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<unictype.h> This include file declares functions that classify Unicode characters and that test whether Unicode characters have specific properties.
The classification assigns a “general category” to every Unicode
character. This is similar to the classification provided by ISO C in
<wctype.h>.
Properties are the data that guides various text processing algorithms in the presence of specific Unicode characters.
Every Unicode character or code point has a general category assigned to it. This classification is important for most algorithms that work on Unicode text.
The GNU libunistring library provides two kinds of API for working with
general categories. The object oriented API uses a variable to denote
every predefined general category value or combinations thereof. The
low-level API uses a bit mask instead. The advantage of the object oriented
API is that if only a few predefined general category values are used,
the data tables are relatively small. When you combine general category
values (using uc_general_category_or, uc_general_category_and,
or uc_general_category_and_not), or when you use the low level
bit masks, a big table is used thats holds the complete general category
information for all Unicode characters.
This data type denotes a general category value. It is an immediate type that can be copied by simple assignment, without involving memory allocation. It is not an array type.
The following are the predefined general category value. Additional general categories may be added in the future.
The UC_CATEGORY_* constants reflect the systematic general category
values assigned by the Unicode Consortium. Whereas the other UC_*
macros are aliases, for use when readable code is preferred.
This represents the general category “Letter”.
This represents the general category “Letter, uppercase”.
This represents the general category “Letter, lowercase”.
This represents the general category “Letter, titlecase”.
This represents the general category “Letter, modifier”.
This represents the general category “Letter, other”.
This represents the general category “Marker”.
This represents the general category “Marker, nonspacing”.
This represents the general category “Marker, spacing combining”.
This represents the general category “Marker, enclosing”.
This represents the general category “Number”.
This represents the general category “Number, decimal digit”.
This represents the general category “Number, letter”.
This represents the general category “Number, other”.
This represents the general category “Punctuation”.
This represents the general category “Punctuation, connector”.
This represents the general category “Punctuation, dash”.
This represents the general category “Punctuation, open”, a.k.a. “start punctuation”.
This represents the general category “Punctuation, close”, a.k.a. “end punctuation”.
This represents the general category “Punctuation, initial quote”.
This represents the general category “Punctuation, final quote”.
This represents the general category “Punctuation, other”.
This represents the general category “Symbol”.
This represents the general category “Symbol, math”.
This represents the general category “Symbol, currency”.
This represents the general category “Symbol, modifier”.
This represents the general category “Symbol, other”.
This represents the general category “Separator”.
This represents the general category “Separator, space”.
This represents the general category “Separator, line”.
This represents the general category “Separator, paragraph”.
This represents the general category “Other”.
This represents the general category “Other, control”.
This represents the general category “Other, format”.
This represents the general category “Other, surrogate”. All code points in this category are invalid characters.
This represents the general category “Other, private use”.
This represents the general category “Other, not assigned”. Some code points in this category are invalid characters.
The following functions combine general categories, like in a boolean algebra, except that there is no ‘not’ operation.
Returns the union of two general categories. This corresponds to the unions of the two sets of characters.
Returns the intersection of two general categories as bit masks. This does not correspond to the intersection of the two sets of characters.
Returns the intersection of a general category with the complement of a second general category, as bit masks. This does not correspond to the intersection with complement, when viewing the categories as sets of characters.
The following functions associate general categories with their name.
Returns the name of a general category, more precisely, the abbreviated name. Returns NULL if the general category corresponds to a bit mask that does not have a name.
Returns the long name of a general category. Returns NULL if the general category corresponds to a bit mask that does not have a name.
Returns the general category given by name, e.g. "Lu", or by long
name, e.g. "Uppercase Letter".
This lookup ignores spaces, underscores, or hyphens as word separators and is
case-insignificant.
The following functions view general categories as sets of Unicode characters.
Returns the general category of a Unicode character.
This function uses a big table.
Tests whether a Unicode character belongs to a given category. The category argument can be a predefined general category or the combination of several predefined general categories.
The following are the predefined general category value as bit masks. Additional general categories may be added in the future.
The following function views general categories as sets of Unicode characters.
