/*
**********************************************************************
* 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