| /* |
| ******************************************************************************* |
| * Copyright (C) 1996-2000, International Business Machines Corporation and * |
| * others. All Rights Reserved. * |
| ******************************************************************************* |
| * |
| * $Source: /xsrl/Nsvn/icu/icu4j/src/com/ibm/text/Attic/Transliterator.java,v $ |
| * $Date: 2001/03/30 22:50:08 $ |
| * $Revision: 1.27 $ |
| * |
| ***************************************************************************************** |
| */ |
| package com.ibm.text; |
| |
| import java.util.*; |
| import java.text.MessageFormat; |
| import java.text.ParsePosition; |
| import java.io.UnsupportedEncodingException; |
| import com.ibm.text.resources.ResourceReader; |
| |
| /** |
| * <code>Transliterator</code> is an abstract class that |
| * transliterates text from one format to another. The most common |
| * kind of transliterator is a script, or alphabet, transliterator. |
| * For example, a Russian to Latin transliterator changes Russian text |
| * written in Cyrillic characters to phonetically equivalent Latin |
| * characters. It does not <em>translate</em> Russian to English! |
| * Transliteration, unlike translation, operates on characters, without |
| * reference to the meanings of words and sentences. |
| * |
| * <p>Although script conversion is its most common use, a |
| * transliterator can actually perform a more general class of tasks. |
| * In fact, <code>Transliterator</code> defines a very general API |
| * which specifies only that a segment of the input text is replaced |
| * by new text. The particulars of this conversion are determined |
| * entirely by subclasses of <code>Transliterator</code>. |
| * |
| * <p><b>Transliterators are stateless</b> |
| * |
| * <p><code>Transliterator</code> objects are <em>stateless</em>; they |
| * retain no information between calls to |
| * <code>transliterate()</code>. As a result, threads may share |
| * transliterators without synchronizing them. This might seem to |
| * limit the complexity of the transliteration operation. In |
| * practice, subclasses perform complex transliterations by delaying |
| * the replacement of text until it is known that no other |
| * replacements are possible. In other words, although the |
| * <code>Transliterator</code> objects are stateless, the source text |
| * itself embodies all the needed information, and delayed operation |
| * allows arbitrary complexity. |
| * |
| * <p><b>Batch transliteration</b> |
| * |
| * <p>The simplest way to perform transliteration is all at once, on a |
| * string of existing text. This is referred to as <em>batch</em> |
| * transliteration. For example, given a string <code>input</code> |
| * and a transliterator <code>t</code>, the call |
| * |
| * <blockquote><code>String result = t.transliterate(input); |
| * </code></blockquote> |
| * |
| * will transliterate it and return the result. Other methods allow |
| * the client to specify a substring to be transliterated and to use |
| * {@link Replaceable} objects instead of strings, in order to |
| * preserve out-of-band information (such as text styles). |
| * |
| * <p><b>Keyboard transliteration</b> |
| * |
| * <p>Somewhat more involved is <em>keyboard</em>, or incremental |
| * transliteration. This is the transliteration of text that is |
| * arriving from some source (typically the user's keyboard) one |
| * character at a time, or in some other piecemeal fashion. |
| * |
| * <p>In keyboard transliteration, a <code>Replaceable</code> buffer |
| * stores the text. As text is inserted, as much as possible is |
| * transliterated on the fly. This means a GUI that displays the |
| * contents of the buffer may show text being modified as each new |
| * character arrives. |
| * |
| * <p>Consider the simple <code>RuleBasedTransliterator</code>: |
| * |
| * <blockquote><code> |
| * th>{theta}<br> |
| * t>{tau} |
| * </code></blockquote> |
| * |
| * When the user types 't', nothing will happen, since the |
| * transliterator is waiting to see if the next character is 'h'. To |
| * remedy this, we introduce the notion of a cursor, marked by a '|' |
| * in the output string: |
| * |
| * <blockquote><code> |
| * t>|{tau}<br> |
| * {tau}h>{theta} |
| * </code></blockquote> |
| * |
| * Now when the user types 't', tau appears, and if the next character |
| * is 'h', the tau changes to a theta. This is accomplished by |
| * maintaining a cursor position (independent of the insertion point, |
| * and invisible in the GUI) across calls to |
| * <code>transliterate()</code>. Typically, the cursor will |
| * be coincident with the insertion point, but in a case like the one |
| * above, it will precede the insertion point. |
| * |
| * <p>Keyboard transliteration methods maintain a set of three indices |
| * that are updated with each call to |
| * <code>transliterate()</code>, including the cursor, start, |
