/*
** strlib.c
** String library to LUA
*/

char *rcs_strlib="$Id: strlib.c,v 1.11 1995/02/02 20:05:37 roberto Exp roberto $";

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

#include "lua.h"
#include "lualib.h"


static char *newstring (lua_Object o)
{
  char *s = lua_getstring(o);
  char *ns = (char *)malloc(strlen(s)+1);
  if (ns == 0)
    lua_error("not enough memory for new string");
  strcpy(ns, s);
  return ns;
}


/*
** Return the position of the first caracter of a substring into a string
** LUA interface:
**			n = strfind (string, substring, init, end)
*/
static void str_find (void)
{
 char *s1, *s2, *f;
 int init; 
 lua_Object o1 = lua_getparam (1);
 lua_Object o2 = lua_getparam (2);
 lua_Object o3 = lua_getparam (3);
 lua_Object o4 = lua_getparam (4);
 if (!lua_isstring(o1) || !lua_isstring(o2))
   lua_error ("incorrect arguments to function `strfind'");
 if (o3 == LUA_NOOBJECT)
  init = 0;
 else if (lua_isnumber(o3))
  init = lua_getnumber(o3)-1;
 else
 {
   lua_error ("incorrect arguments to function `strfind'");
   return;  /* to avoid warnings */
 }
 s1 = lua_getstring(o1);
 s2 = lua_getstring(o2);
 f = strstr(s1+init,s2);
 if (f != NULL)
 {
  int pos = f-s1+1;
  if (o4 == LUA_NOOBJECT)
   lua_pushnumber (pos);
  else if (!lua_isnumber(o4))
   lua_error ("incorrect arguments to function `strfind'");
  else if ((int)lua_getnumber(o4) >= pos+strlen(s2)-1)
   lua_pushnumber (pos);
  else
   lua_pushnil();
 }
 else
  lua_pushnil();
}

/*
** Return the string length
** LUA interface:
**			n = strlen (string)
*/
static void str_len (void)
{
 lua_Object o = lua_getparam (1);
 if (!lua_isstring(o))
   lua_error ("incorrect arguments to function `strlen'");
 lua_pushnumber(strlen(lua_getstring(o)));
}


/*
** Return the substring of a string, from start to end
** LUA interface:
**			substring = strsub (string, start, end)
*/
static void str_sub (void)
{
 int start, end;
 char *s;
 lua_Object o1 = lua_getparam (1);
 lua_Object o2 = lua_getparam (2);
 lua_Object o3 = lua_getparam (3);
 if (!lua_isstring(o1) || !lua_isnumber(o2))
   lua_error ("incorrect arguments to function `strsub'");
 if (o3 != LUA_NOOBJECT && !lua_isnumber(o3))
   lua_error ("incorrect third argument to function `strsub'");
 s = newstring(o1);
 start = lua_getnumber (o2);
 end = o3 == LUA_NOOBJECT ? strlen(s) : lua_getnumber (o3);
 if (end < start || start < 1 || end > strlen(s))
  lua_pushliteral("");
 else
 {
  s[end] = 0;
  lua_pushstring (&s[start-1]);
 }
 free(s);
}

/*
** Convert a string to lower case.
** LUA interface:
**			lowercase = strlower (string)
*/
static void str_lower (void)
{
 char *s, *c;
 lua_Object o = lua_getparam (1);
 if (!lua_isstring(o))
   lua_error ("incorrect arguments to function `strlower'");
 c = s = newstring(o);
 while (*c != 0)
 {
  *c = tolower(*c);
  c++;
 }
 lua_pushstring(s);
 free(s);
} 


/*
** Convert a string to upper case.
** LUA interface:
**			uppercase = strupper (string)
*/
static void str_upper (void)
{
 char *s, *c;
 lua_Object o = lua_getparam (1);
 if (!lua_isstring(o))
   lua_error ("incorrect arguments to function `strlower'");
 c = s = newstring(o);
 while (*c != 0)
 {
  *c = toupper(*c);
  c++;
 }
 lua_pushstring(s);
 free(s);
} 


/*
** Open string library
*/
void strlib_open (void)
{
 lua_register ("strfind", str_find);
 lua_register ("strlen", str_len);
 lua_register ("strsub", str_sub);
 lua_register ("strlower", str_lower);
 lua_register ("strupper", str_upper);
}