SkSLIndexExpression.h revision ccb1dd8f267f9d7fe7c9d0ce222ebc81b41853b3 
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_INDEX
9#define SKSL_INDEX
10
11#include "SkSLExpression.h"
12#include "SkSLUtil.h"
13
14namespace SkSL {
15
16/**
17 * Given a type, returns the type that will result from extracting an array value from it.
18 */
19static const Type& index_type(const Context& context, const Type& type) {
20    if (type.kind() == Type::kMatrix_Kind) {
21        if (type.componentType() == *context.fFloat_Type) {
22            switch (type.rows()) {
23                case 2: return *context.fVec2_Type;
24                case 3: return *context.fVec3_Type;
25                case 4: return *context.fVec4_Type;
26                default: ASSERT(false);
27            }
28        } else {
29            ASSERT(type.componentType() == *context.fDouble_Type);
30            switch (type.rows()) {
31                case 2: return *context.fDVec2_Type;
32                case 3: return *context.fDVec3_Type;
33                case 4: return *context.fDVec4_Type;
34                default: ASSERT(false);
35            }
36        }
37    }
38    return type.componentType();
39}
40
41/**
42 * An expression which extracts a value from an array or matrix, as in 'm[2]'.
43 */
44struct IndexExpression : public Expression {
45    IndexExpression(const Context& context, std::unique_ptr<Expression> base,
46                    std::unique_ptr<Expression> index)
47    : INHERITED(base->fPosition, kIndex_Kind, index_type(context, base->fType))
48    , fBase(std::move(base))
49    , fIndex(std::move(index)) {
50        ASSERT(fIndex->fType == *context.fInt_Type || fIndex->fType == *context.fUInt_Type);
51    }
52
53    std::string description() const override {
54        return fBase->description() + "[" + fIndex->description() + "]";
55    }
56
57    const std::unique_ptr<Expression> fBase;
58    const std::unique_ptr<Expression> fIndex;
59
60    typedef Expression INHERITED;
61};
62
63} // namespace
64
65#endif
66