| * and limit. These indices are changed by the method, and they are |
| * passed in and out via a Position object. The <code>start</code> index |
| * marks the beginning of the substring that the transliterator will |
| * look at. It is advanced as text becomes committed (but it is not |
| * the committed index; that's the <code>cursor</code>). The |
| * <code>cursor</code> index, described above, marks the point at |
| * which the transliterator last stopped, either because it reached |
| * the end, or because it required more characters to disambiguate |
| * between possible inputs. The <code>cursor</code> can also be |
| * explicitly set by rules in a <code>RuleBasedTransliterator</code>. |
| * Any characters before the <code>cursor</code> index are frozen; |
| * future keyboard transliteration calls within this input sequence |
| * will not change them. New text is inserted at the |
| * <code>limit</code> index, which marks the end of the substring that |
| * the transliterator looks at. |
| * |
| * <p>Because keyboard transliteration assumes that more characters |
| * are to arrive, it is conservative in its operation. It only |
| * transliterates when it can do so unambiguously. Otherwise it waits |
| * for more characters to arrive. When the client code knows that no |
| * more characters are forthcoming, perhaps because the user has |
| * performed some input termination operation, then it should call |
| * <code>finishTransliteration()</code> to complete any |
| * pending transliterations. |
| * |
| * <p><b>Inverses</b> |
| * |
| * <p>Pairs of transliterators may be inverses of one another. For |
| * example, if transliterator <b>A</b> transliterates characters by |
| * incrementing their Unicode value (so "abc" -> "def"), and |
| * transliterator <b>B</b> decrements character values, then <b>A</b> |
| * is an inverse of <b>B</b> and vice versa. If we compose <b>A</b> |
| * with <b>B</b> in a compound transliterator, the result is the |
| * indentity transliterator, that is, a transliterator that does not |
| * change its input text. |
| * |
| * The <code>Transliterator</code> method <code>getInverse()</code> |
| * returns a transliterator's inverse, if one exists, or |
| * <code>null</code> otherwise. However, the result of |
| * <code>getInverse()</code> usually will <em>not</em> be a true |
| * mathematical inverse. This is because true inverse transliterators |
| * are difficult to formulate. For example, consider two |
| * transliterators: <b>AB</b>, which transliterates the character 'A' |
| * to 'B', and <b>BA</b>, which transliterates 'B' to 'A'. It might |
| * seem that these are exact inverses, since |
| * |
| * <blockquote>"A" x <b>AB</b> -> "B"<br> |
| * "B" x <b>BA</b> -> "A"</blockquote> |
| * |
| * where 'x' represents transliteration. However, |
| * |
| * <blockquote>"ABCD" x <b>AB</b> -> "BBCD"<br> |
| * "BBCD" x <b>BA</b> -> "AACD"</blockquote> |
| * |
| * so <b>AB</b> composed with <b>BA</b> is not the |
| * identity. Nonetheless, <b>BA</b> may be usefully considered to be |
| * <b>AB</b>'s inverse, and it is on this basis that |
| * <b>AB</b><code>.getInverse()</code> could legitimately return |
| * <b>BA</b>. |
| * |
| * <p><b>IDs and display names</b> |
| * |
| * <p>A transliterator is designated by a short identifier string or |
| * <em>ID</em>. IDs follow the format <em>source-destination</em>, |
| * where <em>source</em> describes the entity being replaced, and |
| * <em>destination</em> describes the entity replacing |
| * <em>source</em>. The entities may be the names of scripts, |
| * particular sequences of characters, or whatever else it is that the |
| * transliterator converts to or from. For example, a transliterator |
| * from Russian to Latin might be named "Russian-Latin". A |
| * transliterator from keyboard escape sequences to Latin-1 characters |
| * might be named "KeyboardEscape-Latin1". By convention, system |
| * entity names are in English, with the initial letters of words |
| * capitalized; user entity names may follow any format so long as |
| * they do not contain dashes. |
| * |
| * <p>In addition to programmatic IDs, transliterator objects have |
| * display names for presentation in user interfaces, returned by |
| * {@link #getDisplayName}. |
| * |
| * <p><b>Factory methods and registration</b> |
| * |
| * <p>In general, client code should use the factory method |
| * <code>getInstance()</code> to obtain an instance of a |
| * transliterator given its ID. Valid IDs may be enumerated using |
| * <code>getAvailableIDs()</code>. Since transliterators are |
| * stateless, multiple calls to <code>getInstance()</code> with the |
| * same ID will return the same object. |
| * |
| * <p>In addition to the system transliterators registered at startup, |
| * user transliterators may be registered by calling |
| * <code>registerInstance()</code> at run time. To register a |
