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scuffed-code/icu4c/source/common/unicode/unorm.h
Markus Scherer 0edc6125a1 ICU-4274 document that source and result buffers must not overlap 
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2007-08-24 16:28:39 +00:00

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/*
*******************************************************************************
* Copyright (c) 1996-2007, International Business Machines Corporation
* and others. All Rights Reserved.
*******************************************************************************
* File unorm.h
*
* Created by: Vladimir Weinstein 12052000
*
* Modification history :
*
* Date Name Description
* 02/01/01 synwee Added normalization quickcheck enum and method.
*/
#ifndef UNORM_H
#define UNORM_H
#include "unicode/utypes.h"
#if !UCONFIG_NO_NORMALIZATION
#include "unicode/uiter.h"
/**
* \file
* \brief C API: Unicode Normalization
*
* <h2>Unicode normalization API</h2>
*
* <code>unorm_normalize</code> transforms Unicode text into an equivalent composed or
* decomposed form, allowing for easier sorting and searching of text.
* <code>unorm_normalize</code> supports the standard normalization forms described in
* <a href="http://www.unicode.org/unicode/reports/tr15/" target="unicode">
* Unicode Standard Annex #15: Unicode Normalization Forms</a>.
*
* Characters with accents or other adornments can be encoded in
* several different ways in Unicode. For example, take the character A-acute.
* In Unicode, this can be encoded as a single character (the
* "composed" form):
*
* \code
* 00C1 LATIN CAPITAL LETTER A WITH ACUTE
* \endcode
*
* or as two separate characters (the "decomposed" form):
*
* \code
* 0041 LATIN CAPITAL LETTER A
* 0301 COMBINING ACUTE ACCENT
* \endcode
*
* To a user of your program, however, both of these sequences should be
* treated as the same "user-level" character "A with acute accent". When you are searching or
* comparing text, you must ensure that these two sequences are treated
* equivalently. In addition, you must handle characters with more than one
* accent. Sometimes the order of a character's combining accents is
* significant, while in other cases accent sequences in different orders are
* really equivalent.
*
* Similarly, the string "ffi" can be encoded as three separate letters:
*
* \code
* 0066 LATIN SMALL LETTER F
* 0066 LATIN SMALL LETTER F
* 0069 LATIN SMALL LETTER I
* \endcode
*
* or as the single character
*
* \code
* FB03 LATIN SMALL LIGATURE FFI
* \endcode
*
* The ffi ligature is not a distinct semantic character, and strictly speaking
* it shouldn't be in Unicode at all, but it was included for compatibility
* with existing character sets that already provided it. The Unicode standard
* identifies such characters by giving them "compatibility" decompositions
* into the corresponding semantic characters. When sorting and searching, you
* will often want to use these mappings.
*
* <code>unorm_normalize</code> helps solve these problems by transforming text into the
* canonical composed and decomposed forms as shown in the first example above.
* In addition, you can have it perform compatibility decompositions so that
* you can treat compatibility characters the same as their equivalents.
* Finally, <code>unorm_normalize</code> rearranges accents into the proper canonical
* order, so that you do not have to worry about accent rearrangement on your
* own.
*
* Form FCD, "Fast C or D", is also designed for collation.
* It allows to work on strings that are not necessarily normalized
* with an algorithm (like in collation) that works under "canonical closure", i.e., it treats precomposed
* characters and their decomposed equivalents the same.
*
* It is not a normalization form because it does not provide for uniqueness of representation. Multiple strings
* may be canonically equivalent (their NFDs are identical) and may all conform to FCD without being identical
* themselves.
*
* The form is defined such that the "raw decomposition", the recursive canonical decomposition of each character,
* results in a string that is canonically ordered. This means that precomposed characters are allowed for as long
* as their decompositions do not need canonical reordering.
*
* Its advantage for a process like collation is that all NFD and most NFC texts - and many unnormalized texts -
* already conform to FCD and do not need to be normalized (NFD) for such a process. The FCD quick check will
* return UNORM_YES for most strings in practice.
*
* unorm_normalize(UNORM_FCD) may be implemented with UNORM_NFD.
*
* For more details on FCD see the collation design document:
* http://source.icu-project.org/repos/icu/icuhtml/trunk/design/collation/ICU_collation_design.htm
*
* ICU collation performs either NFD or FCD normalization automatically if normalization
* is turned on for the collator object.
