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/*
* 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(nullptr) {}
typedef T type;
type* get() { return fPtr; }
bool operator()(T* ptr) {
fPtr = ptr;
return true;
}
template <typename U>
bool operator()(U*) {
fPtr = nullptr;
return false;
}
private:
type* fPtr;
};
// Matches any command that draws, and stores its paint.
class IsDraw {
public:
IsDraw() : fPaint(nullptr) {}
typedef SkPaint type;
type* get() { return fPaint; }
template <typename T>
SK_WHEN(T::kTags & kDraw_Tag, bool) operator()(T* draw) {
fPaint = AsPtr(draw->paint);
return true;
}
bool operator()(DrawDrawable*) {
static_assert(DrawDrawable::kTags & kDraw_Tag, "");
fPaint = nullptr;
return true;
}
template <typename T>
SK_WHEN(!(T::kTags & kDraw_Tag), bool) operator()(T* draw) {
fPaint = nullptr;
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 any of First or Rest... does. Stores nothing.
template <typename First, typename... Rest>
struct Or {
template <typename T>
bool operator()(T* ptr) { return First()(ptr) || Or<Rest...>()(ptr); }
};
template <typename First>
struct Or<First> {
template <typename T>
bool operator()(T* ptr) { return First()(ptr); }
};
// Greedy is a special matcher that greedily matches Matcher 0 or more times. Stores nothing.
template <typename Matcher>
struct Greedy {
template <typename T>
bool operator()(T* ptr) { return Matcher()(ptr); }
};
// Pattern matches each of its matchers in order.
//
// 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, third, ... return the data stored by their respective matchers in the pattern.
template <typename... Matchers> class Pattern;
template <> class Pattern<> {
public:
// Bottoms out recursion. Just return whatever i the front decided on.
int match(SkRecord*, int i) { return i; }
};
template <typename First, typename... Rest>
class Pattern<First, Rest...> {
public:
// If this pattern matches the SkRecord starting from 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->matchFirst(&fFirst, record, i);
return i > 0 ? fRest.match(record, i) : 0;
}
// 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;
}
// TODO: some sort of smart get<i>()
template <typename T> T* first() { return fFirst.get(); }
template <typename T> T* second() { return fRest.template first<T>(); }
template <typename T> T* third() { return fRest.template second<T>(); }
template <typename T> T* fourth() { return fRest.template third<T>(); }
private:
// If first isn't a Greedy, try to match at i once.
template <typename T>
int matchFirst(T* first, SkRecord* record, int i) {
if (i < record->count()) {
if (record->mutate(i, *first)) {
return i+1;
}
}
return 0;
}
// If first is a Greedy, walk i until it doesn't match.
template <typename T>
int matchFirst(Greedy<T>* first, SkRecord* record, int i) {
while (i < record->count()) {
if (!record->mutate(i, *first)) {
return i;
}
i++;
}
return 0;
}
First fFirst;
Pattern<Rest...> fRest;
};
} // namespace SkRecords
#endif//SkRecordPattern_DEFINED
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