858 lines
34 KiB
C++
858 lines
34 KiB
C++
/*
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* Copyright © {1999}, International Business Machines Corporation and others. All Rights Reserved.
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**********************************************************************
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* Date Name Description
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* 11/17/99 aliu Creation.
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**********************************************************************
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*/
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#ifndef TRANSLIT_H
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#define TRANSLIT_H
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#include "unicode/unistr.h"
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#include "unicode/parseerr.h"
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#include "unicode/utrans.h" // UTransPosition, UTransDirection
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class Replaceable;
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class UnicodeFilter;
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class TransliterationRuleData;
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class Hashtable;
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class U_I18N_API UVector;
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class CompoundTransliterator;
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/**
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* <code>Transliterator</code> is an abstract class that
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* transliterates text from one format to another. The most common
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* kind of transliterator is a script, or alphabet, transliterator.
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* For example, a Russian to Latin transliterator changes Russian text
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* written in Cyrillic characters to phonetically equivalent Latin
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* characters. It does not <em>translate</em> Russian to English!
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* Transliteration, unlike translation, operates on characters, without
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* reference to the meanings of words and sentences.
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*
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* <p>Although script conversion is its most common use, a
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* transliterator can actually perform a more general class of tasks.
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* In fact, <code>Transliterator</code> defines a very general API
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* which specifies only that a segment of the input text is replaced
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* by new text. The particulars of this conversion are determined
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* entirely by subclasses of <code>Transliterator</code>.
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*
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* <p><b>Transliterators are stateless</b>
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*
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* <p><code>Transliterator</code> objects are <em>stateless</em>; they
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* retain no information between calls to
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* <code>transliterate()</code>. (However, this does <em>not</em>
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* mean that threads may share transliterators without synchronizing
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* them. Transliterators are not immutable, so they must be
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* synchronized when shared between threads.) This1 might seem to
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* limit the complexity of the transliteration operation. In
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* practice, subclasses perform complex transliterations by delaying
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* the replacement of text until it is known that no other
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* replacements are possible. In other words, although the
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* <code>Transliterator</code> objects are stateless, the source text
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* itself embodies all the needed information, and delayed operation
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* allows arbitrary complexity.
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*
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* <p><b>Batch transliteration</b>
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*
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* <p>The simplest way to perform transliteration is all at once, on a
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* string of existing text. This is referred to as <em>batch</em>
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* transliteration. For example, given a string <code>input</code>
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* and a transliterator <code>t</code>, the call
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*
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* <blockquote><code>String result = t.transliterate(input);
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* </code></blockquote>
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*
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* will transliterate it and return the result. Other methods allow
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* the client to specify a substring to be transliterated and to use
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* {@link Replaceable} objects instead of strings, in order to
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* preserve out-of-band information (such as text styles).
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*
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* <p><b>Keyboard transliteration</b>
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*
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* <p>Somewhat more involved is <em>keyboard</em>, or incremental
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* transliteration. This is the transliteration of text that is
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* arriving from some source (typically the user's keyboard) one
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* character at a time, or in some other piecemeal fashion.
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*
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* <p>In keyboard transliteration, a <code>Replaceable</code> buffer
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* stores the text. As text is inserted, as much as possible is
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* transliterated on the fly. This means a GUI that displays the
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* contents of the buffer may show text being modified as each new
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* character arrives.
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*
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* <p>Consider the simple <code>RuleBasedTransliterator</code>:
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*
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* <blockquote><code>
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* th>{theta}<br>
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* t>{tau}
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* </code></blockquote>
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*
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* When the user types 't', nothing will happen, since the
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* transliterator is waiting to see if the next character is 'h'. To
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* remedy this, we introduce the notion of a cursor, marked by a '|'
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* in the output string:
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*
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* <blockquote><code>
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* t>|{tau}<br>
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* {tau}h>{theta}
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* </code></blockquote>
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*
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* Now when the user types 't', tau appears, and if the next character
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* is 'h', the tau changes to a theta. This is accomplished by
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* maintaining a cursor position (independent of the insertion point,
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* and invisible in the GUI) across calls to
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* <code>transliterate()</code>. Typically, the cursor will
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* be coincident with the insertion point, but in a case like the one
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* above, it will precede the insertion point.
