821 lines
28 KiB
PHP
821 lines
28 KiB
PHP
<?php
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/**
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* Class for efficiently looking up and mapping string keys to string values, with limits.
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*
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* @package WordPress
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* @since 6.6.0
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*/
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/**
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* WP_Token_Map class.
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*
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* Use this class in specific circumstances with a static set of lookup keys which map to
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* a static set of transformed values. For example, this class is used to map HTML named
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* character references to their equivalent UTF-8 values.
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*
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* This class works differently than code calling `in_array()` and other methods. It
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* internalizes lookup logic and provides helper interfaces to optimize lookup and
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* transformation. It provides a method for precomputing the lookup tables and storing
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* them as PHP source code.
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*
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* All tokens and substitutions must be shorter than 256 bytes.
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*
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* Example:
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*
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* $smilies = WP_Token_Map::from_array( array(
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* '8O' => '😯',
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* ':(' => '🙁',
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* ':)' => '🙂',
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* ':?' => '😕',
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* ) );
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*
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* true === $smilies->contains( ':)' );
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* false === $smilies->contains( 'simile' );
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*
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* '😕' === $smilies->read_token( 'Not sure :?.', 9, $length_of_smily_syntax );
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* 2 === $length_of_smily_syntax;
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*
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* ## Precomputing the Token Map.
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*
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* Creating the class involves some work sorting and organizing the tokens and their
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* replacement values. In order to skip this, it's possible for the class to export
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* its state and be used as actual PHP source code.
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*
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* Example:
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*
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* // Export with four spaces as the indent, only for the sake of this docblock.
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* // The default indent is a tab character.
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* $indent = ' ';
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* echo $smilies->precomputed_php_source_table( $indent );
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*
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* // Output, to be pasted into a PHP source file:
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* WP_Token_Map::from_precomputed_table(
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* array(
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* "storage_version" => "6.6.0",
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* "key_length" => 2,
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* "groups" => "",
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* "long_words" => array(),
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* "small_words" => "8O\x00:)\x00:(\x00:?\x00",
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* "small_mappings" => array( "😯", "🙂", "🙁", "😕" )
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* )
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* );
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*
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* ## Large vs. small words.
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*
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* This class uses a short prefix called the "key" to optimize lookup of its tokens.
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* This means that some tokens may be shorter than or equal in length to that key.
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* Those words that are longer than the key are called "large" while those shorter
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* than or equal to the key length are called "small."
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*
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* This separation of large and small words is incidental to the way this class
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* optimizes lookup, and should be considered an internal implementation detail
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* of the class. It may still be important to be aware of it, however.
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*
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* ## Determining Key Length.
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*
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* The choice of the size of the key length should be based on the data being stored in
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* the token map. It should divide the data as evenly as possible, but should not create
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* so many groups that a large fraction of the groups only contain a single token.
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*
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* For the HTML5 named character references, a key length of 2 was found to provide a
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* sufficient spread and should be a good default for relatively large sets of tokens.
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*
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* However, for some data sets this might be too long. For example, a list of smilies
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* may be too small for a key length of 2. Perhaps 1 would be more appropriate. It's
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* best to experiment and determine empirically which values are appropriate.
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*
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* ## Generate Pre-Computed Source Code.
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*
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* Since the `WP_Token_Map` is designed for relatively static lookups, it can be
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* advantageous to precompute the values and instantiate a table that has already
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* sorted and grouped the tokens and built the lookup strings.
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*
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* This can be done with `WP_Token_Map::precomputed_php_source_table()`.
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*
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* Note that if there is a leading character that all tokens need, such as `&` for
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* HTML named character references, it can be beneficial to exclude this from the
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* token map. Instead, find occurrences of the leading character and then use the
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* token map to see if the following characters complete the token.