* Beyond collation and string search, normalized strings may be useful for string equivalence comparisons,
* transliteration/transcription, unique representations, etc.
*
* The W3C generally recommends to exchange texts in NFC.
* Note also that most legacy character encodings use only precomposed forms and often do not
* encode any combining marks by themselves. For conversion to such character encodings the
* Unicode text needs to be normalized to NFC.
* For more usage examples, see the Unicode Standard Annex.
*/
/**
* Constants for normalization modes.
* @stable ICU 2.0
*/
typedef enum {
/** No decomposition/composition. @stable ICU 2.0 */
UNORM_NONE = 1,
/** Canonical decomposition. @stable ICU 2.0 */
UNORM_NFD = 2,
/** Compatibility decomposition. @stable ICU 2.0 */
UNORM_NFKD = 3,
/** Canonical decomposition followed by canonical composition. @stable ICU 2.0 */
UNORM_NFC = 4,
/** Default normalization. @stable ICU 2.0 */
UNORM_DEFAULT = UNORM_NFC,
/** Compatibility decomposition followed by canonical composition. @stable ICU 2.0 */
UNORM_NFKC =5,
/** "Fast C or D" form. @stable ICU 2.0 */
UNORM_FCD = 6,
/** One more than the highest normalization mode constant. @stable ICU 2.0 */
UNORM_MODE_COUNT
} UNormalizationMode;
/**
* Constants for options flags for normalization.
* Use 0 for default options,
* including normalization according to the Unicode version
* that is currently supported by ICU (see u_getUnicodeVersion).
* @stable ICU 2.6
*/
enum {
/**
* Options bit set value to select Unicode 3.2 normalization
* (except NormalizationCorrections).
* At most one Unicode version can be selected at a time.
* @stable ICU 2.6
*/
UNORM_UNICODE_3_2=0x20
};
/**
* Lowest-order bit number of unorm_compare() options bits corresponding to
* normalization options bits.
*
* The options parameter for unorm_compare() uses most bits for
* itself and for various comparison and folding flags.
* The most significant bits, however, are shifted down and passed on
* to the normalization implementation.
* (That is, from unorm_compare(..., options, ...),
* options>>UNORM_COMPARE_NORM_OPTIONS_SHIFT will be passed on to the
* internal normalization functions.)
*
* @see unorm_compare
* @stable ICU 2.6
*/
#define UNORM_COMPARE_NORM_OPTIONS_SHIFT 20
/**
* Normalize a string.
* The string will be normalized according the specified normalization mode
* and options.
* The source and result buffers must not be the same, nor overlap.
*
* @param source The string to normalize.
* @param sourceLength The length of source, or -1 if NUL-terminated.
* @param mode The normalization mode; one of UNORM_NONE,
* UNORM_NFD, UNORM_NFC, UNORM_NFKC, UNORM_NFKD, UNORM_DEFAULT.
* @param options The normalization options, ORed together (0 for no options).
* @param result A pointer to a buffer to receive the result string.
* The result string is NUL-terminated if possible.
* @param resultLength The maximum size of result.
* @param status A pointer to a UErrorCode to receive any errors.
* @return The total buffer size needed; if greater than resultLength,
* the output was truncated, and the error code is set to U_BUFFER_OVERFLOW_ERROR.
* @stable ICU 2.0
*/
U_STABLE int32_t U_EXPORT2
unorm_normalize(const UChar *source, int32_t sourceLength,
UNormalizationMode mode, int32_t options,
UChar *result, int32_t resultLength,
UErrorCode *status);
#endif
/**
* Result values for unorm_quickCheck().
* For details see Unicode Technical Report 15.
* @stable ICU 2.0
*/
typedef enum UNormalizationCheckResult {
/**
* Indicates that string is not in the normalized format
*/
UNORM_NO,
/**
* Indicates that string is in the normalized format
*/
UNORM_YES,
/**
* Indicates that string cannot be determined if it is in the normalized
* format without further thorough checks.
*/
UNORM_MAYBE
} UNormalizationCheckResult;
#if !UCONFIG_NO_NORMALIZATION
/**
* Performing quick check on a string, to quickly determine if the string is
* in a particular normalization format.
