icuplug.h File Reference

C API: ICU Plugin API. More...

#include "unicode/utypes.h"

Go to the source code of this file.

Defines

#define UPLUG_TOKEN   0x54762486
 Random Token to identify a valid ICU plugin.
#define UPLUG_NAME_MAX   100
 Max width of names, symbols, and configuration strings.

Typedefs

typedef uint32_t UPlugTokenReturn
 Return value from a plugin entrypoint.
typedef UPlugTokenReturnUPlugEntrypoint )(UPlugData *plug, UPlugReason reason, UErrorCode *status)
 Entrypoint for an ICU plugin.



typedef struct UPlugData UPlugData

Enumerations

enum  UPlugReason { UPLUG_REASON_QUERY = 0, UPLUG_REASON_LOAD = 1, UPLUG_REASON_UNLOAD = 2, UPLUG_REASON_COUNT }
 

Reason code for the entrypoint's call.

More...
enum  UPlugLevel {
  UPLUG_LEVEL_INVALID = 0, UPLUG_LEVEL_UNKNOWN = 1, UPLUG_LEVEL_LOW = 2, UPLUG_LEVEL_HIGH = 3,
  UPLUG_LEVEL_COUNT
}
 

Level of plugin loading INITIAL: UNKNOWN QUERY: INVALID -> { LOW | HIGH } ERR -> INVALID.

More...

Functions

U_CAPI void uplug_setPlugNoUnload (UPlugData *plug, UBool dontUnload)
 Request that this plugin not be unloaded at cleanup time.
U_CAPI void uplug_setPlugLevel (UPlugData *plug, UPlugLevel level)
 Set the level of this plugin.
U_CAPI UPlugLevel uplug_getPlugLevel (UPlugData *plug)
 Get the level of this plugin.
U_CAPI UPlugLevel uplug_getCurrentLevel ()
 Get the lowest level of plug which can currently load.
U_CAPI UErrorCode uplug_getPlugLoadStatus (UPlugData *plug)
 Get plug load status.
U_CAPI void uplug_setPlugName (UPlugData *plug, const char *name)
 Set the human-readable name of this plugin.
U_CAPI const char * uplug_getPlugName (UPlugData *plug)
 Get the human-readable name of this plugin.
U_CAPI const char * uplug_getSymbolName (UPlugData *plug)
 Return the symbol name for this plugin, if known.
U_CAPI const char * uplug_getLibraryName (UPlugData *plug, UErrorCode *status)
 Return the library name for this plugin, if known.
U_CAPI void * uplug_getLibrary (UPlugData *plug)
 Return the library used for this plugin, if known.
U_CAPI void * uplug_getContext (UPlugData *plug)
 Return the plugin-specific context data.
U_CAPI void uplug_setContext (UPlugData *plug, void *context)
 Set the plugin-specific context data.
U_CAPI const char * uplug_getConfiguration (UPlugData *plug)
 Get the configuration string, if available.
U_CAPI UPlugData * uplug_nextPlug (UPlugData *prior)
 Return all currently installed plugins, from newest to oldest Usage Example:.
U_CAPI UPlugData * uplug_loadPlugFromEntrypoint (UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status)
 Inject a plugin as if it were loaded from a library.
U_CAPI UPlugData * uplug_loadPlugFromLibrary (const char *libName, const char *sym, const char *config, UErrorCode *status)
 Inject a plugin from a library, as if the information came from a config file.
U_CAPI void uplug_removePlug (UPlugData *plug, UErrorCode *status)
 Remove a plugin.

Detailed Description

C API: ICU Plugin API.

C API: ICU Plugin API

C API allowing run-time loadable modules that extend or modify ICU functionality.

Loading and Configuration

At ICU startup time, the environment variable "ICU_PLUGINS" will be queried for a directory name. If it is not set, the preprocessor symbol "DEFAULT_ICU_PLUGINS" will be checked for a default value.

