Increased Node constness and removed type member method

* marked "solve" and "print" implementations as const
* converted member variables into constants where possible
* "type" member method is not necessary and partially defeats the purpose of declaring virtual members

2 files changed, 33 insertions, 48 deletions

diff --git a/src/nodes.cc b/src/nodes.cc
index f15a8c9..283b583 100644
--- a/src/nodes.cc
+++ b/src/nodes.cc
@@ -10,17 +10,13 @@
 namespace SimpleParser {
 
 OperandNode::OperandNode(double value):
-	value_(value) { }
+	value_{value} { }
 
-double OperandNode::solve() {
+double OperandNode::solve() const {
 	return this->value_;
 }
 
-NodeType OperandNode::type() {
-	return NodeType::OPERAND;
-}
-
-std::string OperandNode::print() {
+std::string OperandNode::print() const {
 	std::stringstream convertStream;
 	convertStream.precision(std::numeric_limits<double>::digits10);
 
@@ -30,9 +26,9 @@ std::string OperandNode::print() {
 }
 
 OperatorNode::OperatorNode(TokenType token):
-	operator_(token) { }
+	operator_{token} { }
 
-double OperatorNode::solve() {
+double OperatorNode::solve() const {
 	switch ( this->operator_ ) {
 		case TokenType::OPERATOR_MULTIPLY: {
 			return this->leftChild->solve() * this->rightChild->solve();
@@ -63,11 +59,7 @@ double OperatorNode::solve() {
 	}
 }
 
-NodeType OperatorNode::type() {
-	return NodeType::OPERATOR;
-}
-
-std::string OperatorNode::print() {
+std::string OperatorNode::print() const {
 	switch ( this->operator_ ) {
 		case TokenType::OPERATOR_PLUS: {
 			return std::string(1, '+');
@@ -90,21 +82,23 @@ std::string OperatorNode::print() {
 	}
 }
 
-TokenType OperatorNode::token() {
+TokenType OperatorNode::token() const {
 	return this->operator_;
 }
 
-ConstantNode::ConstantNode(std::string identifier,
-                           const ConstantMap* constants):
+ConstantNode::ConstantNode(
+	const std::string& identifier,
+	const ConstantMap* constants
+):
 	identifier_(identifier),
 	constants_(constants) { }
 
-double ConstantNode::solve() {
+double ConstantNode::solve() const {
 	if ( this->constants_ != nullptr ) {
 		try {
 			return this->constants_->at(this->identifier_);
 		}
-		catch ( std::out_of_range &e ) {
+		catch ( std::out_of_range& ) {
 			throw identifier_exception();
 		}
 	} else {
@@ -112,11 +106,7 @@ double ConstantNode::solve() {
 	}
 }
 
-NodeType ConstantNode::type() {
-	return NodeType::CONSTANT;
-}
-
-std::string ConstantNode::print() {
+std::string ConstantNode::print() const {
 	return this->identifier_;
 }
 
diff --git a/src/nodes.h b/src/nodes.h
index 2581a2d..9559722 100644
--- a/src/nodes.h
+++ b/src/nodes.h
@@ -9,61 +9,56 @@ namespace SimpleParser {
 enum class TokenType;
 typedef std::map<std::string, double> ConstantMap;
 
-enum class NodeType {
-	OPERAND,
-	OPERATOR,
-	CONSTANT,
-};
-
 class Node {
 	public:
 		virtual ~Node() {};
 
-		virtual double solve()      = 0;
-		virtual NodeType type()     = 0;
-		virtual std::string print() = 0;
+		virtual double solve()      const = 0;
+		virtual std::string print() const = 0;
 
 		Node* leftChild;
 		Node* rightChild;
+
 };
 
 class OperatorNode: public Node {
 	public:
 		explicit OperatorNode(TokenType);
 
-		virtual double solve();
-		virtual NodeType type();
-		virtual std::string print();
+		TokenType token() const;
+
+		virtual double solve()      const;
+		virtual std::string print() const;
 
-		TokenType token();
 
 	private:
-		TokenType operator_;
+		const TokenType operator_;
+
 };
 
 class OperandNode: public Node {
 	public:
 		explicit OperandNode(double);
 
-		virtual double solve();
-		virtual NodeType type();
-		virtual std::string print();
+		virtual double solve()      const;
+		virtual std::string print() const;
 
 	private:
-		double value_;
+		const double value_;
+
 };
 
 class ConstantNode: public Node {
 	public:
-		explicit ConstantNode(std::string, const ConstantMap*);
+		ConstantNode(const std::string&, const ConstantMap*);
 
-		virtual double solve();
-		virtual NodeType type();
-		virtual std::string print();
+		virtual double solve()      const;
+		virtual std::string print() const;
 
 	private:
-		std::string identifier_;
-		const ConstantMap* constants_;
+		const std::string identifier_;
+		const ConstantMap* const constants_;
+
 };
 
 }