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evaluator.hpp
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evaluator.hpp
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#pragma once
#include "parser/input_buffer.hpp"
namespace eval
{
//------------------------------------------------------------------------------
struct Token
{
enum class Type
{
Constant,
Var,
BinOp,
LeftParen,
RightParen,
FuncCall,
Comma,
UnaryMinus,
UnaryPlus,
};
enum BinOp
{
BinOpAdd, BinOpSub, BinOpMul, BinOpDiv
};
Token() {}
Token(Type type) : type(type) {}
Token(float constant) : type(Type::Constant), constant(constant) {}
Token(Type type, const std::string& name) : type(type), name(name) {}
Token(BinOp binOp) : type(Type::BinOp), binOp(binOp) {}
Type type;
BinOp binOp;
std::string name;
float constant;
};
struct Evaluator;
typedef std::function<void(Evaluator* eval)> fnFunction;
//------------------------------------------------------------------------------
struct Environment
{
std::unordered_map<std::string, fnFunction> functions;
std::unordered_map<std::string, float> constants;
};
//------------------------------------------------------------------------------
bool Parse(const char* str, std::vector<Token>* expression);
//------------------------------------------------------------------------------
struct Evaluator
{
Evaluator();
float EvaluateFromString(const char* str, const Environment* env);
float Evaluate(const std::vector<Token>& expression, const Environment* env);
void RegisterFunction(const std::string& name, const fnFunction& fn);
void SetConstant(const std::string& name, float value);
float PopValue();
void PushValue(float value);
Token PopOperator();
void ApplyBinOp(Token::BinOp op);
void LookupVar(const Token& t, const Environment* env);
void InvokeFunction(const Token& t, const Environment* env);
void ApplyUntilLeftParen(bool discardParen);
std::deque<Token> operandStack;
std::deque<Token> operatorStack;
std::unordered_map<std::string, fnFunction> functions;
std::unordered_map<std::string, float> constants;
};
}