gcc/d/dmd/common/outbuffer.d - gcc - Git at Google

 /**
  * An expandable buffer in which you can write text or binary data.
  *
  * Copyright: Copyright (C) 1999-2022 by The D Language Foundation, All Rights Reserved
  * Authors:   Walter Bright, https://www.digitalmars.com
  * License:   $(LINK2 https://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
  * Source:    $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/root/outbuffer.d, root/_outbuffer.d)
  * Documentation: https://dlang.org/phobos/dmd_root_outbuffer.html
  * Coverage:    https://codecov.io/gh/dlang/dmd/src/master/src/dmd/root/outbuffer.d
  */

 module dmd.common.outbuffer;

 import core.stdc.stdarg;
 import core.stdc.stdio;
 import core.stdc.string;
 import core.stdc.stdlib;

 nothrow:

 // In theory these functions should also restore errno, but we don't care because
 // we abort application on error anyway.
 extern (C) private pure @system @nogc nothrow
 {
     pragma(mangle, "malloc") void* pureMalloc(size_t);
     pragma(mangle, "realloc") void* pureRealloc(void* ptr, size_t size);
     pragma(mangle, "free") void pureFree(void* ptr);
 }

 debug
 {
     debug = stomp; // flush out dangling pointer problems by stomping on unused memory
 }

 /**
 `OutBuffer` is a write-only output stream of untyped data. It is backed up by
 a contiguous array or a memory-mapped file.
 */
 struct OutBuffer
 {
     import dmd.common.file : FileMapping, touchFile, writeFile;

     // IMPORTANT: PLEASE KEEP STATE AND DESTRUCTOR IN SYNC WITH DEFINITION IN ./outbuffer.h.
     // state {
     private ubyte[] data;
     private size_t offset;
     private bool notlinehead;
     /// File mapping, if any. Use a pointer for ABI compatibility with the C++ counterpart.
     /// If the pointer is non-null the store is a memory-mapped file, otherwise the store is RAM.
     private FileMapping!ubyte* fileMapping;
     /// Whether to indent
     bool doindent;
     /// Whether to indent by 4 spaces or by tabs;
     bool spaces;
     /// Current indent level
     int level;
     // state }

   nothrow:

     /**
     Construct given size.
     */
     this(size_t initialSize) nothrow
     {
         reserve(initialSize);
     }

     /**
     Construct from filename. Will map the file into memory (or create it anew
     if necessary) and start writing at the beginning of it.

     Params:
     filename = zero-terminated name of file to map into memory
     */
     @trusted this(const(char)* filename)
     {
         FileMapping!ubyte model;
         fileMapping = cast(FileMapping!ubyte*) malloc(model.sizeof);
         memcpy(fileMapping, &model, model.sizeof);
         fileMapping.__ctor(filename);
         //fileMapping = new FileMapping!ubyte(filename);
         data = (*fileMapping)[];
     }

     /**
     Frees resources associated.
     */
     extern (C++) void dtor() pure nothrow @trusted
     {
         if (fileMapping)
         {
             if (fileMapping.active)
                 fileMapping.close();
         }
         else
         {
             debug (stomp) memset(data.ptr, 0xFF, data.length);
             pureFree(data.ptr);
         }
     }

     /**
     Frees resources associated automatically.
     */
     extern (C++) ~this() pure nothrow @trusted
     {
         dtor();
     }

     /// For porting with ease from dmd.backend.outbuf.Outbuffer
     ubyte* buf() nothrow @system {
         return data.ptr;
     }

     /// For porting with ease from dmd.backend.outbuf.Outbuffer
     ubyte** bufptr() nothrow @system {
         static struct Array { size_t length; ubyte* ptr; }
         auto a = cast(Array*) &data;
         assert(a.length == data.length && a.ptr == data.ptr);
         return &a.ptr;
     }

     extern (C++) size_t length() const pure @nogc @safe nothrow { return offset; }

     /**********************
      * Transfer ownership of the allocated data to the caller.
      * Returns:
      *  pointer to the allocated data
      */
     extern (C++) char* extractData() pure nothrow @nogc @trusted
     {
         char* p = cast(char*)data.ptr;
         data = null;
         offset = 0;
         return p;
     }

     /**
     Releases all resources associated with `this` and resets it as an empty
     memory buffer. The config variables `notlinehead`, `doindent` etc. are
     not changed.
     */
     extern (C++) void destroy() pure nothrow @trusted
     {
         dtor();
         fileMapping = null;
         data = null;
         offset = 0;
     }

     /**
     Reserves `nbytes` bytes of additional memory (or file space) in advance.
     The resulting capacity is at least the previous length plus `nbytes`.

     Params:
     nbytes = the number of additional bytes to reserve
     */
     extern (C++) void reserve(size_t nbytes) pure nothrow @trusted
     {
         //debug (stomp) printf("OutBuffer::reserve: size = %lld, offset = %lld, nbytes = %lld\n", data.length, offset, nbytes);
         const minSize = offset + nbytes;
         if (data.length >= minSize)
             return;

         /* Increase by factor of 1.5; round up to 16 bytes.
             * The odd formulation is so it will map onto single x86 LEA instruction.
             */
         const size = ((minSize * 3 + 30) / 2) & ~15;

         if (fileMapping && fileMapping.active)
         {
             fileMapping.resize(size);
             data = (*fileMapping)[];
         }
         else
         {
             debug (stomp)
             {
                 auto p = cast(ubyte*) pureMalloc(size);
                 p || assert(0, "OutBuffer: out of memory.");
                 memcpy(p, data.ptr, offset);
                 memset(data.ptr, 0xFF, data.length);  // stomp old location
                 pureFree(data.ptr);
                 memset(p + offset, 0xff, size - offset); // stomp unused data
             }
             else
             {
                 auto p = cast(ubyte*) pureRealloc(data.ptr, size);
                 p || assert(0, "OutBuffer: out of memory.");
                 memset(p + offset + nbytes, 0xff, size - offset - nbytes);
             }
             data = p[0 .. size];
         }
     }