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*
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* <p>Keyboard transliteration methods maintain a set of three indices
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* that are updated with each call to
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* <code>transliterate()</code>, including the cursor, start,
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* and limit. Since these indices are changed by the method, they are
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* passed in an <code>int[]</code> array. The <code>START</code> index
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* marks the beginning of the substring that the transliterator will
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* look at. It is advanced as text becomes committed (but it is not
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* the committed index; that's the <code>CURSOR</code>). The
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* <code>CURSOR</code> index, described above, marks the point at
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* which the transliterator last stopped, either because it reached
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* the end, or because it required more characters to disambiguate
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* between possible inputs. The <code>CURSOR</code> can also be
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* explicitly set by rules in a <code>RuleBasedTransliterator</code>.
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* Any characters before the <code>CURSOR</code> index are frozen;
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* future keyboard transliteration calls within this input sequence
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* will not change them. New text is inserted at the
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* <code>LIMIT</code> index, which marks the end of the substring that
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* the transliterator looks at.
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*
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* <p>Because keyboard transliteration assumes that more characters
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* are to arrive, it is conservative in its operation. It only
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* transliterates when it can do so unambiguously. Otherwise it waits
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* for more characters to arrive. When the client code knows that no
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* more characters are forthcoming, perhaps because the user has
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* performed some input termination operation, then it should call
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* <code>finishTransliteration()</code> to complete any
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* pending transliterations.
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*
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* <p><b>Inverses</b>
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*
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* <p>Pairs of transliterators may be inverses of one another. For
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* example, if transliterator <b>A</b> transliterates characters by
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* incrementing their Unicode value (so "abc" -> "def"), and
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* transliterator <b>B</b> decrements character values, then <b>A</b>
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* is an inverse of <b>B</b> and vice versa. If we compose <b>A</b>
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* with <b>B</b> in a compound transliterator, the result is the
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* indentity transliterator, that is, a transliterator that does not
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* change its input text.
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*
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* The <code>Transliterator</code> method <code>getInverse()</code>
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* returns a transliterator's inverse, if one exists, or
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* <code>null</code> otherwise. However, the result of
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* <code>getInverse()</code> usually will <em>not</em> be a true
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* mathematical inverse. This is because true inverse transliterators
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* are difficult to formulate. For example, consider two
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* transliterators: <b>AB</b>, which transliterates the character 'A'
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* to 'B', and <b>BA</b>, which transliterates 'B' to 'A'. It might
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* seem that these are exact inverses, since
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*
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* <blockquote>"A" x <b>AB</b> -> "B"<br>
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* "B" x <b>BA</b> -> "A"</blockquote>
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*
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* where 'x' represents transliteration. However,
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*
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* <blockquote>"ABCD" x <b>AB</b> -> "BBCD"<br>
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* "BBCD" x <b>BA</b> -> "AACD"</blockquote>
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*
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* so <b>AB</b> composed with <b>BA</b> is not the
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* identity. Nonetheless, <b>BA</b> may be usefully considered to be
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* <b>AB</b>'s inverse, and it is on this basis that
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* <b>AB</b><code>.getInverse()</code> could legitimately return
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* <b>BA</b>.
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*
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* <p><b>IDs and display names</b>
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*
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* <p>A transliterator is designated by a short identifier string or
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* <em>ID</em>. IDs follow the format <em>source-destination</em>,
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* where <em>source</em> describes the entity being replaced, and
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* <em>destination</em> describes the entity replacing
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* <em>source</em>. The entities may be the names of scripts,
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* particular sequences of characters, or whatever else it is that the
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* transliterator converts to or from. For example, a transliterator
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* from Russian to Latin might be named "Russian-Latin". A
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* transliterator from keyboard escape sequences to Latin-1 characters
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* might be named "KeyboardEscape-Latin1". By convention, system
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* entity names are in English, with the initial letters of words
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* capitalized; user entity names may follow any format so long as
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* they do not contain dashes.
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*
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* <p>In addition to programmatic IDs, transliterator objects have
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* display names for presentation in user interfaces, returned by
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* {@link #getDisplayName}.