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*
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* Example:
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*
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* $map = WP_Token_Map::from_array( array( 'simple_smile:' => '🙂', 'sob:' => '😭', 'soba:' => '🍜' ) );
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* echo $map->precomputed_php_source_table();
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* // Output
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* WP_Token_Map::from_precomputed_table(
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* array(
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* "storage_version" => "6.6.0",
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* "key_length" => 2,
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* "groups" => "si\x00so\x00",
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* "long_words" => array(
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* // simple_smile:[🙂].
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* "\x0bmple_smile:\x04🙂",
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* // soba:[🍜] sob:[😭].
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* "\x03ba:\x04🍜\x02b:\x04😭",
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* ),
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* "short_words" => "",
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* "short_mappings" => array()
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* }
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* );
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*
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* This precomputed value can be stored directly in source code and will skip the
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* startup cost of generating the lookup strings. See `$html5_named_character_entities`.
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*
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* Note that any updates to the precomputed format should update the storage version
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* constant. It would also be best to provide an update function to take older known
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* versions and upgrade them in place when loading into `from_precomputed_table()`.
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*
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* ## Future Direction.
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*
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* It may be viable to dynamically increase the length limits such that there's no need to impose them.
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* The limit appears because of the packing structure, which indicates how many bytes each segment of
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* text in the lookup tables spans. If, however, care were taken to track the longest word length, then
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* the packing structure could change its representation to allow for that. Each additional byte storing
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* length, however, increases the memory overhead and lookup runtime.
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*
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* An alternative approach could be to borrow the UTF-8 variable-length encoding and store lengths of less
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* than 127 as a single byte with the high bit unset, storing longer lengths as the combination of
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* continuation bytes.
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*
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* Since it has not been shown during the development of this class that longer strings are required, this
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* update is deferred until such a need is clear.
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*
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* @since 6.6.0
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*/
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class WP_Token_Map {
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/**
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* Denotes the version of the code which produces pre-computed source tables.
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*
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* This version will be used not only to verify pre-computed data, but also
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* to upgrade pre-computed data from older versions. Choosing a name that
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* corresponds to the WordPress release will help people identify where an
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* old copy of data came from.
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*/
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const STORAGE_VERSION = '6.6.0-trunk';
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/**
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* Maximum length for each key and each transformed value in the table (in bytes).
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*
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* @since 6.6.0
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*/
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const MAX_LENGTH = 256;
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/**
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* How many bytes of each key are used to form a group key for lookup.
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* This also determines whether a word is considered short or long.
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*
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* @since 6.6.0
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*
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* @var int
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*/
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private $key_length = 2;
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/**
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* Stores an optimized form of the word set, where words are grouped
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* by a prefix of the `$key_length` and then collapsed into a string.
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*
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* In each group, the keys and lookups form a packed data structure.
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* The keys in the string are stripped of their "group key," which is
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* the prefix of length `$this->key_length` shared by all of the items
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* in the group. Each word in the string is prefixed by a single byte
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* whose raw unsigned integer value represents how many bytes follow.
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*
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* ┌────────────────┬───────────────┬─────────────────┬────────┐
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* │ Length of rest │ Rest of key │ Length of value │ Value │
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* │ of key (bytes) │ │ (bytes) │ │
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* ├────────────────┼───────────────┼─────────────────┼────────┤
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* │ 0x08 │ nterDot; │ 0x02 │ · │
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* └────────────────┴───────────────┴─────────────────┴────────┘
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*
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* In this example, the key `CenterDot;` has a group key `Ce`, leaving
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* eight bytes for the rest of the key, `nterDot;`, and two bytes for
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* the transformed value `·` (or U+B7 or "\xC2\xB7").
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*
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* Example:
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*
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* // Stores array( 'CenterDot;' => '·', 'Cedilla;' => '¸' ).
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* $groups = "Ce\x00";
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* $large_words = array( "\x08nterDot;\x02·\x06dilla;\x02¸" )
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*
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* The prefixes appear in the `$groups` string, each followed by a null
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* byte. This makes for quick lookup of where in the group string the key
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* is found, and then a simple division converts that offset into the index
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* in the `$large_words` array where the group string is to be found.
