/* ********************************************************************** * Copyright (C) 1999-2007, International Business Machines * Corporation and others. All Rights Reserved. ********************************************************************** * Date Name Description * 11/17/99 aliu Creation. ********************************************************************** */ #ifndef RBT_H #define RBT_H #include "unicode/utypes.h" #if !UCONFIG_NO_TRANSLITERATION #include "unicode/translit.h" #include "unicode/utypes.h" #include "unicode/parseerr.h" #include "unicode/udata.h" #define U_ICUDATA_TRANSLIT U_ICUDATA_NAME U_TREE_SEPARATOR_STRING "translit" U_NAMESPACE_BEGIN class TransliterationRuleData; /** * <code>RuleBasedTransliterator</code> is a transliterator * that reads a set of rules in order to determine how to perform * translations. Rule sets are stored in resource bundles indexed by * name. Rules within a rule set are separated by semicolons (';'). * To include a literal semicolon, prefix it with a backslash ('\'). * Whitespace, as defined by <code>Character.isWhitespace()</code>, * is ignored. If the first non-blank character on a line is '#', * the entire line is ignored as a comment. </p> * * <p>Each set of rules consists of two groups, one forward, and one * reverse. This is a convention that is not enforced; rules for one * direction may be omitted, with the result that translations in * that direction will not modify the source text. In addition, * bidirectional forward-reverse rules may be specified for * symmetrical transformations.</p> * * <p><b>Rule syntax</b> </p> * * <p>Rule statements take one of the following forms: </p> * * <dl> * <dt><code>$alefmadda=\u0622;</code></dt> * <dd><strong>Variable definition.</strong> The name on the * left is assigned the text on the right. In this example, * after this statement, instances of the left hand name, * "<code>$alefmadda</code>", will be replaced by * the Unicode character U+0622. Variable names must begin * with a letter and consist only of letters, digits, and * underscores. Case is significant. Duplicate names cause * an exception to be thrown, that is, variables cannot be * redefined. The right hand side may contain well-formed * text of any length, including no text at all ("<code>$empty=;</code>"). * The right hand side may contain embedded <code>UnicodeSet</code> * patterns, for example, "<code>$softvowel=[eiyEIY]</code>".</dd> * <dd> </dd> * <dt><code>ai>$alefmadda;</code></dt> * <dd><strong>Forward translation rule.</strong> This rule * states that the string on the left will be changed to the * string on the right when performing forward * transliteration.</dd> * <dt> </dt> * <dt><code>ai<$alefmadda;</code></dt> * <dd><strong>Reverse translation rule.</strong> This rule * states that the string on the right will be changed to * the string on the left when performing reverse * transliteration.</dd> * </dl> * * <dl> * <dt><code>ai<>$alefmadda;</code></dt> * <dd><strong>Bidirectional translation rule.</strong> This * rule states that the string on the right will be changed * to the string on the left when performing forward * transliteration, and vice versa when performing reverse * transliteration.</dd> * </dl> * * <p>Translation rules consist of a <em>match pattern</em> and an <em>output * string</em>. The match pattern consists of literal characters, * optionally preceded by context, and optionally followed by * context. Context characters, like literal pattern characters, * must be matched in the text being transliterated. However, unlike * literal pattern characters, they are not replaced by the output * text. For example, the pattern "<code>abc{def}</code>" * indicates the characters "<code>def</code>" must be * preceded by "<code>abc</code>" for a successful match. * If there is a successful match, "<code>def</code>" will * be replaced, but not "<code>abc</code>". The final '<code>}</code>' * is optional, so "<code>abc{def</code>" is equivalent to * "<code>abc{def}</code>". Another example is "<code>{123}456</code>" * (or "<code>123}456</code>") in which the literal * pattern "<code>123</code>" must be followed by "<code>456</code>". * </p> * * <p>The output string of a forward or reverse rule consists of * characters to replace the literal pattern characters. If the * output string contains the character '<code>|</code>', this is * taken to indicate the location of the <em>cursor</em> after * replacement. The cursor is the point in the text at which the * next replacement, if any, will be applied. The cursor is usually * placed within the replacement text; however, it can actually be * placed into the precending or following context by using the * special character '<code>@</code>'. Examples:</p> * * <blockquote> * <p><code>a {foo} z > | @ bar; # foo -> bar, move cursor * before a<br> * {foo} xyz > bar @@|; # foo -> bar, cursor between * y and z</code></p> * </blockquote> * * <p><b>UnicodeSet</b></p> * * <p><code>UnicodeSet</code> patterns may appear anywhere that * makes sense. They may appear in variable definitions. * Contrariwise, <code>UnicodeSet</code> patterns may themselves * contain variable references, such as "<code>$a=[a-z];$not_a=[^$a]</code>", * or "<code>$range=a-z;$ll=[$range]</code>".