Merge pull request #2 from jorendorff/master

Minor bug fixes and tests for RegEx and Lexer, lots of thanks to jorendorff

include/Lexer.h

@@ -16,9 +16,10 @@ class Lexer {
 		void addRegEx(std::string regExString);
 		void setInput(std::string inputString);
 		Symbol next();
+		static void test();
 	private:
 		std::vector<RegEx*> regExs;
 		std::string input;
 		int currentPosition;
 };
-#endif
+#endif

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 +19,8 @@
 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

@@ -1,4 +1,5 @@
 #include "Lexer.h"
+#include <cassert>
 
 Lexer::Lexer() {
 	//Do nothing
@@ -23,13 +24,13 @@ void Lexer::addRegEx(std::string regExString) {
 }
 
 Symbol Lexer::next() {
-	//std::cout << "Current at is \"" << input.substr(currentPosition,input.length()-1) << "\" currentPos is " << currentPosition  << " out of " << input.length() <<std::endl;
+	//std::cout << "Current at is \"" << input.substr(currentPosition) << "\" currentPos is " << currentPosition  << " out of " << input.length() <<std::endl;
 	//If we're at the end, return an eof
-	if (currentPosition >= input.length()-1)
+	if (currentPosition >= input.length())
 		return Symbol("$EOF$", true);
 	int longestMatch = -1;
 	RegEx* longestRegEx = NULL;
-	std::string remainingString = input.substr(currentPosition,input.length()-1);
+	std::string remainingString = input.substr(currentPosition);
 	for (std::vector<RegEx*>::size_type i = 0; i < regExs.size(); i++) {
 		//std::cout << "Trying regex " << regExs[i]->getPattern() << std::endl;
 		int currentMatch = regExs[i]->longMatch(remainingString);
@@ -39,13 +40,77 @@ Symbol Lexer::next() {
 		}
 	}
 	if (longestRegEx != NULL) {
-		std::string eatenString = input.substr(currentPosition, longestMatch+1);
-		currentPosition += longestMatch + 1;
-	//std::cout << "Current at is \"" << input.substr(currentPosition,input.length()-1) << "\" currentPos is " << currentPosition <<std::endl;
+		std::string eatenString = input.substr(currentPosition, longestMatch);
+		currentPosition += longestMatch;
+	//std::cout << "Current at is \"" << input.substr(currentPosition) << "\" currentPos is " << currentPosition <<std::endl;
 		return Symbol(longestRegEx->getPattern(), true, eatenString);
 	} else {
 		//std::cout << "Found no applicable regex" << std::endl;
-		//std::cout << "Remaining is ||" << input.substr(currentPosition,input.length()-1) << "||" << std::endl;
+		//std::cout << "Remaining is ||" << input.substr(currentPosition) << "||" << std::endl;
 		return Symbol();
 	}
-}
+}
+
+void Lexer::test() {
+    Symbol s;
+    {
+        Lexer lex;
+        lex.addRegEx("b");
+        lex.setInput("bb");
+        s = lex.next();
+        assert(s.getName() == "b" && s.getValue() == "b");
+        s = lex.next();
+        assert(s.getName() == "b" && s.getValue() == "b");
+        assert(lex.next() == Symbol("$EOF$", true));
+    }
+
+    {
+        Lexer lex;
+        lex.addRegEx("a*");
+        lex.addRegEx("b");
+        lex.setInput("aaabaabb");
+        s = lex.next();
+        assert(s.getName() == "a*" && s.getValue() == "aaa");
+        s = lex.next();
+        assert(s.getName() == "b" && s.getValue() == "b");
+        s = lex.next();
+        assert(s.getName() == "a*" && s.getValue() == "aa");
+        s = lex.next();
+        assert(s.getName() == "b" && s.getValue() == "b");
+        s = lex.next();
+        assert(s.getName() == "b" && s.getValue() == "b");
+        assert(lex.next() == Symbol("$EOF$", true));
+    }
+
+    // Test a lexer error condition.
+    {
+        Lexer lex;
+        lex.addRegEx("a|b");
+        lex.setInput("blah");
+        s = lex.next();
+        assert(s.getName() == "a|b" && s.getValue() == "b");
+        assert(lex.next() == Symbol());
+    }
+
+    // Lexer can consume all the input at once.
+    {
+        Lexer lex;
+        lex.addRegEx("xyzzy");
+        lex.setInput("xyzzy");
+        s = lex.next();
+        assert(s.getName() == "xyzzy" && s.getValue() == "xyzzy");
+        assert(lex.next() == Symbol("$EOF$", true));
+    }
+
+    // Lexer produces the longest match, not the first.
+    {
+        Lexer lex;
+        lex.addRegEx("int");
+        lex.addRegEx("(i|n|t|e)+");
+        lex.setInput("intent");
+        s = lex.next();
+        assert(s.getName() == "(i|n|t|e)+" && s.getValue() == "intent");
+    }
+
+    std::cout << "Lexer tests passed\n";
+}

src/RegEx.cpp

@@ -1,4 +1,5 @@
 #include "RegEx.h"
+#include <cassert>
 
 RegEx::RegEx(std::string inPattern) {
 	pattern = inPattern;
@@ -232,17 +233,18 @@ RegEx::~RegEx() {
 }
 
 int RegEx::longMatch(std::string stringToMatch) {
-	//If the beginning character is wrong, exit immediantly. Otherwise, get all the states we can get from adding the second character to the state where we accepted the first
+	// Start in the begin state (only).
 	int lastMatch = -1;
-	currentStates = *(begin->advance(stringToMatch[0]));
+	currentStates.clear();
+	currentStates.push_back(begin);
 	std::vector<RegExState*> nextStates;
 
-	for (int i = 1; i < stringToMatch.size(); i++) {
+	for (int i = 0; i < stringToMatch.size(); i++) {
 		//Go through every current state. Check to see if it is goal, if so update last goal.
 		//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 +276,7 @@ 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 +288,27 @@ std::string RegEx::getPattern() {
 std::string RegEx::toString() {
 	return pattern + " -> " + begin->toString();
 }
+
+void RegEx::test() {
+    {
+        RegEx re("a*");
+        assert(re.longMatch("a") == 1);
+        assert(re.longMatch("aa") == 2);
+        assert(re.longMatch("aaaab") == 4);
+        assert(re.longMatch("b") == 0);
+    }
+
+    {
+        RegEx re("a+");
+        assert(re.longMatch("aa") == 2);
+        assert(re.longMatch("aaaab") == 4);
+        assert(re.longMatch("b") == -1);
+    }
+
+    {
+        RegEx re("a(bc)?");
+        assert(re.longMatch("ab") == 1);
+    }
+
+    std::cout << "RegEx tests pass\n";
+}