1/*
2 * Copyright 2019 Google LLC
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_EXTERNALVALUE
9#define SKSL_EXTERNALVALUE
10
11#include "src/sksl/ir/SkSLSymbol.h"
12
13namespace SkSL {
14
15class String;
16class Type;
17
18class ExternalValue : public Symbol {
19public:
20 ExternalValue(const char* name, const Type& type)
21 : INHERITED(-1, kExternal_Kind, name)
22 , fType(type) {}
23
24 virtual bool canRead() const {
25 return false;
26 }
27
28 virtual bool canWrite() const {
29 return false;
30 }
31
32 virtual bool canCall() const {
33 return false;
34 }
35
36 /**
37 * Returns the type for purposes of read and write operations.
38 */
39 virtual const Type& type() const {
40 return fType;
41 }
42
43 virtual int callParameterCount() const {
44 return -1;
45 }
46
47 /**
48 * Fills in the outTypes array with pointers to the parameter types. outTypes must be able to
49 * hold callParameterCount() pointers.
50 */
51 virtual void getCallParameterTypes(const Type** outTypes) const {
52 SkASSERT(false);
53 }
54
55 /**
56 * Returns the return type resulting from a call operation.
57 */
58 virtual const Type& callReturnType() const {
59 return fType;
60 }
61
62 /**
63 * Reads the external value and stores the resulting data in target. The caller must ensure
64 * that target is a valid pointer to a region of sufficient size to hold the data contained
65 * in this external value.
66 * 'index' is the element index ([0 .. N-1]) within a call to ByteCode::run()
67 */
68 virtual void read(int index, float* target) {
69 SkASSERT(false);
70 }
71
72 /**
73 * Copies the value in src into this external value. The caller must ensure that src is a
74 * pointer to the type of data expected by this external value.
75 * 'index' is the element index ([0 .. N-1]) within a call to ByteCode::run()
76 */
77 virtual void write(int index, float* src) {
78 SkASSERT(false);
79 }
80
81 /**
82 * Calls the value as a function with the specified parameters. arguments must be a pointer to
83 * a structure containing the arguments expected by the external value in source order, and
84 * outResult must be a pointer to a region of sufficient size to hold the function's return
85 * value.
86 * 'index' is the element index ([0 .. N-1]) within a call to ByteCode::run()
87 */
88 virtual void call(int index, float* arguments, float* outResult) {
89 SkASSERT(false);
90 }
91
92 /**
93 * Resolves 'name' within this context and returns an ExternalValue which represents it, or
94 * null if no such child exists. If the implementation of this method creates new
95 * ExternalValues and there isn't a more convenient place for ownership of the objects to
96 * reside, the compiler's takeOwnership method may be useful.
97 *
98 * The 'name' string may not persist after this call; do not store this pointer.
99 */
100 virtual ExternalValue* getChild(const char* name) const {
101 return nullptr;
102 }
103
104 String description() const override {
105 return String("external<") + fName + ">";
106 }
107
108private:
109 typedef Symbol INHERITED;
110
111 const Type& fType;
112};
113
114} // namespace SkSL
115
116#endif
117