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*
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* This lookup data structure is designed to optimize cache locality and
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* minimize indirect memory reads when matching strings in the set.
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*
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* @since 6.6.0
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*
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* @var array
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*/
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private $large_words = array();
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/**
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* Stores the group keys for sequential string lookup.
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*
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* The offset into this string where the group key appears corresponds with the index
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* into the group array where the rest of the group string appears. This is an optimization
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* to improve cache locality while searching and minimize indirect memory accesses.
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*
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* @since 6.6.0
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*
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* @var string
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*/
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private $groups = '';
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/**
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* Stores an optimized row of small words, where every entry is
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* `$this->key_size + 1` bytes long and zero-extended.
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*
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* This packing allows for direct lookup of a short word followed
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* by the null byte, if extended to `$this->key_size + 1`.
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*
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* Example:
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*
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* // Stores array( 'GT', 'LT', 'gt', 'lt' ).
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* "GT\x00LT\x00gt\x00lt\x00"
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*
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* @since 6.6.0
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*
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* @var string
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*/
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private $small_words = '';
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/**
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* Replacements for the small words, in the same order they appear.
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*
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* With the position of a small word it's possible to index the translation
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* directly, as its position in the `$small_words` string corresponds to
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* the index of the replacement in the `$small_mapping` array.
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*
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* Example:
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*
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* array( '>', '<', '>', '<' )
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*
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* @since 6.6.0
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*
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* @var string[]
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*/
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private $small_mappings = array();
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/**
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* Create a token map using an associative array of key/value pairs as the input.
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*
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* Example:
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*
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* $smilies = WP_Token_Map::from_array( array(
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* '8O' => '😯',
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* ':(' => '🙁',
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* ':)' => '🙂',
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* ':?' => '😕',
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* ) );
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*
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* @since 6.6.0
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*
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* @param array $mappings The keys transform into the values, both are strings.
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* @param int $key_length Determines the group key length. Leave at the default value
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* of 2 unless there's an empirical reason to change it.
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*
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* @return WP_Token_Map|null Token map, unless unable to create it.
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*/
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public static function from_array( array $mappings, int $key_length = 2 ): ?WP_Token_Map {
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$map = new WP_Token_Map();
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$map->key_length = $key_length;
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// Start by grouping words.
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$groups = array();
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$shorts = array();
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foreach ( $mappings as $word => $mapping ) {
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if (
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self::MAX_LENGTH <= strlen( $word ) ||
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self::MAX_LENGTH <= strlen( $mapping )
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) {
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_doing_it_wrong(
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__METHOD__,
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sprintf(
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/* translators: 1: maximum byte length (a count) */
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__( 'Token Map tokens and substitutions must all be shorter than %1$d bytes.' ),
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self::MAX_LENGTH
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),
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'6.6.0'
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);
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return null;
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}
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$length = strlen( $word );
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if ( $key_length >= $length ) {
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$shorts[] = $word;
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} else {
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$group = substr( $word, 0, $key_length );
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if ( ! isset( $groups[ $group ] ) ) {
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$groups[ $group ] = array();
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}
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$groups[ $group ][] = array( substr( $word, $key_length ), $mapping );
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}
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}
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/*
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* Sort the words to ensure that no smaller substring of a match masks the full match.
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* For example, `Cap` should not match before `CapitalDifferentialD`.
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*/
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usort( $shorts, 'WP_Token_Map::longest_first_then_alphabetical' );
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foreach ( $groups as $group_key => $group ) {
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usort(
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$groups[ $group_key ],
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static function ( array $a, array $b ): int {
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return self::longest_first_then_alphabetical( $a[0], $b[0] );
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}
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);
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}
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// Finally construct the optimized lookups.