</p> * * <p><code>UnicodeSet</code> patterns may also be embedded directly * into rule strings. Thus, the following two rules are equivalent:</p> * * <blockquote> * <p><code>$vowel=[aeiou]; $vowel>'*'; # One way to do this<br> * [aeiou]>'*'; * # * Another way</code></p> * </blockquote> * * <p>See {@link UnicodeSet} for more documentation and examples.</p> * * <p><b>Segments</b></p> * * <p>Segments of the input string can be matched and copied to the * output string. This makes certain sets of rules simpler and more * general, and makes reordering possible. For example:</p> * * <blockquote> * <p><code>([a-z]) > $1 $1; * # * double lowercase letters<br> * ([:Lu:]) ([:Ll:]) > $2 $1; # reverse order of Lu-Ll pairs</code></p> * </blockquote> * * <p>The segment of the input string to be copied is delimited by * "<code>(</code>" and "<code>)</code>". Up to * nine segments may be defined. Segments may not overlap. In the * output string, "<code>$1</code>" through "<code>$9</code>" * represent the input string segments, in left-to-right order of * definition.</p> * * <p><b>Anchors</b></p> * * <p>Patterns can be anchored to the beginning or the end of the text. This is done with the * special characters '<code>^</code>' and '<code>$</code>'. For example:</p> * * <blockquote> * <p><code>^ a > 'BEG_A'; # match 'a' at start of text<br> * a > 'A'; # match other instances * of 'a'<br> * z $ > 'END_Z'; # match 'z' at end of text<br> * z > 'Z'; # match other instances * of 'z'</code></p> * </blockquote> * * <p>It is also possible to match the beginning or the end of the text using a <code>UnicodeSet</code>. * This is done by including a virtual anchor character '<code>$</code>' at the end of the * set pattern. Although this is usually the match chafacter for the end anchor, the set will * match either the beginning or the end of the text, depending on its placement. For * example:</p> * * <blockquote> * <p><code>$x = [a-z$]; # match 'a' through 'z' OR anchor<br> * $x 1 > 2; # match '1' after a-z or at the start<br> * 3 $x > 4; # match '3' before a-z or at the end</code></p> * </blockquote> * * <p><b>Example</b> </p> * * <p>The following example rules illustrate many of the features of * the rule language. </p> * * <table border="0" cellpadding="4"> * <tr> * <td valign="top">Rule 1.</td> * <td valign="top" nowrap><code>abc{def}>x|y</code></td> * </tr> * <tr> * <td valign="top">Rule 2.</td> * <td valign="top" nowrap><code>xyz>r</code></td> * </tr> * <tr> * <td valign="top">Rule 3.</td> * <td valign="top" nowrap><code>yz>q</code></td> * </tr> * </table> * * <p>Applying these rules to the string "<code>adefabcdefz</code>" * yields the following results: </p> * * <table border="0" cellpadding="4"> * <tr> * <td valign="top" nowrap><code>|adefabcdefz</code></td> * <td valign="top">Initial state, no rules match. Advance * cursor.</td> * </tr> * <tr> * <td valign="top" nowrap><code>a|defabcdefz</code></td> * <td valign="top">Still no match. Rule 1 does not match * because the preceding context is not present.</td> * </tr> * <tr> * <td valign="top" nowrap><code>ad|efabcdefz</code></td> * <td valign="top">Still no match. Keep advancing until * there is a match...</td> * </tr> * <tr> * <td valign="top" nowrap><code>ade|fabcdefz</code></td> * <td valign="top">...</td> * </tr> * <tr> * <td valign="top" nowrap><code>adef|abcdefz</code></td> * <td valign="top">...</td> * </tr> * <tr> * <td valign="top" nowrap><code>adefa|bcdefz</code></td> * <td valign="top">...</td> * </tr> * <tr> * <td valign="top" nowrap><code>adefab|cdefz</code></td> * <td valign="top">...</td> * </tr> * <tr> * <td valign="top" nowrap><code>adefabc|defz</code></td> * <td valign="top">Rule 1 matches; replace "<code>def</code>" * with "<code>xy</code>" and back up the cursor * to before the '<code>y</code>'.</td> * </tr> * <tr> * <td valign="top" nowrap><code>adefabcx|yz</code></td> * <td valign="top">Although "<code>xyz</code>" is * present, rule 2 does not match because the cursor is * before the '<code>y</code>', not before the '<code>x</code>'. * Rule 3 does match. Replace "<code>yz</code>" * with "<code>q</code>".</td> * </tr> * <tr> * <td valign="top" nowrap><code>adefabcxq|</code></td> * <td valign="top">The cursor is at the end; * transliteration is complete.</td> * </tr> * </table> * * <p>The order of rules is significant. If multiple rules may match * at some point, the first matching rule is applied. </p> * * <p>Forward and reverse rules may have an empty output string. * Otherwise, an empty left or right hand side of any statement is a * syntax error. </p> * * <p>Single quotes are used to quote any character other than a * digit or letter. To specify a single quote itself, inside or * outside of quotes, use two single quotes in a row. For example, * the rule "<code>'>'>o''clock</code>" changes the * string "<code>></code>" to the string "<code>o'clock</code>". * </p> * * <p><b>Notes</b> </p> * * <p>While a RuleBasedTransliterator is being built, it checks that * the rules are added in proper order. For example, if the rule * "a>x" is followed by the rule "ab>y", * then the second rule will throw an exception. The reason is that * the second rule can never be triggered, since the first rule * always matches anything it matches. In other words, the first * rule <em>masks</em> the second rule. </p> * * @author Alan Liu * @internal Use transliterator factory methods instead since this class will be removed in that release. */ class RuleBasedTransliterator : public Transliterator { private: /** * The data object is immutable, so we can freely share it with * other instances of RBT, as long as we do NOT own this object. * TODO: data is no longer immutable. See bugs #1866, 2155 */ TransliterationRuleData* fData; /** * If true, we own the data object and must delete it. */ UBool isDataOwned; public: /** * Constructs a new transliterator from the given rules. * @param rules rules, separated by ';' * @param direction either FORWARD or REVERSE. * @exception IllegalArgumentException if rules are malformed. