mirror of
https://github.com/flutter/flutter.git
synced 2026-02-20 02:29:02 +08:00
123 lines
3.8 KiB
C++
123 lines
3.8 KiB
C++
/*
|
|
* Copyright (C) 2010 Adam Barth. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
|
|
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
|
|
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
|
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
|
|
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#ifndef SKY_ENGINE_PLATFORM_TEXT_SUFFIXTREE_H_
|
|
#define SKY_ENGINE_PLATFORM_TEXT_SUFFIXTREE_H_
|
|
|
|
#include "sky/engine/wtf/Vector.h"
|
|
#include "sky/engine/wtf/text/WTFString.h"
|
|
|
|
namespace blink {
|
|
|
|
class UnicodeCodebook {
|
|
public:
|
|
static int codeWord(UChar c) { return c; }
|
|
enum { codeSize = 1 << 8 * sizeof(UChar) };
|
|
};
|
|
|
|
class ASCIICodebook {
|
|
public:
|
|
static int codeWord(UChar c) { return c & (codeSize - 1); }
|
|
enum { codeSize = 1 << (8 * sizeof(char) - 1) };
|
|
};
|
|
|
|
template<typename Codebook>
|
|
class SuffixTree {
|
|
public:
|
|
SuffixTree(const String& text, unsigned depth)
|
|
: m_depth(depth)
|
|
, m_leaf(true)
|
|
{
|
|
build(text);
|
|
}
|
|
|
|
bool mightContain(const String& query)
|
|
{
|
|
Node* current = &m_root;
|
|
int limit = std::min(m_depth, query.length());
|
|
for (int i = 0; i < limit; ++i) {
|
|
current = current->at(Codebook::codeWord(query[i]));
|
|
if (!current)
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
private:
|
|
class Node {
|
|
public:
|
|
Node(bool isLeaf = false)
|
|
{
|
|
m_children.resize(Codebook::codeSize);
|
|
m_children.fill(0);
|
|
m_isLeaf = isLeaf;
|
|
}
|
|
|
|
~Node()
|
|
{
|
|
for (unsigned i = 0; i < m_children.size(); ++i) {
|
|
Node* child = m_children.at(i);
|
|
if (child && !child->m_isLeaf)
|
|
delete child;
|
|
}
|
|
}
|
|
|
|
Node*& at(int codeWord) { return m_children.at(codeWord); }
|
|
|
|
private:
|
|
typedef Vector<Node*, Codebook::codeSize> ChildrenVector;
|
|
|
|
ChildrenVector m_children;
|
|
bool m_isLeaf;
|
|
};
|
|
|
|
void build(const String& text)
|
|
{
|
|
for (unsigned base = 0; base < text.length(); ++base) {
|
|
Node* current = &m_root;
|
|
unsigned limit = std::min(base + m_depth, text.length());
|
|
for (unsigned offset = 0; base + offset < limit; ++offset) {
|
|
ASSERT(current != &m_leaf);
|
|
Node*& child = current->at(Codebook::codeWord(text[base + offset]));
|
|
if (!child)
|
|
child = base + offset + 1 == limit ? &m_leaf : new Node();
|
|
current = child;
|
|
}
|
|
}
|
|
}
|
|
|
|
Node m_root;
|
|
unsigned m_depth;
|
|
|
|
// Instead of allocating a fresh empty leaf node for ever leaf in the tree
|
|
// (there can be a lot of these), we alias all the leaves to this "static"
|
|
// leaf node.
|
|
Node m_leaf;
|
|
};
|
|
|
|
} // namespace blink
|
|
|
|
#endif // SKY_ENGINE_PLATFORM_TEXT_SUFFIXTREE_H_
|