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_FUNCTIONDECLARATION
9 #define SKSL_FUNCTIONDECLARATION
10 
11 #include "SkSLExpression.h"
12 #include "SkSLModifiers.h"
13 #include "SkSLSymbol.h"
14 #include "SkSLSymbolTable.h"
15 #include "SkSLType.h"
16 #include "SkSLVariable.h"
17 
18 namespace SkSL {
19 
20 /**
21  * A function declaration (not a definition -- does not contain a body).
22  */
23 struct FunctionDeclaration : public Symbol {
FunctionDeclarationFunctionDeclaration24     FunctionDeclaration(Position position, SkString name,
25                         std::vector<const Variable*> parameters, const Type& returnType)
26     : INHERITED(position, kFunctionDeclaration_Kind, std::move(name))
27     , fDefined(false)
28     , fBuiltin(false)
29     , fParameters(std::move(parameters))
30     , fReturnType(returnType) {}
31 
descriptionFunctionDeclaration32     SkString description() const override {
33         SkString result = fReturnType.description() + " " + fName + "(";
34         SkString separator;
35         for (auto p : fParameters) {
36             result += separator;
37             separator = ", ";
38             result += p->description();
39         }
40         result += ")";
41         return result;
42     }
43 
matchesFunctionDeclaration44     bool matches(const FunctionDeclaration& f) const {
45         if (fName != f.fName) {
46             return false;
47         }
48         if (fParameters.size() != f.fParameters.size()) {
49             return false;
50         }
51         for (size_t i = 0; i < fParameters.size(); i++) {
52             if (fParameters[i]->fType != f.fParameters[i]->fType) {
53                 return false;
54             }
55         }
56         return true;
57     }
58 
59     /**
60      * Determine the effective types of this function's parameters and return value when called with
61      * the given arguments. This is relevant for functions with generic parameter types, where this
62      * will collapse the generic types down into specific concrete types.
63      *
64      * Returns true if it was able to select a concrete set of types for the generic function, false
65      * if there is no possible way this can match the argument types. Note that even a true return
66      * does not guarantee that the function can be successfully called with those arguments, merely
67      * indicates that an attempt should be made. If false is returned, the state of
68      * outParameterTypes and outReturnType are undefined.
69      */
determineFinalTypesFunctionDeclaration70     bool determineFinalTypes(const std::vector<std::unique_ptr<Expression>>& arguments,
71                              std::vector<const Type*>* outParameterTypes,
72                              const Type** outReturnType) const {
73         assert(arguments.size() == fParameters.size());
74         int genericIndex = -1;
75         for (size_t i = 0; i < arguments.size(); i++) {
76             if (fParameters[i]->fType.kind() == Type::kGeneric_Kind) {
77                 std::vector<const Type*> types = fParameters[i]->fType.coercibleTypes();
78                 if (genericIndex == -1) {
79                     for (size_t j = 0; j < types.size(); j++) {
80                         if (arguments[i]->fType.canCoerceTo(*types[j])) {
81                             genericIndex = j;
82                             break;
83                         }
84                     }
85                     if (genericIndex == -1) {
86                         return false;
87                     }
88                 }
89                 outParameterTypes->push_back(types[genericIndex]);
90             } else {
91                 outParameterTypes->push_back(&fParameters[i]->fType);
92             }
93         }
94         if (fReturnType.kind() == Type::kGeneric_Kind) {
95             assert(genericIndex != -1);
96             *outReturnType = fReturnType.coercibleTypes()[genericIndex];
97         } else {
98             *outReturnType = &fReturnType;
99         }
100         return true;
101     }
102 
103     mutable bool fDefined;
104     bool fBuiltin;
105     const std::vector<const Variable*> fParameters;
106     const Type& fReturnType;
107 
108     typedef Symbol INHERITED;
109 };
110 
111 } // namespace
112 
113 #endif
114