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 "SkSLContext.h"
12#include "SkSLExpression.h"
13#include "SkSLUtil.h"
14
15namespace SkSL {
16
17/**
18 * Given a type, returns the type that will result from extracting an array value from it.
19 */
20static const Type& index_type(const Context& context, const Type& type) {
21    if (type.kind() == Type::kMatrix_Kind) {
22        if (type.componentType() == *context.fFloat_Type) {
23            switch (type.rows()) {
24                case 2: return *context.fVec2_Type;
25                case 3: return *context.fVec3_Type;
26                case 4: return *context.fVec4_Type;
27                default: ASSERT(false);
28            }
29        } else {
30            ASSERT(type.componentType() == *context.fDouble_Type);
31            switch (type.rows()) {
32                case 2: return *context.fDVec2_Type;
33                case 3: return *context.fDVec3_Type;
34                case 4: return *context.fDVec4_Type;
35                default: ASSERT(false);
36            }
37        }
38    }
39    return type.componentType();
40}
41
42/**
43 * An expression which extracts a value from an array or matrix, as in 'm[2]'.
44 */
45struct IndexExpression : public Expression {
46    IndexExpression(const Context& context, std::unique_ptr<Expression> base,
47                    std::unique_ptr<Expression> index)
48    : INHERITED(base->fPosition, kIndex_Kind, index_type(context, base->fType))
49    , fBase(std::move(base))
50    , fIndex(std::move(index)) {
51        ASSERT(fIndex->fType == *context.fInt_Type || fIndex->fType == *context.fUInt_Type);
52    }
53
54    SkString description() const override {
55        return fBase->description() + "[" + fIndex->description() + "]";
56    }
57
58    std::unique_ptr<Expression> fBase;
59    std::unique_ptr<Expression> fIndex;
60
61    typedef Expression INHERITED;
62};
63
64} // namespace
65
66#endif
67