Tests whether a Unicode character belongs to a given category. The bitmask argument can be a predefined general category bitmask or the combination of several predefined general category bitmasks.
This function uses a big table comprising all general categories.
Every Unicode character or code point has a canonical combining class assigned to it.
What is the meaning of the canonical combining class? Essentially, it indicates the priority with which a combining character is attached to its base character. The characters for which the canonical combining class is 0 are the base characters, and the characters for which it is greater than 0 are the combining characters. Combining characters are rendered near/attached/around their base character, and combining characters with small combining classes are attached "first" or "closer" to the base character.
The canonical combining class of a character is a number in the range 0..255. The possible values are described in the Unicode Character Database http://www.unicode.org/Public/UNIDATA/UCD.html. The list here is not definitive; more values can be added in future versions.
The canonical combining class value for “Not Reordered” characters. The value is 0.
The canonical combining class value for “Overlay” characters.
The canonical combining class value for “Nukta” characters.
The canonical combining class value for “Kana Voicing” characters.
The canonical combining class value for “Virama” characters.
The canonical combining class value for “Attached Below Left” characters.
The canonical combining class value for “Attached Below” characters.
The canonical combining class value for “Attached Above” characters.
The canonical combining class value for “Attached Above Right” characters.
The canonical combining class value for “Below Left” characters.
The canonical combining class value for “Below” characters.
The canonical combining class value for “Below Right” characters.
The canonical combining class value for “Left” characters.
The canonical combining class value for “Right” characters.
The canonical combining class value for “Above Left” characters.
The canonical combining class value for “Above” characters.
The canonical combining class value for “Above Right” characters.
The canonical combining class value for “Double Below” characters.
The canonical combining class value for “Double Above” characters.
The canonical combining class value for “Iota Subscript” characters.
The following functions associate canonical combining classes with their name.
Returns the name of a canonical combining class, more precisely, the abbreviated name. Returns NULL if the canonical combining class is a numeric value without a name.
Returns the long name of a canonical combining class. Returns NULL if the canonical combining class is a numeric value without a name.
Returns the canonical combining class given by name, e.g. "BL", or by
long name, e.g. "Below Left".
This lookup ignores spaces, underscores, or hyphens as word separators and is
case-insignificant.
The following function looks up the canonical combining class of a character.
Returns the canonical combining class of a Unicode character.
Every Unicode character or code point has a bidi class assigned to it. Before Unicode 4.0, this concept was known as bidirectional category.
The bidi class guides the bidirectional algorithm (http://www.unicode.org/reports/tr9/). The possible values are the following.
The bidi class for `Left-to-Right`” characters.
The bidi class for “Left-to-Right Embedding” characters.
The bidi class for “Left-to-Right Override” characters.
The bidi class for “Right-to-Left” characters.
The bidi class for “Right-to-Left Arabic” characters.
The bidi class for “Right-to-Left Embedding” characters.
The bidi class for “Right-to-Left Override” characters.
The bidi class for “Pop Directional Format” characters.
The bidi class for “European Number” characters.
The bidi class for “European Number Separator” characters.
The bidi class for “European Number Terminator” characters.
The bidi class for “Arabic Number” characters.
The bidi class for “Common Number Separator” characters.
The bidi class for “Non-Spacing Mark” characters.
The bidi class for “Boundary Neutral” characters.
The bidi class for “Paragraph Separator” characters.
The bidi class for “Segment Separator” characters.
The bidi class for “Whitespace” characters.
The bidi class for “Other Neutral” characters.
The following functions implement the association between a bidirectional category and its name.
Returns the name of a bidi class, more precisely, the abbreviated name.
Returns the long name of a bidi class.
Returns the bidi class given by name, e.g. "LRE", or by long name,
e.g. "Left-to-Right Embedding".
This lookup ignores spaces, underscores, or hyphens as word separators and is
case-insignificant.
The following functions view bidirectional categories as sets of Unicode characters.
Returns the bidi class of a Unicode character.
Tests whether a Unicode character belongs to a given bidi class.
Decimal digits (like the digits from ‘0’ to ‘9’) exist in many scripts. The following function converts a decimal digit character to its numerical value.