     /************************
      * Shrink the size of the data to `size`.
      * Params:
      *  size = new size of data, must be <= `.length`
      */
     extern (C++) void setsize(size_t size) pure nothrow @nogc @safe
     {
         assert(size <= data.length);
         offset = size;
     }

     extern (C++) void reset() pure nothrow @nogc @safe
     {
         offset = 0;
     }

     private void indent() pure nothrow @safe
     {
         if (level)
         {
             const indentLevel = spaces ? level * 4 : level;
             reserve(indentLevel);
             data[offset .. offset + indentLevel] = (spaces ? ' ' : '\t');
             offset += indentLevel;
         }
         notlinehead = true;
     }

     // Write an array to the buffer, no reserve check
     @system nothrow
     void writen(const void *b, size_t len)
     {
         memcpy(data.ptr + offset, b, len);
         offset += len;
     }

     extern (C++) void write(const(void)* data, size_t nbytes) pure nothrow @system
     {
         write(data[0 .. nbytes]);
     }

     void write(scope const(void)[] buf) pure nothrow @trusted
     {
         if (doindent && !notlinehead)
             indent();
         reserve(buf.length);
         memcpy(this.data.ptr + offset, buf.ptr, buf.length);
         offset += buf.length;
     }

     /**
      * Writes a 16 bit value, no reserve check.
      */
     @trusted nothrow
     void write16n(int v)
     {
         auto x = cast(ushort) v;
         data[offset] = x & 0x00FF;
         data[offset + 1] = x >> 8u;
         offset += 2;
     }

     /**
      * Writes a 16 bit value.
      */
     void write16(int v) nothrow
     {
         auto u = cast(ushort) v;
         write(&u, u.sizeof);
     }

     /**
      * Writes a 32 bit int.
      */
     void write32(int v) nothrow @trusted
     {
         write(&v, v.sizeof);
     }

     /**
      * Writes a 64 bit int.
      */
     @trusted void write64(long v) nothrow
     {
         write(&v, v.sizeof);
     }

     /// NOT zero-terminated
     extern (C++) void writestring(const(char)* s) pure nothrow @system
     {
         if (!s)
             return;
         import core.stdc.string : strlen;
         write(s[0 .. strlen(s)]);
     }

     /// ditto
     void writestring(scope const(char)[] s) pure nothrow @safe
     {
         write(s);
     }

     /// ditto
     void writestring(scope string s) pure nothrow @safe
     {
         write(s);
     }

     /// NOT zero-terminated, followed by newline
     void writestringln(const(char)[] s) pure nothrow @safe
     {
         writestring(s);
         writenl();
     }

     /** Write string to buffer, ensure it is zero terminated
      */
     void writeStringz(const(char)* s) pure nothrow @system
     {
         write(s[0 .. strlen(s)+1]);
     }

     /// ditto
     void writeStringz(const(char)[] s) pure nothrow @safe
     {
         write(s);
         writeByte(0);
     }

     /// ditto
     void writeStringz(string s) pure nothrow @safe
     {
         writeStringz(cast(const(char)[])(s));
     }

     extern (C++) void prependstring(const(char)* string) pure nothrow @system
     {
         size_t len = strlen(string);
         reserve(len);
         memmove(data.ptr + len, data.ptr, offset);
         memcpy(data.ptr, string, len);
         offset += len;
     }

     /// write newline
     extern (C++) void writenl() pure nothrow @safe
     {
         version (Windows)
         {
             writeword(0x0A0D); // newline is CR,LF on Microsoft OS's
         }
         else
         {
             writeByte('\n');
         }
         if (doindent)
             notlinehead = false;
     }

     // Write n zeros; return pointer to start of zeros
     @trusted
     void *writezeros(size_t n) nothrow
     {
         reserve(n);
         auto result = memset(data.ptr + offset, 0, n);
         offset += n;
         return result;
     }

     // Position buffer to accept the specified number of bytes at offset
     @trusted
     void position(size_t where, size_t nbytes) nothrow
     {
         if (where + nbytes > data.length)
         {
             reserve(where + nbytes - offset);
         }
         offset = where;

         debug assert(offset + nbytes <= data.length);
     }

     /**
      * Writes an 8 bit byte, no reserve check.
      */
     extern (C++) @trusted nothrow
     void writeByten(int b)
     {
         this.data[offset++] = cast(ubyte) b;
     }

     extern (C++) void writeByte(uint b) pure nothrow @safe
     {
         if (doindent && !notlinehead && b != '\n')
             indent();
         reserve(1);
         this.data[offset] = cast(ubyte)b;
         offset++;
     }

     extern (C++) void writeUTF8(uint b) pure nothrow @safe
     {
         reserve(6);
         if (b <= 0x7F)
         {
             this.data[offset] = cast(ubyte)b;
             offset++;
         }
         else if (b <= 0x7FF)
         {
             this.data[offset + 0] = cast(ubyte)((b >> 6) | 0xC0);
             this.data[offset + 1] = cast(ubyte)((b & 0x3F) | 0x80);
             offset += 2;
         }
         else if (b <= 0xFFFF)
         {
             this.data[offset + 0] = cast(ubyte)((b >> 12) | 0xE0);
             this.data[offset + 1] = cast(ubyte)(((b >> 6) & 0x3F) | 0x80);
             this.data[offset + 2] = cast(ubyte)((b & 0x3F) | 0x80);
             offset += 3;
         }
         else if (b <= 0x1FFFFF)
         {
             this.data[offset + 0] = cast(ubyte)((b >> 18) | 0xF0);
             this.data[offset + 1] = cast(ubyte)(((b >> 12) & 0x3F) | 0x80);
             this.data[offset + 2] = cast(ubyte)(((b >> 6) & 0x3F) | 0x80);
             this.data[offset + 3] = cast(ubyte)((b & 0x3F) | 0x80);
             offset += 4;
         }
         else
             assert(0);
     }

     extern (C++) void prependbyte(uint b) pure nothrow @trusted
     {
         reserve(1);
         memmove(data.ptr + 1, data.ptr, offset);
         data[0] = cast(ubyte)b;
         offset++;
     }

     extern (C++) void writewchar(uint w) pure nothrow @safe
     {
         version (Windows)
         {
             writeword(w);
         }
         else
         {
             write4(w);
         }
     }

     extern (C++) void writeword(uint w) pure nothrow @trusted
     {
         version (Windows)
         {
             uint newline = 0x0A0D;
         }
         else
         {
             uint newline = '\n';
         }
         if (doindent && !notlinehead && w != newline)
             indent();