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foreach ( $shorts as $word ) {
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$map->small_words .= str_pad( $word, $key_length + 1, "\x00", STR_PAD_RIGHT );
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$map->small_mappings[] = $mappings[ $word ];
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}
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$group_keys = array_keys( $groups );
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sort( $group_keys );
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foreach ( $group_keys as $group ) {
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$map->groups .= "{$group}\x00";
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$group_string = '';
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foreach ( $groups[ $group ] as $group_word ) {
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list( $word, $mapping ) = $group_word;
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$word_length = pack( 'C', strlen( $word ) );
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$mapping_length = pack( 'C', strlen( $mapping ) );
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$group_string .= "{$word_length}{$word}{$mapping_length}{$mapping}";
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}
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$map->large_words[] = $group_string;
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}
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||
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return $map;
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}
|
||
|
||
/**
|
||
* Creates a token map from a pre-computed table.
|
||
* This skips the initialization cost of generating the table.
|
||
*
|
||
* This function should only be used to load data created with
|
||
* WP_Token_Map::precomputed_php_source_tag().
|
||
*
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||
* @since 6.6.0
|
||
*
|
||
* @param array $state {
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||
* Stores pre-computed state for directly loading into a Token Map.
|
||
*
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||
* @type string $storage_version Which version of the code produced this state.
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||
* @type int $key_length Group key length.
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||
* @type string $groups Group lookup index.
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||
* @type array $large_words Large word groups and packed strings.
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||
* @type string $small_words Small words packed string.
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||
* @type array $small_mappings Small word mappings.
|
||
* }
|
||
*
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||
* @return WP_Token_Map Map with precomputed data loaded.
|
||
*/
|
||
public static function from_precomputed_table( $state ): ?WP_Token_Map {
|
||
$has_necessary_state = isset(
|
||
$state['storage_version'],
|
||
$state['key_length'],
|
||
$state['groups'],
|
||
$state['large_words'],
|
||
$state['small_words'],
|
||
$state['small_mappings']
|
||
);
|
||
|
||
if ( ! $has_necessary_state ) {
|
||
_doing_it_wrong(
|
||
__METHOD__,
|
||
__( 'Missing required inputs to pre-computed WP_Token_Map.' ),
|
||
'6.6.0'
|
||
);
|
||
return null;
|
||
}
|
||
|
||
if ( self::STORAGE_VERSION !== $state['storage_version'] ) {
|
||
_doing_it_wrong(
|
||
__METHOD__,
|
||
/* translators: 1: version string, 2: version string. */
|
||
sprintf( __( 'Loaded version \'%1$s\' incompatible with expected version \'%2$s\'.' ), $state['storage_version'], self::STORAGE_VERSION ),
|
||
'6.6.0'
|
||
);
|
||
return null;
|
||
}
|
||
|
||
$map = new WP_Token_Map();
|
||
|
||
$map->key_length = $state['key_length'];
|
||
$map->groups = $state['groups'];
|
||
$map->large_words = $state['large_words'];
|
||
$map->small_words = $state['small_words'];
|
||
$map->small_mappings = $state['small_mappings'];
|
||
|
||
return $map;
|
||
}
|
||
|
||
/**
|
||
* Indicates if a given word is a lookup key in the map.
|
||
*
|
||
* Example:
|
||
*
|
||
* true === $smilies->contains( ':)' );
|
||
* false === $smilies->contains( 'simile' );
|
||
*
|
||
* @since 6.6.0
|
||
*
|
||
* @param string $word Determine if this word is a lookup key in the map.
|
||
* @param string $case_sensitivity Optional. Pass 'ascii-case-insensitive' to ignore ASCII case when matching. Default 'case-sensitive'.
|
||
* @return bool Whether there's an entry for the given word in the map.
