// 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 #include #include #include "base/base_export.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 Adjustments; // Adjusts all offsets in |offsets_for_adjustment| to reflect the adjustments // recorded in |adjustments|. Adjusted offsets greater than |limit| will be // set to std::u16string::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 std::u16string::npos. static void AdjustOffsets(const Adjustments& adjustments, std::vector* offsets_for_adjustment, size_t limit = std::u16string::npos); // Adjusts the single |offset| to reflect the adjustments recorded in // |adjustments|. static void AdjustOffset(const Adjustments& adjustments, size_t* offset, size_t limit = std::u16string::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 // std::u16string::npos. static void UnadjustOffsets(const Adjustments& adjustments, std::vector* 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, std::u16string* output, base::OffsetAdjuster::Adjustments* adjustments); [[nodiscard]] BASE_EXPORT std::u16string 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 std::u16string::npos. See comments by // AdjustOffsets(). BASE_EXPORT std::u16string UTF8ToUTF16AndAdjustOffsets( const base::StringPiece& utf8, std::vector* offsets_for_adjustment); BASE_EXPORT std::string UTF16ToUTF8AndAdjustOffsets( const base::StringPiece16& utf16, std::vector* offsets_for_adjustment); } // namespace base #endif // BASE_STRINGS_UTF_OFFSET_STRING_CONVERSIONS_H_