1 files changed, 39 insertions, 9 deletions

diff --git a/src/tree.cc b/src/tree.cc
index 0f5c2d8..2dfb786 100644
--- a/src/tree.cc
+++ b/src/tree.cc
@@ -84,6 +84,18 @@ Node* Tree::addOperand(Node** place, double value) {
 	return this->node_collection_.back().get();
 }
 
+Node* Tree::addOperand(Node** place, std::string value) {
+	this->node_collection_.emplace_back(
+		new OperandNode(value)
+	);
+
+	if ( place != nullptr ) {
+		*place = this->node_collection_.back().get();
+	}
+
+	return this->node_collection_.back().get();
+}
+
 Node* Tree::addOperator(Node** place, char oper) {
 	this->node_collection_.emplace_back(
 		new OperatorNode(oper)
@@ -117,7 +129,9 @@ Node* Tree::buildTree(std::string term) {
 		const std::string& currTerm = (*termIter);
 		const TokenType token       = getTokenType(currTerm[0]);
 
-		if ( token != TokenType::VALUE_NUMBER && (*termIter).size() == 1 ) {
+		if ( token              != TokenType::VALUE_NUMBER     && 
+		     token              != TokenType::VALUE_IDENTIFIER &&
+		     (*termIter).size() == 1 ) {
 			if ( !operatorStack.empty() ) {
 				OperatorNode* lastNode(
 					static_cast<OperatorNode*>(topNodeFrom(operatorStack))
@@ -150,14 +164,30 @@ Node* Tree::buildTree(std::string term) {
 			tmpLexer = lexer(*termIter);
 
 			if ( tmpLexer.size() == 1 ) {
-				double value;
-				std::istringstream convertStream(tmpLexer[0]);
-				convertStream >> value;
-
-				operandStack.push(
-					this->addOperand(nullptr,value)
-				);
-			} else if ( tmpLexer.size() > 1 ) {
+				switch ( getTokenType(tmpLexer[0][0]) ) {
+					case TokenType::VALUE_NUMBER: {
+						double value;
+						std::istringstream convertStream(tmpLexer[0]);
+						convertStream >> value;
+
+						operandStack.push(
+							this->addOperand(nullptr,value)
+						);
+
+						break;
+					}
+					case TokenType::VALUE_IDENTIFIER: {
+						operandStack.push(
+							this->addOperand(nullptr,tmpLexer[0])
+						);
+
+						break;
+					}
+					default: {
+						throw operator_exception();
+					}
+				}
+			} else {
 				operandStack.push(
 					buildTree(*termIter)
 				);