|
||
*/
|
||
public function contains( string $word, string $case_sensitivity = 'case-sensitive' ): bool {
|
||
$ignore_case = 'ascii-case-insensitive' === $case_sensitivity;
|
||
|
||
if ( $this->key_length >= strlen( $word ) ) {
|
||
if ( 0 === strlen( $this->small_words ) ) {
|
||
return false;
|
||
}
|
||
|
||
$term = str_pad( $word, $this->key_length + 1, "\x00", STR_PAD_RIGHT );
|
||
$word_at = $ignore_case ? stripos( $this->small_words, $term ) : strpos( $this->small_words, $term );
|
||
if ( false === $word_at ) {
|
||
return false;
|
||
}
|
||
|
||
return true;
|
||
}
|
||
|
||
$group_key = substr( $word, 0, $this->key_length );
|
||
$group_at = $ignore_case ? stripos( $this->groups, $group_key ) : strpos( $this->groups, $group_key );
|
||
if ( false === $group_at ) {
|
||
return false;
|
||
}
|
||
$group = $this->large_words[ $group_at / ( $this->key_length + 1 ) ];
|
||
$group_length = strlen( $group );
|
||
$slug = substr( $word, $this->key_length );
|
||
$length = strlen( $slug );
|
||
$at = 0;
|
||
|
||
while ( $at < $group_length ) {
|
||
$token_length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$token_at = $at;
|
||
$at += $token_length;
|
||
$mapping_length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$mapping_at = $at;
|
||
|
||
if ( $token_length === $length && 0 === substr_compare( $group, $slug, $token_at, $token_length, $ignore_case ) ) {
|
||
return true;
|
||
}
|
||
|
||
$at = $mapping_at + $mapping_length;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
/**
|
||
* If the text starting at a given offset is a lookup key in the map,
|
||
* return the corresponding transformation from the map, else `false`.
|
||
*
|
||
* This function returns the translated string, but accepts an optional
|
||
* parameter `$matched_token_byte_length`, which communicates how many
|
||
* bytes long the lookup key was, if it found one. This can be used to
|
||
* advance a cursor in calling code if a lookup key was found.
|
||
*
|
||
* Example:
|
||
*
|
||
* false === $smilies->read_token( 'Not sure :?.', 0, $token_byte_length );
|
||
* '😕' === $smilies->read_token( 'Not sure :?.', 9, $token_byte_length );
|
||
* 2 === $token_byte_length;
|
||
*
|
||
* Example:
|
||
*
|
||
* while ( $at < strlen( $input ) ) {
|
||
* $next_at = strpos( $input, ':', $at );
|
||
* if ( false === $next_at ) {
|
||
* break;
|
||
* }
|
||
*
|
||
* $smily = $smilies->read_token( $input, $next_at, $token_byte_length );
|
||
* if ( false === $next_at ) {
|
||
* ++$at;
|
||
* continue;
|
||
* }
|
||
*
|
||
* $prefix = substr( $input, $at, $next_at - $at );
|
||
* $at += $token_byte_length;
|
||
* $output .= "{$prefix}{$smily}";
|
||
* }
|
||
*
|
||
* @since 6.6.0
|
||
*
|
||
* @param string $text String in which to search for a lookup key.
|
||
* @param int $offset Optional. How many bytes into the string where the lookup key ought to start. Default 0.
|
||
* @param int|null &$matched_token_byte_length Optional. Holds byte-length of found token matched, otherwise not set. Default null.
|
||
* @param string $case_sensitivity Optional. Pass 'ascii-case-insensitive' to ignore ASCII case when matching. Default 'case-sensitive'.
|
||
*
|
||
* @return string|null Mapped value of lookup key if found, otherwise `null`.
|
||
*/
|
||
public function read_token( string $text, int $offset = 0, &$matched_token_byte_length = null, $case_sensitivity = 'case-sensitive' ): ?string {
|
||
$ignore_case = 'ascii-case-insensitive' === $case_sensitivity;
|
||
$text_length = strlen( $text );
|
||
|
||
// Search for a long word first, if the text is long enough, and if that fails, a short one.
