1/*
2 * Copyright 2015 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 SkRecordPattern_DEFINED
9#define SkRecordPattern_DEFINED
10
11#include "include/private/SkTLogic.h"
12#include "src/core/SkRecord.h"
13
14namespace SkRecords {
15
16// First, some matchers. These match a single command in the SkRecord,
17// and may hang onto some data from it. If so, you can get the data by calling .get().
18
19// Matches a command of type T, and stores that command.
20template <typename T>
21class Is {
22public:
23 Is() : fPtr(nullptr) {}
24
25 typedef T type;
26 type* get() { return fPtr; }
27
28 bool operator()(T* ptr) {
29 fPtr = ptr;
30 return true;
31 }
32
33 template <typename U>
34 bool operator()(U*) {
35 fPtr = nullptr;
36 return false;
37 }
38
39private:
40 type* fPtr;
41};
42
43// Matches any command that draws, and stores its paint.
44class IsDraw {
45public:
46 IsDraw() : fPaint(nullptr) {}
47
48 typedef SkPaint type;
49 type* get() { return fPaint; }
50
51 template <typename T>
52 SK_WHEN((T::kTags & kDrawWithPaint_Tag) == kDrawWithPaint_Tag, bool) operator()(T* draw) {
53 fPaint = AsPtr(draw->paint);
54 return true;
55 }
56
57 template <typename T>
58 SK_WHEN((T::kTags & kDrawWithPaint_Tag) == kDraw_Tag, bool) operator()(T* draw) {
59 fPaint = nullptr;
60 return true;
61 }
62
63 template <typename T>
64 SK_WHEN(!(T::kTags & kDraw_Tag), bool) operator()(T* draw) {
65 fPaint = nullptr;
66 return false;
67 }
68
69private:
70 // Abstracts away whether the paint is always part of the command or optional.
71 template <typename T> static T* AsPtr(SkRecords::Optional<T>& x) { return x; }
72 template <typename T> static T* AsPtr(T& x) { return &x; }
73
74 type* fPaint;
75};
76
77// Matches if Matcher doesn't. Stores nothing.
78template <typename Matcher>
79struct Not {
80 template <typename T>
81 bool operator()(T* ptr) { return !Matcher()(ptr); }
82};
83
84// Matches if any of First or Rest... does. Stores nothing.
85template <typename First, typename... Rest>
86struct Or {
87 template <typename T>
88 bool operator()(T* ptr) { return First()(ptr) || Or<Rest...>()(ptr); }
89};
90template <typename First>
91struct Or<First> {
92 template <typename T>
93 bool operator()(T* ptr) { return First()(ptr); }
94};
95
96
97// Greedy is a special matcher that greedily matches Matcher 0 or more times. Stores nothing.
98template <typename Matcher>
99struct Greedy {
100 template <typename T>
101 bool operator()(T* ptr) { return Matcher()(ptr); }
102};
103
104// Pattern matches each of its matchers in order.
105//
106// This is the main entry point to pattern matching, and so provides a couple of extra API bits:
107// - search scans through the record to look for matches;
108// - first, second, third, ... return the data stored by their respective matchers in the pattern.
109
110template <typename... Matchers> class Pattern;
111
112template <> class Pattern<> {
113public:
114 // Bottoms out recursion. Just return whatever i the front decided on.
115 int match(SkRecord*, int i) { return i; }
116};
117
118template <typename First, typename... Rest>
119class Pattern<First, Rest...> {
120public:
121 // If this pattern matches the SkRecord starting from i,
122 // return the index just past the end of the pattern, otherwise return 0.
123 SK_ALWAYS_INLINE int match(SkRecord* record, int i) {
124 i = this->matchFirst(&fFirst, record, i);
125 return i > 0 ? fRest.match(record, i) : 0;
126 }
127
128 // Starting from *end, walk through the SkRecord to find the first span matching this pattern.
129 // If there is no such span, return false. If there is, return true and set [*begin, *end).
130 SK_ALWAYS_INLINE bool search(SkRecord* record, int* begin, int* end) {
131 for (*begin = *end; *begin < record->count(); ++(*begin)) {
132 *end = this->match(record, *begin);
133 if (*end != 0) {
134 return true;
135 }
136 }
137 return false;
138 }
139
140 // TODO: some sort of smart get<i>()
141 template <typename T> T* first() { return fFirst.get(); }
142 template <typename T> T* second() { return fRest.template first<T>(); }
143 template <typename T> T* third() { return fRest.template second<T>(); }
144 template <typename T> T* fourth() { return fRest.template third<T>(); }
145
146private:
147 // If first isn't a Greedy, try to match at i once.
148 template <typename T>
149 int matchFirst(T* first, SkRecord* record, int i) {
150 if (i < record->count()) {
151 if (record->mutate(i, *first)) {
152 return i+1;
153 }
154 }
155 return 0;
156 }
157
158 // If first is a Greedy, walk i until it doesn't match.
159 template <typename T>
160 int matchFirst(Greedy<T>* first, SkRecord* record, int i) {
161 while (i < record->count()) {
162 if (!record->mutate(i, *first)) {
163 return i;
164 }
165 i++;
166 }
167 return 0;
168 }
169
170 First fFirst;
171 Pattern<Rest...> fRest;
172};
173
174} // namespace SkRecords
175
176#endif//SkRecordPattern_DEFINED
177