src/linebreak.c File Reference

Implementation of the line breaking algorithm as described in Unicode Standard Annex 14. More...

#include <assert.h>
#include <stddef.h>
#include <string.h>
#include "linebreak.h"
#include "linebreakdef.h"

Include dependency graph for linebreak.c:

Data Structures
struct	LineBreakPropertiesIndex
	Struct for the second-level index to the line breaking properties. More...
Defines
#define	LINEBREAK_UNDEFINED -1
	Special value used internally to indicate an undefined break result.
#define	LINEBREAK_INDEX_SIZE 40
	Size of the second-level index to the line breaking properties.
Enumerations
enum	BreakAction { DIR_BRK, IND_BRK, CMI_BRK, CMP_BRK, PRH_BRK }
	Enumeration of break actions. More...
Functions
void	init_linebreak (void)
	Initializes the second-level index to the line breaking properties.
static struct LineBreakProperties *	get_lb_prop_lang (const char *lang)
	Gets the language-specific line breaking properties.
static enum LineBreakClass	get_char_lb_class (utf32_t ch, struct LineBreakProperties *lbp)
	Gets the line breaking class of a character from a line breaking properties array.
static enum LineBreakClass	get_char_lb_class_default (utf32_t ch)
	Gets the line breaking class of a character from the default line breaking properties array.
static enum LineBreakClass	get_char_lb_class_lang (utf32_t ch, struct LineBreakProperties *lbpLang)
	Gets the line breaking class of a character for a specific language.
static enum LineBreakClass	resolve_lb_class (enum LineBreakClass lbc, const char *lang)
	Resolves the line breaking class for certain ambiguous or complicated characters.
static void	treat_first_char (struct LineBreakContext *lbpCtx)
	Treats specially for the first character in a line.
static int	get_lb_result_simple (struct LineBreakContext *lbpCtx)
	Tries telling the line break opportunity by simple rules.
static int	get_lb_result_lookup (struct LineBreakContext *lbpCtx)
	Tells the line break opportunity by table lookup.
void	lb_init_break_context (struct LineBreakContext lbpCtx, utf32_t ch, const char lang)
	Initializes line breaking context for a given language.
int	lb_process_next_char (struct LineBreakContext *lbpCtx, utf32_t ch)
	Updates LineBreakingContext for the next code point and returns the detected break.
void	set_linebreaks (const void s, size_t len, const char lang, char *brks, get_next_char_t get_next_char)
	Sets the line breaking information for a generic input string.
void	set_linebreaks_utf8 (const utf8_t s, size_t len, const char lang, char *brks)
	Sets the line breaking information for a UTF-8 input string.
void	set_linebreaks_utf16 (const utf16_t s, size_t len, const char lang, char *brks)
	Sets the line breaking information for a UTF-16 input string.
void	set_linebreaks_utf32 (const utf32_t s, size_t len, const char lang, char *brks)
	Sets the line breaking information for a UTF-32 input string.
int	is_line_breakable (utf32_t char1, utf32_t char2, const char *lang)
	Tells whether a line break can occur between two Unicode characters.
Variables
static enum BreakAction	baTable [LBP_RI][LBP_RI]
	Break action pair table.
static struct LineBreakPropertiesIndex	lb_prop_index [LINEBREAK_INDEX_SIZE]
	Second-level index to the line breaking properties.

Detailed Description

Implementation of the line breaking algorithm as described in Unicode Standard Annex 14.

Version:: 3.0, 2015/05/10

Author:: Wu Yongwei; Petr Filipsky

Define Documentation

#define LINEBREAK_INDEX_SIZE 40

Size of the second-level index to the line breaking properties.

#define LINEBREAK_UNDEFINED -1

Special value used internally to indicate an undefined break result.

Enumeration Type Documentation

enum BreakAction

Enumeration of break actions.

They are used in the break action pair table below.

Enumerator:

DIR_BRK	Direct break opportunity.
IND_BRK	Indirect break opportunity.
CMI_BRK	Indirect break opportunity for combining marks.
CMP_BRK	Prohibited break for combining marks.
PRH_BRK	Prohibited break.

Function Documentation

static enum LineBreakClass get_char_lb_class	(	utf32_t	ch,
		struct LineBreakProperties *	lbp
	)			`[static]`

Gets the line breaking class of a character from a line breaking properties array.

Parameters:

	ch	character to check
	lbp	pointer to the line breaking properties array

Returns:: the line breaking class if found; LBP_XX otherwise

static enum LineBreakClass get_char_lb_class_default ( utf32_t ch ) [static]

Gets the line breaking class of a character from the default line breaking properties array.

Parameters:

ch

character to check

Returns:: the line breaking class if found; LBP_XX otherwise

static enum LineBreakClass get_char_lb_class_lang	(	utf32_t	ch,
		struct LineBreakProperties *	lbpLang
	)			`[static]`

Gets the line breaking class of a character for a specific language.

This function will check the language-specific data first, and then the default data if there is no language-specific property available for the character.

Parameters:

	ch	character to check
	lbpLang	pointer to the language-specific line breaking properties array

Returns:: the line breaking class if found; LBP_XX otherwise

static struct LineBreakProperties* get_lb_prop_lang ( const char * lang ) [static, read]

Gets the language-specific line breaking properties.

Parameters:

lang

language of the text

Returns:: pointer to the language-specific line breaking properties array if found; NULL otherwise

static int get_lb_result_lookup ( struct LineBreakContext * lbpCtx ) [static]

Tells the line break opportunity by table lookup.