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*
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* <p><b>Factory methods and registration</b>
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*
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* <p>In general, client code should use the factory method
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* <code>getInstance()</code> to obtain an instance of a
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* transliterator given its ID. Valid IDs may be enumerated using
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* <code>getAvailableIDs()</code>. Since transliterators are mutable,
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* multiple calls to <code>getInstance()</code> with the same ID will
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* return distinct objects.
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*
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* <p>In addition to the system transliterators registered at startup,
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* user transliterators may be registered by calling
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* <code>registerInstance()</code> at run time. A registered instance
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* acts a template; future calls to <tt>getInstance()</tt> with the ID
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* of the registered object return clones of that object. Thus any
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* object passed to <tt>registerInstance()</tt> must implement
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* <tt>clone()</tt> propertly. To register a transliterator subclass
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* without instantiating it (until it is needed), users may call
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* <code>registerClass()</code>. In this case, the objects are
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* instantiated by invoking the zero-argument public constructor of
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* the class.
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*
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* <p><b>Subclassing</b>
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*
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* Subclasses must implement the abstract method
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* <code>handleTransliterate()</code>. <p>Subclasses should override
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* the <code>transliterate()</code> method taking a
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* <code>Replaceable</code> and the <code>transliterate()</code>
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* method taking a <code>String</code> and <code>StringBuffer</code>
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* if the performance of these methods can be improved over the
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* performance obtained by the default implementations in this class.
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*
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* @author Alan Liu
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* @draft
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*/
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class U_I18N_API Transliterator {
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private:
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/**
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* Programmatic name, e.g., "Latin-Arabic".
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*/
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UnicodeString ID;
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/**
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* This transliterator's filter. Any character for which
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* <tt>filter.contains()</tt> returns <tt>false</tt> will not be
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* altered by this transliterator. If <tt>filter</tt> is
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* <tt>null</tt> then no filtering is applied.
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*/
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UnicodeFilter* filter;
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int32_t maximumContextLength;
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/**
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* Cache of public system transliterators. Keys are UnicodeString
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* names, values are CacheEntry objects.
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*/
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static Hashtable* cache;
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/**
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* Like 'cache', but IDs are not public. Internal transliterators
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* are combined together and aliased to public IDs.
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*/
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static Hashtable* internalCache;
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/**
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* The mutex controlling access to the caches.
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*/
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static UMTX cacheMutex;
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/**
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* When set to TRUE, the cache has been initialized. Any code must
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* check this boolean before accessing the cache, and if the boolean
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* is FALSE, it must call initializeCache(). We do this form of lazy
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* evaluation for two reasons: (1) so we don't initialize if we don't
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* have to (i.e., if no one is using Transliterator, but has included
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* the code as part of a shared library, and (2) to avoid static
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* intialization problems.
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*/
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static UBool cacheInitialized;
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/**
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* In Java, the cache stores objects of different types and
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* singleton objects as placeholders for rule-based
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* transliterators to be built as needed. In C++ we use the
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* following struct to achieve the same purpose. Instances of
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* this struct can be placeholders, can represent prototype
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* transliterators to be cloned, or can represent
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* RuleBasedTransliterator::Data objects. We don't support
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* storing classes in the cache because we don't have the rtti
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* infrastructure for it. We could easily add this if there is a
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* need for it in the future. The rbFile is the resource bundle
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* file name for rule-based transliterators.
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*/
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struct CacheEntry {
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enum Type {
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RULES_FORWARD,
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RULES_REVERSE,
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PROTOTYPE,
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RBT_DATA,
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ALIAS,
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NONE // Only used for uninitialized entries
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} entryType;
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// NOTE: stringArg cannot go inside the union because
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// it has a copy constructor
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UnicodeString stringArg; // For RULES_*, ALIAS
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union {
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Transliterator* prototype; // For PROTOTYPE
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TransliterationRuleData* data; // For RBT_DATA
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} u;
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CacheEntry();
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~CacheEntry();
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void adoptPrototype(Transliterator* adopted);
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};
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/**
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* Prefix for resource bundle key for the display name for a
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* transliterator. The ID is appended to this to form the key.
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* The resource bundle value should be a String.
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*/
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static const char* RB_DISPLAY_NAME_PREFIX;
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/**
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* Prefix for resource bundle key for the display name for a
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* transliterator SCRIPT. The ID is appended to this to form the key.
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* The resource bundle value should be a String.
