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DateTimePart.h (2797B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 #ifndef intl_components_DateTimePart_h_
      5 #define intl_components_DateTimePart_h_
      6 
      7 #include <cstddef>
      8 #include <cstdint>
      9 
     10 #include "mozilla/Vector.h"
     11 
     12 namespace mozilla::intl {
     13 
     14 enum class DateTimePartType : int16_t {
     15  Literal,
     16  Weekday,
     17  Era,
     18  Year,
     19  YearName,
     20  RelatedYear,
     21  Month,
     22  Day,
     23  DayPeriod,
     24  Hour,
     25  Minute,
     26  Second,
     27  FractionalSecondDigits,
     28  TimeZoneName,
     29  Unknown
     30 };
     31 
     32 enum class DateTimePartSource : int16_t { Shared, StartRange, EndRange };
     33 
     34 /**
     35 * The 'Part' object defined in FormatDateTimeToParts and
     36 * FormatDateTimeRangeToParts
     37 *
     38 * Each part consists of three properties: ||Type||, ||Value|| and ||Source||,
     39 * with the ||Source|| property is set to DateTimePartSource::Shared by default.
     40 * (Note: From the spec, the part from FormatDateTimeToParts doesn't have the
     41 * ||Source|| property, so if the caller is FormatDateTimeToParts, it should
     42 * ignore the ||Source|| property).
     43 *
     44 * To store DateTimePart more efficiently, it doesn't store the ||Value|| of
     45 * type string in this struct. Instead, it stores the end index of the string
     46 * in the buffer(which is passed to DateTimeFormat::TryFormatToParts() or
     47 * can be got by calling AutoFormattedDateInterval::ToSpan()). The begin index
     48 * of the ||Value|| is the mEndIndex of the previous part.
     49 *
     50 *  Buffer
     51 *  0               i                j
     52 * +---------------+---------------+---------------+
     53 * | Part[0].Value | Part[1].Value | Part[2].Value | ....
     54 * +---------------+---------------+---------------+
     55 *
     56 *     Part[0].mEndIndex is i. Part[0].Value is stored in the Buffer[0..i].
     57 *     Part[1].mEndIndex is j. Part[1].Value is stored in the Buffer[i..j].
     58 *
     59 * See:
     60 * https://tc39.es/ecma402/#sec-formatdatetimetoparts
     61 * https://tc39.es/ecma402/#sec-formatdatetimerangetoparts
     62 */
     63 struct DateTimePart {
     64  DateTimePart(DateTimePartType type, size_t endIndex,
     65               DateTimePartSource source)
     66      : mEndIndex(endIndex), mType(type), mSource(source) {}
     67 
     68  // See the above comments for details, mEndIndex is placed first for reducing
     69  // padding.
     70  size_t mEndIndex;
     71  DateTimePartType mType;
     72  DateTimePartSource mSource;
     73 };
     74 
     75 // The common parts are 'month', 'literal', 'day', 'literal', 'year', 'literal',
     76 // 'hour', 'literal', 'minute', 'literal', which are 10 parts, for DateTimeRange
     77 // the number will be doubled, so choosing 32 as the initial length to prevent
     78 // heap allocation.
     79 constexpr size_t INITIAL_DATETIME_PART_VECTOR_SIZE = 32;
     80 using DateTimePartVector =
     81    mozilla::Vector<DateTimePart, INITIAL_DATETIME_PART_VECTOR_SIZE>;
     82 
     83 }  // namespace mozilla::intl
     84 #endif