/*
*******************************************************************************
* Copyright (C) 2009-2013, International Business Machines
* Corporation and others. All Rights Reserved.
*******************************************************************************
*/
package com.ibm.icu.text;
import java.io.InputStream;
import com.ibm.icu.impl.Norm2AllModes;
/**
* Unicode normalization functionality for standard Unicode normalization or
* for using custom mapping tables.
* All instances of this class are unmodifiable/immutable.
* The Normalizer2 class is not intended for public subclassing.
* <p>
* The primary functions are to produce a normalized string and to detect whether
* a string is already normalized.
* The most commonly used normalization forms are those defined in
* http://www.unicode.org/unicode/reports/tr15/
* However, this API supports additional normalization forms for specialized purposes.
* For example, NFKC_Casefold is provided via getInstance("nfkc_cf", COMPOSE)
* and can be used in implementations of UTS #46.
* <p>
* Not only are the standard compose and decompose modes supplied,
* but additional modes are provided as documented in the Mode enum.
* <p>
* Some of the functions in this class identify normalization boundaries.
* At a normalization boundary, the portions of the string
* before it and starting from it do not interact and can be handled independently.
* <p>
* The spanQuickCheckYes() stops at a normalization boundary.
* When the goal is a normalized string, then the text before the boundary
* can be copied, and the remainder can be processed with normalizeSecondAndAppend().
* <p>
* The hasBoundaryBefore(), hasBoundaryAfter() and isInert() functions test whether
* a character is guaranteed to be at a normalization boundary,
* regardless of context.
* This is used for moving from one normalization boundary to the next
* or preceding boundary, and for performing iterative normalization.
* <p>
* Iterative normalization is useful when only a small portion of a
* longer string needs to be processed.
* For example, in ICU, iterative normalization is used by the NormalizationTransliterator
* (to avoid replacing already-normalized text) and ucol_nextSortKeyPart()
* (to process only the substring for which sort key bytes are computed).
* <p>
* The set of normalization boundaries returned by these functions may not be
* complete: There may be more boundaries that could be returned.
* Different functions may return different boundaries.
* @stable ICU 4.4
* @author Markus W. Scherer
*/
public abstract class Normalizer2 {
/**
* Constants for normalization modes.
* For details about standard Unicode normalization forms
* and about the algorithms which are also used with custom mapping tables
* see http://www.unicode.org/unicode/reports/tr15/
* @stable ICU 4.4
*/
public enum Mode {
/**
* Decomposition followed by composition.
* Same as standard NFC when using an "nfc" instance.
* Same as standard NFKC when using an "nfkc" instance.
* For details about standard Unicode normalization forms
* see http://www.unicode.org/unicode/reports/tr15/
* @stable ICU 4.4
*/
COMPOSE,
/**
* Map, and reorder canonically.
* Same as standard NFD when using an "nfc" instance.
* Same as standard NFKD when using an "nfkc" instance.
* For details about standard Unicode normalization forms
* see http://www.unicode.org/unicode/reports/tr15/
* @stable ICU 4.4
*/
DECOMPOSE,
/**
* "Fast C or D" form.
* If a string is in this form, then further decomposition <i>without reordering</i>
* would yield the same form as DECOMPOSE.
* Text in "Fast C or D" form can be processed efficiently with data tables
* that are "canonically closed", that is, that provide equivalent data for
* equivalent text, without having to be fully normalized.<br>
* Not a standard Unicode normalization form.<br>
* Not a unique form: Different FCD strings can be canonically equivalent.<br>
* For details see http://www.unicode.org/notes/tn5/#FCD
* @stable ICU 4.4
*/
FCD,
/**
* Compose only contiguously.
* Also known as "FCC" or "Fast C Contiguous".
* The result will often but not always be in NFC.
* The result will conform to FCD which is useful for processing.<br>
* Not a standard Unicode normalization form.<br>
* For details see http://www.unicode.org/notes/tn5/#FCC
* @stable ICU 4.4
*/
COMPOSE_CONTIGUOUS
};
/**
* Returns a Normalizer2 instance for Unicode NFC normalization.
* Same as getInstance(null, "nfc", Mode.COMPOSE).
* Returns an unmodifiable singleton instance.
* @return the requested Normalizer2, if successful
* @stable ICU 49
*/
public static Normalizer2 getNFCInstance() {
return Norm2AllModes.getNFCInstance().comp;
}
/**
* Returns a Normalizer2 instance for Unicode NFD normalization.
* Same as getInstance(null, "nfc", Mode.DECOMPOSE).
* Returns an unmodifiable singleton instance.
* @return the requested Normalizer2, if successful
* @stable ICU 49
*/
public static Normalizer2 getNFDInstance() {
return Norm2AllModes.getNFCInstance().decomp;
}
/**
* Returns a Normalizer2 instance for Unicode NFKC normalization.
* Same as getInstance(null, "nfkc", Mode.COMPOSE).
* Returns an unmodifiable singleton instance.