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*/
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static const char* RB_SCRIPT_DISPLAY_NAME_PREFIX;
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/**
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* Resource bundle key for display name pattern.
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* The resource bundle value should be a String forming a
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* MessageFormat pattern, e.g.:
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* "{0,choice,0#|1#{1} Transliterator|2#{1} to {2} Transliterator}".
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*/
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static const char* RB_DISPLAY_NAME_PATTERN;
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/**
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* Resource bundle key for the list of RuleBasedTransliterator IDs.
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* The resource bundle value should be a String[] with each element
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* being a valid ID. The ID will be appended to RB_RULE_BASED_PREFIX
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* to obtain the class name in which the RB_RULE key will be sought.
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*/
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static const char* RB_RULE_BASED_IDS;
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/**
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* Resource bundle key for the RuleBasedTransliterator rule.
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*/
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static const char* RB_RULE;
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protected:
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/**
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* Default constructor.
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* @param ID the string identifier for this transliterator
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* @param adoptedFilter the filter. Any character for which
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* <tt>filter.contains()</tt> returns <tt>false</tt> will not be
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* altered by this transliterator. If <tt>filter</tt> is
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* <tt>null</tt> then no filtering is applied.
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*/
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Transliterator(const UnicodeString& ID, UnicodeFilter* adoptedFilter);
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/**
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* Copy constructor.
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*/
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Transliterator(const Transliterator&);
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/**
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* Assignment operator.
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*/
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Transliterator& operator=(const Transliterator&);
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public:
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/**
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* Destructor.
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* @draft
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*/
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virtual ~Transliterator();
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/**
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* Implements Cloneable.
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* All subclasses are encouraged to implement this method if it is
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* possible and reasonable to do so. Subclasses that are to be
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* registered with the system using <tt>registerInstance()<tt>
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* are required to implement this method. If a subclass does not
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* implement clone() properly and is registered with the system
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* using registerInstance(), then the default clone() implementation
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* will return null, and calls to createInstance() will fail.
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*
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* @see #registerInstance
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* @draft
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*/
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virtual Transliterator* clone() const { return 0; }
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/**
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* Transliterates a segment of a string, with optional filtering.
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*
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* @param text the string to be transliterated
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* @param start the beginning index, inclusive; <code>0 <= start
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* <= limit</code>.
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* @param limit the ending index, exclusive; <code>start <= limit
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* <= text.length()</code>.
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* @param filter the filter. Any character for which
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* <tt>filter.contains()</tt> returns <tt>false</tt> will not be
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* altered by this transliterator. If <tt>filter</tt> is
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* <tt>null</tt> then no filtering is applied.
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* @return The new limit index. The text previously occupying <code>[start,
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* limit)</code> has been transliterated, possibly to a string of a different
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* length, at <code>[start, </code><em>new-limit</em><code>)</code>, where
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* <em>new-limit</em> is the return value.
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* @draft
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*/
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virtual int32_t transliterate(Replaceable& text,
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int32_t start, int32_t limit) const;
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/**
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* Transliterates an entire string in place. Convenience method.
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* @param text the string to be transliterated
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* @draft
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*/
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virtual void transliterate(Replaceable& text) const;
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/**
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* Transliterates the portion of the text buffer that can be
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* transliterated unambiguosly after new text has been inserted,
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* typically as a result of a keyboard event. The new text in
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* <code>insertion</code> will be inserted into <code>text</code>
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* at <code>index.limit</code>, advancing
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* <code>index.limit</code> by <code>insertion.length()</code>.
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* Then the transliterator will try to transliterate characters of
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* <code>text</code> between <code>index.cursor</code> and
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* <code>index.limit</code>. Characters before
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* <code>index.cursor</code> will not be changed.
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*
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* <p>Upon return, values in <code>index</code> will be updated.
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* <code>index.start</code> will be advanced to the first
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* character that future calls to this method will read.
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* <code>index.cursor</code> and <code>index.limit</code> will
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* be adjusted to delimit the range of text that future calls to
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* this method may change.
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*
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* <p>Typical usage of this method begins with an initial call
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* with <code>index.start</code> and <code>index.limit</code>
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* set to indicate the portion of <code>text</code> to be
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* transliterated, and <code>index.cursor == index.start</code>.
