Simplify calling of rsindex() and strsearch()

Remove the 'how' parameter to rsindex(), making it reverse-search for only the first matching character,
as sindex() already does.  There are only two callers, and one already passed a hardcoded value of 1.

Also change rsindex() so that it starts searching at the character BEFORE the passed in position.  This
makes it easier to repeatedly call rsindex() in a loop to search for the Nth matching character, and
also fixes a technical instance of undefined behaviour where a pointer is decremented to point before
the start of the string.

Remove the 'mark' parameter to strsearch().  Instead, always forward-search from the beginning of the
string and reverse-search from the end of the string, as this is what the two callers want anyway.

Bump the module ABI version because these functions are exported to modules.

Changelog

@@ -1,5 +1,7 @@
 [Changes 1.2.2]
 
+* Simplify rsindex() and strsearch() exported functions. (caf)
+
 * scr-bx now lists the detached screens if there is more than one that matches
   the string supplied by the user. (caf)
 

include/ircaux.h

@@ -30,7 +30,7 @@ char *	BX_upper 			(char *);
 char *	BX_lower 			(char *);
 char *inv_strpbrk(const char *s, const char *reject);
 char *	BX_sindex			(const char *, const char *);
-char *	BX_rsindex 		(const char *, const char *, const char *, int);
+char *	BX_rsindex 		(const char *, const char *, const char *);
 char *	BX_path_search 		(char *, char *);
 char *	BX_double_quote 		(const char *, const char *, char *);
 
@@ -133,7 +133,7 @@ char *	base64_encode	(const void *data, size_t size);
 /* From words.c */
 #define SOS -32767
 #define EOS 32767
-char *BX_strsearch(const char *, const char *, const char *, int);
+char *BX_strsearch(const char *, const char *, int);
 char *BX_move_to_word(const char *, int);
 char *BX_move_word_rel(const char *, char **, int);
 char *BX_extract(char *, int, int);

include/module.h

@@ -10,7 +10,7 @@
  * if we change the table below, we change this module number to the 
  * current date (YYYYMMDDxx where xx is a serial number).
  */
-#define MODULE_VERSION 2017111401UL
+#define MODULE_VERSION 2017112301UL
 
 #include "struct.h"
 

include/modval.h

@@ -146,7 +146,7 @@ extern Function_ptr *global;
 #define expand_twiddle (*(char * (*)(char *))global[EXPAND_TWIDDLE])
 #define check_nickname (*(char * (*)(char *))global[CHECK_NICKNAME])
 #define sindex (*(char * (*)(const char *, const char *))global[SINDEX])
-#define rsindex (*(char * (*)(const char *, const char *, const char *, int))global[RSINDEX])
+#define rsindex (*(char * (*)(const char *, const char *, const char *))global[RSINDEX])
 #define is_number (*(int (*)(const char *))global[ISNUMBER])
 #define rfgets (*(char * (*)(char *, int , FILE *))global[RFGETS])
 #define path_search (*(char * (*)(char *, char *))global[PATH_SEARCH])
@@ -199,7 +199,7 @@ extern Function_ptr *global;
 
 
 /* words.c reg.c */
-#define strsearch (*(char *(*)(const char *, const char *, const char *, int ))global[STRSEARCH])
+#define strsearch (*(char *(*)(const char *, const char *, int))global[STRSEARCH])
 #define move_to_word (*(char *(*)(const char *, int))global[MOVE_TO_WORD])
 #define move_word_rel (*(char *(*)(const char *, char **, int ))global[MOVE_WORD_REL])
 #define extract (*(char *(*)(char *, int , int ))global[EXTRACT])

source/functions.c

@@ -1520,7 +1520,7 @@ BUILT_IN_FUNCTION(function_rindex, word)
 
 	/* need to find out why ^x doesn't work */
 	GET_STR_ARG(chars, word);
-	last = rsindex(word + strlen(word) - 1, word, chars, 1);
+	last = rsindex(word + strlen(word), word, chars);
 	RETURN_INT(last ? last - word : -1);
 }
 
@@ -1993,7 +1993,7 @@ BUILT_IN_FUNCTION(function_idle, input)
  */
 BUILT_IN_FUNCTION(function_before, word)
 {
-	char	*pointer = NULL;
+	char	*pointer;
 	char	*chars;
 	char	*tmp;
 	long	numint;
@@ -2011,10 +2011,7 @@ BUILT_IN_FUNCTION(function_before, word)
 		chars = tmp;
 	}
 