| * transliterator subclass without instantiating it (until it is |
| * needed), users may call <code>registerClass()</code>. |
| * |
| * <p><b>Composed transliterators</b> |
| * |
| * <p>In addition to built-in system transliterators like |
| * "Latin-Greek", there are also built-in <em>composed</em> |
| * transliterators. These are implemented by composing two or more |
| * component transliterators. For example, if we have scripts "A", |
| * "B", "C", and "D", and we want to transliterate between all pairs |
| * of them, then we need to write 12 transliterators: "A-B", "A-C", |
| * "A-D", "B-A",..., "D-A", "D-B", "D-C". If it is possible to |
| * convert all scripts to an intermediate script "M", then instead of |
| * writing 12 rule sets, we only need to write 8: "A~M", "B~M", "C~M", |
| * "D~M", "M~A", "M~B", "M~C", "M~D". (This might not seem like a big |
| * win, but it's really 2<em>n</em> vs. <em>n</em><sup>2</sup> - |
| * <em>n</em>, so as <em>n</em> gets larger the gain becomes |
| * significant. With 9 scripts, it's 18 vs. 72 rule sets, a big |
| * difference.) Note the use of "~" rather than "-" for the script |
| * separator here; this indicates that the given transliterator is |
| * intended to be composed with others, rather than be used as is. |
| * |
| * <p>Composed transliterators can be instantiated as usual. For |
| * example, the system transliterator "Devanagari-Gujarati" is a |
| * composed transliterator built internally as |
| * "Devanagari~InterIndic;InterIndic~Gujarati". When this |
| * transliterator is instantiated, it appears externally to be a |
| * standard transliterator (e.g., getID() returns |
| * "Devanagari-Gujarati"). |
| * |
| * <p><b>Subclassing</b> |
| * |
| * <p>Subclasses must implement the abstract method |
| * <code>handleTransliterate()</code>. <p>Subclasses should override |
| * the <code>transliterate()</code> method taking a |
| * <code>Replaceable</code> and the <code>transliterate()</code> |
| * method taking a <code>String</code> and <code>StringBuffer</code> |
| * if the performance of these methods can be improved over the |
| * performance obtained by the default implementations in this class. |
| * |
| * <p>Copyright © IBM Corporation 1999. All rights reserved. |
| * |
| * @author Alan Liu |
| * @version $RCSfile: Transliterator.java,v $ $Revision: 1.27 $ $Date: 2001/03/30 22:50:08 $ |
| */ |
| public abstract class Transliterator { |
| /** |
| * Direction constant indicating the forward direction in a transliterator, |
| * e.g., the forward rules of a RuleBasedTransliterator. An "A-B" |
| * transliterator transliterates A to B when operating in the forward |
| * direction, and B to A when operating in the reverse direction. |
| * @see RuleBasedTransliterator |
| * @see CompoundTransliterator |
| */ |
| public static final int FORWARD = 0; |
| |
| /** |
| * Direction constant indicating the reverse direction in a transliterator, |
| * e.g., the reverse rules of a RuleBasedTransliterator. An "A-B" |
| * transliterator transliterates A to B when operating in the forward |
| * direction, and B to A when operating in the reverse direction. |
| * @see RuleBasedTransliterator |
| * @see CompoundTransliterator |
| */ |
| public static final int REVERSE = 1; |
| |
| /** |
| * Position structure for incremental transliteration. This data |
| * structure defines two substrings of the text being |
| * transliterated. The first region, [contextStart, |
| * contextLimit), defines what characters the transliterator will |
| * read as context. The second region, [start, limit), defines |
| * what characters will actually be transliterated. The second |
| * region should be a subset of the first. |
| * |
| * <p>After a transliteration operation, some of the indices in this |
| * structure will be modified. See the field descriptions for |
| * details. |
| * |
| * <p>contextStart <= start <= limit <= contextLimit |
| */ |
| public static class Position { |
| |
| /** |
| * Beginning index, inclusive, of the context to be considered for |
| * a transliteration operation. The transliterator will ignore |
| * anything before this index. INPUT/OUTPUT parameter: This parameter |
| * is updated by a transliteration operation to reflect the maximum |
| * amount of antecontext needed by a transliterator. |
| */ |
| public int contextStart; |
| |
| /** |
| * Ending index, exclusive, of the context to be considered for a |
| * transliteration operation. The transliterator will ignore |
| * anything at or after this index. INPUT/OUTPUT parameter: This |
| * parameter is updated to reflect changes in the length of the |
| * text, but points to the same logical position in the text. |
| */ |
| public int contextLimit; |
| |
| /** |
| * Beginning index, inclusive, of the text to be transliteratd. |
| * INPUT/OUTPUT parameter: This parameter is advanced past |
| * characters that have already been transliterated by a |
| * transliteration operation. |
