
-- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases
-- of E_Name). They are placed at the end of the enumeration so that a
-- test for >= E_Name catches all three cases efficiently.
(E_Dummy, -- dummy entry at outer level
E_Case, -- END CASE;
E_If, -- END IF;
E_Loop, -- END LOOP;
E_Record, -- END RECORD;
E_Select, -- END SELECT;
E_Name, -- END [name];
E_Suspicious_Is, -- END [name]; (case of suspicious IS)
E_Bad_Is); -- END [name]; (case of bad IS)
-- The following describes a single entry in the scope table
type Scope_Table_Entry is record
Etyp : SS_End_Type;
-- Type of end entry, as per above description
Lreq : Boolean;
-- A flag indicating whether the label, if present, is required to
-- appear on the end line. It is referenced only in the case of
-- Etyp = E_Name or E_Suspicious_Is where the name may or may not be
-- required (yes for labeled block, no in other cases). Note that for
-- all cases except begin, the question of whether a label is required
-- can be determined from the other fields (for loop, it is required if
-- it is present, and for the other constructs it is never required or
-- allowed).
Ecol : Column_Number;
-- Contains the absolute column number (with tabs expanded) of the
-- the expected column of the end assuming normal Ada indentation
-- usage. If the RM_Column_Check mode is set, this value is used for
-- generating error messages about indentation. Otherwise it is used
-- only to control heuristic error recovery actions.
Labl : Node_Id;
-- This field is used only for the LOOP and BEGIN cases, and is the
-- Node_Id value of the label name. For all cases except child units,
-- this value is an entity whose Chars field contains the name pointer
-- that identifies the label uniquely. For the child unit case the Labl
-- field references an N_Defining_Program_Unit_Name node for the name.
-- For cases other than LOOP or BEGIN, the Label field is set to Error,
-- indicating that it is an error to have a label on the end line.
-- (this is really a misuse of Error since there is no Error ???)
Decl : List_Id;
-- Points to the list of declarations (i.e. the declarative part)
-- associated with this construct. It is set only in the END [name]
-- cases, and is set to No_List for all other cases which do not have a
-- declarative unit associated with them. This is used for determining
-- the proper location for implicit label declarations.
Node : Node_Id;
-- Empty except in the case of entries for IF and CASE statements,
-- in which case it contains the N_If_Statement or N_Case_Statement
-- node. This is used for setting the End_Span field.
Sloc : Source_Ptr;
-- Source location of the opening token of the construct. This is
-- used to refer back to this line in error messages (such as missing
-- or incorrect end lines). The Sloc field is not used, and is not set,
-- if a label is present (the Labl field provides the text name of the
-- label in this case, which is fine for error messages).
S_Is : Source_Ptr;
-- S_Is is relevant only if Etyp is set to E_Suspicious_Is or
-- E_Bad_Is. It records the location of the IS that is considered
-- to be suspicious.
Junk : Boolean;
-- A boolean flag that is set true if the opening entry is the dubious
-- result of some prior error, e.g. a record entry where the record
-- keyword was missing. It is used to suppress the issuing of a
-- corresponding junk complaint about the end line (we do not want
-- to complain about a missing end record when there was no record).
end record;
-- The following declares the scope table itself. The Last field is the
-- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The
-- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to
-- E_Dummy, and the other fields undefined. This dummy entry ensures that
-- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the
-- scope stack pointer is always in range.
package Scope is new Table.Table (
Table_Component_Type => Scope_Table_Entry,
Table_Index_Type => Int,
Table_Low_Bound => 0,
Table_Initial => 50,
Table_Increment => 100,
Table_Name => "Scope");
-- Parsing Routines by Chapter --
-- Uncommented declarations in this section simply parse the construct
-- corresponding to their name, and return an ID value for the Node or
-- List that is created.
package Ch2 is
function P_Pragma return Node_Id;
function P_Identifier (C : Id_Check := None) return Node_Id;
-- Scans out an identifier. The parameter C determines the treatment
-- of reserved identifiers. See declaration of Id_Check for details.
function P_Pragmas_Opt return List_Id;
-- This function scans for a sequence of pragmas in other than a
-- declaration sequence or statement sequence context. All pragmas
-- can appear except pragmas Assert and Debug, which are only allowed
-- in a declaration or statement sequence context.