-	if (numint < 0 && strlen(word))
-		pointer = word + strlen(word) - 1;
-
-	pointer = strsearch(word, pointer, chars, numint);
+	pointer = strsearch(word, chars, numint);
 
 	if (!pointer)
 		RETURN_EMPTY;
@@ -2031,7 +2028,7 @@ BUILT_IN_FUNCTION(function_before, word)
 BUILT_IN_FUNCTION(function_after, word)
 {
 	char	*chars;
-	char	*pointer = NULL;
+	char	*pointer;
 	char 	*tmp;
 	long	numint;
 
@@ -2046,10 +2043,7 @@ BUILT_IN_FUNCTION(function_after, word)
 		chars = tmp;
 	}
 
-	if (numint < 0 && strlen(word))
-		pointer = word + strlen(word) - 1;
-
-	pointer = strsearch(word, pointer, chars, numint);
+	pointer = strsearch(word, chars, numint);
 
 	if (!pointer || !*pointer)
 		RETURN_EMPTY;

source/ircaux.c

@@ -1117,43 +1117,34 @@ char *BX_sindex(const char *string, const char *group)
 
 /* rsindex()
  *
- * Returns a pointer to the howmany'th last matching character in a string, or
- * NULL if there are less than howmany matching characters.  Returns NULL
- * if howmany is zero.
+ * Returns a pointer to the last matching character that appears in a string BEFORE the
+ * initial search point (to search the entire string, set the initial search point to
+ * the terminating NUL). Returns NULL if no matching characters are found.
+ *
+ * The string to be searched starts at 'start' and the initial search point is 'ptr'.
  *
  * A matching character is any character in 'group', unless the first character of 'group'
  * is a ^, in which case a matching character is any character NOT in 'group'.
  */
-char *BX_rsindex(const char *string, const char *start, const char *group, int howmany)
+char *BX_rsindex(const char *ptr, const char *start, const char *group)
 {
-	const char *ptr;
+	if (ptr && start && group && start <= ptr)
+	{
+		int invert = 0;
 
-	if (howmany && string && start && group && start <= string)
-	{
 		if (*group == '^')
 		{
 			group++;
-			for (ptr = string; (ptr >= start) && howmany; ptr--)
+			invert = 1;
+		}
+
+		while (ptr > start)
 		{
-				if (!strchr(group, *ptr))
-				{
-					if (--howmany == 0)
+			ptr--;
+			if (invert == !strchr(group, *ptr))
 				return (char *)ptr;
 		}
 	}
-		}
-		else
-		{
-			for (ptr = string; (ptr >= start) && howmany; ptr--)
-			{
-				if (strchr(group, *ptr))
-				{
-					if (--howmany == 0)
-						return (char *)ptr;
-				}
-			}
-		}
-	}
 	return NULL;
 }
 

source/words.c

@@ -18,27 +18,24 @@ CVS_REVISION(words_c)
 /* strsearch()
  *
  * If how > 0, returns a pointer to the how'th matching character forwards
- * from mark, in the string starting at start.
+ * from the beginning of the string starting at start.
  * If how < 0, returns a pointer to the -how'th matching character backwards
- * from mark, in the string starting at start.
+ * from the end of the string starting at start.
  * If how == 0, returns NULL.
  *
- * NULL mark begins the search at start.
- *
  * A matching character is any character in chars, unless chars starts with ^, 
  * in which case a matching character is any character NOT in chars.
  *
  * If there are insufficient matching characters, NULL is returned.
  */
-extern char	*BX_strsearch(const char *start, const char *mark, const char *chars, int how)
+extern char	*BX_strsearch(const char *start, const char *chars, int how)
 {
 	const char *ptr = NULL;
 
-	if (!mark)
-		mark = start;
-
 	if (how > 0)   /* forward search */
 	{
+		const char *mark = start;
+
 		for (; how > 0 && mark; how--)
 		{
 			ptr = sindex(mark, chars);
@@ -50,7 +47,10 @@ extern char	*BX_strsearch(const char *start, const char *mark, const char *chars
 	}
 	else if (how < 0)
 	{
-		ptr = rsindex(mark, start, chars, -how);
+		ptr = start + strlen(start);
+
+		for (; how < 0 && ptr; how++)
+			ptr = rsindex(ptr, start, chars);
 	}
 
 	return (char *)ptr;