         reserve(2);
         *cast(ushort*)(this.data.ptr + offset) = cast(ushort)w;
         offset += 2;
     }

     extern (C++) void writeUTF16(uint w) pure nothrow @trusted
     {
         reserve(4);
         if (w <= 0xFFFF)
         {
             *cast(ushort*)(this.data.ptr + offset) = cast(ushort)w;
             offset += 2;
         }
         else if (w <= 0x10FFFF)
         {
             *cast(ushort*)(this.data.ptr + offset) = cast(ushort)((w >> 10) + 0xD7C0);
             *cast(ushort*)(this.data.ptr + offset + 2) = cast(ushort)((w & 0x3FF) | 0xDC00);
             offset += 4;
         }
         else
             assert(0);
     }

     extern (C++) void write4(uint w) pure nothrow @trusted
     {
         version (Windows)
         {
             bool notnewline = w != 0x000A000D;
         }
         else
         {
             bool notnewline = true;
         }
         if (doindent && !notlinehead && notnewline)
             indent();
         reserve(4);
         *cast(uint*)(this.data.ptr + offset) = w;
         offset += 4;
     }

     extern (C++) void write(const OutBuffer* buf) pure nothrow @trusted
     {
         if (buf)
         {
             reserve(buf.offset);
             memcpy(data.ptr + offset, buf.data.ptr, buf.offset);
             offset += buf.offset;
         }
     }

     extern (C++) void fill0(size_t nbytes) pure nothrow @trusted
     {
         reserve(nbytes);
         memset(data.ptr + offset, 0, nbytes);
         offset += nbytes;
     }

     /**
      * Allocate space, but leave it uninitialized.
      * Params:
      *  nbytes = amount to allocate
      * Returns:
      *  slice of the allocated space to be filled in
      */
     extern (D) char[] allocate(size_t nbytes) pure nothrow
     {
         reserve(nbytes);
         offset += nbytes;
         return cast(char[])data[offset - nbytes .. offset];
     }

     extern (C++) void vprintf(const(char)* format, va_list args) nothrow @system
     {
         int count;
         if (doindent && !notlinehead)
             indent();
         uint psize = 128;
         for (;;)
         {
             reserve(psize);
             va_list va;
             va_copy(va, args);
             /*
                 The functions vprintf(), vfprintf(), vsprintf(), vsnprintf()
                 are equivalent to the functions printf(), fprintf(), sprintf(),
                 snprintf(), respectively, except that they are called with a
                 va_list instead of a variable number of arguments. These
                 functions do not call the va_end macro. Consequently, the value
                 of ap is undefined after the call. The application should call
                 va_end(ap) itself afterwards.
                 */
             count = vsnprintf(cast(char*)data.ptr + offset, psize, format, va);
             va_end(va);
             if (count == -1) // snn.lib and older libcmt.lib return -1 if buffer too small
                 psize *= 2;
             else if (count >= psize)
                 psize = count + 1;
             else
                 break;
         }
         offset += count;
         // if (mem.isGCEnabled)
              memset(data.ptr + offset, 0xff, psize - count);
     }

     static if (__VERSION__ < 2092)
     {
         extern (C++) void printf(const(char)* format, ...) nothrow @system
         {
             va_list ap;
             va_start(ap, format);
             vprintf(format, ap);
             va_end(ap);
         }
     }
     else
     {
         pragma(printf) extern (C++) void printf(const(char)* format, ...) nothrow @system
         {
             va_list ap;
             va_start(ap, format);
             vprintf(format, ap);
             va_end(ap);
         }
     }

     /**************************************
      * Convert `u` to a string and append it to the buffer.
      * Params:
      *  u = integral value to append
      */
     extern (C++) void print(ulong u) pure nothrow @safe
     {
         UnsignedStringBuf buf = void;
         writestring(unsignedToTempString(u, buf));
     }

     extern (C++) void bracket(char left, char right) pure nothrow @trusted
     {
         reserve(2);
         memmove(data.ptr + 1, data.ptr, offset);
         data[0] = left;
         data[offset + 1] = right;
         offset += 2;
     }

     /******************
      * Insert left at i, and right at j.
      * Return index just past right.
      */
     extern (C++) size_t bracket(size_t i, const(char)* left, size_t j, const(char)* right) pure nothrow @system
     {
         size_t leftlen = strlen(left);
         size_t rightlen = strlen(right);
         reserve(leftlen + rightlen);
         insert(i, left, leftlen);
         insert(j + leftlen, right, rightlen);
         return j + leftlen + rightlen;
     }

     extern (C++) void spread(size_t offset, size_t nbytes) pure nothrow @system
     {
         reserve(nbytes);
         memmove(data.ptr + offset + nbytes, data.ptr + offset, this.offset - offset);
         this.offset += nbytes;
     }

     /****************************************
      * Returns: offset + nbytes
      */
     extern (C++) size_t insert(size_t offset, const(void)* p, size_t nbytes) pure nothrow @system
     {
         spread(offset, nbytes);
         memmove(data.ptr + offset, p, nbytes);
         return offset + nbytes;
     }

     size_t insert(size_t offset, const(char)[] s) pure nothrow @system
     {
         return insert(offset, s.ptr, s.length);
     }

     extern (C++) void remove(size_t offset, size_t nbytes) pure nothrow @nogc @system
     {
         memmove(data.ptr + offset, data.ptr + offset + nbytes, this.offset - (offset + nbytes));
         this.offset -= nbytes;
     }

     /**
      * Returns:
      *   a non-owning const slice of the buffer contents
      */
     extern (D) const(char)[] opSlice() const pure nothrow @nogc @safe
     {
         return cast(const(char)[])data[0 .. offset];
     }

     extern (D) const(char)[] opSlice(size_t lwr, size_t upr) const pure nothrow @nogc @safe
     {
         return cast(const(char)[])data[lwr .. upr];
     }

     extern (D) char opIndex(size_t i) const pure nothrow @nogc @safe
     {
         return cast(char)data[i];
     }

     alias opDollar = length;

