1/*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SKSL_PREFIXEXPRESSION
9#define SKSL_PREFIXEXPRESSION
10
11#include "SkSLExpression.h"
12#include "SkSLFloatLiteral.h"
13#include "SkSLIRGenerator.h"
14#include "SkSLLexer.h"
15
16namespace SkSL {
17
18/**
19 * An expression modified by a unary operator appearing before it, such as '!flag'.
20 */
21struct PrefixExpression : public Expression {
22    PrefixExpression(Token::Kind op, std::unique_ptr<Expression> operand)
23    : INHERITED(operand->fOffset, kPrefix_Kind, operand->fType)
24    , fOperand(std::move(operand))
25    , fOperator(op) {}
26
27    bool isConstant() const override {
28        return fOperator == Token::MINUS && fOperand->isConstant();
29    }
30
31    bool hasSideEffects() const override {
32        return fOperator == Token::PLUSPLUS || fOperator == Token::MINUSMINUS ||
33               fOperand->hasSideEffects();
34    }
35
36    std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
37                                                  const DefinitionMap& definitions) override {
38        if (fOperand->fKind == Expression::kFloatLiteral_Kind) {
39            return std::unique_ptr<Expression>(new FloatLiteral(
40                                                              irGenerator.fContext,
41                                                              fOffset,
42                                                              -((FloatLiteral&) *fOperand).fValue));
43
44        }
45        return nullptr;
46    }
47
48    String description() const override {
49        return Compiler::OperatorName(fOperator) + fOperand->description();
50    }
51
52    std::unique_ptr<Expression> fOperand;
53    const Token::Kind fOperator;
54
55    typedef Expression INHERITED;
56};
57
58} // namespace
59
60#endif
61