// 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.

#ifndef FLUTTER_SHELL_PLATFORM_COMMON_TEXT_RANGE_H_

#define FLUTTER_SHELL_PLATFORM_COMMON_TEXT_RANGE_H_

#include <algorithm>

#include "flutter/fml/logging.h"

namespace flutter {

// A directional range of text.

//

// A |TextRange| describes a range of text with |base| and |extent| positions.

// In the case where |base| == |extent|, the range is said to be collapsed, and

// when |base| > |extent|, the range is said to be reversed.

class TextRange {

public:

explicit TextRange(size_t position) : base_(position), extent_(position) {}

explicit TextRange(size_t base, size_t extent)

: base_(base), extent_(extent) {}

TextRange(const TextRange&) = default;

TextRange& operator=(const TextRange&) = default;

virtual ~TextRange() = default;

// The base position of the range.

size_t base() const { return base_; }

// Sets the base position of the range.

void set_base(size_t pos) { base_ = pos; }

// The extent position of the range.

size_t extent() const { return extent_; }

// Sets the extent position of the range.

void set_extent(size_t pos) { extent_ = pos; }

// The lesser of the base and extent positions.

size_t start() const { return std::min(base_, extent_); }

// Sets the start position of the range.

void set_start(size_t pos) {

if (base_ <= extent_) {

base_ = pos;

} else {

extent_ = pos;

}

}

// The greater of the base and extent positions.

size_t end() const { return std::max(base_, extent_); }

// Sets the end position of the range.

void set_end(size_t pos) {

if (base_ <= extent_) {

extent_ = pos;

} else {

base_ = pos;

}

}

// The position of a collapsed range.

//

// Asserts that the range is of length 0.

size_t position() const {

FML_DCHECK(base_ == extent_);

return extent_;

}

// The length of the range.

size_t length() const { return end() - start(); }

// Returns true if the range is of length 0.

bool collapsed() const { return base_ == extent_; }

// Returns true if the base is greater than the extent.

bool reversed() const { return base_ > extent_; }

// Returns true if |position| is contained within the range.

bool Contains(size_t position) const {

return position >= start() && position <= end();

}

// Returns true if |range| is contained within the range.

bool Contains(const TextRange& range) const {

return range.start() >= start() && range.end() <= end();

}

bool operator==(const TextRange& other) const {

return base_ == other.base_ && extent_ == other.extent_;

}

private:

size_t base_;

size_t extent_;

};

} // namespace flutter

#endif // FLUTTER_SHELL_PLATFORM_COMMON_TEXT_RANGE_H_