procedure P_Pragmas_Misplaced;
-- Skips misplaced pragmas with a complaint
procedure P_Pragmas_Opt (List : List_Id);
-- Parses optional pragmas and appends them to the List
end Ch2;
package Ch3 is
Missing_Begin_Msg : Error_Msg_Id;
-- This variable is set by a call to P_Declarative_Part. Normally it
-- is set to No_Error_Msg, indicating that no special processing is
-- required by the caller. The special case arises when a statement
-- is found in the sequence of declarations. In this case the Id of
-- the message issued ("declaration expected") is preserved in this
-- variable, then the caller can change it to an appropriate missing
-- begin message if indeed the BEGIN is missing.
function P_Access_Definition return Node_Id;
function P_Access_Type_Definition return Node_Id;
function P_Array_Type_Definition return Node_Id;
function P_Basic_Declarative_Items return List_Id;
function P_Constraint_Opt return Node_Id;
function P_Declarative_Part return List_Id;
function P_Discrete_Choice_List return List_Id;
function P_Discrete_Range return Node_Id;
function P_Discrete_Subtype_Definition return Node_Id;
function P_Known_Discriminant_Part_Opt return List_Id;
function P_Signed_Integer_Type_Definition return Node_Id;
function P_Range return Node_Id;
function P_Range_Or_Subtype_Mark return Node_Id;
function P_Range_Constraint return Node_Id;
function P_Record_Definition return Node_Id;
function P_Subtype_Indication return Node_Id;
function P_Subtype_Mark return Node_Id;
function P_Subtype_Mark_Resync return Node_Id;
function P_Unknown_Discriminant_Part_Opt return Boolean;
procedure P_Component_Items (Decls : List_Id);
-- Scan out one or more component items and append them to the
-- given list. Only scans out more than one declaration in the
-- case where the source has a single declaration with multiple
-- defining identifiers.
function P_Defining_Identifier (C : Id_Check := None) return Node_Id;
-- Scan out a defining identifier. The parameter C controls the
-- treatment of errors in case a reserved word is scanned. See the
-- declaration of this type for details.
function Init_Expr_Opt (P : Boolean := False) return Node_Id;
-- If an initialization expression is present (:= expression), then
-- it is scanned out and returned, otherwise Empty is returned if no
-- initialization expression is present. This procedure also handles
-- certain common error cases cleanly. The parameter P indicates if
-- a right paren can follow the expression (default = no right paren
-- allowed).
procedure Skip_Declaration (S : List_Id);
-- Used when scanning statements to skip past a mispaced declaration
-- The declaration is scanned out and appended to the given list.
-- Token is known to be a declaration token (in Token_Class_Declk)
-- on entry, so there definition is a declaration to be scanned.
function P_Subtype_Indication (Subtype_Mark : Node_Id) return Node_Id;
-- This version of P_Subtype_Indication is called when the caller has
-- already scanned out the subtype mark which is passed as a parameter.
function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id;
-- Parse a subtype mark attribute. The caller has already parsed the
-- subtype mark, which is passed in as the argument, and has checked
-- that the current token is apostrophe.
end Ch3;
package Ch4 is
function P_Aggregate return Node_Id;
function P_Expression return Node_Id;
function P_Expression_No_Right_Paren return Node_Id;
function P_Expression_Or_Range_Attribute return Node_Id;
function P_Function_Name return Node_Id;
function P_Name return Node_Id;
function P_Qualified_Simple_Name return Node_Id;
function P_Qualified_Simple_Name_Resync return Node_Id;
function P_Simple_Expression return Node_Id;
function P_Simple_Expression_Or_Range_Attribute return Node_Id;
function P_Qualified_Expression
(Subtype_Mark : Node_Id)
return Node_Id;
-- This routine scans out a qualified expression when the caller has
-- already scanned out the name and apostrophe of the construct.
end Ch4;
package Ch5 is
function P_Statement_Name (Name_Node : Node_Id) return Node_Id;
-- Given a node representing a name (which is a call), converts it
-- to the syntactically corresponding procedure call statement.
function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id;
-- The argument indicates the acceptable termination tokens.
