src/sksl/ir/SkSLPrefixExpression.h

/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SKSL_PREFIXEXPRESSION
#define SKSL_PREFIXEXPRESSION

#include "SkSLExpression.h"
#include "SkSLFloatLiteral.h"
#include "SkSLIRGenerator.h"
#include "SkSLLexer.h"

namespace SkSL {

/**
 * An expression modified by a unary operator appearing before it, such as '!flag'.
 */
struct PrefixExpression : public Expression {
    PrefixExpression(Token::Kind op, std::unique_ptr<Expression> operand)
    : INHERITED(operand->fOffset, kPrefix_Kind, operand->fType)
    , fOperand(std::move(operand))
    , fOperator(op) {}

    bool isConstant() const override {
        return fOperator == Token::MINUS && fOperand->isConstant();
    }

    bool hasSideEffects() const override {
        return fOperator == Token::PLUSPLUS || fOperator == Token::MINUSMINUS ||
               fOperand->hasSideEffects();
    }

    std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
                                                  const DefinitionMap& definitions) override {
        if (fOperand->fKind == Expression::kFloatLiteral_Kind) {
            return std::unique_ptr<Expression>(new FloatLiteral(
                                                              irGenerator.fContext,
                                                              fOffset,
                                                              -((FloatLiteral&) *fOperand).fValue));

        }
        return nullptr;
    }

    String description() const override {
        return Compiler::OperatorName(fOperator) + fOperand->description();
    }

    std::unique_ptr<Expression> fOperand;
    const Token::Kind fOperator;

    typedef Expression INHERITED;
};

} // namespace

#endif