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* Thereafter, <code>index</code> can be used without
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* modification in future calls, provided that all changes to
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* <code>text</code> are made via this method.
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*
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* <p>This method assumes that future calls may be made that will
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* insert new text into the buffer. As a result, it only performs
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* unambiguous transliterations. After the last call to this
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* method, there may be untransliterated text that is waiting for
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* more input to resolve an ambiguity. In order to perform these
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* pending transliterations, clients should call {@link
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* #finishTransliteration} after the last call to this
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* method has been made.
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*
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* @param text the buffer holding transliterated and untransliterated text
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* @param index an array of three integers.
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*
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* <ul><li><code>index.start</code>: the beginning index,
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* inclusive; <code>0 <= index.start <= index.limit</code>.
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*
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* <li><code>index.limit</code>: the ending index, exclusive;
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* <code>index.start <= index.limit <= text.length()</code>.
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* <code>insertion</code> is inserted at
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* <code>index.limit</code>.
|
|
*
|
|
* <li><code>index.cursor</code>: the next character to be
|
|
* considered for transliteration; <code>index.start <=
|
|
* index.cursor <= index.limit</code>. Characters before
|
|
* <code>index.cursor</code> will not be changed by future calls
|
|
* to this method.</ul>
|
|
*
|
|
* @param insertion text to be inserted and possibly
|
|
* transliterated into the translation buffer at
|
|
* <code>index.limit</code>. If <code>null</code> then no text
|
|
* is inserted.
|
|
* @see #handleTransliterate
|
|
* @exception IllegalArgumentException if <code>index</code>
|
|
* is invalid
|
|
* @draft
|
|
*/
|
|
virtual void transliterate(Replaceable& text, UTransPosition& index,
|
|
const UnicodeString& insertion,
|
|
UErrorCode& status) const;
|
|
|
|
/**
|
|
* Transliterates the portion of the text buffer that can be
|
|
* transliterated unambiguosly after a new character has been
|
|
* inserted, typically as a result of a keyboard event. This is a
|
|
* convenience method; see {@link
|
|
* #transliterate(Replaceable, int[], String)} for details.
|
|
* @param text the buffer holding transliterated and
|
|
* untransliterated text
|
|
* @param index an array of three integers. See {@link
|
|
* #transliterate(Replaceable, int[], String)}.
|
|
* @param insertion text to be inserted and possibly
|
|
* transliterated into the translation buffer at
|
|
* <code>index.limit</code>.
|
|
* @see #transliterate(Replaceable, int[], String)
|
|
* @draft
|
|
*/
|
|
virtual void transliterate(Replaceable& text, UTransPosition& index,
|
|
UChar insertion,
|
|
UErrorCode& status) const;
|
|
|
|
/**
|
|
* Transliterates the portion of the text buffer that can be
|
|
* transliterated unambiguosly. This is a convenience method; see
|
|
* {@link #transliterate(Replaceable, int[], String)} for
|
|
* details.
|
|
* @param text the buffer holding transliterated and
|
|
* untransliterated text
|
|
* @param index an array of three integers. See {@link
|
|
* #transliterate(Replaceable, int[], String)}.
|
|
* @see #transliterate(Replaceable, int[], String)
|
|
* @draft
|
|
*/
|
|
virtual void transliterate(Replaceable& text, UTransPosition& index,
|
|
UErrorCode& status) const;
|
|
|
|
/**
|
|
* Finishes any pending transliterations that were waiting for
|
|
* more characters. Clients should call this method as the last
|
|
* call after a sequence of one or more calls to
|
|
* <code>transliterate()</code>.
|
|
* @param text the buffer holding transliterated and
|
|
* untransliterated text.
|
|
* @param index the array of indices previously passed to {@link
|
|
* #transliterate}
|
|
* @draft
|
|
*/
|
|
virtual void finishTransliteration(Replaceable& text,
|
|
UTransPosition& index) const;
|
|
|
|
private:
|
|
|
|
/**
|
|
* This internal method does incremental transliteration. If the
|
|
* 'insertion' is non-null then we append it to 'text' before
|
|
* proceeding. This method calls through to the pure virtual
|
|
* framework method handleTransliterate() to do the actual
|
|
* work.