-- See body in Par.Ch5 for details of the use of this parameter.
procedure Parse_Decls_Begin_End (Parent : Node_Id);
-- Parses declarations and handled statement sequence, setting
-- fields of Parent node appropriately.
end Ch5;
package Ch6 is
function P_Designator return Node_Id;
function P_Defining_Program_Unit_Name return Node_Id;
function P_Formal_Part return List_Id;
function P_Parameter_Profile return List_Id;
function P_Return_Statement return Node_Id;
function P_Subprogram_Specification return Node_Id;
procedure P_Mode (Node : Node_Id);
-- Sets In_Present and/or Out_Present flags in Node scanning past
-- IN, OUT or IN OUT tokens in the source.
function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id;
-- Scans out any construct starting with either of the keywords
-- PROCEDURE or FUNCTION. The parameter indicates which possible
-- possible kinds of construct (body, spec, instantiation etc.)
-- are permissible in the current context.
end Ch6;
package Ch7 is
function P_Package (Pf_Flags : Pf_Rec) return Node_Id;
-- Scans out any construct starting with the keyword PACKAGE. The
-- parameter indicates which possible kinds of construct (body, spec,
-- instantiation etc.) are permissible in the current context.
end Ch7;
package Ch8 is
function P_Use_Clause return Node_Id;
end Ch8;
package Ch9 is
function P_Abort_Statement return Node_Id;
function P_Abortable_Part return Node_Id;
function P_Accept_Statement return Node_Id;
function P_Delay_Statement return Node_Id;
function P_Entry_Body return Node_Id;
function P_Protected return Node_Id;
function P_Requeue_Statement return Node_Id;
function P_Select_Statement return Node_Id;
function P_Task return Node_Id;
function P_Terminate_Alternative return Node_Id;
end Ch9;
package Ch10 is
function P_Compilation_Unit return Node_Id;
-- Note: this function scans a single compilation unit, and
-- checks that an end of file follows this unit, diagnosing
-- any unexpected input as an error, and then skipping it, so
-- that Token is set to Tok_EOF on return. An exception is in
-- syntax-only mode, where multiple compilation units are
-- permitted. In this case, P_Compilation_Unit does not check
-- for end of file and there may be more compilation units to
-- scan. The caller can uniquely detect this situation by the
-- fact that Token is not set to Tok_EOF on return.
end Ch10;
package Ch11 is
function P_Handled_Sequence_Of_Statements return Node_Id;
function P_Raise_Statement return Node_Id;
function Parse_Exception_Handlers return List_Id;
-- Parses the partial construct EXCEPTION followed by a list of
-- exception handlers which appears in a number of productions,
-- and returns the list of exception handlers.
end Ch11;
package Ch12 is
function P_Generic return Node_Id;
function P_Generic_Actual_Part_Opt return List_Id;
end Ch12;
package Ch13 is
function P_Representation_Clause return Node_Id;
function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id;
-- Function to parse a code statement. The caller has scanned out
-- the name to be used as the subtype mark (but has not checked that
-- it is suitable for use as a subtype mark, i.e. is either an
-- identifier or a selected component). The current token is an
-- apostrophe and the following token is either a left paren or
-- RANGE (the latter being an error to be caught by P_Code_Statement.
end Ch13;
-- Note: the parsing for annexe J features (i.e. obsolescent features)
-- is found in the logical section where these features would be if
-- they were not obsolescent. In particular:
-- Delta constraint is parsed by P_Delta_Constraint (3.5.9)
-- At clause is parsed by P_At_Clause (13.1)
-- Mod clause is parsed by P_Mod_Clause (13.5.1)
-- End Handling --
-- Routines for handling end lines, including scope recovery
package Endh is
function Check_End return Boolean;
-- Called when an end sequence is required. In the absence of an error
-- situation, Token contains Tok_End on entry, but in a missing end
-- case, this may not be the case. Pop_End_Context is used to determine
-- the appropriate action to be taken. The returned result is True if
-- an End sequence was encountered and False if no End sequence was
-- present. This occurs if the END keyword encountered was determined
-- to be improper and deleted (i.e. Pop_End_Context set End_Action to
-- Skip_And_Reject). Note that the END sequence includes a semicolon,
-- except in the case of END RECORD, where a semicolon follows the END
-- RECORD, but is not part of the record type definition itself.