| */ |
| public int start; |
| |
| /** |
| * Ending index, exclusive, of the text to be transliteratd. |
| * INPUT/OUTPUT parameter: This parameter is updated to reflect |
| * changes in the length of the text, but points to the same |
| * logical position in the text. |
| */ |
| public int limit; |
| |
| public Position() { |
| this(0, 0, 0, 0); |
| } |
| |
| public Position(int contextStart, int contextLimit, int start) { |
| this(contextStart, contextLimit, start, contextLimit); |
| } |
| |
| public Position(int contextStart, int contextLimit, |
| int start, int limit) { |
| this.contextStart = contextStart; |
| this.contextLimit = contextLimit; |
| this.start = start; |
| this.limit = limit; |
| } |
| } |
| |
| /** |
| * Programmatic name, e.g., "Latin-Arabic". |
| */ |
| private String ID; |
| |
| /** |
| * This transliterator's filter. Any character for which |
| * <tt>filter.contains()</tt> returns <tt>false</tt> will not be |
| * altered by this transliterator. If <tt>filter</tt> is |
| * <tt>null</tt> then no filtering is applied. |
| */ |
| private UnicodeFilter filter; |
| |
| private int maximumContextLength = 0; |
| |
| /** |
| * Cache of system transliterators. Keys are <code>String</code> |
| * names, values are one of the following: |
| * |
| * <ul><li><code>String</code> objects. These represent |
| * RuleBasedTransliterators that have not been loaded yet, or |
| * aliases. The first character determines the type: 'f' |
| * indicates a FORWARD RBT, with the rest of the string giving the |
| * resource name and encoding, separated by a colon. 'r' is |
| * similar, but indicates a REVERSE RBT. 'a' indicates an alias, |
| * with the rest of the string giving the ID to create. |
| * |
| * <li><code>Class</code> objects. Such objects must represent |
| * subclasses of <code>Transliterator</code>, and must satisfy the |
| * constraints described in <code>registerClass()</code>. |
| * |
| * <li><code>RuleBasedTransliterator.Data</code> objects. These |
| * are built in-memory transliterator data cores that are wrapped |
| * thinly to create RuleBasedTransliterator objects. When an RBT |
| * is created, its Data core is cached and shared among future |
| * instances of the same ID. |
| * </ul> |
| */ |
| private static Hashtable cache; |
| |
| /** |
| * Identical to 'cache' but contains internal transliterators. |
| * These are not enumerated by getAvailableIDs(). |
| */ |
| private static Hashtable internalCache; |
| |
| private static Hashtable displayNameCache; |
| |
| /** |
| * Prefix for resource bundle key for the display name for a |
| * transliterator. The ID is appended to this to form the key. |
| * The resource bundle value should be a String. |
| */ |
| private static final String RB_DISPLAY_NAME_PREFIX = "%Translit%%"; |
| |
| /** |
| * Prefix for resource bundle key for the display name for a |
| * transliterator SCRIPT. The ID is appended to this to form the key. |
| * The resource bundle value should be a String. |
| */ |
| private static final String RB_SCRIPT_DISPLAY_NAME_PREFIX = "%Translit%"; |
| |
| /** |
| * Resource bundle key for display name pattern. |
| * The resource bundle value should be a String forming a |
| * MessageFormat pattern, e.g.: |
| * "{0,choice,0#|1#{1} Transliterator|2#{1} to {2} Transliterator}". |
| */ |
| private static final String RB_DISPLAY_NAME_PATTERN = "TransliteratorNamePattern"; |
| |
| /** |
| * Resource bundle containing display name keys and the |
| * RB_RULE_BASED_IDS array. |
| * |
| * <p>If we ever integrate this with the Sun JDK, the resource bundle |
| * root will change to java.text.resources.LocaleElements |
| */ |
| private static final String RB_LOCALE_ELEMENTS = |
| "com.ibm.text.resources.LocaleElements"; |
| |
| private static final String COPYRIGHT = |
| "\u00A9 IBM Corporation 1999. All rights reserved."; |
| |
| /** |
| * Default constructor. |
| * @param ID the string identifier for this transliterator |
| * @param filter the filter. Any character for which |
| * <tt>filter.contains()</tt> returns <tt>false</tt> will not be |
| * altered by this transliterator. If <tt>filter</tt> is |
| * <tt>null</tt> then no filtering is applied. |
| */ |
| protected Transliterator(String ID, UnicodeFilter filter) { |
| if (ID == null) { |
| throw new NullPointerException(); |
| } |
| this.ID = ID; |
| this.filter = filter; |
| } |
| |
| /** |
| * Transliterates a segment of a string, with optional filtering. |
| * |
| * @param text the string to be transliterated |
| * @param start the beginning index, inclusive; <code>0 <= start |
| * <= limit</code>. |
| * @param limit the ending index, exclusive; <code>start <= limit |
| * <= text.length()</code>. |
| * @param filter the filter. Any character for which |
| * <tt>filter.contains()</tt> returns <tt>false</tt> will not be |
| * altered by this transliterator. If <tt>filter</tt> is |
| * <tt>null</tt> then no filtering is applied. |
