match.c

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/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */
 
/**
 * @file match.c
 * @brief Implements the OP_PCRE2_MATCH opcode (conditional build).
 *
 * Executes a single PCRE2 pattern match against a subject string and returns
 * a map describing the first match and its capture groups when FUN_WITH_PCRE2
 * is enabled. Returns Nil when there is no match or on error. When PCRE2
 * support is disabled at build time, the opcode always returns Nil.
 */
 
/**
 * OP_PCRE2_MATCH: (pattern:any, text:any, flags:int|bool=0) -> map|Nil
 *
 * Behavior when FUN_WITH_PCRE2 is enabled:
 * - Pops: pattern, text, flags. Converts pattern/text to strings.
 * - Flags bits:
 *   - 1 = PCRE2_CASELESS (I)
 *   - 2 = PCRE2_MULTILINE (M)
 *   - 4 = PCRE2_DOTALL (S)
 *   - 8 = PCRE2_UTF (U)
 *   - 16 = PCRE2_EXTENDED (X)
 * - On successful match, returns a map with keys:
 *   - "full": matched substring (group 0)
 *   - "start": start index (int)
 *   - "end": end index (int, exclusive)
 *   - "groups": array of captured group strings (excluding group 0)
 * - On no match or compile error, returns Nil.
 *
 * Behavior when FUN_WITH_PCRE2 is disabled:
 * - Pops three values and returns Nil.
 */
 
/* PCRE2_MATCH */
case OP_PCRE2_MATCH: {
#ifdef FUN_WITH_PCRE2
  Value vflags = pop_value(vm);
  Value vtext = pop_value(vm);
  Value vpat = pop_value(vm);
  int flags = 0;
  if (vflags.type == VAL_INT || vflags.type == VAL_BOOL) flags = (int)vflags.i;
  char *pattern = value_to_string_alloc(&vpat);
  char *subject = value_to_string_alloc(&vtext);
  free_value(vflags);
  free_value(vtext);
  free_value(vpat);
  if (!pattern || !subject) {
    if (pattern) free(pattern);
    if (subject) free(subject);
    push_value(vm, make_nil());
    break;
  }
#ifndef PCRE2_CODE_UNIT_WIDTH
#define PCRE2_CODE_UNIT_WIDTH 8
#endif
#include <pcre2.h>
  int errorcode;
  PCRE2_SIZE erroff;
  uint32_t opt = 0;
  if (flags & 1) opt |= PCRE2_CASELESS;  /* I */
  if (flags & 2) opt |= PCRE2_MULTILINE; /* M */
  if (flags & 4) opt |= PCRE2_DOTALL;    /* S */
  if (flags & 8) opt |= PCRE2_UTF;       /* U */
  if (flags & 16) opt |= PCRE2_EXTENDED; /* X */
  pcre2_code *re = pcre2_compile((PCRE2_SPTR)pattern, PCRE2_ZERO_TERMINATED, opt, &errorcode, &erroff, NULL);
  if (!re) {
    free(pattern);
    free(subject);
    push_value(vm, make_nil());
    break;
  }
  pcre2_match_data *mdata = pcre2_match_data_create_from_pattern(re, NULL);
  int rc = pcre2_match(re, (PCRE2_SPTR)subject, (PCRE2_SIZE)strlen(subject), 0, 0, mdata, NULL);
  if (rc <= 0) {
    pcre2_match_data_free(mdata);
    pcre2_code_free(re);
    free(pattern);
    free(subject);
    push_value(vm, make_nil());
    break;
  }
  PCRE2_SIZE *ov = pcre2_get_ovector_pointer(mdata);
  /* Build result map */
  Value res = make_map_empty();
  int start0 = (int)ov[0];
  int end0 = (int)ov[1];
  char *full = string_substr(subject, start0, end0 - start0);
  (void)map_set(&res, "full", make_string(full ? full : ""));
  if (full) free(full);
  (void)map_set(&res, "start", make_int(start0));
  (void)map_set(&res, "end", make_int(end0));
  /* groups array (excluding group 0) */
  Value groups = make_array_from_values(NULL, 0);
  for (int i = 1; i < rc; ++i) {
    int s = (int)ov[2 * i];
    int e = (int)ov[2 * i + 1];
    char *gstr = (s >= 0 && e >= s) ? string_substr(subject, s, e - s) : NULL;
    Value gv = make_string(gstr ? gstr : "");
    if (gstr) free(gstr);
    (void)array_push(&groups, gv);
  }
  (void)map_set(&res, "groups", groups);
  pcre2_match_data_free(mdata);
  pcre2_code_free(re);
  free(pattern);
  free(subject);
  push_value(vm, res);
#else
  Value a = pop_value(vm);
  free_value(a);
  Value b = pop_value(vm);
  free_value(b);
  Value c = pop_value(vm);
  free_value(c);
  push_value(vm, make_nil());
#endif
  break;
}