* Three types of result can be returned UNORM_YES, UNORM_NO or
* UNORM_MAYBE. Result UNORM_YES indicates that the argument
* string is in the desired normalized format, UNORM_NO determines that
* argument string is not in the desired normalized format. A
* UNORM_MAYBE result indicates that a more thorough check is required,
* the user may have to put the string in its normalized form and compare the
* results.
*
* @param source string for determining if it is in a normalized format
* @param sourcelength length of source to test, or -1 if NUL-terminated
* @param mode which normalization form to test for
* @param status a pointer to a UErrorCode to receive any errors
* @return UNORM_YES, UNORM_NO or UNORM_MAYBE
*
* @see unorm_isNormalized
* @stable ICU 2.0
*/
U_STABLE UNormalizationCheckResult U_EXPORT2
unorm_quickCheck(const UChar *source, int32_t sourcelength,
UNormalizationMode mode,
UErrorCode *status);
/**
* Performing quick check on a string; same as unorm_quickCheck but
* takes an extra options parameter like most normalization functions.
*
* @param src String that is to be tested if it is in a normalization format.
* @param srcLength Length of source to test, or -1 if NUL-terminated.
* @param mode Which normalization form to test for.
* @param options The normalization options, ORed together (0 for no options).
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return UNORM_YES, UNORM_NO or UNORM_MAYBE
*
* @see unorm_quickCheck
* @see unorm_isNormalized
* @stable ICU 2.6
*/
U_STABLE UNormalizationCheckResult U_EXPORT2
unorm_quickCheckWithOptions(const UChar *src, int32_t srcLength,
UNormalizationMode mode, int32_t options,
UErrorCode *pErrorCode);
/**
* Test if a string is in a given normalization form.
* This is semantically equivalent to source.equals(normalize(source, mode)) .
*
* Unlike unorm_quickCheck(), this function returns a definitive result,
* never a "maybe".
* For NFD, NFKD, and FCD, both functions work exactly the same.
* For NFC and NFKC where quickCheck may return "maybe", this function will
* perform further tests to arrive at a TRUE/FALSE result.
*
* @param src String that is to be tested if it is in a normalization format.
* @param srcLength Length of source to test, or -1 if NUL-terminated.
* @param mode Which normalization form to test for.
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return Boolean value indicating whether the source string is in the
* "mode" normalization form.
*
* @see unorm_quickCheck
* @stable ICU 2.2
*/
U_STABLE UBool U_EXPORT2
unorm_isNormalized(const UChar *src, int32_t srcLength,
UNormalizationMode mode,
UErrorCode *pErrorCode);
/**
* Test if a string is in a given normalization form; same as unorm_isNormalized but
* takes an extra options parameter like most normalization functions.
*
* @param src String that is to be tested if it is in a normalization format.
* @param srcLength Length of source to test, or -1 if NUL-terminated.
* @param mode Which normalization form to test for.
* @param options The normalization options, ORed together (0 for no options).
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return Boolean value indicating whether the source string is in the
* "mode/options" normalization form.
*
* @see unorm_quickCheck
* @see unorm_isNormalized
* @stable ICU 2.6
*/
U_STABLE UBool U_EXPORT2
unorm_isNormalizedWithOptions(const UChar *src, int32_t srcLength,
UNormalizationMode mode, int32_t options,
UErrorCode *pErrorCode);
/**
* Iterative normalization forward.
* This function (together with unorm_previous) is somewhat
* similar to the C++ Normalizer class (see its non-static functions).
*
* Iterative normalization is useful when only a small portion of a longer
* string/text needs to be processed.
*
* For example, the likelihood may be high that processing the first 10% of some
* text will be sufficient to find certain data.
* Another example: When one wants to concatenate two normalized strings and get a
* normalized result, it is much more efficient to normalize just a small part of
* the result around the concatenation place instead of re-normalizing everything.
*
* The input text is an instance of the C character iteration API UCharIterator.
* It may wrap around a simple string, a CharacterIterator, a Replaceable, or any
* other kind of text object.
*
* If a buffer overflow occurs, then the caller needs to reset the iterator to the
* old index and call the function again with a larger buffer - if the caller cares
* for the actual output.
