525 lines
15 KiB
C
525 lines
15 KiB
C
/***********************************************************************/
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/* */
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/* Objective Caml */
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/* */
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/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
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/* */
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/* Copyright 1996 Institut National de Recherche en Informatique et */
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/* en Automatique. All rights reserved. This file is distributed */
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/* under the terms of the GNU Library General Public License, with */
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/* the special exception on linking described in file ../../LICENSE. */
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/* */
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/***********************************************************************/
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/* $Id$ */
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#include <string.h>
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#include <ctype.h>
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#include <mlvalues.h>
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#include <alloc.h>
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#include <memory.h>
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#include <fail.h>
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/* The backtracking NFA interpreter */
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union backtrack_point {
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struct {
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value * pc; /* with low bit set */
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unsigned char * txt;
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} pos;
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struct {
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unsigned char ** loc; /* with low bit clear */
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unsigned char * val;
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} undo;
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};
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#define Set_tag(p) ((value *) ((long)(p) | 1))
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#define Clear_tag(p) ((value *) ((long)(p) & ~1))
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#define Tag_is_set(p) ((long)(p) & 1)
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#define BACKTRACK_STACK_BLOCK_SIZE 500
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struct backtrack_stack {
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struct backtrack_stack * previous;
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union backtrack_point point[BACKTRACK_STACK_BLOCK_SIZE];
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};
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#define Opcode(x) ((x) & 0xFF)
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#define Arg(x) ((unsigned long)(x) >> 8)
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#define SignedArg(x) ((long)(x) >> 8)
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enum {
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CHAR, /* match a single character */
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CHARNORM, /* match a single character, after normalization */
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STRING, /* match a character string */
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STRINGNORM, /* match a character string, after normalization */
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CHARCLASS, /* match a character class */
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BOL, /* match at beginning of line */
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EOL, /* match at end of line */
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WORDBOUNDARY, /* match on a word boundary */
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BEGGROUP, /* record the beginning of a group */
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ENDGROUP, /* record the end of a group */
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REFGROUP, /* match a previously matched group */
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ACCEPT, /* report success */
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SIMPLEOPT, /* match a character class 0 or 1 times */
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SIMPLESTAR, /* match a character class 0, 1 or several times */
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SIMPLEPLUS, /* match a character class 1 or several times */
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GOTO, /* unconditional branch */
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PUSHBACK, /* record a backtrack point --
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where to jump in case of failure */
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SETMARK, /* remember current position in given register # */
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CHECKPROGRESS /* backtrack if no progress was made w.r.t. reg # */
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};
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/* Accessors in a compiled regexp */
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#define Prog(re) Field(re, 0)
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#define Cpool(re) Field(re, 1)
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#define Normtable(re) Field(re, 2)
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#define Numgroups(re) Int_val(Field(re, 3))
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#define Numregisters(re) Int_val(Field(re, 4))
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#define Startchars(re) Int_val(Field(re, 5))
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/* Record positions of matched groups */
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#define NUM_GROUPS 32
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struct re_group {
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unsigned char * start;
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unsigned char * end;
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};
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static struct re_group re_group[NUM_GROUPS];
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/* Record positions reached during matching; used to check progress
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in repeated matching of a regexp. */
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#define NUM_REGISTERS 64
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static unsigned char * re_register[NUM_REGISTERS];
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/* The initial backtracking stack */
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static struct backtrack_stack initial_stack = { NULL, };
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/* Free a chained list of backtracking stacks */
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static void free_backtrack_stack(struct backtrack_stack * stack)
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{
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struct backtrack_stack * prevstack;
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while ((prevstack = stack->previous) != NULL) {
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stat_free(stack);
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stack = prevstack;
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}
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}
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/* Membership in a bit vector representing a set of booleans */
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#define In_bitset(s,i,tmp) (tmp = (i), ((s)[tmp >> 3] >> (tmp & 7)) & 1)
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/* Determine if a character is a word constituent */
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static unsigned char re_word_letters[32] = {
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0, 0, 0, 0, 0, 0, 0, 0, 254, 255, 255, 7, 254, 255, 255, 7,
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0, 0, 0, 0, 0, 0, 0, 0, 255, 255, 127, 255, 255, 255, 127, 255
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};
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#define Is_word_letter(c) ((re_word_letters[(c) >> 3] >> ((c) & 7)) & 1)
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/* The bytecode interpreter for the NFA */
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static int re_match(value re,
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unsigned char * starttxt,
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register unsigned char * txt,
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register unsigned char * endtxt,
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int accept_partial_match)
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{
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register value * pc;