|
||
if ( $text_length > $this->key_length ) {
|
||
$group_key = substr( $text, $offset, $this->key_length );
|
||
|
||
$group_at = $ignore_case ? stripos( $this->groups, $group_key ) : strpos( $this->groups, $group_key );
|
||
if ( false === $group_at ) {
|
||
// Perhaps a short word then.
|
||
return strlen( $this->small_words ) > 0
|
||
? $this->read_small_token( $text, $offset, $matched_token_byte_length, $case_sensitivity )
|
||
: null;
|
||
}
|
||
|
||
$group = $this->large_words[ $group_at / ( $this->key_length + 1 ) ];
|
||
$group_length = strlen( $group );
|
||
$at = 0;
|
||
while ( $at < $group_length ) {
|
||
$token_length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$token = substr( $group, $at, $token_length );
|
||
$at += $token_length;
|
||
$mapping_length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$mapping_at = $at;
|
||
|
||
if ( 0 === substr_compare( $text, $token, $offset + $this->key_length, $token_length, $ignore_case ) ) {
|
||
$matched_token_byte_length = $this->key_length + $token_length;
|
||
return substr( $group, $mapping_at, $mapping_length );
|
||
}
|
||
|
||
$at = $mapping_at + $mapping_length;
|
||
}
|
||
}
|
||
|
||
// Perhaps a short word then.
|
||
return strlen( $this->small_words ) > 0
|
||
? $this->read_small_token( $text, $offset, $matched_token_byte_length, $case_sensitivity )
|
||
: null;
|
||
}
|
||
|
||
/**
|
||
* Finds a match for a short word at the index.
|
||
*
|
||
* @since 6.6.0
|
||
*
|
||
* @param string $text String in which to search for a lookup key.
|
||
* @param int $offset Optional. How many bytes into the string where the lookup key ought to start. Default 0.
|
||
* @param int|null &$matched_token_byte_length Optional. Holds byte-length of found lookup key if matched, otherwise not set. Default null.
|
||
* @param string $case_sensitivity Optional. Pass 'ascii-case-insensitive' to ignore ASCII case when matching. Default 'case-sensitive'.
|
||
*
|
||
* @return string|null Mapped value of lookup key if found, otherwise `null`.
|
||
*/
|
||
private function read_small_token( string $text, int $offset = 0, &$matched_token_byte_length = null, $case_sensitivity = 'case-sensitive' ): ?string {
|
||
$ignore_case = 'ascii-case-insensitive' === $case_sensitivity;
|
||
$small_length = strlen( $this->small_words );
|
||
$search_text = substr( $text, $offset, $this->key_length );
|
||
if ( $ignore_case ) {
|
||
$search_text = strtoupper( $search_text );
|
||
}
|
||
$starting_char = $search_text[0];
|
||
|
||
$at = 0;
|
||
while ( $at < $small_length ) {
|
||
if (
|
||
$starting_char !== $this->small_words[ $at ] &&
|
||
( ! $ignore_case || strtoupper( $this->small_words[ $at ] ) !== $starting_char )
|
||
) {
|
||
$at += $this->key_length + 1;
|
||
continue;
|
||
}
|
||
|
||
for ( $adjust = 1; $adjust < $this->key_length; $adjust++ ) {
|
||
if ( "\x00" === $this->small_words[ $at + $adjust ] ) {
|
||
$matched_token_byte_length = $adjust;
|
||
return $this->small_mappings[ $at / ( $this->key_length + 1 ) ];
|
||
}
|
||
|
||
if (
|
||
$search_text[ $adjust ] !== $this->small_words[ $at + $adjust ] &&
|
||
( ! $ignore_case || strtoupper( $this->small_words[ $at + $adjust ] !== $search_text[ $adjust ] ) )
|
||
) {
|
||
$at += $this->key_length + 1;
|
||
continue 2;
|
||
}
|
||
}
|
||
|
||
$matched_token_byte_length = $adjust;
|
||
return $this->small_mappings[ $at / ( $this->key_length + 1 ) ];
|
||
}
|
||
|
||
return null;
|
||
}
|
||
|
||
/**
|
||
* Exports the token map into an associate array of key/value pairs.