Returns the decimal digit value of a Unicode character. The return value is an integer in the range 0..9, or -1 for characters that do not represent a decimal digit.
Digit characters are like decimal digit characters, possibly in special forms, like as superscript, subscript, or circled. The following function converts a digit character to its numerical value.
Returns the digit value of a Unicode character. The return value is an integer in the range 0..9, or -1 for characters that do not represent a digit.
There are also characters that represent numbers without a digit system, like the Roman numerals, and fractional numbers, like 1/4 or 3/4.
The following type represents the numeric value of a Unicode character.
This is a structure type with the following fields:
int numerator; int denominator; |
An integer n is represented by numerator = n,
denominator = 1.
The following function converts a number character to its numerical value.
Returns the numeric value of a Unicode character.
The return value is a fraction, or the pseudo-fraction { 0, 0 } for
characters that do not represent a number.
Character mirroring is used to associate the closing parenthesis character to the opening parenthesis character, the closing brace character with the opening brace character, and so on.
The following function looks up the mirrored character of a Unicode character.
Stores the mirrored character of a Unicode character uc in
*puc and returns true, if it exists. Otherwise it
stores uc unmodified in *puc and returns false.
When Arabic characters are rendered, after bidi reordering has taken place, the shape of the glyphs are modified so that many adjacent glyphs are joined. Two character properties describe how this “Arabic shaping” takes place: the joining type and the joining group.
The joining type of a character describes on which of the left and right neighbour characters the character's shape depends, and which of the two neighbour characters are rendered depending on this character.
The joining type has the following possible values:
“Non joining”: Characters of this joining type prohibit joining.
“Transparent”: Characters of this joining type are skipped when considering joining.
“Join causing”: Characters of this joining type cause their neighbour characters to change their shapes but don't change their own shape.
“Left joining”: Characters of this joining type have two shapes, isolated and initial. Such characters currently don't exist.
“Right joining”: Characters of this joining type have two shapes, isolated and final.
“Dual joining”: Characters of this joining type have four shapes, initial, medial, final, and isolated.
The following functions implement the association between a joining type and its name.
Returns the name of a joining type.
Returns the long name of a joining type.
Returns the joining type given by name, e.g. "D", or by long name,
e.g. "Dual Joining.
This lookup ignores spaces, underscores, or hyphens as word separators and is
case-insignificant.
The following function gives the joining type of every Unicode character.
Returns the joining type of a Unicode character.
The joining group of a character describes how the character's shape is modified in the four contexts of dual-joining characters or in the two contexts of right-joining characters.
The joining group has the following possible values:
The following functions implement the association between a joining group and its name.
Returns the name of a joining group.
Returns the joining group given by name, e.g. "Teh_Marbuta".
This lookup ignores spaces, underscores, or hyphens as word separators and is
case-insignificant.
The following function gives the joining group of every Unicode character.
Returns the joining group of a Unicode character.
This section defines boolean properties of Unicode characters. This means, a character either has the given property or does not have it. In other words, the property can be viewed as a subset of the set of Unicode characters.
The GNU libunistring library provides two kinds of API for working with
properties. The object oriented API uses a type uc_property_t
to designate a property. In the function-based API, which is a bit more
low level, a property is merely a function.
The following type designates a property on Unicode characters.
This data type denotes a boolean property on Unicode characters. It is an immediate type that can be copied by simple assignment, without involving memory allocation. It is not an array type.
Many Unicode properties are predefined.
The following are general properties.
The following properties are related to case folding.
The following properties are related to identifiers.
The following properties have an influence on shaping and rendering.
The following properties relate to bidirectional reordering.
The following properties deal with number representations.
The following properties deal with CJK.
Other miscellaneous properties are:
The following function looks up a property by its name.
Returns the property given by name, e.g. "White space". If a property
with the given name exists, the result will satisfy the
uc_property_is_valid predicate. Otherwise the result will not satisfy
this predicate and must not be passed to functions that expect an
uc_property_t argument.
This lookup ignores spaces, underscores, or hyphens as word separators, is case-insignificant, and supports the aliases listed in Unicode's ‘PropertyAliases.txt’ file.