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long instr;
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struct backtrack_stack * stack;
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union backtrack_point * sp;
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value cpool;
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value normtable;
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unsigned char c;
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union backtrack_point back;
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{ int i;
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struct re_group * p;
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unsigned char ** q;
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for (p = &re_group[1], i = Numgroups(re); i > 1; i--, p++)
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p->start = p->end = NULL;
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for (q = &re_register[0], i = Numregisters(re); i > 0; i--, q++)
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*q = NULL;
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}
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pc = &Field(Prog(re), 0);
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stack = &initial_stack;
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sp = stack->point;
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cpool = Cpool(re);
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normtable = Normtable(re);
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re_group[0].start = txt;
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while (1) {
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instr = Long_val(*pc++);
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switch (Opcode(instr)) {
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case CHAR:
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if (txt == endtxt) goto prefix_match;
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if (*txt != Arg(instr)) goto backtrack;
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txt++;
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break;
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case CHARNORM:
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if (txt == endtxt) goto prefix_match;
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if (Byte_u(normtable, *txt) != Arg(instr)) goto backtrack;
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txt++;
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break;
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case STRING: {
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unsigned char * s =
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(unsigned char *) String_val(Field(cpool, Arg(instr)));
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while ((c = *s++) != 0) {
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if (txt == endtxt) goto prefix_match;
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if (c != *txt) goto backtrack;
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txt++;
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}
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break;
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}
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case STRINGNORM: {
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unsigned char * s =
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(unsigned char *) String_val(Field(cpool, Arg(instr)));
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while ((c = *s++) != 0) {
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if (txt == endtxt) goto prefix_match;
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if (c != Byte_u(normtable, *txt)) goto backtrack;
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txt++;
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}
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break;
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}
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case CHARCLASS:
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if (txt == endtxt) goto prefix_match;
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if (! In_bitset(String_val(Field(cpool, Arg(instr))), *txt, c))
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goto backtrack;
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txt++;
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break;
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case BOL:
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if (txt > starttxt && txt[-1] != '\n') goto backtrack;
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break;
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case EOL:
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if (txt < endtxt && *txt != '\n') goto backtrack;
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break;
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case WORDBOUNDARY:
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/* At beginning and end of text: no
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At beginning of text: OK if current char is a letter
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At end of text: OK if previous char is a letter
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Otherwise:
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OK if previous char is a letter and current char not a letter
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or previous char is not a letter and current char is a letter */
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if (txt == starttxt) {
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if (txt == endtxt) goto prefix_match;
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if (Is_word_letter(txt[0])) break;
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goto backtrack;
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} else if (txt == endtxt) {
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if (Is_word_letter(txt[-1])) break;
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goto backtrack;
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} else {
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if (Is_word_letter(txt[-1]) != Is_word_letter(txt[0])) break;
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goto backtrack;
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}
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case BEGGROUP: {
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int group_no = Arg(instr);
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struct re_group * group = &(re_group[group_no]);
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back.undo.loc = &(group->start);
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back.undo.val = group->start;
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group->start = txt;
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goto push;
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}
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case ENDGROUP: {
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int group_no = Arg(instr);
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struct re_group * group = &(re_group[group_no]);
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back.undo.loc = &(group->end);
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back.undo.val = group->end;
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group->end = txt;
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goto push;
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}
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case REFGROUP: {
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int group_no = Arg(instr);
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struct re_group * group = &(re_group[group_no]);
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unsigned char * s;
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if (group->start == NULL || group->end == NULL) goto backtrack;
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for (s = group->start; s < group->end; s++) {
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if (txt == endtxt) goto prefix_match;
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if (*s != *txt) goto backtrack;
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txt++;
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}
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break;
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}
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case ACCEPT:
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goto accept;
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case SIMPLEOPT: {
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char * set = String_val(Field(cpool, Arg(instr)));
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if (txt < endtxt && In_bitset(set, *txt, c)) txt++;
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break;
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}
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case SIMPLESTAR: {
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char * set = String_val(Field(cpool, Arg(instr)));
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while (txt < endtxt && In_bitset(set, *txt, c))