procedure End_Skip;
-- Skip past an end sequence. On entry Token contains Tok_End, and we
-- we know that the end sequence is syntactically incorrect, and that
-- an appropriate error message has already been posted. The mission
-- is simply to position the scan pointer to be the best guess of the
-- position after the end sequence. We do not issue any additional
-- error messages while carrying this out.
procedure End_Statements (Parent : Node_Id := Empty);
-- Called when an end is required or expected to terminate a sequence
-- of statements. The caller has already made an appropriate entry in
-- the Scope.Table to describe the expected form of the end. This can
-- only be used in cases where the only appropriate terminator is end.
-- If Parent is non-empty, then if a correct END line is encountered,
-- the End_Label field of Parent is set appropriately.
end Endh;
-- Resynchronization After Errors --
-- These procedures are used to resynchronize after errors. Following an
-- error which is not immediately locally recoverable, the exception
-- Error_Resync is raised. The handler for Error_Resync typically calls
-- one of these recovery procedures to resynchronize the source position
-- to a point from which parsing can be restarted.
-- Note: these procedures output an information message that tokens are
-- being skipped, but this message is output only if the option for
-- Multiple_Errors_Per_Line is set in Options.
package Sync is
procedure Resync_Choice;
-- Used if an error occurs scanning a choice. The scan pointer is
-- advanced to the next vertical bar, arrow, or semicolon, whichever
-- comes first. We also quit if we encounter an end of file.
procedure Resync_Expression;
-- Used if an error is detected during the parsing of an expression.
-- It skips past tokens until either a token which cannot be part of
-- an expression is encountered (an expression terminator), or if a
-- comma or right parenthesis or vertical bar is encountered at the
-- current parenthesis level (a parenthesis level counter is maintained
-- to carry out this test).
procedure Resync_Past_Semicolon;
-- Used if an error occurs while scanning a sequence of declarations.
-- The scan pointer is positioned past the next semicolon and the scan
-- resumes. The scan is also resumed on encountering a token which
-- starts a declaration (but we make sure to skip at least one token
-- in this case, to avoid getting stuck in a loop).
procedure Resync_To_Semicolon;
-- Similar to Resync_Past_Semicolon, except that the scan pointer is
-- left pointing to the semicolon rather than past it.
procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then;
-- Used if an error occurs while scanning a sequence of statements.
-- The scan pointer is positioned past the next semicolon, or to the
-- next occurrence of either then or loop, and the scan resumes.
procedure Resync_To_When;
-- Used when an error occurs scanning an entry index specification.
-- The scan pointer is positioned to the next WHEN (or to IS or
-- semicolon if either of these appear before WHEN, indicating
-- another error has occurred).
procedure Resync_Semicolon_List;
-- Used if an error occurs while scanning a parenthesized list of items
-- separated by semicolons. The scan pointer is advanced to the next
-- semicolon or right parenthesis at the outer parenthesis level, or
-- to the next is or RETURN keyword occurence, whichever comes first.
procedure Resync_Cunit;
-- Synchronize to next token which could be the start of a compilation
-- unit, or to the end of file token.
end Sync;
-- Token Scan Routines --
-- Routines to check for expected tokens
package Tchk is
-- Procedures with names of the form T_xxx, where Tok_xxx is a token
-- name, check that the current token matches the required token, and
-- if so, scan past it. If not, an error is issued indicating that
-- the required token is not present (xxx expected). In most cases, the
-- scan pointer is not moved in the not-found case, but there are some
-- exceptions to this, see for example T_Id, where the scan pointer is
-- moved across a literal appearing where an identifier is expected.
procedure T_Abort;
procedure T_Arrow;
procedure T_At;
procedure T_Body;
procedure T_Box;
procedure T_Colon;
procedure T_Colon_Equal;
procedure T_Comma;
procedure T_Dot_Dot;
procedure T_For;
procedure T_Greater_Greater;
procedure T_Identifier;
procedure T_In;
procedure T_Is;
procedure T_Left_Paren;
procedure T_Loop;
procedure T_Mod;
procedure T_New;
procedure T_Of;
procedure T_Or;
procedure T_Private;
procedure T_Range;
procedure T_Record;
procedure T_Right_Paren;
procedure T_Semicolon;
procedure T_Then;
procedure T_Type;
procedure T_Use;
procedure T_When;
procedure T_With;
-- Procedures have names of the form TF_xxx, where Tok_xxx is a token
-- name check that the current token matches the required token, and
-- if so, scan past it. If not, an error message is issued indicating
-- that the required token is not present (xxx expected).