|
|
*/
|
|
void _transliterate(Replaceable& text,
|
|
UTransPosition& index,
|
|
const UnicodeString* insertion,
|
|
UErrorCode &status) const;
|
|
|
|
protected:
|
|
|
|
/**
|
|
* Abstract method that concrete subclasses define to implement
|
|
* keyboard transliteration. This method should transliterate all
|
|
* characters between <code>index.cursor</code> and
|
|
* <code>index.limit</code> that can be unambiguously
|
|
* transliterated, regardless of future insertions of text at
|
|
* <code>index.limit</code>. <code>index.cursor</code> should
|
|
* be advanced past committed characters (those that will not
|
|
* change in future calls to this method).
|
|
* <code>index.limit</code> should be updated to reflect text
|
|
* replacements that shorten or lengthen the text between
|
|
* <code>index.cursor</code> and <code>index.limit</code>. Upon
|
|
* return, neither <code>index.cursor</code> nor
|
|
* <code>index.limit</code> should be less than the initial value
|
|
* of <code>index.cursor</code>. <code>index.start</code>
|
|
* should <em>not</em> be changed.
|
|
*
|
|
* @param text the buffer holding transliterated and
|
|
* untransliterated text
|
|
* @param index an array of three integers. See {@link
|
|
* #transliterate(Replaceable, int[], String)}.
|
|
* @see #transliterate
|
|
*/
|
|
virtual void handleTransliterate(Replaceable& text,
|
|
UTransPosition& index,
|
|
UBool incremental) const = 0;
|
|
|
|
// C++ requires this friend declaration so CompoundTransliterator
|
|
// can access handleTransliterate. Alternatively, we could
|
|
// make handleTransliterate public.
|
|
friend class CompoundTransliterator;
|
|
|
|
public:
|
|
|
|
/**
|
|
* Returns the length of the longest context required by this transliterator.
|
|
* This is <em>preceding</em> context. The default implementation supplied
|
|
* by <code>Transliterator</code> returns zero; subclasses
|
|
* that use preceding context should override this method to return the
|
|
* correct value. For example, if a transliterator translates "ddd" (where
|
|
* d is any digit) to "555" when preceded by "(ddd)", then the preceding
|
|
* context length is 5, the length of "(ddd)".
|
|
*
|
|
* @return The maximum number of preceding context characters this
|
|
* transliterator needs to examine
|
|
* @draft
|
|
*/
|
|
int32_t getMaximumContextLength(void) const;
|
|
|
|
protected:
|
|
|
|
/**
|
|
* Method for subclasses to use to set the maximum context length.
|
|
* @see #getMaximumContextLength
|
|
*/
|
|
void setMaximumContextLength(int32_t maxContextLength);
|
|
|
|
public:
|
|
|
|
/**
|
|
* Returns a programmatic identifier for this transliterator.
|
|
* If this identifier is passed to <code>getInstance()</code>, it
|
|
* will return this object, if it has been registered.
|
|
* @see #registerInstance
|
|
* @see #registerClass
|
|
* @see #getAvailableIDs
|
|
* @draft
|
|
*/
|
|
virtual const UnicodeString& getID(void) const;
|
|
|
|
/**
|
|
* Returns a name for this transliterator that is appropriate for
|
|
* display to the user in the default locale. See {@link
|
|
* #getDisplayName(Locale)} for details.
|
|
* @draft
|
|
*/
|
|
static UnicodeString& getDisplayName(const UnicodeString& ID,
|
|
UnicodeString& result);
|
|
|
|
/**
|
|
* Returns a name for this transliterator that is appropriate for
|
|
* display to the user in the given locale. This name is taken
|
|
* from the locale resource data in the standard manner of the
|
|
* <code>java.text</code> package.
|
|
*
|
|
* <p>If no localized names exist in the system resource bundles,
|
|
* a name is synthesized using a localized
|
|
* <code>MessageFormat</code> pattern from the resource data. The
|
|
* arguments to this pattern are an integer followed by one or two
|
|
* strings. The integer is the number of strings, either 1 or 2.
|
|
* The strings are formed by splitting the ID for this
|
|
* transliterator at the first '-'. If there is no '-', then the
|
|
* entire ID forms the only string.
|
|
* @param inLocale the Locale in which the display name should be
|
|
* localized.