| * @return The new limit index. The text previously occupying <code>[start, |
| * limit)</code> has been transliterated, possibly to a string of a different |
| * length, at <code>[start, </code><em>new-limit</em><code>)</code>, where |
| * <em>new-limit</em> is the return value. |
| */ |
| public final int transliterate(Replaceable text, int start, int limit) { |
| Position pos = new Position(start, limit, start); |
| handleTransliterate(text, pos, false); |
| return pos.contextLimit; |
| } |
| |
| /** |
| * Transliterates an entire string in place. Convenience method. |
| * @param text the string to be transliterated |
| */ |
| public final void transliterate(Replaceable text) { |
| transliterate(text, 0, text.length()); |
| } |
| |
| /** |
| * Transliterate an entire string and returns the result. Convenience method. |
| * |
| * @param text the string to be transliterated |
| * @return The transliterated text |
| */ |
| public final String transliterate(String text) { |
| ReplaceableString result = new ReplaceableString(text); |
| transliterate(result); |
| return result.toString(); |
| } |
| |
| /** |
| * Transliterates the portion of the text buffer that can be |
| * transliterated unambiguosly after new text has been inserted, |
| * typically as a result of a keyboard event. The new text in |
| * <code>insertion</code> will be inserted into <code>text</code> |
| * at <code>index.contextLimit</code>, advancing |
| * <code>index.contextLimit</code> by <code>insertion.length()</code>. |
| * Then the transliterator will try to transliterate characters of |
| * <code>text</code> between <code>index.start</code> and |
| * <code>index.contextLimit</code>. Characters before |
| * <code>index.start</code> will not be changed. |
| * |
| * <p>Upon return, values in <code>index</code> will be updated. |
| * <code>index.contextStart</code> will be advanced to the first |
| * character that future calls to this method will read. |
| * <code>index.start</code> and <code>index.contextLimit</code> will |
| * be adjusted to delimit the range of text that future calls to |
| * this method may change. |
| * |
| * <p>Typical usage of this method begins with an initial call |
| * with <code>index.contextStart</code> and <code>index.contextLimit</code> |
| * set to indicate the portion of <code>text</code> to be |
| * transliterated, and <code>index.start == index.contextStart</code>. |
| * Thereafter, <code>index</code> can be used without |
| * modification in future calls, provided that all changes to |
| * <code>text</code> are made via this method. |
| * |
| * <p>This method assumes that future calls may be made that will |
| * insert new text into the buffer. As a result, it only performs |
| * unambiguous transliterations. After the last call to this |
| * method, there may be untransliterated text that is waiting for |
| * more input to resolve an ambiguity. In order to perform these |
| * pending transliterations, clients should call {@link |
| * #finishTransliteration} after the last call to this |
| * method has been made. |
| * |
| * @param text the buffer holding transliterated and untransliterated text |
| * @param index the start and limit of the text, the position |
| * of the cursor, and the start and limit of transliteration. |
| * @param insertion text to be inserted and possibly |
| * transliterated into the translation buffer at |
| * <code>index.contextLimit</code>. If <code>null</code> then no text |
| * is inserted. |
| * @see #handleTransliterate |
| * @exception IllegalArgumentException if <code>index</code> |
| * is invalid |
| */ |
| public final void transliterate(Replaceable text, Position index, |
| String insertion) { |
| if (index.contextStart < 0 || |
| index.contextLimit > text.length() || |
| index.start < index.contextStart || |
| index.start > index.contextLimit) { |
| throw new IllegalArgumentException("Invalid index"); |
| } |
| |
| int originalStart = index.contextStart; |
| if (insertion != null) { |
| text.replace(index.limit, index.limit, insertion); |
| index.limit += insertion.length(); |
| index.contextLimit += insertion.length(); |
| } |
| |
| handleTransliterate(text, index, true); |
| |
| index.contextStart = Math.max(index.start - getMaximumContextLength(), |
| originalStart); |
| } |
| |
| /** |
| * 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, |
| * Transliterator.Position, String)} for details. |
| * @param text the buffer holding transliterated and |
| * untransliterated text |
| * @param index the start and limit of the text, the position |
| * of the cursor, and the start and limit of transliteration. |
| * @param insertion text to be inserted and possibly |
| * transliterated into the translation buffer at |
| * <code>index.contextLimit</code>. |
| * @see #transliterate(Replaceable, Transliterator.Position, String) |
| */ |
| public final void transliterate(Replaceable text, Position index, |
| char insertion) { |