Parameters:

[in,out] lbpCtx pointer to the line breaking context

Precondition:: lbpCtx->lbcCur has the current line break class; lbpCtx->lbcLast has the line break class for the last character; and lbcCur->lbcNew has the line break class for the next character

Postcondition:: lbpCtx->lbcCur has the updated line break class

Returns:: break result, one of LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, and LINEBREAK_NOBREAK

static int get_lb_result_simple ( struct LineBreakContext * lbpCtx ) [static]

Tries telling the line break opportunity by simple rules.

Parameters:

[in,out] lbpCtx pointer to the line breaking context

Precondition:: lbpCtx->lbcCur has the current line break class; and lbpCtx->lbcNew has the line break class for the next character

Postcondition:: lbpCtx->lbcCur has the updated line break class

Returns:: break result, one of LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, and LINEBREAK_NOBREAK if identified; or LINEBREAK_UNDEFINED if table lookup is needed

void init_linebreak ( void )

Initializes the second-level index to the line breaking properties.

If it is not called, the performance of get_char_lb_class_lang (and thus the main functionality) can be pretty bad, especially for big code points like those of Chinese.

int is_line_breakable	(	utf32_t	char1,
		utf32_t	char2,
		const char *	lang
	)

Tells whether a line break can occur between two Unicode characters.

This is a wrapper function to expose a simple interface. Generally speaking, it is better to use set_linebreaks_utf32 instead, since complicated cases involving combining marks, spaces, etc. cannot be correctly processed.

Parameters:

	char1	the first Unicode character
	char2	the second Unicode character
	lang	language of the input

Returns:: one of LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, LINEBREAK_NOBREAK, or LINEBREAK_INSIDEACHAR

void lb_init_break_context	(	struct LineBreakContext *	lbpCtx,
		utf32_t	ch,
		const char *	lang
	)

Initializes line breaking context for a given language.

Parameters:

`[in,out]`	lbpCtx	pointer to the line breaking context
`[in]`	ch	the first character to process
`[in]`	lang	language of the input

Postcondition:: the line breaking context is initialized

int lb_process_next_char	(	struct LineBreakContext *	lbpCtx,
		utf32_t	ch
	)

Updates LineBreakingContext for the next code point and returns the detected break.

Parameters:

`[in,out]`	lbpCtx	pointer to the line breaking context
`[in]`	ch	Unicode code point

Returns:: break result, one of LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, and LINEBREAK_NOBREAK

Postcondition:: the line breaking context is updated

static enum LineBreakClass resolve_lb_class	(	enum LineBreakClass	lbc,
		const char *	lang
	)			`[static]`

Resolves the line breaking class for certain ambiguous or complicated characters.

They are treated in a simplistic way in this implementation.

Parameters:

	lbc	line breaking class to resolve
	lang	language of the text

Returns:: the resolved line breaking class

void set_linebreaks	(	const void *	s,
		size_t	len,
		const char *	lang,
		char *	brks,
		get_next_char_t	get_next_char
	)

Sets the line breaking information for a generic input string.

Parameters:

`[in]`	s	input string
`[in]`	len	length of the input
`[in]`	lang	language of the input
`[out]`	brks	pointer to the output breaking data, containing LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, LINEBREAK_NOBREAK, or LINEBREAK_INSIDEACHAR
`[in]`	get_next_char	function to get the next UTF-32 character

void set_linebreaks_utf16	(	const utf16_t *	s,
		size_t	len,
		const char *	lang,
		char *	brks
	)

Sets the line breaking information for a UTF-16 input string.

Parameters:

`[in]`	s	input UTF-16 string
`[in]`	len	length of the input
`[in]`	lang	language of the input
`[out]`	brks	pointer to the output breaking data, containing LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, LINEBREAK_NOBREAK, or LINEBREAK_INSIDEACHAR

void set_linebreaks_utf32	(	const utf32_t *	s,
		size_t	len,
		const char *	lang,
		char *	brks
	)

Sets the line breaking information for a UTF-32 input string.

Parameters:

`[in]`	s	input UTF-32 string
`[in]`	len	length of the input
`[in]`	lang	language of the input
`[out]`	brks	pointer to the output breaking data, containing LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, LINEBREAK_NOBREAK, or LINEBREAK_INSIDEACHAR

void set_linebreaks_utf8	(	const utf8_t *	s,
		size_t	len,
		const char *	lang,
		char *	brks
	)

Sets the line breaking information for a UTF-8 input string.

Parameters:

`[in]`	s	input UTF-8 string
`[in]`	len	length of the input
`[in]`	lang	language of the input
`[out]`	brks	pointer to the output breaking data, containing LINEBREAK_MUSTBREAK, LINEBREAK_ALLOWBREAK, LINEBREAK_NOBREAK, or LINEBREAK_INSIDEACHAR

static void treat_first_char ( struct LineBreakContext * lbpCtx ) [static]

Treats specially for the first character in a line.

Parameters:

[in,out] lbpCtx pointer to the line breaking context

Precondition:: lbpCtx->lbcCur has a valid line break class

Postcondition:: lbpCtx->lbcCur has the updated line break class

Variable Documentation

enum BreakAction baTable[LBP_RI][LBP_RI] [static]

Break action pair table.

This is a direct mapping of Table 2 of Unicode Standard Annex 14, Revision 30.

struct LineBreakPropertiesIndex lb_prop_index[LINEBREAK_INDEX_SIZE] [static]

Initial value:

{
    { 0xFFFFFFFF, lb_prop_default }
}

Second-level index to the line breaking properties.

src/linebreak.c File Reference

Data Structures

Defines

Enumerations

Functions

Variables

Detailed Description

Define Documentation

Enumeration Type Documentation

Function Documentation

Variable Documentation