-- If the missing token is at the end of the line, then control returns
-- immediately after posting the message. If there are remaining tokens
-- on the current line, a search is conducted to see if the token
-- appears later on the current line, as follows:
-- A call to Scan_Save is issued and a forward search for the token
-- is carried out. If the token is found on the current line before a
-- semicolon, then it is scanned out and the scan continues from that
-- point. If not the scan is restored to the point where it was missing.
procedure TF_Arrow;
procedure TF_Is;
procedure TF_Loop;
procedure TF_Return;
procedure TF_Semicolon;
procedure TF_Then;
procedure TF_Use;
end Tchk;
-- Utility Routines --
package Util is
function Bad_Spelling_Of (T : Token_Type) return Boolean;
-- This function is called in an error situation. It checks if the
-- current token is an identifier whose name is a plausible bad
-- spelling of the given keyword token, and if so, issues an error
-- message, sets Token from T, and returns True. Otherwise Token is
-- unchanged, and False is returned.
procedure Check_Bad_Layout;
-- Check for bad indentation in RM checking mode. Used for statements
-- and declarations. Checks if current token is at start of line and
-- is exdented from the current expected end column, and if so an
-- error message is generated.
procedure Check_Misspelling_Of (T : Token_Type);
pragma Inline (Check_Misspelling_Of);
-- This is similar to the function above, except that it does not
-- return a result. It is typically used in a situation where any
-- identifier is an error, and it makes sense to simply convert it
-- to the given token if it is a plausible misspelling of it.
procedure Check_95_Keyword (Token_95, Next : Token_Type);
-- This routine checks if the token after the current one matches the
-- Next argument. If so, the scan is backed up to the current token
-- and Token_Type is changed to Token_95 after issuing an appropriate
-- error message ("(Ada 83) keyword xx cannot be used"). If not,
-- the scan is backed up with Token_Type unchanged. This routine
-- is used to deal with an attempt to use a 95 keyword in Ada 83
-- mode. The caller has typically checked that the current token,
-- an identifier, matches one of the 95 keywords.
procedure Check_Simple_Expression (E : Node_Id);
-- Given an expression E, that has just been scanned, so that Expr_Form
-- is still set, outputs an error if E is a non-simple expression. E is
-- not modified by this call.
procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id);
-- Like Check_Simple_Expression, except that the error message is only
-- given when operating in Ada 83 mode, and includes "in Ada 83".
function Check_Subtype_Mark (Mark : Node_Id) return Node_Id;
-- Called to check that a node representing a name (or call) is
-- suitable for a subtype mark, i.e, that it is an identifier or
-- a selected component. If so, or if it is already Error, then
-- it is returned unchanged. Otherwise an error message is issued
-- and Error is returned.
function Comma_Present return Boolean;
-- Used in comma delimited lists to determine if a comma is present, or
-- can reasonably be assumed to have been present (an error message is
-- generated in the latter case). If True is returned, the scan has been
-- positioned past the comma. If False is returned, the scan position
-- is unchanged. Note that all comma-delimited lists are terminated by
-- a right paren, so the only legitimate tokens when Comma_Present is
-- called are right paren and comma. If some other token is found, then
-- Comma_Present has the job of deciding whether it is better to pretend
-- a comma was present, post a message for a missing comma and return
-- True, or return False and let the caller diagnose the missing right
-- parenthesis.
procedure Discard_Junk_Node (N : Node_Id);
procedure Discard_Junk_List (L : List_Id);
pragma Inline (Discard_Junk_Node);
pragma Inline (Discard_Junk_List);
-- These procedures do nothing at all, their effect is simply to discard
-- the argument. A typical use is to skip by some junk that is not
-- expected in the current context.
