Implemented constant identifier functionality

* SimpleParser optionally acceps a pointer to an ConstantMap containing string keys mapping to values
* Constants are handled in their own ConstantNode class derived from the standard Node class
* Operator precedence is now determined separated from the TokenType using a new PrecedenceLevel enum
** Conversion between tokens and their PrecedenceLevel is possible using the new utility function getPrecedence
* Added additional test cases for constant identifier resolutions

1 files changed, 31 insertions, 3 deletions

diff --git a/src/utils.cc b/src/utils.cc
index 4e2ed91..9a081f3 100644
--- a/src/utils.cc
+++ b/src/utils.cc
@@ -12,9 +12,9 @@ TokenType getTokenType(char tmp) {
 	} else {
 		switch ( tmp ) {
 			case '-':
-				return TokenType::OPERATOR_PLUS;
-			case '+':
 				return TokenType::OPERATOR_MINUS;
+			case '+':
+				return TokenType::OPERATOR_PLUS;
 			case '/':
 				return TokenType::OPERATOR_DIVIDE;
 			case '*':
@@ -33,6 +33,33 @@ TokenType getTokenType(char tmp) {
 	}
 }
 
+PrecedenceLevel getPrecedence(TokenType token) {
+	switch ( token ) {
+		case TokenType::VALUE_NUMBER:
+		case TokenType::VALUE_IDENTIFIER: {
+			return PrecedenceLevel::FIRST;
+		}
+		case TokenType::OPERATOR_MINUS:
+		case TokenType::OPERATOR_PLUS: {
+			return PrecedenceLevel::SECOND;
+		}
+		case TokenType::OPERATOR_DIVIDE:
+		case TokenType::OPERATOR_MULTIPLY: {
+			return PrecedenceLevel::THIRD;
+		}
+		case TokenType::OPERATOR_POWER: {
+			return PrecedenceLevel::FOURTH;
+		}
+		case TokenType::PARENTHESES_OPEN:
+		case TokenType::PARENTHESES_CLOSE: {
+			return PrecedenceLevel::FIFTH;
+		}
+		default: {
+			return PrecedenceLevel::FIRST;
+		}
+	}
+}
+
 std::vector<std::string> lexer(std::string term) {
 	std::string tmp;
 	std::string tmpNumber;
@@ -55,7 +82,8 @@ std::vector<std::string> lexer(std::string term) {
 			if ( level > 0 ) {
 				tmp += *termIter;
 			} else {
-				if ( token == TokenType::VALUE_NUMBER ) {
+				if ( token == TokenType::VALUE_NUMBER ||
+				     token == TokenType::OPERATOR_MINUS ) {
 					tmpNumber += *termIter;
 				} else if ( token == TokenType::VALUE_IDENTIFIER ) {
 					tmpIdentifier += *termIter;