|
||
*
|
||
* Example:
|
||
*
|
||
* $smilies->to_array() === array(
|
||
* '8O' => '😯',
|
||
* ':(' => '🙁',
|
||
* ':)' => '🙂',
|
||
* ':?' => '😕',
|
||
* );
|
||
*
|
||
* @return array The lookup key/substitution values as an associate array.
|
||
*/
|
||
public function to_array(): array {
|
||
$tokens = array();
|
||
|
||
$at = 0;
|
||
$small_mapping = 0;
|
||
$small_length = strlen( $this->small_words );
|
||
while ( $at < $small_length ) {
|
||
$key = rtrim( substr( $this->small_words, $at, $this->key_length + 1 ), "\x00" );
|
||
$value = $this->small_mappings[ $small_mapping++ ];
|
||
$tokens[ $key ] = $value;
|
||
|
||
$at += $this->key_length + 1;
|
||
}
|
||
|
||
foreach ( $this->large_words as $index => $group ) {
|
||
$prefix = substr( $this->groups, $index * ( $this->key_length + 1 ), 2 );
|
||
$group_length = strlen( $group );
|
||
$at = 0;
|
||
while ( $at < $group_length ) {
|
||
$length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$key = $prefix . substr( $group, $at, $length );
|
||
|
||
$at += $length;
|
||
$length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$value = substr( $group, $at, $length );
|
||
|
||
$tokens[ $key ] = $value;
|
||
$at += $length;
|
||
}
|
||
}
|
||
|
||
return $tokens;
|
||
}
|
||
|
||
/**
|
||
* Export the token map for quick loading in PHP source code.
|
||
*
|
||
* This function has a specific purpose, to make loading of static token maps fast.
|
||
* It's used to ensure that the HTML character reference lookups add a minimal cost
|
||
* to initializing the PHP process.
|
||
*
|
||
* Example:
|
||
*
|
||
* echo $smilies->precomputed_php_source_table();
|
||
*
|
||
* // Output.
|
||
* WP_Token_Map::from_precomputed_table(
|
||
* array(
|
||
* "storage_version" => "6.6.0",
|
||
* "key_length" => 2,
|
||
* "groups" => "",
|
||
* "long_words" => array(),
|
||
* "small_words" => "8O\x00:)\x00:(\x00:?\x00",
|
||
* "small_mappings" => array( "😯", "🙂", "🙁", "😕" )
|
||
* )
|
||
* );
|
||
*
|
||
* @since 6.6.0
|
||
*
|
||
* @param string $indent Optional. Use this string for indentation, or rely on the default horizontal tab character. Default "\t".
|
||
* @return string Value which can be pasted into a PHP source file for quick loading of table.
