File: text/js/text-accentfold.js
/**
* Text utilities.
*
* @module text
* @since 3.3.0
*/
/**
* Provides a basic accent folding implementation that converts common accented
* letters (like "á") to their non-accented forms (like "a").
*
* @module text
* @submodule text-accentfold
*/
/**
* <p>
* Provides a basic accent folding implementation that converts common accented
* letters (like "á") to their non-accented forms (like "a").
* </p>
*
* <p>
* This implementation is not comprehensive, and should only be used as a last
* resort when accent folding can't be done on the server. A comprehensive
* accent folding implementation would require much more character data to be
* sent to the browser, resulting in a significant performance penalty. This
* implementation strives for a compromise between usefulness and performance.
* </p>
*
* <p>
* Accent folding is a destructive operation that can't be reversed, and may
* change or destroy the actual meaning of the text depending on the language.
* It should not be used on strings that will later be displayed to a user,
* unless this is done with the understanding that linguistic meaning may be
* lost and that you may in fact confuse or insult the user by doing so.
* </p>
*
* <p>
* When used for matching, accent folding is likely to produce erroneous matches
* for languages in which characters with diacritics are considered different
* from their base characters, or where correct folding would map to other
* character sequences than just stripped characters. For example, in German
* "ü" is a character that's clearly different from "u" and should match "ue"
* instead. The word "betrügen" means "to defraud", while "betrugen" is the past
* tense of "to behave". The name "Müller" is expected to match "Mueller", but
* not "Muller". On the other hand, accent folding falls short for languages
* where different base characters are expected to match. In Japanese, for
* example, hiragana and katakana characters with the same pronunciation ("あ"
* and "ア") are commonly treated as equivalent for lookups, but accent folding
* treats them as different.
* </p>
*
* @class Text.AccentFold
* @static
*/
var YArray = Y.Array,
Text = Y.Text,
FoldData = Text.Data.AccentFold,
AccentFold = {
// -- Public Static Methods ------------------------------------------------
/**
* Returns <code>true</code> if the specified string contains one or more
* characters that can be folded, <code>false</code> otherwise.
*
* @method canFold
* @param {String} string String to test.
* @return {Boolean}
* @static
*/
canFold: function (string) {
var letter;
for (letter in FoldData) {
if (FoldData.hasOwnProperty(letter) &&
string.search(FoldData[letter]) !== -1) {
return true;
}
}
return false;
},
/**
* Compares the accent-folded versions of two strings and returns
* <code>true</code> if they're the same, <code>false</code> otherwise. If
* a custom comparison function is supplied, the accent-folded strings will
* be passed to that function for comparison.
*
* @method compare
* @param {String} a First string to compare.
* @param {String} b Second string to compare.
* @param {Function} func (optional) Custom comparison function. Should
* return a truthy or falsy value.
* @return {Boolean} Results of the comparison.
* @static
*/
compare: function (a, b, func) {
var aFolded = AccentFold.fold(a),
bFolded = AccentFold.fold(b);
return func ? !!func(aFolded, bFolded) : aFolded === bFolded;
},
/**
* <p>
* Returns a copy of <em>haystack</em> containing only the strings for which
* the supplied function returns <code>true</code>.
* </p>
*
* <p>
* While comparisons will be made using accent-folded strings, the returned
* array of matches will contain the original strings that were passed in.
* </p>
*
* @method filter
* @param {Array} haystack Array of strings to filter.
* @param {Function} func Comparison function. Will receive an accent-folded
* haystack string as an argument, and should return a truthy or falsy
* value.
* @return {Array} Filtered copy of <em>haystack</em>.
* @static
*/
filter: function (haystack, func) {
return YArray.filter(haystack, function (item) {
return func(AccentFold.fold(item));
});
},
/**
* Accent-folds the specified string or array of strings and returns a copy
* in which common accented letters have been converted to their closest
* non-accented, lowercase forms.
*
* @method fold
* @param {String|Array} input String or array of strings to be folded.
* @return {String|Array} Folded string or array of strings.
* @static
*/
fold: function (input) {
if (Y.Lang.isArray(input)) {
return YArray.map(input, AccentFold.fold);
}
input = input.toLowerCase();
Y.Object.each(FoldData, function (regex, letter) {
input = input.replace(regex, letter);
});
return input;
}
};
Text.AccentFold = AccentFold;