     /***********************************
      * Extract the data as a slice and take ownership of it.
      *
      * When `true` is passed as an argument, this function behaves
      * like `dmd.utils.toDString(thisbuffer.extractChars())`.
      *
      * Params:
      *   nullTerminate = When `true`, the data will be `null` terminated.
      *                   This is useful to call C functions or store
      *                   the result in `Strings`. Defaults to `false`.
      */
     extern (D) char[] extractSlice(bool nullTerminate = false) pure nothrow
     {
         const length = offset;
         if (!nullTerminate)
             return extractData()[0 .. length];
         // There's already a terminating `'\0'`
         if (length && data[length - 1] == '\0')
             return extractData()[0 .. length - 1];
         writeByte(0);
         return extractData()[0 .. length];
     }

     extern (D) byte[] extractUbyteSlice(bool nullTerminate = false) pure nothrow
     {
         return cast(byte[]) extractSlice(nullTerminate);
     }

     // Append terminating null if necessary and get view of internal buffer
     extern (C++) char* peekChars() pure nothrow
     {
         if (!offset || data[offset - 1] != '\0')
         {
             writeByte(0);
             offset--; // allow appending more
         }
         return cast(char*)data.ptr;
     }

     // Append terminating null if necessary and take ownership of data
     extern (C++) char* extractChars() pure nothrow
     {
         if (!offset || data[offset - 1] != '\0')
             writeByte(0);
         return extractData();
     }

     void writesLEB128(int value) pure nothrow @safe
     {
         while (1)
         {
             ubyte b = value & 0x7F;

             value >>= 7;            // arithmetic right shift
             if ((value == 0 && !(b & 0x40)) ||
                 (value == -1 && (b & 0x40)))
             {
                  writeByte(b);
                  break;
             }
             writeByte(b | 0x80);
         }
     }

     void writeuLEB128(uint value) pure nothrow @safe
     {
         do
         {
             ubyte b = value & 0x7F;

             value >>= 7;
             if (value)
                 b |= 0x80;
             writeByte(b);
         } while (value);
     }

     /**
     Destructively saves the contents of `this` to `filename`. As an
     optimization, if the file already has identical contents with the buffer,
     no copying is done. This is because on SSD drives reading is often much
     faster than writing and because there's a high likelihood an identical
     file is written during the build process.

     Params:
     filename = the name of the file to receive the contents

     Returns: `true` iff the operation succeeded.
     */
     extern(D) bool moveToFile(const char* filename) @system
     {
         bool result = true;
         const bool identical = this[] == FileMapping!(const ubyte)(filename)[];

         if (fileMapping && fileMapping.active)
         {
             // Defer to corresponding functions in FileMapping.
             if (identical)
             {
                 result = fileMapping.discard();
             }
             else
             {
                 // Resize to fit to get rid of the slack bytes at the end
                 fileMapping.resize(offset);
                 result = fileMapping.moveToFile(filename);
             }
             // Can't call destroy() here because the file mapping is already closed.
             data = null;
             offset = 0;
         }
         else
         {
             if (!identical)
                 writeFile(filename, this[]);
             destroy();
         }

         return identical
             ? result && touchFile(filename)
             : result;
     }
 }

 /****** copied from core.internal.string *************/

 private:

 alias UnsignedStringBuf = char[20];

 char[] unsignedToTempString(ulong value, return scope char[] buf, uint radix = 10) @safe pure nothrow @nogc
 {
     size_t i = buf.length;
     do
     {
         if (value < radix)
         {
             ubyte x = cast(ubyte)value;
             buf[--i] = cast(char)((x < 10) ? x + '0' : x - 10 + 'a');
             break;
         }
         else
         {
             ubyte x = cast(ubyte)(value % radix);
             value /= radix;
             buf[--i] = cast(char)((x < 10) ? x + '0' : x - 10 + 'a');
         }
     } while (value);
     return buf[i .. $];
 }

 /************* unit tests **************************************************/

 unittest
 {
     OutBuffer buf;
     buf.printf("betty");
     buf.insert(1, "xx".ptr, 2);
     buf.insert(3, "yy");
     buf.remove(4, 1);
     buf.bracket('(', ')');
     const char[] s = buf[];
     assert(s == "(bxxyetty)");
     buf.destroy();
 }

 unittest
 {
     OutBuffer buf;
     buf.writestring("abc".ptr);
     buf.prependstring("def");
     buf.prependbyte('x');
     OutBuffer buf2;
     buf2.writestring("mmm");
     buf.write(&buf2);
     char[] s = buf.extractSlice();
     assert(s == "xdefabcmmm");
 }

 unittest
 {
     OutBuffer buf;
     buf.writeByte('a');
     char[] s = buf.extractSlice();
     assert(s == "a");

     buf.writeByte('b');
     char[] t = buf.extractSlice();
     assert(t == "b");
 }

 unittest
 {
     OutBuffer buf;
     char* p = buf.peekChars();
     assert(*p == 0);

     buf.writeByte('s');
     char* q = buf.peekChars();
     assert(strcmp(q, "s") == 0);
 }

 unittest
 {
     char[10] buf;
     char[] s = unsignedToTempString(278, buf[], 10);
     assert(s == "278");

     s = unsignedToTempString(1, buf[], 10);
     assert(s == "1");

     s = unsignedToTempString(8, buf[], 2);
     assert(s == "1000");

     s = unsignedToTempString(29, buf[], 16);
     assert(s == "1d");
 }

 unittest
 {
     OutBuffer buf;
     buf.writeUTF8(0x0000_0011);
     buf.writeUTF8(0x0000_0111);
     buf.writeUTF8(0x0000_1111);
     buf.writeUTF8(0x0001_1111);
     buf.writeUTF8(0x0010_0000);
     assert(buf[] == "\x11\U00000111\U00001111\U00011111\U00100000");

     buf.reset();
     buf.writeUTF16(0x0000_0011);
     buf.writeUTF16(0x0010_FFFF);
     assert(buf[] == cast(string) "\u0011\U0010FFFF"w);
 }

 unittest
 {
     OutBuffer buf;
     buf.doindent = true;

     const(char)[] s = "abc";
     buf.writestring(s);
     buf.level += 1;
     buf.indent();
     buf.writestring("abs");

     assert(buf[] == "abc\tabs");

     buf.setsize(4);
     assert(buf.length == 4);
 }
	/**
	* An expandable buffer in which you can write text or binary data.
	*
	* Copyright: Copyright (C) 1999-2022 by The D Language Foundation, All Rights Reserved
	* Authors: Walter Bright, https://www.digitalmars.com
	* License: $(LINK2 https://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
	* Source: $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/root/outbuffer.d, root/_outbuffer.d)
	* Documentation: https://dlang.org/phobos/dmd_root_outbuffer.html
	* Coverage: https://codecov.io/gh/dlang/dmd/src/master/src/dmd/root/outbuffer.d
	*/

	module dmd.common.outbuffer;

	import core.stdc.stdarg;
	import core.stdc.stdio;
	import core.stdc.string;
	import core.stdc.stdlib;

	nothrow:

