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, 5 insertions, 2 deletions

diff --git a/src/nodes.h b/src/nodes.h
index 6783f3d..170b88f 100644
--- a/src/nodes.h
+++ b/src/nodes.h
@@ -1,11 +1,13 @@
 #ifndef PARSER_SRC_NODES_H_
 #define PARSER_SRC_NODES_H_
 
+#include <map>
 #include <string>
 
 namespace SimpleParser {
 
-enum class TokenType : int8_t;
+enum class TokenType;
+typedef std::map<std::string, double> ConstantMap;
 
 enum class NodeType {
 	OPERAND,
@@ -53,7 +55,7 @@ class OperandNode: public Node {
 
 class ConstantNode: public Node {
 	public:
-		explicit ConstantNode(std::string);
+		explicit ConstantNode(std::string, const ConstantMap*);
 
 		virtual double solve();
 		virtual NodeType getType();
@@ -61,6 +63,7 @@ class ConstantNode: public Node {
 
 	private:
 		std::string identifier_;
+		const ConstantMap* constants_;
 };
 
 }