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txt++;
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break;
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}
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case SIMPLEPLUS: {
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char * set = String_val(Field(cpool, Arg(instr)));
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if (txt == endtxt) goto prefix_match;
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if (! In_bitset(set, *txt, c)) goto backtrack;
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txt++;
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while (txt < endtxt && In_bitset(set, *txt, c))
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txt++;
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break;
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}
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case GOTO:
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pc = pc + SignedArg(instr);
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break;
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case PUSHBACK:
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back.pos.pc = Set_tag(pc + SignedArg(instr));
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back.pos.txt = txt;
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goto push;
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case SETMARK: {
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int reg_no = Arg(instr);
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unsigned char ** reg = &(re_register[reg_no]);
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back.undo.loc = reg;
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back.undo.val = *reg;
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*reg = txt;
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goto push;
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}
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case CHECKPROGRESS: {
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int reg_no = Arg(instr);
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if (re_register[reg_no] == txt)
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goto backtrack;
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break;
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}
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default:
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caml_fatal_error ("impossible case in re_match");
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}
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/* Continue with next instruction */
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continue;
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push:
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/* Push an item on the backtrack stack and continue with next instr */
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if (sp == stack->point + BACKTRACK_STACK_BLOCK_SIZE) {
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struct backtrack_stack * newstack =
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stat_alloc(sizeof(struct backtrack_stack));
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newstack->previous = stack;
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stack = newstack;
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sp = stack->point;
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}
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*sp = back;
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sp++;
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continue;
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prefix_match:
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/* We get here when matching failed because the end of text
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was encountered. */
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if (accept_partial_match) goto accept;
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backtrack:
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/* We get here when matching fails. Backtrack to most recent saved
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program point, undoing variable assignments on the way. */
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while (1) {
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if (sp == stack->point) {
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struct backtrack_stack * prevstack = stack->previous;
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if (prevstack == NULL) return 0;
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stat_free(stack);
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stack = prevstack;
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sp = stack->point + BACKTRACK_STACK_BLOCK_SIZE;
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}
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sp--;
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if (Tag_is_set(sp->pos.pc)) {
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pc = Clear_tag(sp->pos.pc);
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txt = sp->pos.txt;
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break;
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} else {
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*(sp->undo.loc) = sp->undo.val;
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}
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}
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continue;
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}
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accept:
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/* We get here when the regexp was successfully matched */
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free_backtrack_stack(stack);
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re_group[0].end = txt;
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return 1;
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}
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/* Allocate an integer array containing the positions of the matched groups.
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Beginning of group #N is at 2N, end is at 2N+1.
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Take position = -1 when group wasn't matched. */
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static value re_alloc_groups(value re, value str)
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{
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CAMLparam1(str);
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CAMLlocal1(res);
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unsigned char * starttxt = (unsigned char *) String_val(str);
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int n = Numgroups(re);
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int i;
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struct re_group * group;
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res = alloc(n * 2, 0);
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for (i = 0; i < n; i++) {
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group = &(re_group[i]);
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if (group->start == NULL || group->end == NULL) {
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Field(res, i * 2) = Val_int(-1);
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Field(res, i * 2 + 1) = Val_int(-1);
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} else {
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Field(res, i * 2) = Val_long(group->start - starttxt);
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Field(res, i * 2 + 1) = Val_long(group->end - starttxt);
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}
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}
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CAMLreturn(res);
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}
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/* String matching and searching. All functions return the empty array
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on failure, and an array of positions on success. */
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CAMLprim value re_string_match(value re, value str, value pos)
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{
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unsigned char * starttxt = &Byte_u(str, 0);
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unsigned char * txt = &Byte_u(str, Long_val(pos));
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unsigned char * endtxt = &Byte_u(str, string_length(str));
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if (txt < starttxt || txt > endtxt)
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invalid_argument("Str.string_match");
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if (re_match(re, starttxt, txt, endtxt, 0)) {
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return re_alloc_groups(re, str);
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} else {
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return Atom(0);
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}
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}
