| /* |
| * Copyright 2015 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkRecordPattern_DEFINED |
| #define SkRecordPattern_DEFINED |
| |
| #include "SkTLogic.h" |
| |
| namespace SkRecords { |
| |
| // First, some matchers. These match a single command in the SkRecord, |
| // and may hang onto some data from it. If so, you can get the data by calling .get(). |
| |
| // Matches a command of type T, and stores that command. |
| template <typename T> |
| class Is { |
| public: |
| Is() : fPtr(NULL) {} |
| |
| typedef T type; |
| type* get() { return fPtr; } |
| |
| bool operator()(T* ptr) { |
| fPtr = ptr; |
| return true; |
| } |
| |
| template <typename U> |
| bool operator()(U*) { |
| fPtr = NULL; |
| return false; |
| } |
| |
| private: |
| type* fPtr; |
| }; |
| |
| // Matches any command that draws, and stores its paint. |
| class IsDraw { |
| SK_CREATE_MEMBER_DETECTOR(paint); |
| public: |
| IsDraw() : fPaint(NULL) {} |
| |
| typedef SkPaint type; |
| type* get() { return fPaint; } |
| |
| template <typename T> |
| SK_WHEN(HasMember_paint<T>, bool) operator()(T* draw) { |
| fPaint = AsPtr(draw->paint); |
| return true; |
| } |
| |
| template <typename T> |
| SK_WHEN(!HasMember_paint<T>, bool) operator()(T*) { |
| fPaint = NULL; |
| return false; |
| } |
| |
| // SaveLayer has an SkPaint named paint, but it's not a draw. |
| bool operator()(SaveLayer*) { |
| fPaint = NULL; |
| return false; |
| } |
| |
| private: |
| // Abstracts away whether the paint is always part of the command or optional. |
| template <typename T> static T* AsPtr(SkRecords::Optional<T>& x) { return x; } |
| template <typename T> static T* AsPtr(T& x) { return &x; } |
| |
| type* fPaint; |
| }; |
| |
| // Matches if Matcher doesn't. Stores nothing. |
| template <typename Matcher> |
| struct Not { |
| template <typename T> |
| bool operator()(T* ptr) { return !Matcher()(ptr); } |
| }; |
| |
| // Matches if either of A or B does. Stores nothing. |
| template <typename A, typename B> |
| struct Or { |
| template <typename T> |
| bool operator()(T* ptr) { return A()(ptr) || B()(ptr); } |
| }; |
| |
| // Matches if any of A, B or C does. Stores nothing. |
| template <typename A, typename B, typename C> |
| struct Or3 : Or<A, Or<B, C> > {}; |
| |
| // Matches if any of A, B, C or D does. Stores nothing. |
| template <typename A, typename B, typename C, typename D> |
| struct Or4 : Or<A, Or<B, Or<C, D> > > {}; |
| |
| // Star is a special matcher that greedily matches Matcher 0 or more times. Stores nothing. |
| template <typename Matcher> |
| struct Star { |
| template <typename T> |
| bool operator()(T* ptr) { return Matcher()(ptr); } |
| }; |
| |
| // Cons builds a list of Matchers. |
| // It first matches Matcher (something from above), then Pattern (another Cons or Nil). |
| // |
| // This is the main entry point to pattern matching, and so provides a couple of extra API bits: |
| // - search scans through the record to look for matches; |
| // - first, second, and third return the data stored by their respective matchers in the pattern. |
| // |
| // These Cons build lists analogously to Lisp's "cons". See Pattern# for the "list" equivalent. |
| template <typename Matcher, typename Pattern> |
| class Cons { |
| public: |
| // If this pattern matches the SkRecord starting at i, |
| // return the index just past the end of the pattern, otherwise return 0. |
| SK_ALWAYS_INLINE int match(SkRecord* record, int i) { |
| i = this->matchHead(&fHead, record, i); |
| return i == 0 ? 0 : fTail.match(record, i); |
| } |
| |
| // Starting from *end, walk through the SkRecord to find the first span matching this pattern. |
| // If there is no such span, return false. If there is, return true and set [*begin, *end). |
| SK_ALWAYS_INLINE bool search(SkRecord* record, int* begin, int* end) { |
| for (*begin = *end; *begin < record->count(); ++(*begin)) { |
| *end = this->match(record, *begin); |
| if (*end != 0) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| // Once either match or search has succeeded, access the stored data of the first, second, |
| // or third matcher in this pattern. Add as needed for longer patterns. |
| // T is checked statically at compile time; no casting is involved. It's just an API wart. |
| template <typename T> T* first() { return fHead.get(); } |
| template <typename T> T* second() { return fTail.fHead.get(); } |
| template <typename T> T* third() { return fTail.fTail.fHead.get(); } |
| template <typename T> T* fourth() { return fTail.fTail.fTail.fHead.get(); } |
| |
| private: |
| // If head isn't a Star, try to match at i once. |
| template <typename T> |
| int matchHead(T*, SkRecord* record, int i) { |
| if (i < record->count()) { |
| if (record->mutate<bool>(i, fHead)) { |
| return i+1; |
| } |
| } |
| return 0; |
| } |
| |
| // If head is a Star, walk i until it doesn't match. |
| template <typename T> |
| int matchHead(Star<T>*, SkRecord* record, int i) { |
| while (i < record->count()) { |
| if (!record->mutate<bool>(i, fHead)) { |
| return i; |
| } |
| i++; |
| } |
| return 0; |
| } |
| |
| Matcher fHead; |
| Pattern fTail; |
| |
| // All Cons are friends with each other. This lets first, second, and third work. |
| template <typename, typename> friend class Cons; |
| }; |
| |
| // Nil is the end of every pattern Cons chain. |
| struct Nil { |
| // Bottoms out recursion down the fTail chain. Just return whatever i the front decided on. |
| int match(SkRecord*, int i) { return i; } |
| }; |
| |
| // These Pattern# types are syntax sugar over Cons and Nil, just to help eliminate some of the |
| // template noise. Use these if you can. Feel free to add more for longer patterns. |
| // All types A, B, C, ... are Matchers. |
| template <typename A> |
| struct Pattern1 : Cons<A, Nil> {}; |
| |
| template <typename A, typename B> |
| struct Pattern2 : Cons<A, Pattern1<B> > {}; |
| |
| template <typename A, typename B, typename C> |
| struct Pattern3 : Cons<A, Pattern2<B, C> > {}; |
| |
| template <typename A, typename B, typename C, typename D> |
| struct Pattern4 : Cons<A, Pattern3<B, C, D> > {}; |
| |
| template <typename A, typename B, typename C, typename D, typename E> |
| struct Pattern5 : Cons<A, Pattern4<B, C, D, E> > {}; |
| |
| template <typename A, typename B, typename C, typename D, typename E, typename F> |
| struct Pattern6 : Cons<A, Pattern5<B, C, D, E, F> > {}; |
| |
| template <typename A, typename B, typename C, typename D, typename E, typename F, typename G> |
| struct Pattern7 : Cons<A, Pattern6<B, C, D, E, F, G> > {}; |
| |
| } // namespace SkRecords |
| |
| #endif//SkRecordPattern_DEFINED |