	// In theory these functions should also restore errno, but we don't care because
	// we abort application on error anyway.
	extern (C) private pure @system @nogc nothrow
	{
	pragma(mangle, "malloc") void* pureMalloc(size_t);
	pragma(mangle, "realloc") void* pureRealloc(void* ptr, size_t size);
	pragma(mangle, "free") void pureFree(void* ptr);
	}

	debug
	{
	debug = stomp; // flush out dangling pointer problems by stomping on unused memory
	}

	/**
	`OutBuffer` is a write-only output stream of untyped data. It is backed up by
	a contiguous array or a memory-mapped file.
	*/
	struct OutBuffer
	{
	import dmd.common.file : FileMapping, touchFile, writeFile;

	// IMPORTANT: PLEASE KEEP STATE AND DESTRUCTOR IN SYNC WITH DEFINITION IN ./outbuffer.h.
	// state {
	private ubyte[] data;
	private size_t offset;
	private bool notlinehead;
	/// File mapping, if any. Use a pointer for ABI compatibility with the C++ counterpart.
	/// If the pointer is non-null the store is a memory-mapped file, otherwise the store is RAM.
	private FileMapping!ubyte* fileMapping;
	/// Whether to indent
	bool doindent;
	/// Whether to indent by 4 spaces or by tabs;
	bool spaces;
	/// Current indent level
	int level;
	// state }

	nothrow:

	/**
	Construct given size.
	*/
	this(size_t initialSize) nothrow
	{
	reserve(initialSize);
	}

	/**
	Construct from filename. Will map the file into memory (or create it anew
	if necessary) and start writing at the beginning of it.

	Params:
	filename = zero-terminated name of file to map into memory
	*/
	@trusted this(const(char)* filename)
	{
	FileMapping!ubyte model;
	fileMapping = cast(FileMapping!ubyte*) malloc(model.sizeof);
	memcpy(fileMapping, &model, model.sizeof);
	fileMapping.__ctor(filename);
	//fileMapping = new FileMapping!ubyte(filename);
	data = (*fileMapping)[];
	}

	/**
	Frees resources associated.
	*/
	extern (C++) void dtor() pure nothrow @trusted
	{
	if (fileMapping)
	{
	if (fileMapping.active)
	fileMapping.close();
	}
	else
	{
	debug (stomp) memset(data.ptr, 0xFF, data.length);
	pureFree(data.ptr);
	}
	}

	/**
	Frees resources associated automatically.
	*/
	extern (C++) ~this() pure nothrow @trusted
	{
	dtor();
	}

	/// For porting with ease from dmd.backend.outbuf.Outbuffer
	ubyte* buf() nothrow @system {
	return data.ptr;
	}

	/// For porting with ease from dmd.backend.outbuf.Outbuffer
	ubyte** bufptr() nothrow @system {
	static struct Array { size_t length; ubyte* ptr; }
	auto a = cast(Array*) &data;
	assert(a.length == data.length && a.ptr == data.ptr);
	return &a.ptr;
	}

	extern (C++) size_t length() const pure @nogc @safe nothrow { return offset; }

	/**********************
	* Transfer ownership of the allocated data to the caller.
	* Returns:
	* pointer to the allocated data
	*/
	extern (C++) char* extractData() pure nothrow @nogc @trusted
	{
	char* p = cast(char*)data.ptr;
	data = null;
	offset = 0;
	return p;
	}

	/**
	Releases all resources associated with `this` and resets it as an empty
	memory buffer. The config variables `notlinehead`, `doindent` etc. are
	not changed.
	*/
	extern (C++) void destroy() pure nothrow @trusted
	{
	dtor();
	fileMapping = null;
	data = null;
	offset = 0;
	}

	/**
	Reserves `nbytes` bytes of additional memory (or file space) in advance.
	The resulting capacity is at least the previous length plus `nbytes`.

	Params:
	nbytes = the number of additional bytes to reserve
	*/
	extern (C++) void reserve(size_t nbytes) pure nothrow @trusted
	{
	//debug (stomp) printf("OutBuffer::reserve: size = %lld, offset = %lld, nbytes = %lld\n", data.length, offset, nbytes);
	const minSize = offset + nbytes;
	if (data.length >= minSize)
	return;

	/* Increase by factor of 1.5; round up to 16 bytes.
	* The odd formulation is so it will map onto single x86 LEA instruction.
	*/
	const size = ((minSize * 3 + 30) / 2) & ~15;

	if (fileMapping && fileMapping.active)
	{
	fileMapping.resize(size);
	data = (*fileMapping)[];
	}
	else
	{
	debug (stomp)
	{
	auto p = cast(ubyte*) pureMalloc(size);
	p \|\| assert(0, "OutBuffer: out of memory.");
	memcpy(p, data.ptr, offset);
	memset(data.ptr, 0xFF, data.length); // stomp old location
	pureFree(data.ptr);
	memset(p + offset, 0xff, size - offset); // stomp unused data
	}
	else
	{
	auto p = cast(ubyte*) pureRealloc(data.ptr, size);
	p \|\| assert(0, "OutBuffer: out of memory.");
	memset(p + offset + nbytes, 0xff, size - offset - nbytes);
	}
	data = p[0 .. size];
	}
	}