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CAMLprim value re_partial_match(value re, value str, value pos)
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{
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unsigned char * starttxt = &Byte_u(str, 0);
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unsigned char * txt = &Byte_u(str, Long_val(pos));
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unsigned char * endtxt = &Byte_u(str, string_length(str));
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if (txt < starttxt || txt > endtxt)
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invalid_argument("Str.string_partial_match");
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if (re_match(re, starttxt, txt, endtxt, 1)) {
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return re_alloc_groups(re, str);
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} else {
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return Atom(0);
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}
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}
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CAMLprim value re_search_forward(value re, value str, value startpos)
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{
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unsigned char * starttxt = &Byte_u(str, 0);
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unsigned char * txt = &Byte_u(str, Long_val(startpos));
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unsigned char * endtxt = &Byte_u(str, string_length(str));
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unsigned char * startchars;
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if (txt < starttxt || txt > endtxt)
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invalid_argument("Str.search_forward");
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if (Startchars(re) == -1) {
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do {
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if (re_match(re, starttxt, txt, endtxt, 0))
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return re_alloc_groups(re, str);
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txt++;
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} while (txt <= endtxt);
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return Atom(0);
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} else {
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startchars =
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(unsigned char *) String_val(Field(Cpool(re), Startchars(re)));
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do {
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while (txt < endtxt && startchars[*txt] == 0) txt++;
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if (re_match(re, starttxt, txt, endtxt, 0))
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return re_alloc_groups(re, str);
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txt++;
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} while (txt <= endtxt);
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return Atom(0);
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}
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}
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CAMLprim value re_search_backward(value re, value str, value startpos)
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{
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unsigned char * starttxt = &Byte_u(str, 0);
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unsigned char * txt = &Byte_u(str, Long_val(startpos));
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unsigned char * endtxt = &Byte_u(str, string_length(str));
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unsigned char * startchars;
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if (txt < starttxt || txt > endtxt)
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invalid_argument("Str.search_backward");
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if (Startchars(re) == -1) {
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do {
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if (re_match(re, starttxt, txt, endtxt, 0))
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return re_alloc_groups(re, str);
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txt--;
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} while (txt >= starttxt);
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return Atom(0);
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} else {
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startchars =
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(unsigned char *) String_val(Field(Cpool(re), Startchars(re)));
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do {
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while (txt > starttxt && startchars[*txt] == 0) txt--;
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if (re_match(re, starttxt, txt, endtxt, 0))
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return re_alloc_groups(re, str);
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txt--;
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} while (txt >= starttxt);
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return Atom(0);
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}
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}
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/* Replacement */
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CAMLprim value re_replacement_text(value repl, value groups, value orig)
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{
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CAMLparam3(repl, groups, orig);
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CAMLlocal1(res);
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mlsize_t start, end, len, n;
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char * p, * q;
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int c;
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len = 0;
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p = String_val(repl);
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n = string_length(repl);
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while (n > 0) {
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c = *p++; n--;
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if(c != '\\')
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len++;
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else {
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if (n == 0) failwith("Str.replace: illegal backslash sequence");
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c = *p++; n--;
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switch (c) {
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case '\\':
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len++; break;
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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c -= '0';
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if (c*2 >= Wosize_val(groups))
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failwith("Str.replace: reference to unmatched group");
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start = Long_val(Field(groups, c*2));
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end = Long_val(Field(groups, c*2 + 1));
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if (start == (mlsize_t) -1)
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failwith("Str.replace: reference to unmatched group");
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len += end - start;
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break;
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default:
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len += 2; break;
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}
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}
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}
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res = alloc_string(len);
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p = String_val(repl);
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q = String_val(res);
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n = string_length(repl);
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while (n > 0) {
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c = *p++; n--;
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if(c != '\\')
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*q++ = c;
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else {
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c = *p++; n--;
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switch (c) {
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case '\\':
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*q++ = '\\'; break;
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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c -= '0';
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start = Long_val(Field(groups, c*2));
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end = Long_val(Field(groups, c*2 + 1));
|
|
len = end - start;
|
|
memmove (q, &Byte(orig, start), len);
|
|
q += len;
|
|
break;
|
|
default:
|
|
*q++ = '\\'; *q++ = c; break;
|
|
}
|
|
}
|
|
}
|
|
CAMLreturn(res);
|
|
}
|
|
|