shithub: mc

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Add strrfind function for reverse string searches.

--- a/libstd/strfind.myr

+++ b/libstd/strfind.myr

@@ -3,14 +3,31 @@

 pkg std =

 	const strfind	: (haystack : byte[:], needle : byte[:] -> option(size))

+	const strrfind	: (haystack : byte[:], needle : byte[:] -> option(size))

 ;;

 const strfind = {haystack, needle

-	var i, j

+	-> strfindin(haystack, needle, 0, haystack.len)

+}

-	for i = 0; i < haystack.len; i++

+const strrfind = {haystack, needle

+	-> strfindin(haystack, needle, haystack.len - 1, -1)

+}

+

+const strfindin = {haystack, needle, start, end

+	var i, j, inc : size

+

+	inc = 1

+	if start > end

+		inc = -1

+	;;

+	for i = start; i != end; i += inc

+		/* 

+		if we knew the direction we could terminate early,

+		but we allow the start and end to be passed in.

+		*/

 		if i + needle.len > haystack.len

-			-> `None

+			continue

 		;;

 		if haystack[i] == needle[0]

 			for j = 0; j < needle.len; j++

@@ -24,3 +41,4 @@

 	;;

 	-> `None

 }

+