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# Character
[CORE API]

Character objects and API for them. More...

## Variables: Keys of character properties
These symbols are used as keys of character properties.
MSymbol | Mscript
| Key for script.
MSymbol | Mname
| Key for character name.
MSymbol | Mcategory
| Key for general category.
MSymbol | Mcombining_class
| Key for canonical combining class.
MSymbol | Mbidi_category
| Key for bidi category.
MSymbol | Msimple_case_folding
| Key for corresponding single lowercase character.
MSymbol | Mcomplicated_case_folding
| Key for corresponding multiple lowercase characters.
MSymbol | Mcased
| Key for values used in case operation.
MSymbol | Msoft_dotted
| Key for values used in case operation.
MSymbol | Mcase_mapping
| Key for values used in case operation.
MSymbol | Mblock
| Key for script block name.
## Defines
#define | MCHAR_MAX
| Maximum character code.
## Functions
MSymbol | mchar_define_property (const char *name, MSymbol type)
| Define a character property.
void * | mchar_get_prop (int c, MSymbol key)
| Get the value of a character property.
int | mchar_put_prop (int c, MSymbol key, void *val)
| Set the value of a character property.
MCharTable * | mchar_get_prop_table (MSymbol key, MSymbol *type)
| Get the char-table for a character property.

## Detailed Description

Character objects and API for them.

The m17n library represents a character by a character code (an integer). The minimum character code is `0`. The maximum character code is defined by the macro MCHAR_MAX. It is assured that MCHAR_MAX is not smaller than `0x3FFFFF` (22 bits).

Characters `0` to `0x10FFFF` are equivalent to the Unicode characters of the same code values.

A character can have zero or more properties called character properties. A character property consists of a key and a value, where key is a symbol and value is anything that can be cast to `(void *)`. "The character property that belongs to character C and whose key is K" may be shortened to "the K property of C".

## Define Documentation

#define MCHAR_MAX

Maximum character code.

The macro MCHAR_MAX gives the maximum character code.

## Function Documentation

MSymbol mchar_define_property | ( | const char * | name,
|  | MSymbol | type |
| ) |  |  |

Define a character property.

The mchar_define_property() function searches the m17n database for a data whose tags are <Mchar_table, type, sym >. Here, sym is a symbol whose name is name. type must be Mstring, Mtext, Msymbol, Minteger, or Mplist.

Return value:
  If the operation was successful, mchar_define_property() returns sym. Otherwise it returns Mnil.

Errors:
  `MERROR_DB`

See Also:
  mchar_get_prop(), mchar_put_prop()

void* mchar_get_prop | ( | int | c,
|  | MSymbol | key |
| ) |  |  |

Get the value of a character property.

The mchar_get_prop() function searches character c for the character property whose key is key.

Return value:
  If the operation was successful, mchar_get_prop() returns the value of the character property. Otherwise it returns `NULL`.

Errors:
  `MERROR_SYMBOL`, `MERROR_DB`

See Also:
  mchar_define_property(), mchar_put_prop()

MCharTable* mchar_get_prop_table | ( | MSymbol | key,
|  | MSymbol * | type |
| ) |  |  |

Get the char-table for a character property.

The mchar_get_prop_table() function returns a char-table that contains the character property whose key is key. If type is not NULL, this function stores the type of the property in the place pointed by type. See mchar_define_property() for types of character property.

Return value:
  If key is a valid character property key, this function returns a char-table. Otherwise NULL is retuned.

int mchar_put_prop | ( | int | c,
|  | MSymbol | key,
|  | void * | val |
| ) |  |  |

Set the value of a character property.

The mchar_put_prop() function searches character c for the character property whose key is key and assigns val to the value of the found property.

Return value:
  If the operation was successful, mchar_put_prop() returns 0. Otherwise, it returns -1.

Errors:
  `MERROR_SYMBOL`, `MERROR_DB`

See Also:
  mchar_define_property(), mchar_get_prop()

## Variable Documentation

MSymbol Mbidi_category

Key for bidi category.

The symbol Mbidi_category has the name `"bidi-category"` and is used as the key of a character property. The value of such a property is a symbol that represents the bidirectional category of the character.

Each symbol that represents a bidirectional category has one of the names listed as types of Bidirectional Category in Unicode.

MSymbol Mblock

Key for script block name.

The symbol Mblock the name `"block"` and is used as the key of charater property. The value of such a property is a symbol representing a script block of the corresponding character.

MSymbol Mcase_mapping

Key for values used in case operation.

The symbol Mcase_mapping has the name `"case-mapping"` and is used as the key of charater property. The value of such a property is a plist of three M-Texts; lower, title, and upper of the corresponding character. See the Unicode Standard 5.0 (Section 5.18 Case Mappings) for the detail.

MSymbol Mcased

Key for values used in case operation.

The symbol Mcased has the name `"cased"` and is used as the key of charater property. The value of such a property is an integer value 1, 2, or 3 representing "cased", "case-ignorable", and both of them respective. See the Unicode Standard 5.0 (Section 3.13 Default Case Algorithm) for the detail.

MSymbol Mcategory

Key for general category.

The symbol Mcategory has the name `"category"` and is used as the key of a character property. The value of such a property is a symbol representing the general category of the character.

Each symbol that represents a general category has one of the names listed as abbreviations for General Category in Unicode.

MSymbol Mcombining_class

Key for canonical combining class.

The symbol Mcombining_class has the name `"combining-class"` and is used as the key of a character property. The value of such a property is an integer that represents the canonical combining class of the character.

The meaning of each integer that represents a canonical combining class is identical to the one defined in Unicode.

MSymbol Mcomplicated_case_folding

Key for corresponding multiple lowercase characters.

The symbol Mcomplicated_case_folding has the name `"complicated-case-folding"` and is used as the key of a character property. The value of such a property is the corresponding M-text that contains a sequence of lowercase characters to be used for comparing M-texts ignoring case.

MSymbol Mname

Key for character name.

The symbol Mname has the name `"name"` and is used as the key of a character property. The value of such a property is a C-string representing the name of the character.

MSymbol Mscript

Key for script.

The symbol Mscript has the name `"script"` and is used as the key of a character property. The value of such a property is a symbol representing the script to which the character belongs.

Each symbol that represents a script has one of the names listed in the Unicode Technical Report #24.

MSymbol Msimple_case_folding

Key for corresponding single lowercase character.

The symbol Msimple_case_folding has the name `"simple-case-folding"` and is used as the key of a character property. The value of such a property is the corresponding single lowercase character that is used when comparing M-texts ignoring cases.

If a character requires a complicated comparison (i.e. cannot be compared by simply mapping to another single character), the value of such a property is `0xFFFF`. In this case, the character has another property whose key is Mcomplicated_case_folding.

MSymbol Msoft_dotted

Key for values used in case operation.

The symbol Msoft_dotted has the name `"soft-dotted"` and is used as the key of charater property. The value of such a property is Mt if a character has "Soft_Dotted" property, and Mnil otherwise. See the Unicode Standard 5.0 (Section 3.13 Default Case Algorithm) for the detail.

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