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 "SkSLConstructor.h"
12#include "SkSLContext.h"
13#include "SkSLExpression.h"
14#include "SkSLIRGenerator.h"
15#include "SkSLUtil.h"
16
17namespace SkSL {
18
19/**
20 * Given a type and a swizzle component count, returns the type that will result from swizzling. For
21 * instance, swizzling a float3with two components will result in a float2 It is possible to swizzle
22 * with more components than the source vector, as in 'float21).xxxx'.
23 */
24static const Type& get_type(const Context& context, Expression& value, size_t count) {
25    const Type& base = value.fType.componentType();
26    if (count == 1) {
27        return base;
28    }
29    if (base == *context.fFloat_Type) {
30        switch (count) {
31            case 2: return *context.fFloat2_Type;
32            case 3: return *context.fFloat3_Type;
33            case 4: return *context.fFloat4_Type;
34        }
35    } else if (base == *context.fHalf_Type) {
36        switch (count) {
37            case 2: return *context.fHalf2_Type;
38            case 3: return *context.fHalf3_Type;
39            case 4: return *context.fHalf4_Type;
40        }
41    } else if (base == *context.fDouble_Type) {
42        switch (count) {
43            case 2: return *context.fDouble2_Type;
44            case 3: return *context.fDouble3_Type;
45            case 4: return *context.fDouble4_Type;
46        }
47    } else if (base == *context.fInt_Type) {
48        switch (count) {
49            case 2: return *context.fInt2_Type;
50            case 3: return *context.fInt3_Type;
51            case 4: return *context.fInt4_Type;
52        }
53    } else if (base == *context.fShort_Type) {
54        switch (count) {
55            case 2: return *context.fShort2_Type;
56            case 3: return *context.fShort3_Type;
57            case 4: return *context.fShort4_Type;
58        }
59    } else if (base == *context.fUInt_Type) {
60        switch (count) {
61            case 2: return *context.fUInt2_Type;
62            case 3: return *context.fUInt3_Type;
63            case 4: return *context.fUInt4_Type;
64        }
65    } else if (base == *context.fUShort_Type) {
66        switch (count) {
67            case 2: return *context.fUShort2_Type;
68            case 3: return *context.fUShort3_Type;
69            case 4: return *context.fUShort4_Type;
70        }
71    } else if (base == *context.fBool_Type) {
72        switch (count) {
73            case 2: return *context.fBool2_Type;
74            case 3: return *context.fBool3_Type;
75            case 4: return *context.fBool4_Type;
76        }
77    }
78    ABORT("cannot swizzle %s\n", value.description().c_str());
79}
80
81/**
82 * Represents a vector swizzle operation such as 'float21, 2, 3).zyx'.
83 */
84struct Swizzle : public Expression {
85    Swizzle(const Context& context, std::unique_ptr<Expression> base, std::vector<int> components)
86    : INHERITED(base->fOffset, kSwizzle_Kind, get_type(context, *base, components.size()))
87    , fBase(std::move(base))
88    , fComponents(std::move(components)) {
89        ASSERT(fComponents.size() >= 1 && fComponents.size() <= 4);
90    }
91
92    std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
93                                                  const DefinitionMap& definitions) override {
94        if (fBase->fKind == Expression::kConstructor_Kind && fBase->isConstant()) {
95            // we're swizzling a constant vector, e.g. float4(1).x. Simplify it.
96            ASSERT(fBase->fKind == Expression::kConstructor_Kind);
97            if (fType == *irGenerator.fContext.fInt_Type) {
98                ASSERT(fComponents.size() == 1);
99                int64_t value = ((Constructor&) *fBase).getIVecComponent(fComponents[0]);
100                return std::unique_ptr<Expression>(new IntLiteral(irGenerator.fContext,
101                                                                  -1,
102                                                                  value));
103            } else if (fType == *irGenerator.fContext.fFloat_Type) {
104                ASSERT(fComponents.size() == 1);
105                double value = ((Constructor&) *fBase).getFVecComponent(fComponents[0]);
106                return std::unique_ptr<Expression>(new FloatLiteral(irGenerator.fContext,
107                                                                    -1,
108                                                                    value));
109            }
110        }
111        return nullptr;
112    }
113
114    bool hasSideEffects() const override {
115        return fBase->hasSideEffects();
116    }
117
118    String description() const override {
119        String result = fBase->description() + ".";
120        for (int x : fComponents) {
121            result += "xyzw"[x];
122        }
123        return result;
124    }
125
126    std::unique_ptr<Expression> fBase;
127    const std::vector<int> fComponents;
128
129    typedef Expression INHERITED;
130};
131
132} // namespace
133
134#endif
135