procedure Ignore (T : Token_Type);
-- If current token matches T, then give an error message and skip
-- past it, otherwise the call has no effect at all. T may be any
-- reserved word token, or comma, left or right paren, or semicolon.
function Is_Reserved_Identifier (C : Id_Check := None) return Boolean;
-- Test if current token is a reserved identifier. This test is based
-- on the token being a keyword and being spelled in typical identifier
-- style (i.e. starting with an upper case letter). The parameter C
-- determines the special treatment if a reserved word is encountered
-- that has the normal casing of a reserved word.
procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type);
-- Called when the previous token is an identifier (whose Token_Node
-- value is given by Prev) to check if current token is an identifier
-- that can be merged with the previous one adding an underscore. The
-- merge is only attempted if the following token matches Nxt. If all
-- conditions are met, an error message is issued, and the merge is
-- carried out, modifying the Chars field of Prev.
procedure No_Constraint;
-- Called in a place where no constraint is allowed, but one might
-- appear due to a common error (e.g. after the type mark in a procedure
-- parameter. If a constraint is present, an error message is posted,
-- and the constraint is scanned and discarded.
function No_Right_Paren (Expr : Node_Id) return Node_Id;
-- Function to check for no right paren at end of expression, returns
-- its argument if no right paren, else flags paren and returns Error.
procedure Push_Scope_Stack;
pragma Inline (Push_Scope_Stack);
-- Push a new entry onto the scope stack. Scope.Last (the stack pointer)
-- is incremented. The Junk field is preinitialized to False. The caller
-- is expected to fill in all remaining entries of the new new top stack
-- entry at Scope.Table (Scope.Last).
procedure Pop_Scope_Stack;
-- Pop an entry off the top of the scope stack. Scope_Last (the scope
-- table stack pointer) is decremented by one. It is a fatal error to
-- try to pop off the dummy entry at the bottom of the stack (i.e.
-- Scope.Last must be non-zero at the time of call).
function Separate_Present return Boolean;
-- Determines if the current token is either Tok_Separate, or an
-- identifier that is a possible misspelling of "separate" followed
-- by a semicolon. True is returned if so, otherwise False.
procedure Signal_Bad_Attribute;
-- The current token is an identifier that is supposed to be an
-- attribute identifier but is not. This routine posts appropriate
-- error messages, including a check for a near misspelling.
function Token_Is_At_Start_Of_Line return Boolean;
pragma Inline (Token_Is_At_Start_Of_Line);
-- Determines if the current token is the first token on the line
function Token_Is_At_End_Of_Line return Boolean;
-- Determines if the current token is the last token on the line
end Util;
-- Specialized Syntax Check Routines --
function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id;
-- This function is passed a tree for a pragma that has been scanned out.
-- The pragma is syntactically well formed according to the general syntax
-- for pragmas and the pragma identifier is for one of the recognized
-- pragmas. It performs specific syntactic checks for specific pragmas.
-- The result is the input node if it is OK, or Error otherwise. The
-- reason that this is separated out is to facilitate the addition
-- of implementation defined pragmas. The second parameter records the
-- location of the semicolon following the pragma (this is needed for
-- correct processing of the List and Page pragmas). The returned value
-- is a copy of Pragma_Node, or Error if an error is found. Note that
-- at the point where Prag is called, the right paren ending the pragma
-- has been scanned out, and except in the case of pragma Style_Checks,
-- so has the following semicolon. For Style_Checks, the caller delays
-- the scanning of the semicolon so that it will be scanned using the
-- settings from the Style_Checks pragma preceding it.
-- Subsidiary Routines --
procedure Labl;
-- This procedure creates implicit label declarations for all label that
-- are declared in the current unit. Note that this could conceptually
-- be done at the point where the labels are declared, but it is tricky
-- to do it then, since the tree is not hooked up at the point where the
-- label is declared (e.g. a sequence of statements is not yet attached
-- to its containing scope at the point a label in the sequence is found)
procedure Load;
-- This procedure loads all subsidiary units that are required by this
-- unit, including with'ed units, specs for bodies, and parents for child
-- units. It does not load bodies for inlined procedures and generics,
-- since we don't know till semantic analysis is complete what is needed.
