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Annotation of gcc/cp-input.c, revision 1.1

1.1     ! root        1: /* Input handling for G++.
        !             2:    Written by Ken Raeburn of Watchmaker Computing.
        !             3:    Copyright (C) 1992 Free Software Foundation, Inc.
        !             4: 
        !             5: This file is part of GNU CC.
        !             6: 
        !             7: GNU CC is free software; you can redistribute it and/or modify
        !             8: it under the terms of the GNU General Public License as published by
        !             9: the Free Software Foundation; either version 2, or (at your option)
        !            10: any later version.
        !            11: 
        !            12: GNU CC is distributed in the hope that it will be useful,
        !            13: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            15: GNU General Public License for more details.
        !            16: 
        !            17: You should have received a copy of the GNU General Public License
        !            18: along with GNU CC; see the file COPYING.  If not, write to
        !            19: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
        !            20: 
        !            21: /* G++ needs to do enough saving and re-parsing of text that it is
        !            22:    necessary to abandon the simple FILE* model and use a mechanism where
        !            23:    we can pre-empt one input stream with another derived from saved text;
        !            24:    we may need to do this arbitrarily often, and cannot depend on having
        !            25:    the GNU library available, so FILE objects just don't cut it.
        !            26: 
        !            27:    This file is written as a separate module, but can be included by
        !            28:    cp-lex.c for very minor efficiency gains (primarily in function
        !            29:    inlining).  */
        !            30: 
        !            31: #include <assert.h>
        !            32: #include <stdio.h>
        !            33: #include "obstack.h"
        !            34: 
        !            35: extern FILE *finput;
        !            36: 
        !            37: struct pending_input *save_pending_input ();
        !            38: void restore_pending_input ();
        !            39: 
        !            40: struct input_source {
        !            41:   /* saved string */
        !            42:   char *str;
        !            43:   int length;
        !            44:   /* current position, when reading as input */
        !            45:   int offset;
        !            46:   /* obstack to free this input string from when finished, if any */
        !            47:   struct obstack *obstack;
        !            48:   /* linked list maintenance */
        !            49:   struct input_source *next;
        !            50:   /* values to restore after reading all of current string */
        !            51:   char *filename;
        !            52:   int lineno;
        !            53:   struct pending_input *input;
        !            54:   int putback_char;
        !            55: };
        !            56: 
        !            57: static struct input_source *input, *free_inputs;
        !            58: 
        !            59: extern char *input_filename;
        !            60: extern int lineno;
        !            61: 
        !            62: #ifdef __GNUC__
        !            63: #define inline __inline__
        !            64: #else
        !            65: #define inline
        !            66: #endif
        !            67: 
        !            68: static inline struct input_source *
        !            69: allocate_input ()
        !            70: {
        !            71:   struct input_source *inp;
        !            72:   if (free_inputs)
        !            73:     {
        !            74:       inp = free_inputs;
        !            75:       free_inputs = inp->next;
        !            76:       inp->next = 0;
        !            77:       return inp;
        !            78:     }
        !            79:   inp = (struct input_source *) xmalloc (sizeof (struct input_source));
        !            80:   inp->next = 0;
        !            81:   inp->obstack = 0;
        !            82:   return inp;
        !            83: }
        !            84: 
        !            85: static inline void
        !            86: free_input (inp)
        !            87:      struct input_source *inp;
        !            88: {
        !            89:   if (inp->obstack)
        !            90:     obstack_free (inp->obstack, inp->str);
        !            91:   inp->obstack = 0;
        !            92:   inp->str = 0;
        !            93:   inp->length = 0;
        !            94:   inp->next = free_inputs;
        !            95:   free_inputs = inp;
        !            96: }
        !            97: 
        !            98: static int putback_char = -1;
        !            99: 
        !           100: /* Some of these external functions are declared inline in case this file
        !           101:    is included in cp-lex.c.  */
        !           102: 
        !           103: inline
        !           104: void
        !           105: feed_input (str, len, delete)
        !           106:      char *str;
        !           107:      struct obstack *delete;
        !           108: {
        !           109:   struct input_source *inp = allocate_input ();
        !           110: 
        !           111:   /* This shouldn't be necessary.  */
        !           112:   while (len && !str[len-1])
        !           113:     len--;
        !           114: 
        !           115:   inp->str = str;
        !           116:   inp->length = len;
        !           117:   inp->obstack = delete;
        !           118:   inp->offset = 0;
        !           119:   inp->next = input;
        !           120:   inp->filename = input_filename;
        !           121:   inp->lineno = lineno;
        !           122:   inp->input = save_pending_input ();
        !           123:   inp->putback_char = putback_char;
        !           124:   putback_char = -1;
        !           125:   input = inp;
        !           126: }
        !           127: 
        !           128: struct pending_input *to_be_restored; /* XXX */
        !           129: extern int end_of_file;
        !           130: 
        !           131: int
        !           132: getch ()
        !           133: {
        !           134:   if (putback_char != -1)
        !           135:     {
        !           136:       int ch = putback_char;
        !           137:       putback_char = -1;
        !           138:       return ch;
        !           139:     }
        !           140:   if (input)
        !           141:     {
        !           142:       if (input->offset == input->length)
        !           143:        {
        !           144:          struct input_source *inp = input;
        !           145:          assert (putback_char == -1);
        !           146:          to_be_restored = inp->input;
        !           147:          input->offset++;
        !           148:          return EOF;
        !           149:        }
        !           150:       else if (input->offset > input->length)
        !           151:        {
        !           152:          struct input_source *inp = input;
        !           153: 
        !           154:          end_of_file = 0;
        !           155:          input = inp->next;
        !           156:          input_filename = inp->filename;
        !           157:          lineno = inp->lineno;
        !           158:          /* Get interface/implementation back in sync. */
        !           159:          extract_interface_info ();
        !           160:          putback_char = inp->putback_char;
        !           161:          free_input (inp);
        !           162:          return getch ();
        !           163:        }
        !           164:       if (input)
        !           165:        return input->str[input->offset++];
        !           166:     }
        !           167:   return getc (finput);
        !           168: }
        !           169: 
        !           170: inline
        !           171: void
        !           172: put_back (ch)
        !           173:      int ch;
        !           174: {
        !           175:   assert (putback_char == -1);
        !           176:   putback_char = ch;
        !           177: }
        !           178: 
        !           179: inline
        !           180: int
        !           181: input_redirected ()
        !           182: {
        !           183:   return input != 0;
        !           184: }

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