	/************************
	* Shrink the size of the data to `size`.
	* Params:
	* size = new size of data, must be <= `.length`
	*/
	extern (C++) void setsize(size_t size) pure nothrow @nogc @safe
	{
	assert(size <= data.length);
	offset = size;
	}

	extern (C++) void reset() pure nothrow @nogc @safe
	{
	offset = 0;
	}

	private void indent() pure nothrow @safe
	{
	if (level)
	{
	const indentLevel = spaces ? level * 4 : level;
	reserve(indentLevel);
	data[offset .. offset + indentLevel] = (spaces ? ' ' : '\t');
	offset += indentLevel;
	}
	notlinehead = true;
	}

	// Write an array to the buffer, no reserve check
	@system nothrow
	void writen(const void *b, size_t len)
	{
	memcpy(data.ptr + offset, b, len);
	offset += len;
	}

	extern (C++) void write(const(void)* data, size_t nbytes) pure nothrow @system
	{
	write(data[0 .. nbytes]);
	}

	void write(scope const(void)[] buf) pure nothrow @trusted
	{
	if (doindent && !notlinehead)
	indent();
	reserve(buf.length);
	memcpy(this.data.ptr + offset, buf.ptr, buf.length);
	offset += buf.length;
	}

	/**
	* Writes a 16 bit value, no reserve check.
	*/
	@trusted nothrow
	void write16n(int v)
	{
	auto x = cast(ushort) v;
	data[offset] = x & 0x00FF;
	data[offset + 1] = x >> 8u;
	offset += 2;
	}

	/**
	* Writes a 16 bit value.
	*/
	void write16(int v) nothrow
	{
	auto u = cast(ushort) v;
	write(&u, u.sizeof);
	}

	/**
	* Writes a 32 bit int.
	*/
	void write32(int v) nothrow @trusted
	{
	write(&v, v.sizeof);
	}

	/**
	* Writes a 64 bit int.
	*/
	@trusted void write64(long v) nothrow
	{
	write(&v, v.sizeof);
	}

	/// NOT zero-terminated
	extern (C++) void writestring(const(char)* s) pure nothrow @system
	{
	if (!s)
	return;
	import core.stdc.string : strlen;
	write(s[0 .. strlen(s)]);
	}

	/// ditto
	void writestring(scope const(char)[] s) pure nothrow @safe
	{
	write(s);
	}

	/// ditto
	void writestring(scope string s) pure nothrow @safe
	{
	write(s);
	}

	/// NOT zero-terminated, followed by newline
	void writestringln(const(char)[] s) pure nothrow @safe
	{
	writestring(s);
	writenl();
	}

	/** Write string to buffer, ensure it is zero terminated
	*/
	void writeStringz(const(char)* s) pure nothrow @system
	{
	write(s[0 .. strlen(s)+1]);
	}

	/// ditto
	void writeStringz(const(char)[] s) pure nothrow @safe
	{
	write(s);
	writeByte(0);
	}

	/// ditto
	void writeStringz(string s) pure nothrow @safe
	{
	writeStringz(cast(const(char)[])(s));
	}

	extern (C++) void prependstring(const(char)* string) pure nothrow @system
	{
	size_t len = strlen(string);
	reserve(len);
	memmove(data.ptr + len, data.ptr, offset);
	memcpy(data.ptr, string, len);
	offset += len;
	}

	/// write newline
	extern (C++) void writenl() pure nothrow @safe
	{
	version (Windows)
	{
	writeword(0x0A0D); // newline is CR,LF on Microsoft OS's
	}
	else
	{
	writeByte('\n');
	}
	if (doindent)
	notlinehead = false;
	}

	// Write n zeros; return pointer to start of zeros
	@trusted
	void *writezeros(size_t n) nothrow
	{
	reserve(n);
	auto result = memset(data.ptr + offset, 0, n);
	offset += n;
	return result;
	}

	// Position buffer to accept the specified number of bytes at offset
	@trusted
	void position(size_t where, size_t nbytes) nothrow
	{
	if (where + nbytes > data.length)
	{
	reserve(where + nbytes - offset);
	}
	offset = where;

	debug assert(offset + nbytes <= data.length);
	}

	/**
	* Writes an 8 bit byte, no reserve check.
	*/
	extern (C++) @trusted nothrow
	void writeByten(int b)
	{
	this.data[offset++] = cast(ubyte) b;
	}

	extern (C++) void writeByte(uint b) pure nothrow @safe
	{
	if (doindent && !notlinehead && b != '\n')
	indent();
	reserve(1);
	this.data[offset] = cast(ubyte)b;
	offset++;
	}

	extern (C++) void writeUTF8(uint b) pure nothrow @safe
	{
	reserve(6);
	if (b <= 0x7F)
	{
	this.data[offset] = cast(ubyte)b;
	offset++;
	}
	else if (b <= 0x7FF)
	{
	this.data[offset + 0] = cast(ubyte)((b >> 6) \| 0xC0);
	this.data[offset + 1] = cast(ubyte)((b & 0x3F) \| 0x80);
	offset += 2;
	}
	else if (b <= 0xFFFF)
	{
	this.data[offset + 0] = cast(ubyte)((b >> 12) \| 0xE0);
	this.data[offset + 1] = cast(ubyte)(((b >> 6) & 0x3F) \| 0x80);
	this.data[offset + 2] = cast(ubyte)((b & 0x3F) \| 0x80);
	offset += 3;
	}
	else if (b <= 0x1FFFFF)
	{
	this.data[offset + 0] = cast(ubyte)((b >> 18) \| 0xF0);
	this.data[offset + 1] = cast(ubyte)(((b >> 12) & 0x3F) \| 0x80);
	this.data[offset + 2] = cast(ubyte)(((b >> 6) & 0x3F) \| 0x80);
	this.data[offset + 3] = cast(ubyte)((b & 0x3F) \| 0x80);
	offset += 4;
	}
	else
	assert(0);
	}

	extern (C++) void prependbyte(uint b) pure nothrow @trusted
	{
	reserve(1);
	memmove(data.ptr + 1, data.ptr, offset);
	data[0] = cast(ubyte)b;
	offset++;
	}

	extern (C++) void writewchar(uint w) pure nothrow @safe
	{
	version (Windows)
	{
	writeword(w);
	}
	else
	{
	write4(w);
	}
	}

