lstrlib.c

小游戏 linux very happy

/*
** $Id: lstrlib.c,v 1.1 2002/02/14 10:46:59 jcatki Exp $
** Standard library for string operations and pattern-matching
** See Copyright Notice in lua.h
*/


#include <ctype.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"



static int str_len (lua_State *L) {
  size_t l;
  luaL_check_lstr(L, 1, &l);
  lua_pushnumber(L, l);
  return 1;
}


static long posrelat (long pos, size_t len) {
  /* relative string position: negative means back from end */
  return (pos>=0) ? pos : (long)len+pos+1;
}


static int str_sub (lua_State *L) {
  size_t l;
  const char *s = luaL_check_lstr(L, 1, &l);
  long start = posrelat(luaL_check_long(L, 2), l);
  long end = posrelat(luaL_opt_long(L, 3, -1), l);
  if (start < 1) start = 1;
  if (end > (long)l) end = l;
  if (start <= end)
    lua_pushlstring(L, s+start-1, end-start+1);
  else lua_pushstring(L, "");
  return 1;
}


static int str_lower (lua_State *L) {
  size_t l;
  size_t i;
  luaL_Buffer b;
  const char *s = luaL_check_lstr(L, 1, &l);
  luaL_buffinit(L, &b);
  for (i=0; i<l; i++)
    luaL_putchar(&b, tolower((unsigned char)(s[i])));
  luaL_pushresult(&b);
  return 1;
}


static int str_upper (lua_State *L) {
  size_t l;
  size_t i;
  luaL_Buffer b;
  const char *s = luaL_check_lstr(L, 1, &l);
  luaL_buffinit(L, &b);
  for (i=0; i<l; i++)
    luaL_putchar(&b, toupper((unsigned char)(s[i])));
  luaL_pushresult(&b);
  return 1;
}

static int str_rep (lua_State *L) {
  size_t l;
  luaL_Buffer b;
  const char *s = luaL_check_lstr(L, 1, &l);
  int n = luaL_check_int(L, 2);
  luaL_buffinit(L, &b);
  while (n-- > 0)
    luaL_addlstring(&b, s, l);
  luaL_pushresult(&b);
  return 1;
}


static int str_byte (lua_State *L) {
  size_t l;
  const char *s = luaL_check_lstr(L, 1, &l);
  long pos = posrelat(luaL_opt_long(L, 2, 1), l);
  luaL_arg_check(L, 0<pos && (size_t)pos<=l, 2,  "out of range");
  lua_pushnumber(L, (unsigned char)s[pos-1]);
  return 1;
}


static int str_char (lua_State *L) {
  int n = lua_gettop(L);  /* number of arguments */
  int i;
  luaL_Buffer b;
  luaL_buffinit(L, &b);
  for (i=1; i<=n; i++) {
    int c = luaL_check_int(L, i);
    luaL_arg_check(L, (unsigned char)c == c, i, "invalid value");
    luaL_putchar(&b, (unsigned char)c);
  }
  luaL_pushresult(&b);
  return 1;
}



/*
** {======================================================
** PATTERN MATCHING
** =======================================================
*/

#ifndef MAX_CAPTURES
#define MAX_CAPTURES 32  /* arbitrary limit */
#endif


struct Capture {
  const char *src_end;  /* end ('\0') of source string */
  int level;  /* total number of captures (finished or unfinished) */
  struct {
    const char *init;
    long len;  /* -1 signals unfinished capture */
  } capture[MAX_CAPTURES];
};


#define ESC		'%'
#define SPECIALS	"^$*+?.([%-"


static int check_capture (lua_State *L, int l, struct Capture *cap) {
  l -= '1';
  if (!(0 <= l && l < cap->level && cap->capture[l].len != -1))
    lua_error(L, "invalid capture index");
  return l;
}


static int capture_to_close (lua_State *L, struct Capture *cap) {
  int level = cap->level;
  for (level--; level>=0; level--)
    if (cap->capture[level].len == -1) return level;
  lua_error(L, "invalid pattern capture");
  return 0;  /* to avoid warnings */
}


const char *luaI_classend (lua_State *L, const char *p) {
  switch (*p++) {
    case ESC:
      if (*p == '\0') lua_error(L, "malformed pattern (ends with `%')");
      return p+1;
    case '[':
      if (*p == '^') p++;
      do {  /* look for a ']' */
        if (*p == '\0') lua_error(L, "malformed pattern (missing `]')");
        if (*(p++) == ESC && *p != '\0') p++;  /* skip escapes (e.g. '%]') */
      } while (*p != ']');
      return p+1;
    default:
      return p;
  }
}


