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212 lines (175 loc) · 5.34 KB
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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "flutter/fml/string_view.h"
#include <string.h>
#include <algorithm>
#include <limits>
namespace fml {
constexpr size_t StringView::npos;
namespace {
// For each character in characters_wanted, sets the index corresponding
// to the code for that character to 1 in table. This is used by the
// find_.*_of methods below to tell whether or not a character is in the lookup
// table in constant time.
// The argument `table' must be an array that is large enough to hold all
// the possible values of an unsigned char. Thus it should be be declared
// as follows:
// bool table[std::numeric_limits<unsigned char>::max() + 1]
inline void BuildLookupTable(StringView characters_wanted, bool* table) {
size_t length = characters_wanted.size();
const char* data = characters_wanted.data();
for (size_t i = 0; i < length; ++i) {
table[static_cast<unsigned char>(data[i])] = true;
}
}
} // namespace
int StringView::compare(StringView other) {
size_t len = std::min(size_, other.size_);
int retval = memcmp(data_, other.data_, len);
if (retval == 0) {
if (size_ == other.size_) {
return 0;
}
return size_ < other.size_ ? -1 : 1;
}
return retval;
}
bool operator==(StringView lhs, StringView rhs) {
if (lhs.size() != rhs.size())
return false;
return lhs.compare(rhs) == 0;
}
bool operator!=(StringView lhs, StringView rhs) {
if (lhs.size() != rhs.size())
return true;
return lhs.compare(rhs) != 0;
}
bool operator<(StringView lhs, StringView rhs) {
return lhs.compare(rhs) < 0;
}
bool operator>(StringView lhs, StringView rhs) {
return lhs.compare(rhs) > 0;
}
bool operator<=(StringView lhs, StringView rhs) {
return lhs.compare(rhs) <= 0;
}
bool operator>=(StringView lhs, StringView rhs) {
return lhs.compare(rhs) >= 0;
}
std::ostream& operator<<(std::ostream& o, StringView string_view) {
o.write(string_view.data(), static_cast<std::streamsize>(string_view.size()));
return o;
}
size_t StringView::find(StringView s, size_t pos) const {
if (pos > size_)
return npos;
if (s.empty())
return pos;
auto* result = std::search(begin() + pos, end(), s.begin(), s.end());
if (result == end())
return npos;
return result - begin();
}
size_t StringView::find(char c, size_t pos) const {
if (pos > size_)
return npos;
auto* result = std::find(begin() + pos, end(), c);
if (result == end())
return npos;
return result - begin();
}
size_t StringView::rfind(StringView s, size_t pos) const {
if (size_ < s.size())
return npos;
if (s.empty())
return std::min(pos, size_);
auto* last = begin() + std::min(size_ - s.size(), pos) + s.size();
auto* result = std::find_end(begin(), last, s.begin(), s.end());
if (result == last)
return npos;
return result - begin();
}
size_t StringView::rfind(char c, size_t pos) const {
if (size_ == 0)
return npos;
auto begin = rend() - std::min(size_ - 1, pos) - 1;
auto result = std::find(begin, rend(), c);
if (result == rend())
return npos;
return rend() - result - 1;
}
size_t StringView::find_first_of(StringView s, size_t pos) const {
if (pos >= size_ || s.size() == 0)
return npos;
// Avoid the cost of BuildLookupTable() for a single-character search.
if (s.size() == 1)
return find(s.data()[0], pos);
bool lookup[std::numeric_limits<unsigned char>::max() + 1] = {false};
BuildLookupTable(s, lookup);
for (size_t i = pos; i < size_; ++i) {
if (lookup[static_cast<unsigned char>(data_[i])]) {
return i;
}
}
return npos;
}
size_t StringView::find_last_of(StringView s, size_t pos) const {
if (size_ == 0 || s.size() == 0)
return npos;
// Avoid the cost of BuildLookupTable() for a single-character search.
if (s.size() == 1)
return rfind(s.data()[0], pos);
bool lookup[std::numeric_limits<unsigned char>::max() + 1] = {false};
BuildLookupTable(s, lookup);
for (size_t i = std::min(pos, size_ - 1);; --i) {
if (lookup[static_cast<unsigned char>(data_[i])])
return i;
if (i == 0)
break;
}
return npos;
}
size_t StringView::find_first_not_of(StringView s, size_t pos) const {
if (pos >= size_)
return npos;
// Avoid the cost of BuildLookupTable() for a single-character search.
if (s.size() == 1) {
for (size_t i = pos; i < size_; ++i) {
if (data_[i] != s[0])
return i;
}
return npos;
}
bool lookup[std::numeric_limits<unsigned char>::max() + 1] = {false};
BuildLookupTable(s, lookup);
for (size_t i = pos; i < size_; ++i) {
if (!lookup[static_cast<unsigned char>(data_[i])]) {
return i;
}
}
return npos;
}
size_t StringView::find_last_not_of(StringView s, size_t pos) const {
if (size_ == 0)
return npos;
// Avoid the cost of BuildLookupTable() for a single-character search.
if (s.size() == 1) {
for (size_t i = std::min(pos, size_ - 1);; --i) {
if (data_[i] != s[0])
return i;
if (i == 0)
break;
}
}
bool lookup[std::numeric_limits<unsigned char>::max() + 1] = {false};
BuildLookupTable(s, lookup);
for (size_t i = std::min(pos, size_ - 1);; --i) {
if (!lookup[static_cast<unsigned char>(data_[i])])
return i;
if (i == 0)
break;
}
return npos;
}
} // namespace fml