COLLATOR(3) 1 COLLATOR(3)
The Collator class
INTRODUCTION
Provides string comparison capability with support for appropriate locale-sensitive sort orderings.
CLASS SYNOPSIS
Collator
Collator
Methods
o public Collator::__construct (string $locale)
o public bool Collator::asort (array &$arr, [int $sort_flag])
o public int Collator::compare (string $str1, string $str2)
o publicstatic Collator Collator::create (string $locale)
o public int Collator::getAttribute (int $attr)
o public int Collator::getErrorCode (void )
o public string Collator::getErrorMessage (void )
o public string Collator::getLocale (int $type)
o public string Collator::getSortKey (string $str)
o public int Collator::getStrength (void )
o public bool Collator::setAttribute (int $attr, int $val)
o public bool Collator::setStrength (int $strength)
o public bool Collator::sortWithSortKeys (array &$arr)
o public bool Collator::sort (array &$arr, [int $sort_flag])
PREDEFINED CONSTANTS
o Collator::FRENCH_COLLATION ( integer) - Sort strings with different accents from the back of the string. This attribute is auto-
matically set to On for the French locales and a few others. Users normally would not need to explicitly set this attribute. There
is a string comparison performance cost when it is set On, but sort key length is unaffected. Possible values are:
o Collator::ON
o Collator::OFF(default)
o Collator::DEFAULT_VALUE
Example #1
FRENCH_COLLATION rules
oF=OFF cote < cote < cote < cote
oF=ON cote < cote < cote < cote
o Collator::ALTERNATE_HANDLING ( integer) - The Alternate attribute is used to control the handling of the so called variable char-
acters in the UCA: whitespace, punctuation and symbols. If Alternate is set to NonIgnorable (N), then differences among these
characters are of the same importance as differences among letters. If Alternate is set to Shifted (S), then these characters are
of only minor importance. The Shifted value is often used in combination with Strength set to Quaternary. In such a case, white-
space, punctuation, and symbols are considered when comparing strings, but only if all other aspects of the strings (base letters,
accents, and case) are identical. If Alternate is not set to Shifted, then there is no difference between a Strength of 3 and a
Strength of 4. For more information and examples, see Variable_Weighting in the UCA. The reason the Alternate values are not sim-
ply On and Off is that additional Alternate values may be added in the future. The UCA option Blanked is expressed with Strength
set to 3, and Alternate set to Shifted. The default for most locales is NonIgnorable. If Shifted is selected, it may be slower if
there are many strings that are the same except for punctuation; sort key length will not be affected unless the strength level is
also increased. Possible values are:
o Collator::NON_IGNORABLE(default)
o Collator::SHIFTED
o Collator::DEFAULT_VALUE
Example #2
ALTERNATE_HANDLING rules
o S=3, A=N di Silva < Di Silva < diSilva < U.S.A. < USA
o S=3, A=S di Silva = diSilva < Di Silva < U.S.A. = USA
o S=4, A=S di Silva < diSilva < Di Silva < U.S.A. < USA
o Collator::CASE_FIRST ( integer) - The Case_First attribute is used to control whether uppercase letters come before lowercase let-
ters or vice versa, in the absence of other differences in the strings. The possible values are Uppercase_First (U) and Lower-
case_First (L), plus the standard Default and Off. There is almost no difference between the Off and Lowercase_First options in
terms of results, so typically users will not use Lowercase_First: only Off or Uppercase_First. (People interested in the detailed
differences between X and L should consult the Collation Customization). Specifying either L or U won't affect string comparison
performance, but will affect the sort key length. Possible values are:
o Collator::OFF(default)
o Collator::LOWER_FIRST
o Collator::UPPER_FIRST
o Collator:DEFAULT
Example #3
CASE_FIRST rules
oC=X or C=L "china" < "China" < "denmark" < "Denmark"
oC=U "China" < "china" < "Denmark" < "denmark"
o Collator::CASE_LEVEL ( integer) - The Case_Level attribute is used when ignoring accents but not case. In such a situation, set
Strength to be Primary, and Case_Level to be On. In most locales, this setting is Off by default. There is a small string compari-
son performance and sort key impact if this attribute is set to be On. Possible values are:
o Collator::OFF(default)
o Collator::ON
o Collator::DEFAULT_VALUE
Example #4
CASE_LEVEL rules
oS=1, E=X role = Role = role
oS=1, E=O role = role < Role
o Collator::NORMALIZATION_MODE ( integer) - The Normalization setting determines whether text is thoroughly normalized or not in
comparison. Even if the setting is off (which is the default for many locales), text as represented in common usage will compare
correctly (for details, see UTN #5). Only if the accent marks are in noncanonical order will there be a problem. If the setting is
On, then the best results are guaranteed for all possible text input. There is a medium string comparison performance cost if this
attribute is On, depending on the frequency of sequences that require normalization. There is no significant effect on sort key
length. If the input text is known to be in NFD or NFKD normalization forms, there is no need to enable this Normalization option.
Possible values are:
o Collator::OFF(default)
o Collator::ON
o Collator::DEFAULT_VALUE
o Collator::STRENGTH ( integer) - The ICU Collation Service supports many levels of comparison (named "Levels", but also known as
"Strengths"). Having these categories enables ICU to sort strings precisely according to local conventions. However, by allowing
the levels to be selectively employed, searching for a string in text can be performed with various matching conditions. For more
detailed information, see collator_set_strength(3) chapter. Possible values are:
o Collator::PRIMARY
o Collator::SECONDARY
o Collator::TERTIARY(default)
o Collator::QUATERNARY
o Collator::IDENTICAL
o Collator::DEFAULT_VALUE
o Collator::HIRAGANA_QUATERNARY_MODE ( integer) - Compatibility with JIS x 4061 requires the introduction of an additional level to
distinguish Hiragana and Katakana characters. If compatibility with that standard is required, then this attribute should be set
On, and the strength set to Quaternary. This will affect sort key length and string comparison string comparison performance.
Possible values are:
o Collator::OFF(default)
o Collator::ON
o Collator::DEFAULT_VALUE
o Collator::NUMERIC_COLLATION ( integer) - When turned on, this attribute generates a collation key for the numeric value of sub-
strings of digits. This is a way to get '100' to sort AFTER '2'. Possible values are:
o Collator::OFF(default)
o Collator::ON
o Collator::DEFAULT_VALUE
o Collator::DEFAULT_VALUE ( integer) -
o Collator::PRIMARY ( integer) -
o Collator::SECONDARY ( integer) -
o Collator::TERTIARY ( integer) -
o Collator::DEFAULT_STRENGTH ( integer) -
o Collator::QUATERNARY ( integer) -
o Collator::IDENTICAL ( integer) -
o Collator::OFF ( integer) -
o Collator::ON ( integer) -
o Collator::SHIFTED ( integer) -
o Collator::NON_IGNORABLE ( integer) -
o Collator::LOWER_FIRST ( integer) -
o Collator::UPPER_FIRST ( integer) -
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