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_SWIZZLE
9#define SKSL_SWIZZLE
10
11#include "SkSLContext.h"
12#include "SkSLExpression.h"
13#include "SkSLUtil.h"
14
15namespace SkSL {
16
17/**
18 * Given a type and a swizzle component count, returns the type that will result from swizzling. For
19 * instance, swizzling a vec3 with two components will result in a vec2. It is possible to swizzle
20 * with more components than the source vector, as in 'vec2(1).xxxx'.
21 */
22static const Type& get_type(const Context& context, Expression& value, size_t count) {
23    const Type& base = value.fType.componentType();
24    if (count == 1) {
25        return base;
26    }
27    if (base == *context.fFloat_Type) {
28        switch (count) {
29            case 2: return *context.fVec2_Type;
30            case 3: return *context.fVec3_Type;
31            case 4: return *context.fVec4_Type;
32        }
33    } else if (base == *context.fDouble_Type) {
34        switch (count) {
35            case 2: return *context.fDVec2_Type;
36            case 3: return *context.fDVec3_Type;
37            case 4: return *context.fDVec4_Type;
38        }
39    } else if (base == *context.fInt_Type) {
40        switch (count) {
41            case 2: return *context.fIVec2_Type;
42            case 3: return *context.fIVec3_Type;
43            case 4: return *context.fIVec4_Type;
44        }
45    } else if (base == *context.fUInt_Type) {
46        switch (count) {
47            case 2: return *context.fUVec2_Type;
48            case 3: return *context.fUVec3_Type;
49            case 4: return *context.fUVec4_Type;
50        }
51    } else if (base == *context.fBool_Type) {
52        switch (count) {
53            case 2: return *context.fBVec2_Type;
54            case 3: return *context.fBVec3_Type;
55            case 4: return *context.fBVec4_Type;
56        }
57    }
58    ABORT("cannot swizzle %s\n", value.description().c_str());
59}
60
61/**
62 * Represents a vector swizzle operation such as 'vec2(1, 2, 3).zyx'.
63 */
64struct Swizzle : public Expression {
65    Swizzle(const Context& context, std::unique_ptr<Expression> base, std::vector<int> components)
66    : INHERITED(base->fPosition, kSwizzle_Kind, get_type(context, *base, components.size()))
67    , fBase(std::move(base))
68    , fComponents(std::move(components)) {
69        ASSERT(fComponents.size() >= 1 && fComponents.size() <= 4);
70    }
71
72    SkString description() const override {
73        SkString result = fBase->description() + ".";
74        for (int x : fComponents) {
75            result += "xyzw"[x];
76        }
77        return result;
78    }
79
80    std::unique_ptr<Expression> fBase;
81    const std::vector<int> fComponents;
82
83    typedef Expression INHERITED;
84};
85
86} // namespace
87
88#endif
89