* 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 * https://www.unicode.org/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. *
* Not only are the standard compose and decompose modes supplied, * but additional modes are provided as documented in the Mode enum. *
* 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. *
* 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(). *
* 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. *
* 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). *
* 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.
* @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 https://www.unicode.org/reports/tr15/
*/
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 https://www.unicode.org/reports/tr15/
*/
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 https://www.unicode.org/reports/tr15/
*/
DECOMPOSE,
/**
* "Fast C or D" form.
* If a string is in this form, then further decomposition without reordering
* 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.
* Not a standard Unicode normalization form.
* Not a unique form: Different FCD strings can be canonically equivalent.
* For details see http://www.unicode.org/notes/tn5/#FCD
*/
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.
* Not a standard Unicode normalization form.
* For details see http://www.unicode.org/notes/tn5/#FCC
*/
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
*/
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
*/
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
*/
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
*/
public static Normalizer2 getNFKDInstance() {
return Norm2AllModes.getNFKCInstance().decomp;
}
/**
* Returns a Normalizer2 instance for Unicode toNFKC_Casefold() normalization
* which is equivalent to applying the NFKC_Casefold mappings and then NFC.
* See https://www.unicode.org/reports/tr44/#NFKC_Casefold
*
*
Same as getInstance(null, "nfkc_cf", Mode.COMPOSE). * Returns an unmodifiable singleton instance. * @return the requested Normalizer2, if successful */ public static Normalizer2 getNFKCCasefoldInstance() { return Norm2AllModes.getNFKC_CFInstance().comp; } /** * Returns a Normalizer2 instance for a variant of Unicode toNFKC_Casefold() normalization * which is equivalent to applying the NFKC_Simple_Casefold mappings and then NFC. * See https://www.unicode.org/reports/tr44/#NFKC_Simple_Casefold * *
Same as getInstance(null, "nfkc_scf", Mode.COMPOSE). * Returns an unmodifiable singleton instance. * @return the requested Normalizer2, if successful * @hide draft / provisional / internal are hidden on Android */ public static Normalizer2 getNFKCSimpleCasefoldInstance() { return Norm2AllModes.getNFKC_SCFInstance().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. *
Any {@link java.io.IOException} is wrapped into a {@link android.icu.util.ICUUncheckedIOException}. * @param data the binary, big-endian normalization (.nrm file) data, or null for ICU data * @param name "nfc" or "nfkc" or "nfkc_cf" or "nfkc_scf" or name of custom data file * @param mode normalization mode (compose or decompose etc.) * @return the requested Normalizer2, if successful * @deprecated Don't use because the binary {@code data} format is not stable across API levels. */ @Deprecated public static Normalizer2 getInstance(InputStream data, String name, Mode mode) { // TODO: If callers really use this API, then we should add an overload that takes a ByteBuffer. ByteBuffer bytes = null; if (data != null) { try { bytes = ICUBinary.getByteBufferFromInputStreamAndCloseStream(data); } catch (IOException e) { throw new ICUUncheckedIOException(e); } } Norm2AllModes all2Modes=Norm2AllModes.getInstance(bytes, 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 */ 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; } if (spanLength != 0) { 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 */ 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. * *
Any {@link java.io.IOException} is wrapped into a {@link android.icu.util.ICUUncheckedIOException}. * * @param src source string * @param dest destination Appendable; gets normalized src appended * @return dest */ 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 */ 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 */ 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 */ public abstract String getDecomposition(int c); /** * Gets the raw decomposition mapping of c. * *
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. * *
When used on a standard NFKC Normalizer2 instance, * getRawDecomposition() returns the Unicode Decomposition_Mapping (dm) property. * *
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). * *
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 */ public String getRawDecomposition(int c) { return null; } /** * Performs pairwise composition of a & b and returns the composite if there is one. * *
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. * *
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.
*/
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
*/
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
*/
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
*/
public abstract Normalizer.QuickCheckResult quickCheck(CharSequence s);
/**
* Returns the end of the normalized substring of the input string.
* In other words, with end=spanQuickCheckYes(s);
* the substring s.subSequence(0, end)
* will pass the quick check with a "yes" result.
*
* 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.) *
* 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 */ 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 */ 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. *
* 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 */ 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. *
* Note that this operation may be significantly slower than hasBoundaryBefore(). * @param c character to test * @return true if c is normalization-inert */ public abstract boolean isInert(int c); /** * Sole constructor. (For invocation by subclass constructors, * typically implicit.) * @deprecated This API is ICU internal only. * @hide original deprecated declaration * @hide draft / provisional / internal are hidden on Android */ @Deprecated protected Normalizer2() { } }