-- Stubs --
-- The package bodies can see all routines defined in all other subpackages
use Ch2;
use Ch3;
use Ch4;
use Ch5;
use Ch6;
use Ch7;
use Ch8;
use Ch9;
use Ch10;
use Ch11;
use Ch12;
use Ch13;
use Endh;
use Tchk;
use Sync;
use Util;
package body Ch2 is separate;
package body Ch3 is separate;
package body Ch4 is separate;
package body Ch5 is separate;
package body Ch6 is separate;
package body Ch7 is separate;
package body Ch8 is separate;
package body Ch9 is separate;
package body Ch10 is separate;
package body Ch11 is separate;
package body Ch12 is separate;
package body Ch13 is separate;
package body Endh is separate;
package body Tchk is separate;
package body Sync is separate;
package body Util is separate;
function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id
is separate;
procedure Labl is separate;
procedure Load is separate;
-- Par --
-- This function is the parse routine called at the outer level. It parses
-- the current compilation unit and adds implicit label declarations.
-- Deal with configuration pragmas case first
if Configuration_Pragmas then
Ecount : constant Int := Serious_Errors_Detected;
Pragmas : constant List_Id := Empty_List;
P_Node : Node_Id;
if Token = Tok_EOF then
return Pragmas;
elsif Token /= Tok_Pragma then
Error_Msg_SC ("only pragmas allowed in configuration file");
return Error_List;
P_Node := P_Pragma;
if Serious_Errors_Detected > Ecount then
return Error_List;
end if;
if Chars (P_Node) > Last_Configuration_Pragma_Name
and then Chars (P_Node) /= Name_Source_Reference
("only configuration pragmas allowed " &
"in configuration file");
return Error_List;
end if;
Append (P_Node, Pragmas);
end if;
end loop;
-- Normal case of compilation unit
Save_Opt_Config_Switches (Save_Config_Switches);
-- Special processing for language defined units. For this purpose
-- we do NOT consider the renamings in annex J as predefined. That
-- allows users to compile their own versions of these files, and
-- in particular, in the VMS implementation, the DEC versions can
-- be substituted for the standard Ada 95 versions.
if Is_Predefined_File_Name
(Fname => File_Name (Current_Source_File),
Renamings_Included => False)
(Is_Internal_File_Name (File_Name (Current_Source_File)));
-- If this is the main unit, disallow compilation unless the -gnatg
-- (GNAT mode) switch is set (from a user point of view, the rule is
-- that language defined units cannot be recompiled).
-- However, an exception is s-rpc, and its children. We test this
-- by looking at the character after the minus, the rule is that
-- System.RPC and its children are the only children in System
-- whose second level name can start with the letter r.
Get_Name_String (File_Name (Current_Source_File));
if (Name_Len < 3 or else Name_Buffer (1 .. 3) /= "s-r")
and then Current_Source_Unit = Main_Unit
and then not GNAT_Mode
and then Operating_Mode = Generate_Code
Error_Msg_SC ("language defined units may not be recompiled");
end if;
end if;
-- The following loop runs more than once only in syntax check mode
-- where we allow multiple compilation units in the same file.
(Is_Internal_File_Name (File_Name (Current_Source_File)));
-- Initialize scope table and other parser control variables
Compiler_State := Parsing;
Scope.Table (0).Etyp := E_Dummy;
SIS_Entry_Active := False;
Last_Resync_Point := No_Location;
Label_List := New_Elmt_List;
Discard_Node (P_Compilation_Unit);
-- If we are not at an end of file, then this means that we are
-- in syntax scan mode, and we can have another compilation unit,
-- otherwise we will exit from the loop.
exit when Token = Tok_EOF;
Restore_Opt_Config_Switches (Save_Config_Switches);
end loop;
-- Now that we have completely parsed the source file, we can
-- complete the source file table entry.
-- An internal error check, the scope stack should now be empty
pragma Assert (Scope.Last = 0);
-- Remaining steps are to create implicit label declarations and to
-- load required subsidiary sources. These steps are required only
-- if we are doing semantic checking.
if Operating_Mode /= Check_Syntax or else Debug_Flag_F then
end if;
-- Restore settings of switches saved on entry
Restore_Opt_Config_Switches (Save_Config_Switches);
Set_Comes_From_Source_Default (False);
return Empty_List;
end if;
end Par;