static int match_class (int c, int cl) {
  int res;
  switch (tolower(cl)) {
    case 'a' : res = isalpha(c); break;
    case 'c' : res = iscntrl(c); break;
    case 'd' : res = isdigit(c); break;
    case 'l' : res = islower(c); break;
    case 'p' : res = ispunct(c); break;
    case 's' : res = isspace(c); break;
    case 'u' : res = isupper(c); break;
    case 'w' : res = isalnum(c); break;
    case 'x' : res = isxdigit(c); break;
    case 'z' : res = (c == '\0'); break;
    default: return (cl == c);
  }
  return (islower(cl) ? res : !res);
}



static int matchbracketclass (int c, const char *p, const char *endclass) {
  int sig = 1;
  if (*(p+1) == '^') {
    sig = 0;
    p++;  /* skip the '^' */
  }
  while (++p < endclass) {
    if (*p == ESC) {
      p++;
      if (match_class(c, (unsigned char)*p))
        return sig;
    }
    else if ((*(p+1) == '-') && (p+2 < endclass)) {
      p+=2;
      if ((int)(unsigned char)*(p-2) <= c && c <= (int)(unsigned char)*p)
        return sig;
    }
    else if ((int)(unsigned char)*p == c) return sig;
  }
  return !sig;
}



int luaI_singlematch (int c, const char *p, const char *ep) {
  switch (*p) {
    case '.':  /* matches any char */
      return 1;
    case ESC:
      return match_class(c, (unsigned char)*(p+1));
    case '[':
      return matchbracketclass(c, p, ep-1);
    default:
      return ((unsigned char)*p == c);
  }
}


static const char *match (lua_State *L, const char *s, const char *p,
                          struct Capture *cap);


static const char *matchbalance (lua_State *L, const char *s, const char *p,
                                 struct Capture *cap) {
  if (*p == 0 || *(p+1) == 0)
    lua_error(L, "unbalanced pattern");
  if (*s != *p) return NULL;
  else {
    int b = *p;
    int e = *(p+1);
    int cont = 1;
    while (++s < cap->src_end) {
      if (*s == e) {
        if (--cont == 0) return s+1;
      }
      else if (*s == b) cont++;
    }
  }
  return NULL;  /* string ends out of balance */
}


static const char *max_expand (lua_State *L, const char *s, const char *p,
                               const char *ep, struct Capture *cap) {
  long i = 0;  /* counts maximum expand for item */
  while ((s+i)<cap->src_end && luaI_singlematch((unsigned char)*(s+i), p, ep))
    i++;
  /* keeps trying to match with the maximum repetitions */
  while (i>=0) {
    const char *res = match(L, (s+i), ep+1, cap);
    if (res) return res;
    i--;  /* else didn't match; reduce 1 repetition to try again */
  }
  return NULL;
}


static const char *min_expand (lua_State *L, const char *s, const char *p,
                               const char *ep, struct Capture *cap) {
  for (;;) {
    const char *res = match(L, s, ep+1, cap);
    if (res != NULL)
      return res;
    else if (s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep))
      s++;  /* try with one more repetition */
    else return NULL;
  }
}


static const char *start_capture (lua_State *L, const char *s, const char *p,
                                  struct Capture *cap) {
  const char *res;
  int level = cap->level;
  if (level >= MAX_CAPTURES) lua_error(L, "too many captures");
  cap->capture[level].init = s;
  cap->capture[level].len = -1;
  cap->level = level+1;
  if ((res=match(L, s, p+1, cap)) == NULL)  /* match failed? */
    cap->level--;  /* undo capture */
  return res;
}


static const char *end_capture (lua_State *L, const char *s, const char *p,
                                struct Capture *cap) {
  int l = capture_to_close(L, cap);
  const char *res;
  cap->capture[l].len = s - cap->capture[l].init;  /* close capture */
  if ((res = match(L, s, p+1, cap)) == NULL)  /* match failed? */
    cap->capture[l].len = -1;  /* undo capture */
  return res;
}


static const char *match_capture (lua_State *L, const char *s, int level,
                                  struct Capture *cap) {
  int l = check_capture(L, level, cap);
  size_t len = cap->capture[l].len;