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/*
Copyright (C) 2006 - 2015 Evan Teran
evan.teran@gmail.com
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef EXPRESSION_H_20070402_
#define EXPRESSION_H_20070402_
#include "Status.h"
#include <QString>
#include <functional>
struct ExpressionError {
public:
enum ErrorMessage {
None,
Syntax,
UnbalancedParens,
UnbalancedBraces,
DivideByZero,
InvalidNumber,
UnknownVariable,
CannotReadMemory,
UnexpectedOperator,
UnexpectedNumber,
VariableLargerThanAddress
};
public:
ExpressionError() = default;
explicit ExpressionError(ErrorMessage type)
: error_(type) {
}
const char *what() const noexcept {
switch (error_) {
case Syntax:
return "Syntax Error";
case UnbalancedParens:
return "Unbalanced Parenthesis";
case DivideByZero:
return "Divide By Zero";
case InvalidNumber:
return "Invalid Numerical Constant";
case UnknownVariable:
return "Unknown Variable";
case UnbalancedBraces:
return "Unbalanced Braces";
case CannotReadMemory:
return "Cannot Read Memory At the Effective Address";
case UnexpectedOperator:
return "Unexpected Operator";
case UnexpectedNumber:
return "Unexpected Numerical Constant";
case VariableLargerThanAddress:
return "Variable Does Not Fit Into An Address. Is it an FPU Register?";
default:
return "Unknown Error";
}
}
private:
ErrorMessage error_ = None;
};
template <class T>
class Expression {
public:
using variable_getter_t = std::function<T(const QString &, bool *, ExpressionError *)>;
using memoryReader_t = std::function<T(T, bool *, ExpressionError *)>;
public:
Expression(const QString &s, variable_getter_t vg, memoryReader_t mr);
~Expression() = default;
private:
struct Token {
Token() = default;
Token(const Token &other) = default;
enum Operator {
NONE,
AND,
OR,
XOR,
LSHFT,
RSHFT,
PLUS,
MINUS,
MUL,
DIV,
MOD,
CMP,
LPAREN,
RPAREN,
LBRACE,
RBRACE,
NOT,
LT,
LE,
GT,
GE,
EQ,
NE,
LOGICAL_AND,
LOGICAL_OR
};
enum Type {
UNKNOWN,
OPERATOR,
NUMBER,
VARIABLE
};
void set(const QString &data, Operator oper, Type type) {
data_ = data;
operator_ = oper;
type_ = type;
}
QString data_;
Operator operator_ = NONE;
Type type_ = UNKNOWN;
};
private:
T evalInternal() {
T result;
getToken();
evalExp(result);
return result;
}
public:
Result<T, ExpressionError> evaluate() noexcept {
try {
return evalInternal();
} catch (const ExpressionError &e) {
return make_unexpected(e);
}
}
private:
void evalExp(T &result);
void evalExp0(T &result);
void evalExp1(T &result);
void evalExp2(T &result);
void evalExp3(T &result);
void evalExp4(T &result);
void evalExp5(T &result);
void evalExp6(T &result);
void evalExp7(T &result);
void evalAtom(T &result);
void getToken();
private:
QString expression_;
QString::const_iterator expressionPtr_;
Token token_;
variable_getter_t variableReader_;
memoryReader_t memoryReader_;
};
#include "Expression.tcc"
#endif
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