This function references a big table of all predefined properties. Its use can significantly increase the size of your application.
Returns true when the given property is valid, or false
otherwise.
The following function views a property as a set of Unicode characters.
Tests whether the Unicode character uc has the given property.
The following are general properties.
The following properties are related to case folding.
The following properties are related to identifiers.
The following properties have an influence on shaping and rendering.
The following properties relate to bidirectional reordering.
The following properties deal with number representations.
The following properties deal with CJK.
Other miscellaneous properties are:
The Unicode characters are subdivided into scripts.
The following type is used to represent a script:
This data type is a structure type that refers to statically allocated read-only data. It contains the following fields:
const char *name; |
The name field contains the name of the script.
The following functions look up a script.
Returns the script of a Unicode character. Returns NULL if uc does not belong to any script.
Returns the script given by its name, e.g. "HAN". Returns NULL if a
script with the given name does not exist.
The following function views a script as a set of Unicode characters.
Tests whether a Unicode character belongs to a given script.
The following gives a global picture of all scripts.
Get the list of all scripts. Stores a pointer to an array of all scripts in
*scripts and the length of this array in *count.
The Unicode characters are subdivided into blocks. A block is an interval of Unicode code points.
The following type is used to represent a block.
This data type is a structure type that refers to statically allocated data. It contains the following fields:
ucs4_t start; ucs4_t end; const char *name; |
The start field is the first Unicode code point in the block.
The end field is the last Unicode code point in the block.
The name field is the name of the block.
The following function looks up a block.
Returns the block a character belongs to.
The following function views a block as a set of Unicode characters.
Tests whether a Unicode character belongs to a given block.
The following gives a global picture of all block.
Get the list of all blocks. Stores a pointer to an array of all blocks in
*blocks and the length of this array in *count.
The following properties are taken from language standards. The supported language standards are ISO C 99 and Java.
Tests whether a Unicode character is considered whitespace in ISO C 99.
Tests whether a Unicode character is considered whitespace in Java.
The following enumerated values are the possible return values of the functions
uc_c_ident_category and uc_java_ident_category.
This return value means that the given character is valid as first or subsequent character in an identifier.
This return value means that the given character is valid as subsequent character only.
This return value means that the given character is not valid in an identifier.
This return value (only for Java) means that the given character is ignorable.
The following function determine whether a given character can be a constituent of an identifier in the given programming language.
Returns the categorization of a Unicode character with respect to the ISO C 99 identifier syntax.
Returns the categorization of a Unicode character with respect to the Java identifier syntax.
The following character classifications mimic those declared in the ISO C
header files <ctype.h> and <wctype.h>. These functions are
deprecated, because this set of functions was designed with ASCII in mind and
cannot reflect the more diverse reality of the Unicode character set. But
they can be a quick-and-dirty porting aid when migrating from wchar_t
APIs to Unicode strings.
Tests for any character for which uc_is_alpha or uc_is_digit is
true.
Tests for any character for which uc_is_upper or uc_is_lower is
true, or any character that is one of a locale-specific set of characters for
which none of uc_is_cntrl, uc_is_digit, uc_is_punct, or
uc_is_space is true.
Tests for any control character.
Tests for any character that corresponds to a decimal-digit character.
Tests for any character for which uc_is_print is true and
uc_is_space is false.
Tests for any character that corresponds to a lowercase letter or is one
of a locale-specific set of characters for which none of uc_is_cntrl,
uc_is_digit, uc_is_punct, or uc_is_space is true.
Tests for any printing character.
Tests for any printing character that is one of a locale-specific set of
characters for which neither uc_is_space nor uc_is_alnum is true.
Test for any character that corresponds to a locale-specific set of characters
for which none of uc_is_alnum, uc_is_graph, or uc_is_punct
is true.
Tests for any character that corresponds to an uppercase letter or is one
of a locale-specific set of characters for which none of uc_is_cntrl,
uc_is_digit, uc_is_punct, or uc_is_space is true.
Tests for any character that corresponds to a hexadecimal-digit character.
Tests for any character that corresponds to a standard blank character or
a locale-specific set of characters for which uc_is_alnum is false.
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