Fix what looks like an off-by-one error in RegEx::longestMatch()'s lastMatch calculation, and a corresponding +1 in code using longestMatch, and add a test.

include/RegEx.h

@@ -21,9 +21,10 @@ class RegEx {
 		int longMatch(std::string stringToMatch);
 		std::string getPattern();
 		std::string toString();
+		static void test();
 	private:
 		std::string pattern;
 		RegExState* begin;
 		std::vector<RegExState*> currentStates;
 };
-#endif
+#endif

main.cpp

@@ -19,6 +19,7 @@
 int main(int argc, char* argv[]) {
 	if (argc == 2 && std::string(argv[1]) == "--test") {
 		StringReader::test();
+		RegEx::test();
 		Lexer::test();
 		return 0;
 	}

src/Lexer.cpp

@@ -40,8 +40,8 @@ Symbol Lexer::next() {
 		}
 	}
 	if (longestRegEx != NULL) {
-		std::string eatenString = input.substr(currentPosition, longestMatch+1);
-		currentPosition += longestMatch + 1;
+		std::string eatenString = input.substr(currentPosition, longestMatch);
+		currentPosition += longestMatch;
 	//std::cout << "Current at is \"" << input.substr(currentPosition,input.length()-1) << "\" currentPos is " << currentPosition <<std::endl;
 		return Symbol(longestRegEx->getPattern(), true, eatenString);
 	} else {

src/RegEx.cpp

@@ -1,4 +1,5 @@
 #include "RegEx.h"
+#include <cassert>
 
 RegEx::RegEx(std::string inPattern) {
 	pattern = inPattern;
@@ -242,7 +243,7 @@ int RegEx::longMatch(std::string stringToMatch) {
 		//Also, add each state's advance to nextStates
 		for (std::vector<RegExState*>::size_type j = 0; j < currentStates.size(); j++) {
 			if (currentStates[j]->isGoal()) {
-				lastMatch = i-1;
+				lastMatch = i;
 				//std::cout << "Hit goal at " << i << " character: " << stringToMatch[i-1] << std::endl;
 			} else {
 				//std::cout << "currentState " << j << ", " << currentStates[j]->toString() << " is not goal" <<std::endl;
@@ -274,7 +275,7 @@ int RegEx::longMatch(std::string stringToMatch) {
 	//Check to see if we match on the last character in the string
 	for (std::vector<RegExState*>::size_type j = 0; j < currentStates.size(); j++) {
 		if (currentStates[j]->isGoal())
-			lastMatch = stringToMatch.size()-1;
+			lastMatch = stringToMatch.size();
 	}
 	return lastMatch;
 }
@@ -286,3 +287,12 @@ std::string RegEx::getPattern() {
 std::string RegEx::toString() {
 	return pattern + " -> " + begin->toString();
 }
+
+void RegEx::test() {
+    {
+        RegEx re("a*");
+        assert(re.longMatch("aa") == 2);
+    }
+
+    std::cout << "RegEx tests pass\n";
+}