| transliterate(text, index, String.valueOf(insertion)); |
| } |
| |
| /** |
| * Transliterates the portion of the text buffer that can be |
| * transliterated unambiguosly. This is a convenience method; see |
| * {@link #transliterate(Replaceable, Transliterator.Position, |
| * String)} for details. |
| * @param text the buffer holding transliterated and |
| * untransliterated text |
| * @param index the start and limit of the text, the position |
| * of the cursor, and the start and limit of transliteration. |
| * @see #transliterate(Replaceable, Transliterator.Position, String) |
| */ |
| public final void transliterate(Replaceable text, Position index) { |
| transliterate(text, index, null); |
| } |
| |
| /** |
| * 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} |
| */ |
| public final void finishTransliteration(Replaceable text, |
| Position index) { |
| handleTransliterate(text, index, false); |
| } |
| |
| /** |
| * Abstract method that concrete subclasses define to implement |
| * keyboard transliteration. This method should transliterate all |
| * characters between <code>index.start</code> and |
| * <code>index.contextLimit</code> that can be unambiguously |
| * transliterated, regardless of future insertions of text at |
| * <code>index.contextLimit</code>. <code>index.start</code> should |
| * be advanced past committed characters (those that will not |
| * change in future calls to this method). |
| * <code>index.contextLimit</code> should be updated to reflect text |
| * replacements that shorten or lengthen the text between |
| * <code>index.start</code> and <code>index.contextLimit</code>. Upon |
| * return, neither <code>index.start</code> nor |
| * <code>index.contextLimit</code> should be less than the initial value |
| * of <code>index.start</code>. <code>index.contextStart</code> |
| * should <em>not</em> be changed. |
| * |
| * @param text the buffer holding transliterated and |
| * untransliterated text |
| * @param pos the start and limit of the text, the position |
| * of the cursor, and the start and limit of transliteration. |
| * @param incremental if true, assume more text may be coming after |
| * pos.contextLimit. Otherwise, assume the text is complete. |
| * @see #transliterate |
| */ |
| protected abstract void handleTransliterate(Replaceable text, |
| Position pos, boolean incremental); |
| |
| /** |
| * Returns the length of the longest context required by this transliterator. |
| * This is <em>preceding</em> context. The default value is zero, but |
| * subclasses can change this by calling <code>setMaximumContextLength()</code>. |
| * 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 |
| */ |
| protected final int getMaximumContextLength() { |
| return maximumContextLength; |
| } |
| |
| /** |
| * Method for subclasses to use to set the maximum context length. |
| * @see #getMaximumContextLength |
| */ |
| protected void setMaximumContextLength(int a) { |
| if (a < 0) { |
| throw new IllegalArgumentException("Invalid context length " + a); |
| } |
| maximumContextLength = a; |
| } |
| |
| /** |
| * 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 #registerClass |
| * @see #getAvailableIDs |
| */ |
| public final String getID() { |
| return ID; |
| } |
| |
| /** |
| * Returns a name for this transliterator that is appropriate for |
| * display to the user in the default locale. See {@link |
| * #getDisplayName(String,Locale)} for details. |
| */ |
| public final static String getDisplayName(String ID) { |
| return getDisplayName(ID, Locale.getDefault()); |
| } |
| |
| /** |
| * 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 |
| */ |
| public static String getDisplayName(String ID, Locale inLocale) { |
| ResourceBundle bundle = ResourceBundle.getBundle( |
| RB_LOCALE_ELEMENTS, inLocale); |
| |
| // Use the registered display name, if any |
| String n = (String) displayNameCache.get(ID); |
| if (n != null) { |
| return n; |
| } |
| |
| // Use display name for the entire transliterator, if it |
| // exists. |
| try { |
| return bundle.getString(RB_DISPLAY_NAME_PREFIX + ID); |
| } catch (MissingResourceException e) {} |
| |
| try { |
| // Construct the formatter first; if getString() fails |
| // we'll exit the try block |
| MessageFormat format = new MessageFormat( |
| bundle.getString(RB_DISPLAY_NAME_PATTERN)); |
| // Construct the argument array |
| int i = ID.indexOf('-'); |
| Object[] args = (i < 0) |
| ? new Object[] { new Integer(1), ID } |
| : new Object[] { new Integer(2), ID.substring(0, i), |
| ID.substring(i+1) }; |
| |
| // Use display names for the scripts, if they exist |
| for (int j=1; j<=((i<0)?1:2); ++j) { |
| try { |
| args[j] = bundle.getString(RB_SCRIPT_DISPLAY_NAME_PREFIX + |
| (String) args[j]); |
| } catch (MissingResourceException e) {} |
| } |
| |
| // Format it using the pattern in the resource |
| return format.format(args); |
| } catch (MissingResourceException e2) {} |