|
||
*/
|
||
public function precomputed_php_source_table( string $indent = "\t" ): string {
|
||
$i1 = $indent;
|
||
$i2 = $i1 . $indent;
|
||
$i3 = $i2 . $indent;
|
||
|
||
$class_version = self::STORAGE_VERSION;
|
||
|
||
$output = self::class . "::from_precomputed_table(\n";
|
||
$output .= "{$i1}array(\n";
|
||
$output .= "{$i2}\"storage_version\" => \"{$class_version}\",\n";
|
||
$output .= "{$i2}\"key_length\" => {$this->key_length},\n";
|
||
|
||
$group_line = str_replace( "\x00", "\\x00", $this->groups );
|
||
$output .= "{$i2}\"groups\" => \"{$group_line}\",\n";
|
||
|
||
$output .= "{$i2}\"large_words\" => array(\n";
|
||
|
||
$prefixes = explode( "\x00", $this->groups );
|
||
foreach ( $prefixes as $index => $prefix ) {
|
||
if ( '' === $prefix ) {
|
||
break;
|
||
}
|
||
$group = $this->large_words[ $index ];
|
||
$group_length = strlen( $group );
|
||
$comment_line = "{$i3}//";
|
||
$data_line = "{$i3}\"";
|
||
$at = 0;
|
||
while ( $at < $group_length ) {
|
||
$token_length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$token = substr( $group, $at, $token_length );
|
||
$at += $token_length;
|
||
$mapping_length = unpack( 'C', $group[ $at++ ] )[1];
|
||
$mapping = substr( $group, $at, $mapping_length );
|
||
$at += $mapping_length;
|
||
|
||
$token_digits = str_pad( dechex( $token_length ), 2, '0', STR_PAD_LEFT );
|
||
$mapping_digits = str_pad( dechex( $mapping_length ), 2, '0', STR_PAD_LEFT );
|
||
|
||
$mapping = preg_replace_callback(
|
||
"~[\\x00-\\x1f\\x22\\x5c]~",
|
||
static function ( $match_result ) {
|
||
switch ( $match_result[0] ) {
|
||
case '"':
|
||
return '\\"';
|
||
|
||
case '\\':
|
||
return '\\\\';
|
||
|
||
default:
|
||
$hex = dechex( ord( $match_result[0] ) );
|
||
return "\\x{$hex}";
|
||
}
|
||
},
|
||
$mapping
|
||
);
|
||
|
||
$comment_line .= " {$prefix}{$token}[{$mapping}]";
|
||
$data_line .= "\\x{$token_digits}{$token}\\x{$mapping_digits}{$mapping}";
|
||
}
|
||
$comment_line .= ".\n";
|
||
$data_line .= "\",\n";
|
||
|
||
$output .= $comment_line;
|
||
$output .= $data_line;
|
||
}
|
||
|
||
$output .= "{$i2}),\n";
|
||
|
||
$small_words = array();
|
||
$small_length = strlen( $this->small_words );
|
||
$at = 0;
|
||
while ( $at < $small_length ) {
|
||
$small_words[] = substr( $this->small_words, $at, $this->key_length + 1 );
|
||
$at += $this->key_length + 1;
|
||
}
|
||
|
||
$small_text = str_replace( "\x00", '\x00', implode( '', $small_words ) );
|
||
$output .= "{$i2}\"small_words\" => \"{$small_text}\",\n";
|
||
|
||
$output .= "{$i2}\"small_mappings\" => array(\n";
|
||
foreach ( $this->small_mappings as $mapping ) {
|
||
$output .= "{$i3}\"{$mapping}\",\n";
|
||
}
|
||
$output .= "{$i2})\n";
|
||
$output .= "{$i1})\n";
|
||
$output .= ')';
|
||
|
||
return $output;
|
||
}
|
||
|
||
/**
|
||
* Compares two strings, returning the longest, or whichever
|
||
* is first alphabetically if they are the same length.
|
||
*
|
||
* This is an important sort when building the token map because
|
||
* it should not form a match on a substring of a longer potential
|
||
* match. For example, it should not detect `Cap` when matching
|
||
* against the string `CapitalDifferentialD`.
|
||
*
|
||
* @since 6.6.0
|
||
*
|
||
* @param string $a First string to compare.
|
||
* @param string $b Second string to compare.
|
||
* @return int -1 or lower if `$a` is less than `$b`; 1 or greater if `$a` is greater than `$b`, and 0 if they are equal.
|
||
*/
|
||
private static function longest_first_then_alphabetical( string $a, string $b ): int {
|
||
if ( $a === $b ) {
|
||
return 0;
|
||
}
|
||
|
||
$length_a = strlen( $a );
|
||
$length_b = strlen( $b );
|
||
|
||
// Longer strings are less-than for comparison's sake.
|
||
if ( $length_a !== $length_b ) {
|
||
return $length_b - $length_a;
|
||
}
|
||
|
||
return strcmp( $a, $b );
|
||
}
|
||
}
|