Within the above-named directory, the file "icuplugins##.txt" will be opened, if present, where ## is the major+minor number of the currently running ICU (such as, 44 for ICU 4.4, thus icuplugins44.txt)

The configuration file has this format:

An example configuration file is, in its entirety:

 # this is icuplugins44.txt
 testplug.dll    myPlugin        hello=world

Plugins are categorized as "high" or "low" level. Low level are those which must be run BEFORE high level plugins, and before any operations which cause ICU to be 'initialized'. If a plugin is low level but causes ICU to allocate memory or become initialized, that plugin is said to cause a 'level change'.

At load time, ICU first queries all plugins to determine their level, then loads all 'low' plugins first, and then loads all 'high' plugins. Plugins are otherwise loaded in the order listed in the configuration file.

Implementing a Plugin

 U_CAPI UPlugTokenReturn U_EXPORT2 
 myPlugin (UPlugData *plug, UPlugReason reason, UErrorCode *status) {
   if(reason==UPLUG_REASON_QUERY) {
      uplug_setPlugName(plug, "Simple Plugin");
      uplug_setPlugLevel(plug, UPLUG_LEVEL_HIGH);
    } else if(reason==UPLUG_REASON_LOAD) {
       ... Set up some ICU things here.... 
    } else if(reason==UPLUG_REASON_UNLOAD) {
       ... unload, clean up ...
    }
   return UPLUG_TOKEN;
  }

The UPlugData* is an opaque pointer to the plugin-specific data, and is used in all other API calls.

The API contract is:

  1. The plugin MUST always return UPLUG_TOKEN as a return value- to indicate that it is a valid plugin.

  2. When the 'reason' parameter is set to UPLUG_REASON_QUERY, the plugin MUST call uplug_setPlugLevel() to indicate whether it is a high level or low level plugin.

  3. When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin SHOULD call uplug_setPlugName to indicate a human readable plugin name.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition in file icuplug.h.


Define Documentation

#define UPLUG_NAME_MAX   100

Max width of names, symbols, and configuration strings.

Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 136 of file icuplug.h.

#define UPLUG_TOKEN   0x54762486

Random Token to identify a valid ICU plugin.

Plugins must return this from the entrypoint.

Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 130 of file icuplug.h.


Typedef Documentation

typedef UPlugTokenReturn( UPlugEntrypoint)(UPlugData *plug, UPlugReason reason, UErrorCode *status)

Entrypoint for an ICU plugin.

Parameters:
plug the UPlugData handle.
status the plugin's extended status code.
Returns:
A valid plugin must return UPLUG_TOKEN
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 181 of file icuplug.h.

typedef uint32_t UPlugTokenReturn

Return value from a plugin entrypoint.

Must always be set to UPLUG_TOKEN

See also:
UPLUG_TOKEN
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview

Definition at line 145 of file icuplug.h.


Enumeration Type Documentation

enum UPlugLevel

Level of plugin loading INITIAL: UNKNOWN QUERY: INVALID -> { LOW | HIGH } ERR -> INVALID.

Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
Enumerator:
UPLUG_LEVEL_INVALID 

The plugin is invalid, hasn't called uplug_setLevel, or can't load.

UPLUG_LEVEL_UNKNOWN 

The plugin is waiting to be installed.

UPLUG_LEVEL_LOW 

The plugin must be called before u_init completes.

UPLUG_LEVEL_HIGH 

The plugin can run at any time.

UPLUG_LEVEL_COUNT 

count of known reasons

Definition at line 166 of file icuplug.h.

Reason code for the entrypoint's call.

Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
Enumerator:
UPLUG_REASON_QUERY 

The plugin is being queried for info.

UPLUG_REASON_LOAD 

The plugin is being loaded.

UPLUG_REASON_UNLOAD 

The plugin is being unloaded.

UPLUG_REASON_COUNT 

count of known reasons

Definition at line 151 of file icuplug.h.


Function Documentation

U_CAPI const char* uplug_getConfiguration ( UPlugData *  plug  ) 

Get the configuration string, if available.

The string is in the platform default codepage.

Parameters:
plug plugin data handle
Returns:
configuration string, or else null.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void* uplug_getContext ( UPlugData *  plug  ) 

Return the plugin-specific context data.