| |
| // We should not reach this point unless there is something |
| // wrong with the build or the RB_DISPLAY_NAME_PATTERN has |
| // been deleted from the root RB_LOCALE_ELEMENTS resource. |
| throw new RuntimeException(); |
| } |
| |
| /** |
| * Returns the filter used by this transliterator, or <tt>null</tt> |
| * if this transliterator uses no filter. |
| */ |
| public UnicodeFilter getFilter() { |
| return filter; |
| } |
| |
| /** |
| * 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. |
| */ |
| public void setFilter(UnicodeFilter filter) { |
| this.filter = filter; |
| } |
| |
| /** |
| * Returns a <code>Transliterator</code> object given its ID. |
| * The ID must be either a system transliterator ID or a ID registered |
| * using <code>registerClass()</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 #registerClass |
| * @see #getAvailableIDs |
| * @see #getID |
| */ |
| public static Transliterator getInstance(String ID, int direction) { |
| if (ID.indexOf(';') >= 0) { |
| return new CompoundTransliterator(ID, direction, null); |
| } |
| |
| for (;;) { |
| UnicodeFilter filter = null; |
| int i = ID.indexOf('['); |
| if (i >= 0) { |
| ParsePosition pos = new ParsePosition(i); |
| filter = new UnicodeSet(ID, pos, null); |
| if (pos.getIndex() != ID.length()) { |
| break; // unparsed junk after ']' |
| } |
| ID = ID.substring(0, i); |
| } |
| |
| if (direction == REVERSE) { |
| i = ID.indexOf('-'); |
| if (i < 0) { |
| throw new IllegalArgumentException("No inverse for: " |
| + ID); |
| } |
| ID = ID.substring(i+1) + '-' + ID.substring(0, i); |
| } |
| |
| Transliterator t = internalGetInstance(ID); |
| if (t != null) { |
| if (filter != null) { |
| t.setFilter(filter); |
| } |
| return t; |
| } |
| |
| break; |
| } |
| throw new IllegalArgumentException("Unsupported transliterator: " |
| + ID); |
| } |
| |
| public static final Transliterator getInstance(String ID) { |
| return getInstance(ID, FORWARD); |
| } |
| |
| /** |
| * 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 #registerClass |
| */ |
| public final Transliterator getInverse() { |
| return getInstance(ID, REVERSE); |
| } |
| |
| /** |
| * Returns a transliterator object given its ID. Unlike getInstance(), |
| * this method returns null if it cannot make use of the given ID. |
| */ |
| private static Transliterator internalGetInstance(String ID) { |
| RuleBasedTransliterator.Data data = null; |
| Hashtable sourceCache = cache; |
| Object obj = cache.get(ID); |
| if (obj == null) { |
| obj = internalCache.get(ID); |
| sourceCache = internalCache; |
| } |
| |
| if (obj != null) { |
| if (obj instanceof RuleBasedTransliterator.Data) { |
| data = (RuleBasedTransliterator.Data) obj; |
| // Fall through to construct transliterator from cached Data object. |
| } else if (obj instanceof Class) { |
| try { |
| return (Transliterator) ((Class) obj).newInstance(); |
| } catch (InstantiationException e) { |
| } catch (IllegalAccessException e2) {} |
| } else if (obj instanceof String) { |
| String spec = (String) obj; |
| if (spec.charAt(0) == 'a') { |
| // alias |
| Transliterator t = getInstance(spec.substring(1)); |
| t.ID = ID; |
| return t; |
| } else { |
| synchronized (cache) { |
| // file, either forward or reverse |
| int dir = (spec.charAt(0) == 'f') ? FORWARD:REVERSE; |
| int colon = spec.indexOf(':', 1); |
| String resourceName = spec.substring(1, colon); |
| String encoding = spec.substring(colon+1); |
| ResourceReader r = null; |
| try { |
| r = new ResourceReader(resourceName, encoding); |
| } catch (UnsupportedEncodingException e) { |
| // This should never happen; UTF8 is always supported |
| } catch (IllegalArgumentException e2) { |
| // Can't load UTF8 file |
| } |
| |
| if (r != null) { |
| data = RuleBasedTransliterator.parse(r, dir); |
| sourceCache.put(ID, data); |
| // Fall through to construct transliterator from Data object. |
| } |
| } |
| } |
| } else { |
| throw new RuntimeException("Bogus cache object"); |
| } |
| |
| if (data != null) { |
| return new RuleBasedTransliterator(ID, data, null); |
| } |
| } |
| |
| return null; |
| } |
| |
| // Currently unused, but may be of use in the future. |
| // /** |
| // * Find a path through the composed transliterator graph. This |
| // * will not necessarily be the only path, or the shortest path. |
| // * This is a simple recursive algorithm. |
| // * |
| // * <p><code>composedGraph</code> is the links table. |
| // * composedGraph.get(x) should return a String[] array, each of |
| // * which is a node that x is connected to. |
| // * @param start the starting node |
| // * @param end the ending node |
| // * @param path the result vector; should be empty on entry. Upon |
| // * success, it will contain successive nodes on the path from |
| // * start to end, including start and end. If false is returned, |
| // * then path is unchanged. |
| // * @return true if a path from start to end is found |
| // */ |
