Regex implementation (yet to be implemented)

conf/regex.go

@@ -0,0 +1,62 @@
+package conf
+
+/* This file contains regex helper functions for parsing configs  */
+
+import (
+	"strings"
+)
+
+/* Splits and normalises */
+func splitPath(path string) []string {
+	return strings.Split(strings.Trim(path, "/"), "/")
+}
+
+/* Attempts to match a request path to a set of whitelisted paths
+   @return false for anything other than a valid match */
+func match(request string, matchTo []string) bool {
+	requestSplit := splitPath(request)
+	for _, matchToAttempt := range matchTo {
+		matchToAttemptSplit := splitPath(matchToAttempt);
+		if matchSegments(requestSplit, matchToAttemptSplit) {
+			return true;
+		}
+	}
+	
+	return false;
+}
+
+/* Returns false for anything other than a valid match */
+func matchSegments(request []string, matchTo []string) bool {
+	/* This is a recursive function which, at each recursion level, matches the
+	   path segments that are in the front of the request and matchTo lists
+	   It matches identical strings, anything to &, and splits in two when
+	   matching anything to *, to account for consuming or not consuming the *
+	   at the current recursion level. */
+	
+	// Recursion base case for perfect match
+	if len(request) == 0 && len(matchTo) == 0 {return true}
+	// End of path for one but not the other
+	if (len(request) & len(matchTo)) == 0 {return false}
+	
+	// Grab current path segments
+	requestCurrent := request[0];
+	matchToCurrent := matchTo[0];
+	
+	// & character and direct match have the same behavior
+	if (matchToCurrent == "&") || (requestCurrent == matchToCurrent) {
+		return matchSegments(request[1:], matchTo[1:]);
+	}
+	
+	// * character
+	if (matchToCurrent == "*") {
+		// These are split for performance
+		// Usually the * only refers to 1 or 2 things so putting consumption
+		// first is probably a better choice
+		if (matchSegments(request[1:], matchTo[1:])) {return true}
+		if (matchSegments(request[1:], matchTo)) {return true}
+		return false;
+	}
+	
+	// Code will reach here if there's no match for the current segment
+	return false;
+}