Parameters:
plug plugin data handle
Returns:
the context, or NULL if not set
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI UPlugLevel uplug_getCurrentLevel (  ) 

Get the lowest level of plug which can currently load.

For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load.

Returns:
the lowest level of plug which can currently load
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void* uplug_getLibrary ( UPlugData *  plug  ) 

Return the library used for this plugin, if known.

Plugins could use this to load data out of their

Parameters:
plug plugin data handle
Returns:
the library, or NULL
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI const char* uplug_getLibraryName ( UPlugData *  plug,
UErrorCode status 
)

Return the library name for this plugin, if known.

Parameters:
plug plugin data handle
status error code
Returns:
the library name, or NULL
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI UPlugLevel uplug_getPlugLevel ( UPlugData *  plug  ) 

Get the level of this plugin.

Parameters:
plug plugin data handle
Returns:
the level of this plugin
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI UErrorCode uplug_getPlugLoadStatus ( UPlugData *  plug  ) 

Get plug load status.

Returns:
The error code of this plugin's load attempt.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI const char* uplug_getPlugName ( UPlugData *  plug  ) 

Get the human-readable name of this plugin.

Parameters:
plug plugin data handle
Returns:
the name of this plugin
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI const char* uplug_getSymbolName ( UPlugData *  plug  ) 

Return the symbol name for this plugin, if known.

Parameters:
plug plugin data handle
Returns:
the symbol name, or NULL
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI UPlugData* uplug_loadPlugFromEntrypoint ( UPlugEntrypoint entrypoint,
const char *  config,
UErrorCode status 
)

Inject a plugin as if it were loaded from a library.

This is useful for testing plugins. Note that it will have a 'NULL' library pointer associated with it, and therefore no llibrary will be closed at cleanup time. Low level plugins may not be able to load, as ordering can't be enforced.

Parameters:
entrypoint entrypoint to install
config user specified configuration string, if available, or NULL.
status error result
Returns:
the new UPlugData associated with this plugin, or NULL if error.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI UPlugData* uplug_loadPlugFromLibrary ( const char *  libName,
const char *  sym,
const char *  config,
UErrorCode status 
)

Inject a plugin from a library, as if the information came from a config file.

Low level plugins may not be able to load, and ordering can't be enforced.

Parameters:
libName DLL name to load
sym symbol of plugin (UPlugEntrypoint function)
config configuration string, or NULL
status error result
Returns:
the new UPlugData associated with this plugin, or NULL if error.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI UPlugData* uplug_nextPlug ( UPlugData *  prior  ) 

Return all currently installed plugins, from newest to oldest Usage Example:.

    UPlugData *plug = NULL;
    while(plug=uplug_nextPlug(plug)) {
        ... do something with 'plug' ...
    }

Not thread safe- do not call while plugs are added or removed.

Parameters:
prior pass in 'NULL' to get the first (most recent) plug, otherwise pass the value returned on a prior call to uplug_nextPlug
Returns:
the next oldest plugin, or NULL if no more.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void uplug_removePlug ( UPlugData *  plug,
UErrorCode status 
)

Remove a plugin.

Will request the plugin to be unloaded, and close the library if needed

Parameters:
plug plugin handle to close
status error result
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void uplug_setContext ( UPlugData *  plug,
void *  context 
)

Set the plugin-specific context data.

Parameters:
plug plugin data handle
context new context to set
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void uplug_setPlugLevel ( UPlugData *  plug,
UPlugLevel  level 
)

Set the level of this plugin.

Parameters:
plug plugin data handle
level the level of this plugin
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void uplug_setPlugName ( UPlugData *  plug,
const char *  name 
)

Set the human-readable name of this plugin.

Parameters:
plug plugin data handle
name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
U_CAPI void uplug_setPlugNoUnload ( UPlugData *  plug,
UBool  dontUnload 
)

Request that this plugin not be unloaded at cleanup time.

This is appropriate for plugins which cannot be cleaned up.

See also:
u_cleanup()
Parameters:
plug plugin
dontUnload set true if this plugin can't be unloaded
Internal:
Do not use. This API is for internal use only. ICU 4.4 Technology Preview
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