| // private static boolean findComposedPath(String start, String end, |
| // Vector path) { |
| // path.addElement(start); |
| // // composedGraph lists all links emanating from a node |
| // String[] links = (String[]) composedGraph.get(start); |
| // if (links != null) { |
| // for (int i=0; i<links.length; ++i) { |
| // if (links[i].equals(end)) { |
| // path.addElement(end); |
| // return true; |
| // } |
| // } |
| // for (int i=0; i<links.length; ++i) { |
| // // Avoid cycles: ignore links already on our path |
| // if (path.indexOf(links[i]) >= 0) { |
| // continue; |
| // } |
| // if (findComposedPath(links[i], end, path)) { |
| // return true; |
| // } |
| // } |
| // } |
| // path.removeElementAt(path.size() - 1); |
| // return false; |
| // } |
| |
| /** |
| * Registers a subclass of <code>Transliterator</code> with the |
| * system. This subclass must have a public constructor taking no |
| * arguments. When that constructor is called, the resulting |
| * object must return the <code>ID</code> passed to this method if |
| * its <code>getID()</code> method is called. |
| * |
| * @param ID the result of <code>getID()</code> for this |
| * transliterator |
| * @param transClass a subclass of <code>Transliterator</code> |
| * @see #unregister |
| */ |
| public static void registerClass(String ID, Class transClass, String displayName) { |
| cache.put(ID, transClass); |
| if (displayName != null) { |
| displayNameCache.put(ID, displayName); |
| } |
| } |
| |
| /** |
| * 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 #registerClass |
| */ |
| public static Object unregister(String ID) { |
| displayNameCache.remove(ID); |
| return cache.remove(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>registerClass()</code>. The enumerated names may be |
| * passed to <code>getInstance()</code>. |
| * |
| * @return An <code>Enumeration</code> over <code>String</code> objects |
| * @see #getInstance |
| * @see #registerClass |
| */ |
| public static final Enumeration getAvailableIDs() { |
| return cache.keys(); |
| } |
| |
| /** |
| * 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. |
| */ |
| protected char filteredCharAt(Replaceable text, int i) { |
| char c; |
| UnicodeFilter filter = getFilter(); |
| return (filter == null) ? text.charAt(i) : |
| (filter.contains(c = text.charAt(i)) ? c : '\uFFFE'); |
| } |
| |
| static { |
| // The display name cache starts out empty |
| displayNameCache = new Hashtable(); |
| |
| // Read the index file and construct the cache/internalCache. |
| // Each line of the index file is either blank, a '#' comment, |
| // or a colon-delimited line. In the latter case the first |
| // field is the ID being defined. The second field is one of |
| // three strings: "file", "internal", or "alias". Remaining |
| // fields vary according the value fo the second field. See |
| // the index file itself for further documentation. |
| cache = new Hashtable(); |
| internalCache = new Hashtable(); |
| ResourceReader r = new ResourceReader("Transliterator_index.txt"); |
| for (;;) { |
| String line = null; |
| try { |
| line = r.readLine(); |
| } catch (java.io.IOException e) {} |
| if (line == null) { |
| break; |
| } |
| // Skip over whitespace |
| int pos = 0; |
| while (pos < line.length() && |
| Character.isWhitespace(line.charAt(pos))) { |
| ++pos; |
| } |
| // Ignore blank lines and comments |
| if (pos == line.length() || line.charAt(pos) == '#') { |
| continue; |
| } |
| // Parse colon-delimited line |
| int colon = line.indexOf(':', pos); |
| String ID = line.substring(pos, colon); |
| pos = colon+1; |
| colon = line.indexOf(':', pos); |
| String type = line.substring(pos, colon); |
| pos = colon+1; |
| |
| if (type.equals("file") || type.equals("internal")) { |
| // Rest of line is <resource>:<encoding>:<direction> |
| colon = line.indexOf(':', pos); |
| colon = line.indexOf(':', colon+1); // skip over 1 colon |
| String fileNameAndEncoding = line.substring(pos, colon); |
| pos = colon+1; |
| boolean isForward = line.substring(pos).equals("FORWARD"); |
| Hashtable h = type.equals("internal") ? internalCache:cache; |
| h.put(ID, (isForward ? "f" : "r") + fileNameAndEncoding); |
| } else if (type.equals("alias")) { |
| // Rest of line is the <getInstanceArg> |
| cache.put(ID, "a" + line.substring(pos)); |
| } else { |
| // Unknown type |
| throw new RuntimeException("Can't parse line: " + line); |
| } |
| } |
| |
| // Register non-rule-based transliterators |
| registerClass(HangulJamoTransliterator._ID, |
| HangulJamoTransliterator.class, null); |
| registerClass(JamoHangulTransliterator._ID, |
| JamoHangulTransliterator.class, null); |
| |
| registerClass(HexToUnicodeTransliterator._ID, |
| HexToUnicodeTransliterator.class, null); |
| registerClass(UnicodeToHexTransliterator._ID, |
| UnicodeToHexTransliterator.class, null); |
| registerClass(NullTransliterator._ID, |
| NullTransliterator.class, null); |
| } |
| } |