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ RuleBasedTransliterator(const UnicodeString& id, const UnicodeString& rules, UTransDirection direction, UnicodeFilter* adoptedFilter, UParseError& parseError, UErrorCode& status); /** * Constructs a new transliterator from the given rules. * @param rules rules, separated by ';' * @param direction either FORWARD or REVERSE. * @exception IllegalArgumentException if rules are malformed. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ /*RuleBasedTransliterator(const UnicodeString& id, const UnicodeString& rules, UTransDirection direction, UnicodeFilter* adoptedFilter, UErrorCode& status);*/ /** * Covenience constructor with no filter. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ /*RuleBasedTransliterator(const UnicodeString& id, const UnicodeString& rules, UTransDirection direction, UErrorCode& status);*/ /** * Covenience constructor with no filter and FORWARD direction. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ /*RuleBasedTransliterator(const UnicodeString& id, const UnicodeString& rules, UErrorCode& status);*/ /** * Covenience constructor with FORWARD direction. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ /*RuleBasedTransliterator(const UnicodeString& id, const UnicodeString& rules, UnicodeFilter* adoptedFilter, UErrorCode& status);*/ private: friend class TransliteratorRegistry; // to access TransliterationRuleData convenience ctor /** * Covenience constructor. * @param id the id for the transliterator. * @param theData the rule data for the transliterator. * @param adoptedFilter the filter for the transliterator */ RuleBasedTransliterator(const UnicodeString& id, const TransliterationRuleData* theData, UnicodeFilter* adoptedFilter = 0); friend class Transliterator; // to access following ct /** * Internal constructor. * @param id the id for the transliterator. * @param theData the rule data for the transliterator. * @param isDataAdopted determine who will own the 'data' object. True, the caller should not delete 'data'. */ RuleBasedTransliterator(const UnicodeString& id, TransliterationRuleData* data, UBool isDataAdopted); public: /** * Copy constructor. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ RuleBasedTransliterator(const RuleBasedTransliterator&); virtual ~RuleBasedTransliterator(); /** * Implement Transliterator API. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ virtual Transliterator* clone(void) const; protected: /** * Implements {@link Transliterator#handleTransliterate}. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ virtual void handleTransliterate(Replaceable& text, UTransPosition& offsets, UBool isIncremental) const; public: /** * Return a representation of this transliterator as source rules. * These rules will produce an equivalent transliterator if used * to construct a new transliterator. * @param result the string to receive the rules. Previous * contents will be deleted. * @param escapeUnprintable if TRUE then convert unprintable * character to their hex escape representations, \uxxxx or * \Uxxxxxxxx. Unprintable characters are those other than * U+000A, U+0020..U+007E. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ virtual UnicodeString& toRules(UnicodeString& result, UBool escapeUnprintable) const; protected: /** * Implement Transliterator framework */ virtual void handleGetSourceSet(UnicodeSet& result) const; public: /** * Override Transliterator framework */ virtual UnicodeSet& getTargetSet(UnicodeSet& result) const; /** * Return the class ID for this class. This is useful only for * comparing to a return value from getDynamicClassID(). For example: * <pre> * . Base* polymorphic_pointer = createPolymorphicObject(); * . if (polymorphic_pointer->getDynamicClassID() == * . Derived::getStaticClassID()) ... * </pre> * @return The class ID for all objects of this class. * @internal Use transliterator factory methods instead since this class will be removed in that release. */ U_I18N_API static UClassID U_EXPORT2 getStaticClassID(void); /** * Returns a unique class ID <b>polymorphically</b>. This method * is to implement a simple version of RTTI, since not all C++ * compilers support genuine RTTI. Polymorphic operator==() and * clone() methods call this method. * * @return The class ID for this object. All objects of a given * class have the same class ID. Objects of other classes have * different class IDs. */ virtual UClassID getDynamicClassID(void) const; private: void _construct(const UnicodeString& rules, UTransDirection direction, UParseError& parseError, UErrorCode& status); }; U_NAMESPACE_END #endif /* #if !UCONFIG_NO_TRANSLITERATION */ #endif