|
|
* @see java.text.MessageFormat
|
|
* @draft
|
|
*/
|
|
static UnicodeString& getDisplayName(const UnicodeString& ID,
|
|
const Locale& inLocale,
|
|
UnicodeString& result);
|
|
|
|
/**
|
|
* Returns the filter used by this transliterator, or <tt>NULL</tt>
|
|
* if this transliterator uses no filter.
|
|
* @draft
|
|
*/
|
|
virtual const UnicodeFilter* getFilter(void) const;
|
|
|
|
/**
|
|
* Returns the filter used by this transliterator, or <tt>NULL</tt> if this
|
|
* transliterator uses no filter. The caller must eventually delete the
|
|
* result. After this call, this transliterator's filter is set to
|
|
* <tt>NULL</tt>. Calls adoptFilter().
|
|
*/
|
|
UnicodeFilter* orphanFilter(void);
|
|
|
|
/**
|
|
* Changes the filter used by this transliterator. If the filter
|
|
* is set to <tt>null</tt> then no filtering will occur.
|
|
*
|
|
* <p>Callers must take care if a transliterator is in use by
|
|
* multiple threads. The filter should not be changed by one
|
|
* thread while another thread may be transliterating.
|
|
* @draft
|
|
*/
|
|
virtual void adoptFilter(UnicodeFilter* adoptedFilter);
|
|
|
|
/**
|
|
* Returns this transliterator's inverse. See the class
|
|
* documentation for details. This implementation simply inverts
|
|
* the two entities in the ID and attempts to retrieve the
|
|
* resulting transliterator. That is, if <code>getID()</code>
|
|
* returns "A-B", then this method will return the result of
|
|
* <code>getInstance("B-A")</code>, or <code>null</code> if that
|
|
* call fails.
|
|
*
|
|
* <p>This method does not take filtering into account. The
|
|
* returned transliterator will have no filter.
|
|
*
|
|
* <p>Subclasses with knowledge of their inverse may wish to
|
|
* override this method.
|
|
*
|
|
* @return a transliterator that is an inverse, not necessarily
|
|
* exact, of this transliterator, or <code>null</code> if no such
|
|
* transliterator is registered.
|
|
* @see #registerInstance
|
|
* @draft
|
|
*/
|
|
Transliterator* createInverse(void) const;
|
|
|
|
/**
|
|
* Returns a <code>Transliterator</code> object given its ID.
|
|
* The ID must be either a system transliterator ID or a ID registered
|
|
* using <code>registerInstance()</code>.
|
|
*
|
|
* @param ID a valid ID, as enumerated by <code>getAvailableIDs()</code>
|
|
* @return A <code>Transliterator</code> object with the given ID
|
|
* @exception IllegalArgumentException if the given ID is invalid.
|
|
* @see #registerInstance
|
|
* @see #getAvailableIDs
|
|
* @see #getID
|
|
* @draft
|
|
*/
|
|
static Transliterator* createInstance(const UnicodeString& ID,
|
|
UTransDirection dir = UTRANS_FORWARD,
|
|
UParseError* parseError = 0);
|
|
|
|
private:
|
|
|
|
/**
|
|
* Returns a transliterator object given its ID. Unlike getInstance(),
|
|
* this method returns null if it cannot make use of the given ID.
|
|
* @param aliasReturn if ID is an alias transliterator this is set
|
|
* the the parameter to be passed to createInstance() and 0 is
|
|
* returned; otherwise, this is unchanged
|
|
*/
|
|
static Transliterator* _createInstance(const UnicodeString& ID,
|
|
UnicodeString& aliasReturn,
|
|
UParseError* parseError = 0);
|
|
|
|
public:
|
|
|
|
/**
|
|
* Registers a instance <tt>obj</tt> of a subclass of
|
|
* <code>Transliterator</code> with the system. When
|
|
* <tt>createInstance()</tt> is called with an ID string that is
|
|
* equal to <tt>obj->getID()</tt>, then <tt>obj->clone()</tt> is
|
|
* returned.
|
|
*
|
|
* After this call the Transliterator class owns the adoptedObj
|
|
* and will delete it.