	extern (C++) void writeword(uint w) pure nothrow @trusted
	{
	version (Windows)
	{
	uint newline = 0x0A0D;
	}
	else
	{
	uint newline = '\n';
	}
	if (doindent && !notlinehead && w != newline)
	indent();

	reserve(2);
	cast(ushort)(this.data.ptr + offset) = cast(ushort)w;
	offset += 2;
	}

	extern (C++) void writeUTF16(uint w) pure nothrow @trusted
	{
	reserve(4);
	if (w <= 0xFFFF)
	{
	cast(ushort)(this.data.ptr + offset) = cast(ushort)w;
	offset += 2;
	}
	else if (w <= 0x10FFFF)
	{
	cast(ushort)(this.data.ptr + offset) = cast(ushort)((w >> 10) + 0xD7C0);
	cast(ushort)(this.data.ptr + offset + 2) = cast(ushort)((w & 0x3FF) \| 0xDC00);
	offset += 4;
	}
	else
	assert(0);
	}

	extern (C++) void write4(uint w) pure nothrow @trusted
	{
	version (Windows)
	{
	bool notnewline = w != 0x000A000D;
	}
	else
	{
	bool notnewline = true;
	}
	if (doindent && !notlinehead && notnewline)
	indent();
	reserve(4);
	cast(uint)(this.data.ptr + offset) = w;
	offset += 4;
	}

	extern (C++) void write(const OutBuffer* buf) pure nothrow @trusted
	{
	if (buf)
	{
	reserve(buf.offset);
	memcpy(data.ptr + offset, buf.data.ptr, buf.offset);
	offset += buf.offset;
	}
	}

	extern (C++) void fill0(size_t nbytes) pure nothrow @trusted
	{
	reserve(nbytes);
	memset(data.ptr + offset, 0, nbytes);
	offset += nbytes;
	}

	/**
	* Allocate space, but leave it uninitialized.
	* Params:
	* nbytes = amount to allocate
	* Returns:
	* slice of the allocated space to be filled in
	*/
	extern (D) char[] allocate(size_t nbytes) pure nothrow
	{
	reserve(nbytes);
	offset += nbytes;
	return cast(char[])data[offset - nbytes .. offset];
	}

	extern (C++) void vprintf(const(char)* format, va_list args) nothrow @system
	{
	int count;
	if (doindent && !notlinehead)
	indent();
	uint psize = 128;
	for (;;)
	{
	reserve(psize);
	va_list va;
	va_copy(va, args);
	/*
	The functions vprintf(), vfprintf(), vsprintf(), vsnprintf()
	are equivalent to the functions printf(), fprintf(), sprintf(),
	snprintf(), respectively, except that they are called with a
	va_list instead of a variable number of arguments. These
	functions do not call the va_end macro. Consequently, the value
	of ap is undefined after the call. The application should call
	va_end(ap) itself afterwards.
	*/
	count = vsnprintf(cast(char*)data.ptr + offset, psize, format, va);
	va_end(va);
	if (count == -1) // snn.lib and older libcmt.lib return -1 if buffer too small
	psize *= 2;
	else if (count >= psize)
	psize = count + 1;
	else
	break;
	}
	offset += count;
	// if (mem.isGCEnabled)
	memset(data.ptr + offset, 0xff, psize - count);
	}

	static if (__VERSION__ < 2092)
	{
	extern (C++) void printf(const(char)* format, ...) nothrow @system
	{
	va_list ap;
	va_start(ap, format);
	vprintf(format, ap);
	va_end(ap);
	}
	}
	else
	{
	pragma(printf) extern (C++) void printf(const(char)* format, ...) nothrow @system
	{
	va_list ap;
	va_start(ap, format);
	vprintf(format, ap);
	va_end(ap);
	}
	}

	/**************************************
	* Convert `u` to a string and append it to the buffer.
	* Params:
	* u = integral value to append
	*/
	extern (C++) void print(ulong u) pure nothrow @safe
	{
	UnsignedStringBuf buf = void;
	writestring(unsignedToTempString(u, buf));
	}

	extern (C++) void bracket(char left, char right) pure nothrow @trusted
	{
	reserve(2);
	memmove(data.ptr + 1, data.ptr, offset);
	data[0] = left;
	data[offset + 1] = right;
	offset += 2;
	}

	/******************
	* Insert left at i, and right at j.
	* Return index just past right.
	*/
	extern (C++) size_t bracket(size_t i, const(char)* left, size_t j, const(char)* right) pure nothrow @system
	{
	size_t leftlen = strlen(left);
	size_t rightlen = strlen(right);
	reserve(leftlen + rightlen);
	insert(i, left, leftlen);
	insert(j + leftlen, right, rightlen);
	return j + leftlen + rightlen;
	}

	extern (C++) void spread(size_t offset, size_t nbytes) pure nothrow @system
	{
	reserve(nbytes);
	memmove(data.ptr + offset + nbytes, data.ptr + offset, this.offset - offset);
	this.offset += nbytes;
	}

	/****************************************
	* Returns: offset + nbytes
	*/
	extern (C++) size_t insert(size_t offset, const(void)* p, size_t nbytes) pure nothrow @system
	{
	spread(offset, nbytes);
	memmove(data.ptr + offset, p, nbytes);
	return offset + nbytes;
	}

	size_t insert(size_t offset, const(char)[] s) pure nothrow @system
	{
	return insert(offset, s.ptr, s.length);
	}

	extern (C++) void remove(size_t offset, size_t nbytes) pure nothrow @nogc @system
	{
	memmove(data.ptr + offset, data.ptr + offset + nbytes, this.offset - (offset + nbytes));
	this.offset -= nbytes;
	}

	/**
	* Returns:
	* a non-owning const slice of the buffer contents
	*/
	extern (D) const(char)[] opSlice() const pure nothrow @nogc @safe
	{
	return cast(const(char)[])data[0 .. offset];
	}

	extern (D) const(char)[] opSlice(size_t lwr, size_t upr) const pure nothrow @nogc @safe
	{
	return cast(const(char)[])data[lwr .. upr];
	}

	extern (D) char opIndex(size_t i) const pure nothrow @nogc @safe
	{
	return cast(char)data[i];
	}

	alias opDollar = length;