* Regardless of the output buffer, the iterator will always be moved to the next
* normalization boundary.
*
* This function (like unorm_previous) serves two purposes:
*
* 1) To find the next boundary so that the normalization of the part of the text
* from the current position to that boundary does not affect and is not affected
* by the part of the text beyond that boundary.
*
* 2) To normalize the text up to the boundary.
*
* The second step is optional, per the doNormalize parameter.
* It is omitted for operations like string concatenation, where the two adjacent
* string ends need to be normalized together.
* In such a case, the output buffer will just contain a copy of the text up to the
* boundary.
*
* pNeededToNormalize is an output-only parameter. Its output value is only defined
* if normalization was requested (doNormalize) and successful (especially, no
* buffer overflow).
* It is useful for operations like a normalizing transliterator, where one would
* not want to replace a piece of text if it is not modified.
*
* If doNormalize==TRUE and pNeededToNormalize!=NULL then *pNeeded... is set TRUE
* if the normalization was necessary.
*
* If doNormalize==FALSE then *pNeededToNormalize will be set to FALSE.
*
* If the buffer overflows, then *pNeededToNormalize will be undefined;
* essentially, whenever U_FAILURE is true (like in buffer overflows), this result
* will be undefined.
*
* @param src The input text in the form of a C character iterator.
* @param dest The output buffer; can be NULL if destCapacity==0 for pure preflighting.
* @param destCapacity The number of UChars that fit into dest.
* @param mode The normalization mode.
* @param options The normalization options, ORed together (0 for no options).
* @param doNormalize Indicates if the source text up to the next boundary
* is to be normalized (TRUE) or just copied (FALSE).
* @param pNeededToNormalize Output flag indicating if the normalization resulted in
* different text from the input.
* Not defined if an error occurs including buffer overflow.
* Always FALSE if !doNormalize.
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return Length of output (number of UChars) when successful or buffer overflow.
*
* @see unorm_previous
* @see unorm_normalize
*
* @stable ICU 2.1
*/
U_STABLE int32_t U_EXPORT2
unorm_next(UCharIterator *src,
UChar *dest, int32_t destCapacity,
UNormalizationMode mode, int32_t options,
UBool doNormalize, UBool *pNeededToNormalize,
UErrorCode *pErrorCode);
/**
* Iterative normalization backward.
* This function (together with unorm_next) is somewhat
* similar to the C++ Normalizer class (see its non-static functions).
* For all details see unorm_next.
*
* @param src The input text in the form of a C character iterator.
* @param dest The output buffer; can be NULL if destCapacity==0 for pure preflighting.
* @param destCapacity The number of UChars that fit into dest.
* @param mode The normalization mode.
* @param options The normalization options, ORed together (0 for no options).
* @param doNormalize Indicates if the source text up to the next boundary
* is to be normalized (TRUE) or just copied (FALSE).
* @param pNeededToNormalize Output flag indicating if the normalization resulted in
* different text from the input.
* Not defined if an error occurs including buffer overflow.
* Always FALSE if !doNormalize.
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return Length of output (number of UChars) when successful or buffer overflow.
*
* @see unorm_next
* @see unorm_normalize
*
* @stable ICU 2.1
*/
U_STABLE int32_t U_EXPORT2
unorm_previous(UCharIterator *src,
UChar *dest, int32_t destCapacity,
UNormalizationMode mode, int32_t options,
UBool doNormalize, UBool *pNeededToNormalize,
UErrorCode *pErrorCode);
/**
* Concatenate normalized strings, making sure that the result is normalized as well.
*
* If both the left and the right strings are in
* the normalization form according to "mode/options",
* then the result will be
*
* \code
* dest=normalize(left+right, mode, options)
* \endcode
*
* With the input strings already being normalized,
* this function will use unorm_next() and unorm_previous()
* to find the adjacent end pieces of the input strings.
* Only the concatenation of these end pieces will be normalized and
* then concatenated with the remaining parts of the input strings.
*
* It is allowed to have dest==left to avoid copying the entire left string.
*
* @param left Left source string, may be same as dest.
* @param leftLength Length of left source string, or -1 if NUL-terminated.
* @param right Right source string. Must not be the same as dest, nor overlap.
* @param rightLength Length of right source string, or -1 if NUL-terminated.
