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, 7 insertions, 0 deletions

diff --git a/src/exceptions.h b/src/exceptions.h
index cd76368..b17f424 100644
--- a/src/exceptions.h
+++ b/src/exceptions.h
@@ -24,6 +24,13 @@ class divide_exception: public std::exception {
 	}
 };
 
+class identifier_exception: public std::exception {
+	virtual const char* what() const throw()
+	{
+		return "Identifier could not be correctly resolved.";
+	}
+};
+
 }
 
 #endif  // PARSER_SRC_EXCEPTIONS_H_