* @return the requested Normalizer2, if successful
* @stable ICU 49
*/
public static Normalizer2 getNFKCInstance() {
return Norm2AllModes.getNFKCInstance().comp;
}
/**
* Returns a Normalizer2 instance for Unicode NFKD normalization.
* Same as getInstance(null, "nfkc", Mode.DECOMPOSE).
* Returns an unmodifiable singleton instance.
* @return the requested Normalizer2, if successful
* @stable ICU 49
*/
public static Normalizer2 getNFKDInstance() {
return Norm2AllModes.getNFKCInstance().decomp;
}
/**
* Returns a Normalizer2 instance for Unicode NFKC_Casefold normalization.
* Same as getInstance(null, "nfkc_cf", Mode.COMPOSE).
* Returns an unmodifiable singleton instance.
* @return the requested Normalizer2, if successful
* @stable ICU 49
*/
public static Normalizer2 getNFKCCasefoldInstance() {
return Norm2AllModes.getNFKC_CFInstance().comp;
}
/**
* Returns a Normalizer2 instance which uses the specified data file
* (an ICU data file if data=null, or else custom binary data)
* and which composes or decomposes text according to the specified mode.
* Returns an unmodifiable singleton instance.
* <ul>
* <li>Use data=null for data files that are part of ICU's own data.
* <li>Use name="nfc" and COMPOSE/DECOMPOSE for Unicode standard NFC/NFD.
* <li>Use name="nfkc" and COMPOSE/DECOMPOSE for Unicode standard NFKC/NFKD.
* <li>Use name="nfkc_cf" and COMPOSE for Unicode standard NFKC_CF=NFKC_Casefold.
* </ul>
* If data!=null, then the binary data is read once and cached using the provided
* name as the key.
* If you know or expect the data to be cached already, you can use data!=null
* for non-ICU data as well.
* @param data the binary, big-endian normalization (.nrm file) data, or null for ICU data
* @param name "nfc" or "nfkc" or "nfkc_cf" or name of custom data file
* @param mode normalization mode (compose or decompose etc.)
* @return the requested Normalizer2, if successful
* @stable ICU 4.4
*/
public static Normalizer2 getInstance(InputStream data, String name, Mode mode) {
Norm2AllModes all2Modes=Norm2AllModes.getInstance(data, name);
switch(mode) {
case COMPOSE: return all2Modes.comp;
case DECOMPOSE: return all2Modes.decomp;
case FCD: return all2Modes.fcd;
case COMPOSE_CONTIGUOUS: return all2Modes.fcc;
default: return null; // will not occur
}
}
/**
* Returns the normalized form of the source string.
* @param src source string
* @return normalized src
* @stable ICU 4.4
*/
public String normalize(CharSequence src) {
if(src instanceof String) {
// Fastpath: Do not construct a new String if the src is a String
// and is already normalized.
int spanLength=spanQuickCheckYes(src);
if(spanLength==src.length()) {
return (String)src;
}
StringBuilder sb=new StringBuilder(src.length()).append(src, 0, spanLength);
return normalizeSecondAndAppend(sb, src.subSequence(spanLength, src.length())).toString();
}
return normalize(src, new StringBuilder(src.length())).toString();
}
/**
* Writes the normalized form of the source string to the destination string
* (replacing its contents) and returns the destination string.
* The source and destination strings must be different objects.
* @param src source string
* @param dest destination string; its contents is replaced with normalized src
* @return dest
* @stable ICU 4.4
*/
public abstract StringBuilder normalize(CharSequence src, StringBuilder dest);
/**
* Writes the normalized form of the source string to the destination Appendable
* and returns the destination Appendable.
* The source and destination strings must be different objects.
* @param src source string
* @param dest destination Appendable; gets normalized src appended
* @return dest
* @stable ICU 4.6
*/
public abstract Appendable normalize(CharSequence src, Appendable dest);
/**
* Appends the normalized form of the second string to the first string
* (merging them at the boundary) and returns the first string.
* The result is normalized if the first string was normalized.
* The first and second strings must be different objects.
* @param first string, should be normalized
* @param second string, will be normalized
* @return first
* @stable ICU 4.4
*/
public abstract StringBuilder normalizeSecondAndAppend(
StringBuilder first, CharSequence second);
/**
* Appends the second string to the first string
* (merging them at the boundary) and returns the first string.
* The result is normalized if both the strings were normalized.
* The first and second strings must be different objects.
* @param first string, should be normalized
* @param second string, should be normalized
* @return first
* @stable ICU 4.4
*/
public abstract StringBuilder append(StringBuilder first, CharSequence second);
/**
* Gets the decomposition mapping of c.
* Roughly equivalent to normalizing the String form of c
* on a DECOMPOSE Normalizer2 instance, but much faster, and except that this function
* returns null if c does not have a decomposition mapping in this instance's data.
* This function is independent of the mode of the Normalizer2.
* @param c code point
* @return c's decomposition mapping, if any; otherwise null
* @stable ICU 4.6
*/
public abstract String getDecomposition(int c);
/**
* Gets the raw decomposition mapping of c.
