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// Copyright (c) 2011 The Chromium 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 BASE_STRINGS_UTF_OFFSET_STRING_CONVERSIONS_H_
#define BASE_STRINGS_UTF_OFFSET_STRING_CONVERSIONS_H_
#include <stddef.h>
#include <string>
#include <vector>
#include "base/base_export.h"
#include "base/strings/string16.h"
#include "base/strings/string_piece.h"
namespace base {
// A helper class and associated data structures to adjust offsets into a
// string in response to various adjustments one might do to that string
// (e.g., eliminating a range). For details on offsets, see the comments by
// the AdjustOffsets() function below.
class BASE_EXPORT OffsetAdjuster {
public:
struct BASE_EXPORT Adjustment {
Adjustment(size_t original_offset,
size_t original_length,
size_t output_length);
size_t original_offset;
size_t original_length;
size_t output_length;
};
typedef std::vector<Adjustment> Adjustments;
// Adjusts all offsets in |offsets_for_adjustment| to reflect the adjustments
// recorded in |adjustments|. Adjusted offsets greater than |limit| will be
// set to string16::npos.
//
// Offsets represents insertion/selection points between characters: if |src|
// is "abcd", then 0 is before 'a', 2 is between 'b' and 'c', and 4 is at the
// end of the string. Valid input offsets range from 0 to |src_len|. On
// exit, each offset will have been modified to point at the same logical
// position in the output string. If an offset cannot be successfully
// adjusted (e.g., because it points into the middle of a multibyte sequence),
// it will be set to string16::npos.
static void AdjustOffsets(const Adjustments& adjustments,
std::vector<size_t>* offsets_for_adjustment,
size_t limit = string16::npos);
// Adjusts the single |offset| to reflect the adjustments recorded in
// |adjustments|.
static void AdjustOffset(const Adjustments& adjustments,
size_t* offset,
size_t limit = string16::npos);
// Adjusts all offsets in |offsets_for_unadjustment| to reflect the reverse
// of the adjustments recorded in |adjustments|. In other words, the offsets
// provided represent offsets into an adjusted string and the caller wants
// to know the offsets they correspond to in the original string. If an
// offset cannot be successfully unadjusted (e.g., because it points into
// the middle of a multibyte sequence), it will be set to string16::npos.
static void UnadjustOffsets(const Adjustments& adjustments,
std::vector<size_t>* offsets_for_unadjustment);
// Adjusts the single |offset| to reflect the reverse of the adjustments
// recorded in |adjustments|.
static void UnadjustOffset(const Adjustments& adjustments,
size_t* offset);
// Combines two sequential sets of adjustments, storing the combined revised
// adjustments in |adjustments_on_adjusted_string|. That is, suppose a
// string was altered in some way, with the alterations recorded as
// adjustments in |first_adjustments|. Then suppose the resulting string is
// further altered, with the alterations recorded as adjustments scored in
// |adjustments_on_adjusted_string|, with the offsets recorded in these
// adjustments being with respect to the intermediate string. This function
// combines the two sets of adjustments into one, storing the result in
// |adjustments_on_adjusted_string|, whose offsets are correct with respect
// to the original string.
//
// Assumes both parameters are sorted by increasing offset.
//
// WARNING: Only supports |first_adjustments| that involve collapsing ranges
// of text, not expanding ranges.
static void MergeSequentialAdjustments(
const Adjustments& first_adjustments,
Adjustments* adjustments_on_adjusted_string);
};
// Like the conversions in utf_string_conversions.h, but also fills in an
// |adjustments| parameter that reflects the alterations done to the string.
// It may be NULL.
BASE_EXPORT bool UTF8ToUTF16WithAdjustments(
const char* src,
size_t src_len,
string16* output,
base::OffsetAdjuster::Adjustments* adjustments);
BASE_EXPORT string16 UTF8ToUTF16WithAdjustments(
const base::StringPiece& utf8,
base::OffsetAdjuster::Adjustments* adjustments);
// As above, but instead internally examines the adjustments and applies them
// to |offsets_for_adjustment|. Input offsets greater than the length of the
// input string will be set to string16::npos. See comments by AdjustOffsets().
BASE_EXPORT string16 UTF8ToUTF16AndAdjustOffsets(
const base::StringPiece& utf8,
std::vector<size_t>* offsets_for_adjustment);
BASE_EXPORT std::string UTF16ToUTF8AndAdjustOffsets(
const base::StringPiece16& utf16,
std::vector<size_t>* offsets_for_adjustment);
} // namespace base
#endif // BASE_STRINGS_UTF_OFFSET_STRING_CONVERSIONS_H_
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