#include "copyright.h"

/* String utilities */

#include <ctype.h>

#define DOWNCASE(x) (isupper(x) ? tolower(x) : (x))

int string_compare (const char *s1, const char *s2)
{
  while (*s1 && *s2 && DOWNCASE (*s1) == DOWNCASE (*s2))
    s1++, s2++;

  return (DOWNCASE (*s1) - DOWNCASE (*s2));
}

int string_prefix (const char *string, const char *prefix)
{
  while (*string && *prefix && DOWNCASE (*string) == DOWNCASE (*prefix))
    string++, prefix++;
  return *prefix == '\0';
}

/* accepts only nonempty matches starting at the beginning of a word */
const char *string_match (const char *src, const char *sub)
{
  if (*sub != '\0') {
    while (*src) {
      if (string_prefix (src, sub))
        return src;
      /* else scan to beginning of next word */
      while (*src && isalnum (*src))
        src++;
      while (*src && !isalnum (*src))
        src++;
    }
  }

  return 0;
}