| 1 | /* GNU m4 -- A simple macro processor
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| 2 |
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| 3 | Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 2006 Free Software
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| 4 | Foundation, Inc.
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| 5 |
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| 6 | This program is free software; you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation; either version 2 of the License, or
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| 9 | (at your option) any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License
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| 17 | along with this program; if not, write to the Free Software
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| 18 | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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| 19 | 02110-1301 USA
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| 20 | */
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| 21 |
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| 22 | /* This file contains the functions, that performs the basic argument
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| 23 | parsing and macro expansion. */
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| 24 |
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| 25 | #include "m4.h"
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| 26 |
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| 27 | static void expand_macro (symbol *);
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| 28 | static void expand_token (struct obstack *, token_type, token_data *);
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| 29 |
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| 30 | /* Current recursion level in expand_macro (). */
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| 31 | int expansion_level = 0;
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| 32 |
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| 33 | /* The number of the current call of expand_macro (). */
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| 34 | static int macro_call_id = 0;
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| 35 |
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| 36 | /* The shared stack of collected arguments for macro calls; as each
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| 37 | argument is collected, it is finished and its location stored in
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| 38 | argv_stack. Normally, this stack can be used simultaneously by
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| 39 | multiple macro calls; the exception is when an outer macro has
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| 40 | generated some text, then calls a nested macro, in which case the
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| 41 | nested macro must use a local stack to leave the unfinished text
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| 42 | alone. Too bad obstack.h does not provide an easy way to reopen a
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| 43 | finished object for further growth, but in practice this does not
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| 44 | hurt us too much. */
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| 45 | static struct obstack argc_stack;
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| 46 |
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| 47 | /* The shared stack of pointers to collected arguments for macro
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| 48 | calls. This object is never finished; we exploit the fact that
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| 49 | obstack_blank is documented to take a negative size to reduce the
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| 50 | size again. */
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| 51 | static struct obstack argv_stack;
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| 52 |
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| 53 | /*----------------------------------------------------------------------.
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| 54 | | This function read all input, and expands each token, one at a time. |
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| 55 | `----------------------------------------------------------------------*/
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| 56 |
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| 57 | void
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| 58 | expand_input (void)
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| 59 | {
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| 60 | token_type t;
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| 61 | token_data td;
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| 62 |
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| 63 | obstack_init (&argc_stack);
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| 64 | obstack_init (&argv_stack);
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| 65 |
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| 66 | while ((t = next_token (&td)) != TOKEN_EOF)
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| 67 | expand_token ((struct obstack *) NULL, t, &td);
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| 68 |
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| 69 | obstack_free (&argc_stack, NULL);
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| 70 | obstack_free (&argv_stack, NULL);
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| 71 | }
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| 72 | |
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| 73 |
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| 74 |
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| 75 | /*------------------------------------------------------------------------.
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| 76 | | Expand one token, according to its type. Potential macro names |
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| 77 | | (TOKEN_WORD) are looked up in the symbol table, to see if they have a |
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| 78 | | macro definition. If they have, they are expanded as macros, otherwise |
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| 79 | | the text are just copied to the output. |
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| 80 | `------------------------------------------------------------------------*/
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| 81 |
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| 82 | static void
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| 83 | expand_token (struct obstack *obs, token_type t, token_data *td)
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| 84 | {
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| 85 | symbol *sym;
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| 86 |
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| 87 | switch (t)
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| 88 | { /* TOKSW */
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| 89 | case TOKEN_EOF:
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| 90 | case TOKEN_MACDEF:
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| 91 | break;
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| 92 |
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| 93 | case TOKEN_OPEN:
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| 94 | case TOKEN_COMMA:
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| 95 | case TOKEN_CLOSE:
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| 96 | case TOKEN_SIMPLE:
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| 97 | case TOKEN_STRING:
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| 98 | shipout_text (obs, TOKEN_DATA_TEXT (td), strlen (TOKEN_DATA_TEXT (td)));
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| 99 | break;
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| 100 |
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| 101 | case TOKEN_WORD:
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| 102 | sym = lookup_symbol (TOKEN_DATA_TEXT (td), SYMBOL_LOOKUP);
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