*
* <p>This is similar to the getDecomposition() method but returns the
* raw decomposition mapping as specified in UnicodeData.txt or
* (for custom data) in the mapping files processed by the gennorm2 tool.
* By contrast, getDecomposition() returns the processed,
* recursively-decomposed version of this mapping.
*
* <p>When used on a standard NFKC Normalizer2 instance,
* getRawDecomposition() returns the Unicode Decomposition_Mapping (dm) property.
*
* <p>When used on a standard NFC Normalizer2 instance,
* it returns the Decomposition_Mapping only if the Decomposition_Type (dt) is Canonical (Can);
* in this case, the result contains either one or two code points (=1..4 Java chars).
*
* <p>This function is independent of the mode of the Normalizer2.
* The default implementation returns null.
* @param c code point
* @return c's raw decomposition mapping, if any; otherwise null
* @stable ICU 49
*/
public String getRawDecomposition(int c) { return null; }
/**
* Performs pairwise composition of a & b and returns the composite if there is one.
*
* <p>Returns a composite code point c only if c has a two-way mapping to a+b.
* In standard Unicode normalization, this means that
* c has a canonical decomposition to a+b
* and c does not have the Full_Composition_Exclusion property.
*
* <p>This function is independent of the mode of the Normalizer2.
* The default implementation returns a negative value.
* @param a A (normalization starter) code point.
* @param b Another code point.
* @return The non-negative composite code point if there is one; otherwise a negative value.
* @stable ICU 49
*/
public int composePair(int a, int b) { return -1; }
/**
* Gets the combining class of c.
* The default implementation returns 0
* but all standard implementations return the Unicode Canonical_Combining_Class value.
* @param c code point
* @return c's combining class
* @stable ICU 49
*/
public int getCombiningClass(int c) { return 0; }
/**
* Tests if the string is normalized.
* Internally, in cases where the quickCheck() method would return "maybe"
* (which is only possible for the two COMPOSE modes) this method
* resolves to "yes" or "no" to provide a definitive result,
* at the cost of doing more work in those cases.
* @param s input string
* @return true if s is normalized
* @stable ICU 4.4
*/
public abstract boolean isNormalized(CharSequence s);
/**
* Tests if the string is normalized.
* For the two COMPOSE modes, the result could be "maybe" in cases that
* would take a little more work to resolve definitively.
* Use spanQuickCheckYes() and normalizeSecondAndAppend() for a faster
* combination of quick check + normalization, to avoid
* re-checking the "yes" prefix.
* @param s input string
* @return the quick check result
* @stable ICU 4.4
*/
public abstract Normalizer.QuickCheckResult quickCheck(CharSequence s);
/**
* Returns the end of the normalized substring of the input string.
* In other words, with <code>end=spanQuickCheckYes(s);</code>
* the substring <code>s.subSequence(0, end)</code>
* will pass the quick check with a "yes" result.
* <p>
* The returned end index is usually one or more characters before the
* "no" or "maybe" character: The end index is at a normalization boundary.
* (See the class documentation for more about normalization boundaries.)
* <p>
* When the goal is a normalized string and most input strings are expected
* to be normalized already, then call this method,
* and if it returns a prefix shorter than the input string,
* copy that prefix and use normalizeSecondAndAppend() for the remainder.
* @param s input string
* @return "yes" span end index
* @stable ICU 4.4
*/
public abstract int spanQuickCheckYes(CharSequence s);
/**
* Tests if the character always has a normalization boundary before it,
* regardless of context.
* If true, then the character does not normalization-interact with
* preceding characters.
* In other words, a string containing this character can be normalized
* by processing portions before this character and starting from this
* character independently.
* This is used for iterative normalization. See the class documentation for details.
* @param c character to test
* @return true if c has a normalization boundary before it
* @stable ICU 4.4
*/
public abstract boolean hasBoundaryBefore(int c);
/**
* Tests if the character always has a normalization boundary after it,
* regardless of context.
* If true, then the character does not normalization-interact with
* following characters.
* In other words, a string containing this character can be normalized
* by processing portions up to this character and after this
* character independently.
* This is used for iterative normalization. See the class documentation for details.
* <p>
* Note that this operation may be significantly slower than hasBoundaryBefore().
* @param c character to test
* @return true if c has a normalization boundary after it
* @stable ICU 4.4
*/
public abstract boolean hasBoundaryAfter(int c);
/**
* Tests if the character is normalization-inert.
* If true, then the character does not change, nor normalization-interact with
* preceding or following characters.
* In other words, a string containing this character can be normalized
* by processing portions before this character and after this
* character independently.
* This is used for iterative normalization. See the class documentation for details.
* <p>
* Note that this operation may be significantly slower than hasBoundaryBefore().
* @param c character to test
* @return true if c is normalization-inert
* @stable ICU 4.4
*/
public abstract boolean isInert(int c);
/**
* Sole constructor. (For invocation by subclass constructors,
* typically implicit.)
* @internal
* @deprecated This API is ICU internal only.
*/
protected Normalizer2() {
}
}