	/***********************************
	* Extract the data as a slice and take ownership of it.
	*
	* When `true` is passed as an argument, this function behaves
	* like `dmd.utils.toDString(thisbuffer.extractChars())`.
	*
	* Params:
	* nullTerminate = When `true`, the data will be `null` terminated.
	* This is useful to call C functions or store
	* the result in `Strings`. Defaults to `false`.
	*/
	extern (D) char[] extractSlice(bool nullTerminate = false) pure nothrow
	{
	const length = offset;
	if (!nullTerminate)
	return extractData()[0 .. length];
	// There's already a terminating `'\0'`
	if (length && data[length - 1] == '\0')
	return extractData()[0 .. length - 1];
	writeByte(0);
	return extractData()[0 .. length];
	}

	extern (D) byte[] extractUbyteSlice(bool nullTerminate = false) pure nothrow
	{
	return cast(byte[]) extractSlice(nullTerminate);
	}

	// Append terminating null if necessary and get view of internal buffer
	extern (C++) char* peekChars() pure nothrow
	{
	if (!offset \|\| data[offset - 1] != '\0')
	{
	writeByte(0);
	offset--; // allow appending more
	}
	return cast(char*)data.ptr;
	}

	// Append terminating null if necessary and take ownership of data
	extern (C++) char* extractChars() pure nothrow
	{
	if (!offset \|\| data[offset - 1] != '\0')
	writeByte(0);
	return extractData();
	}

	void writesLEB128(int value) pure nothrow @safe
	{
	while (1)
	{
	ubyte b = value & 0x7F;

	value >>= 7; // arithmetic right shift
	if ((value == 0 && !(b & 0x40)) \|\|
	(value == -1 && (b & 0x40)))
	{
	writeByte(b);
	break;
	}
	writeByte(b \| 0x80);
	}
	}

	void writeuLEB128(uint value) pure nothrow @safe
	{
	do
	{
	ubyte b = value & 0x7F;

	value >>= 7;
	if (value)
	b \|= 0x80;
	writeByte(b);
	} while (value);
	}

	/**
	Destructively saves the contents of `this` to `filename`. As an
	optimization, if the file already has identical contents with the buffer,
	no copying is done. This is because on SSD drives reading is often much
	faster than writing and because there's a high likelihood an identical
	file is written during the build process.

	Params:
	filename = the name of the file to receive the contents

	Returns: `true` iff the operation succeeded.
	*/
	extern(D) bool moveToFile(const char* filename) @system
	{
	bool result = true;
	const bool identical = this[] == FileMapping!(const ubyte)(filename)[];

	if (fileMapping && fileMapping.active)
	{
	// Defer to corresponding functions in FileMapping.
	if (identical)
	{
	result = fileMapping.discard();
	}
	else
	{
	// Resize to fit to get rid of the slack bytes at the end
	fileMapping.resize(offset);
	result = fileMapping.moveToFile(filename);
	}
	// Can't call destroy() here because the file mapping is already closed.
	data = null;
	offset = 0;
	}
	else
	{
	if (!identical)
	writeFile(filename, this[]);
	destroy();
	}

	return identical
	? result && touchFile(filename)
	: result;
	}
	}

	/**** copied from core.internal.string ***********/

	private:

	alias UnsignedStringBuf = char[20];

	char[] unsignedToTempString(ulong value, return scope char[] buf, uint radix = 10) @safe pure nothrow @nogc
	{
	size_t i = buf.length;
	do
	{
	if (value < radix)
	{
	ubyte x = cast(ubyte)value;
	buf[--i] = cast(char)((x < 10) ? x + '0' : x - 10 + 'a');
	break;
	}
	else
	{
	ubyte x = cast(ubyte)(value % radix);
	value /= radix;
	buf[--i] = cast(char)((x < 10) ? x + '0' : x - 10 + 'a');
	}
	} while (value);
	return buf[i .. $];
	}

	/*********** unit tests ************************************************/

	unittest
	{
	OutBuffer buf;
	buf.printf("betty");
	buf.insert(1, "xx".ptr, 2);
	buf.insert(3, "yy");
	buf.remove(4, 1);
	buf.bracket('(', ')');
	const char[] s = buf[];
	assert(s == "(bxxyetty)");
	buf.destroy();
	}

	unittest
	{
	OutBuffer buf;
	buf.writestring("abc".ptr);
	buf.prependstring("def");
	buf.prependbyte('x');
	OutBuffer buf2;
	buf2.writestring("mmm");
	buf.write(&buf2);
	char[] s = buf.extractSlice();
	assert(s == "xdefabcmmm");
	}

	unittest
	{
	OutBuffer buf;
	buf.writeByte('a');
	char[] s = buf.extractSlice();
	assert(s == "a");

	buf.writeByte('b');
	char[] t = buf.extractSlice();
	assert(t == "b");
	}

	unittest
	{
	OutBuffer buf;
	char* p = buf.peekChars();
	assert(*p == 0);

	buf.writeByte('s');
	char* q = buf.peekChars();
	assert(strcmp(q, "s") == 0);
	}

	unittest
	{
	char[10] buf;
	char[] s = unsignedToTempString(278, buf[], 10);
	assert(s == "278");

	s = unsignedToTempString(1, buf[], 10);
	assert(s == "1");

	s = unsignedToTempString(8, buf[], 2);
	assert(s == "1000");

	s = unsignedToTempString(29, buf[], 16);
	assert(s == "1d");
	}

	unittest
	{
	OutBuffer buf;
	buf.writeUTF8(0x0000_0011);
	buf.writeUTF8(0x0000_0111);
	buf.writeUTF8(0x0000_1111);
	buf.writeUTF8(0x0001_1111);
	buf.writeUTF8(0x0010_0000);
	assert(buf[] == "\x11\U00000111\U00001111\U00011111\U00100000");

	buf.reset();
	buf.writeUTF16(0x0000_0011);
	buf.writeUTF16(0x0010_FFFF);
	assert(buf[] == cast(string) "\u0011\U0010FFFF"w);
	}

	unittest
	{
	OutBuffer buf;
	buf.doindent = true;

	const(char)[] s = "abc";
	buf.writestring(s);
	buf.level += 1;
	buf.indent();
	buf.writestring("abs");

	assert(buf[] == "abc\tabs");

	buf.setsize(4);
	assert(buf.length == 4);
	}