* @param dest The output buffer; can be NULL if destCapacity==0 for pure preflighting.
* @param destCapacity The number of UChars that fit into dest.
* @param mode The normalization mode.
* @param options The normalization options, ORed together (0 for no options).
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return Length of output (number of UChars) when successful or buffer overflow.
*
* @see unorm_normalize
* @see unorm_next
* @see unorm_previous
*
* @stable ICU 2.1
*/
U_STABLE int32_t U_EXPORT2
unorm_concatenate(const UChar *left, int32_t leftLength,
const UChar *right, int32_t rightLength,
UChar *dest, int32_t destCapacity,
UNormalizationMode mode, int32_t options,
UErrorCode *pErrorCode);
/**
* Option bit for unorm_compare:
* Both input strings are assumed to fulfill FCD conditions.
* @stable ICU 2.2
*/
#define UNORM_INPUT_IS_FCD 0x20000
/**
* Option bit for unorm_compare:
* Perform case-insensitive comparison.
* @stable ICU 2.2
*/
#define U_COMPARE_IGNORE_CASE 0x10000
#ifndef U_COMPARE_CODE_POINT_ORDER
/* see also unistr.h and ustring.h */
/**
* Option bit for u_strCaseCompare, u_strcasecmp, unorm_compare, etc:
* Compare strings in code point order instead of code unit order.
* @stable ICU 2.2
*/
#define U_COMPARE_CODE_POINT_ORDER 0x8000
#endif
/**
* Compare two strings for canonical equivalence.
* Further options include case-insensitive comparison and
* code point order (as opposed to code unit order).
*
* Canonical equivalence between two strings is defined as their normalized
* forms (NFD or NFC) being identical.
* This function compares strings incrementally instead of normalizing
* (and optionally case-folding) both strings entirely,
* improving performance significantly.
*
* Bulk normalization is only necessary if the strings do not fulfill the FCD
* conditions. Only in this case, and only if the strings are relatively long,
* is memory allocated temporarily.
* For FCD strings and short non-FCD strings there is no memory allocation.
*
* Semantically, this is equivalent to
* strcmp[CodePointOrder](NFD(foldCase(NFD(s1))), NFD(foldCase(NFD(s2))))
* where code point order and foldCase are all optional.
*
* UAX 21 2.5 Caseless Matching specifies that for a canonical caseless match
* the case folding must be performed first, then the normalization.
*
* @param s1 First source string.
* @param length1 Length of first source string, or -1 if NUL-terminated.
*
* @param s2 Second source string.
* @param length2 Length of second source string, or -1 if NUL-terminated.
*
* @param options A bit set of options:
* - U_FOLD_CASE_DEFAULT or 0 is used for default options:
* Case-sensitive comparison in code unit order, and the input strings
* are quick-checked for FCD.
*
* - UNORM_INPUT_IS_FCD
* Set if the caller knows that both s1 and s2 fulfill the FCD conditions.
* If not set, the function will quickCheck for FCD
* and normalize if necessary.
*
* - U_COMPARE_CODE_POINT_ORDER
* Set to choose code point order instead of code unit order
* (see u_strCompare for details).
*
* - U_COMPARE_IGNORE_CASE
* Set to compare strings case-insensitively using case folding,
* instead of case-sensitively.
* If set, then the following case folding options are used.
*
* - Options as used with case-insensitive comparisons, currently:
*
* - U_FOLD_CASE_EXCLUDE_SPECIAL_I
* (see u_strCaseCompare for details)
*
* - regular normalization options shifted left by UNORM_COMPARE_NORM_OPTIONS_SHIFT
*
* @param pErrorCode ICU error code in/out parameter.
* Must fulfill U_SUCCESS before the function call.
* @return <0 or 0 or >0 as usual for string comparisons
*
* @see unorm_normalize
* @see UNORM_FCD
* @see u_strCompare
* @see u_strCaseCompare
*
* @stable ICU 2.2
*/
U_STABLE int32_t U_EXPORT2
unorm_compare(const UChar *s1, int32_t length1,
const UChar *s2, int32_t length2,
uint32_t options,
UErrorCode *pErrorCode);
#endif /* #if !UCONFIG_NO_NORMALIZATION */
#endif
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