|
|
*
|
|
* @param obj an instance of subclass of
|
|
* <code>Transliterator</code> that defines <tt>clone()</tt>
|
|
* @see #getInstance
|
|
* @see #registerClass
|
|
* @see #unregister
|
|
* @draft
|
|
*/
|
|
static void registerInstance(Transliterator* adoptedObj,
|
|
UErrorCode& status);
|
|
|
|
private:
|
|
|
|
/**
|
|
* This internal method registers a prototype instance in the cache.
|
|
* The CALLER MUST MUTEX using cacheMutex before calling this method.
|
|
*/
|
|
static void _registerInstance(Transliterator* adoptedPrototype,
|
|
UErrorCode &status);
|
|
|
|
public:
|
|
|
|
/**
|
|
* Unregisters a transliterator or class. This may be either
|
|
* a system transliterator or a user transliterator or class.
|
|
*
|
|
* @param ID the ID of the transliterator or class
|
|
* @return the <code>Object</code> that was registered with
|
|
* <code>ID</code>, or <code>null</code> if none was
|
|
* @see #registerInstance
|
|
* @see #registerClass
|
|
* @draft
|
|
*/
|
|
static void unregister(const UnicodeString& ID);
|
|
|
|
private:
|
|
|
|
/**
|
|
* Unregisters a transliterator or class. Internal method.
|
|
* Prerequisites: The cache must be initialized, and the
|
|
* caller must own the cacheMutex.
|
|
*/
|
|
static void _unregister(const UnicodeString& ID);
|
|
|
|
/**
|
|
* Returns an enumeration over the programmatic names of registered
|
|
* <code>Transliterator</code> objects. This includes both system
|
|
* transliterators and user transliterators registered using
|
|
* <code>registerInstance()</code>. The enumerated names may be
|
|
* passed to <code>getInstance()</code>.
|
|
*
|
|
* @return An <code>Enumeration</code> over <code>String</code> objects
|
|
* @see #getInstance
|
|
* @see #registerInstance
|
|
*/
|
|
// virtual Enumeration getAvailableIDs();
|
|
|
|
/**
|
|
* Vector of registered IDs.
|
|
*/
|
|
static UVector cacheIDs;
|
|
|
|
public:
|
|
|
|
/**
|
|
* Return the number of IDs currently registered with the system.
|
|
* To retrieve the actual IDs, call getAvailableID(i) with
|
|
* i from 0 to countAvailableIDs() - 1.
|
|
* @draft
|
|
*/
|
|
static int32_t countAvailableIDs(void);
|
|
|
|
/**
|
|
* Return the index-th available ID. index must be between 0
|
|
* and countAvailableIDs() - 1, inclusive. If index is out of
|
|
* range, the result of getAvailableID(0) is returned.
|
|
* @draft
|
|
*/
|
|
static const UnicodeString& getAvailableID(int32_t index);
|
|
|
|
protected:
|
|
|
|
/**
|
|
* Method for subclasses to use to obtain a character in the given
|
|
* string, with filtering. If the character at the given offset
|
|
* is excluded by this transliterator's filter, then U+FFFE is returned.
|
|
*/
|
|
UChar filteredCharAt(const Replaceable& text, int32_t i) const;
|
|
|
|
/**
|
|
* Set the ID of this transliterators. Subclasses shouldn't do
|
|
* this, unless the underlying script behavior has changed.
|
|
*/
|
|
void setID(const UnicodeString& id);
|
|
|
|
private:
|
|
/**
|
|
* Comparison function for UVector. Compares two UnicodeString
|
|
* objects given void* pointers to them.
|
|
*/
|
|
static UBool compareIDs(void* a, void* b);
|
|
|
|
static void initializeCache(void);
|
|
|
|
/* IDs take the form <source> ID_SEP <target>, where
|
|
* <source> and <target> are (usually) script names.
|
|
* Compound IDs take the form <ID> ( ID_DELIM <ID> )+.
|
|
*/
|
|
static const UChar ID_SEP; // ((UChar)0x002D) /*-*/
|
|
static const UChar ID_DELIM; // ((UChar)0x003B) /*;*/
|
|
};
|
|
|
|
inline int32_t Transliterator::getMaximumContextLength(void) const {
|
|
return maximumContextLength;
|
|
}
|
|
|
|
inline void Transliterator::setID(const UnicodeString& id) {
|
|
ID = id;
|
|
}
|
|
|
|
#endif
|