/*
******************************************************************************
*
* Copyright (C) 2009-2010, International Business Machines
* Corporation and others. All Rights Reserved.
*
******************************************************************************
*
* FILE NAME : icuplug.h
*
* Date Name Description
* 10/29/2009 sl New.
******************************************************************************
*/
/**
* \file
* \brief C API: ICU Plugin API
*
* <h2>C API: ICU Plugin API</h2>
*
* <p>C API allowing run-time loadable modules that extend or modify ICU functionality.</p>
*
* <h3>Loading and Configuration</h3>
*
* <p>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.</p>
*
* <p>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)</p>
*
* <p>The configuration file has this format:</p>
*
* <ul>
* <li>Hash (#) begins a comment line</li>
*
* <li>Non-comment lines have two or three components:
* LIBRARYNAME ENTRYPOINT [ CONFIGURATION .. ]</li>
*
* <li>Tabs or spaces separate the three items.</li>
*
* <li>LIBRARYNAME is the name of a shared library, either a short name if
* it is on the loader path, or a full pathname.</li>
*
* <li>ENTRYPOINT is the short (undecorated) symbol name of the plugin's
* entrypoint, as above.</li>
*
* <li>CONFIGURATION is the entire rest of the line . It's passed as-is to
* the plugin.</li>
* </ul>
*
* <p>An example configuration file is, in its entirety:</p>
*
* \code
* # this is icuplugins44.txt
* testplug.dll myPlugin hello=world
* \endcode
* <p>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'. </p>
*
* <p>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.</p>
*
* <h3>Implementing a Plugin</h3>
* \code
* 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;
* }
* \endcode
*
* <p>The UPlugData* is an opaque pointer to the plugin-specific data, and is
* used in all other API calls.</p>
*
* <p>The API contract is:</p>
* <ol><li>The plugin MUST always return UPLUG_TOKEN as a return value- to
* indicate that it is a valid plugin.</li>
*
* <li>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.</li>
*
* <li>When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin
* SHOULD call uplug_setPlugName to indicate a human readable plugin name.</li></ol>
*
*
* \internal ICU 4.4 Technology Preview
*/
#ifndef ICUPLUG_H
#define ICUPLUG_H
#include "unicode/utypes.h"
/* === Basic types === */
/**
* @{
* Opaque structure passed to/from a plugin.
* use the APIs to access it.
* @internal ICU 4.4 Technology Preview
*/
struct UPlugData;
typedef struct UPlugData UPlugData;
/** @} */
/**
* Random Token to identify a valid ICU plugin. Plugins must return this
* from the entrypoint.
* @internal ICU 4.4 Technology Preview
*/
#define UPLUG_TOKEN 0x54762486
/**
* Max width of names, symbols, and configuration strings
* @internal ICU 4.4 Technology Preview
*/
#define UPLUG_NAME_MAX 100
/**
* Return value from a plugin entrypoint.
* Must always be set to UPLUG_TOKEN
* @see UPLUG_TOKEN
* @internal ICU 4.4 Technology Preview
*/
typedef uint32_t UPlugTokenReturn;
/**
* Reason code for the entrypoint's call
* @internal ICU 4.4 Technology Preview
*/
typedef enum {
UPLUG_REASON_QUERY = 0, /**< The plugin is being queried for info. **/
UPLUG_REASON_LOAD = 1, /**< The plugin is being loaded. **/
UPLUG_REASON_UNLOAD = 2, /**< The plugin is being unloaded. **/
UPLUG_REASON_COUNT /**< count of known reasons **/
} UPlugReason;
/**
* Level of plugin loading
* INITIAL: UNKNOWN
* QUERY: INVALID -> { LOW | HIGH }
* ERR -> INVALID
* @internal ICU 4.4 Technology Preview
*/
typedef enum {
UPLUG_LEVEL_INVALID = 0, /**< The plugin is invalid, hasn't called uplug_setLevel, or can't load. **/
UPLUG_LEVEL_UNKNOWN = 1, /**< The plugin is waiting to be installed. **/
UPLUG_LEVEL_LOW = 2, /**< The plugin must be called before u_init completes **/
UPLUG_LEVEL_HIGH = 3, /**< The plugin can run at any time. **/
UPLUG_LEVEL_COUNT /**< count of known reasons **/
} UPlugLevel;
/**
* Entrypoint for an ICU plugin.
* @param plug the UPlugData handle.
* @param status the plugin's extended status code.
* @return A valid plugin must return UPLUG_TOKEN
* @internal ICU 4.4 Technology Preview
*/
typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) (
UPlugData *plug,
UPlugReason reason,
UErrorCode *status);
/* === Needed for Implementing === */
/**
* Request that this plugin not be unloaded at cleanup time.
* This is appropriate for plugins which cannot be cleaned up.
* @see u_cleanup()
* @param plug plugin
* @param dontUnload set true if this plugin can't be unloaded
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void U_EXPORT2
uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload);
/**
* Set the level of this plugin.
* @param plug plugin data handle
* @param level the level of this plugin
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void U_EXPORT2
uplug_setPlugLevel(UPlugData *plug, UPlugLevel level);
/**
* Get the level of this plugin.
* @param plug plugin data handle
* @return the level of this plugin
* @internal ICU 4.4 Technology Preview
*/
U_CAPI UPlugLevel U_EXPORT2
uplug_getPlugLevel(UPlugData *plug);
/**
* 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.
* @return the lowest level of plug which can currently load
* @internal ICU 4.4 Technology Preview
*/
U_CAPI UPlugLevel U_EXPORT2
uplug_getCurrentLevel(void);
/**
* Get plug load status
* @return The error code of this plugin's load attempt.
* @internal ICU 4.4 Technology Preview
*/
U_CAPI UErrorCode U_EXPORT2
uplug_getPlugLoadStatus(UPlugData *plug);
/**
* Set the human-readable name of this plugin.
* @param plug plugin data handle
* @param name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void U_EXPORT2
uplug_setPlugName(UPlugData *plug, const char *name);
/**
* Get the human-readable name of this plugin.
* @param plug plugin data handle
* @return the name of this plugin
* @internal ICU 4.4 Technology Preview
*/
U_CAPI const char * U_EXPORT2
uplug_getPlugName(UPlugData *plug);
/**
* Return the symbol name for this plugin, if known.
* @param plug plugin data handle
* @return the symbol name, or NULL
* @internal ICU 4.4 Technology Preview
*/
U_CAPI const char * U_EXPORT2
uplug_getSymbolName(UPlugData *plug);
/**
* Return the library name for this plugin, if known.
* @param plug plugin data handle
* @param status error code
* @return the library name, or NULL
* @internal ICU 4.4 Technology Preview
*/
U_CAPI const char * U_EXPORT2
uplug_getLibraryName(UPlugData *plug, UErrorCode *status);
/**
* Return the library used for this plugin, if known.
* Plugins could use this to load data out of their
* @param plug plugin data handle
* @return the library, or NULL
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void * U_EXPORT2
uplug_getLibrary(UPlugData *plug);
/**
* Return the plugin-specific context data.
* @param plug plugin data handle
* @return the context, or NULL if not set
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void * U_EXPORT2
uplug_getContext(UPlugData *plug);
/**
* Set the plugin-specific context data.
* @param plug plugin data handle
* @param context new context to set
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void U_EXPORT2
uplug_setContext(UPlugData *plug, void *context);
/**
* Get the configuration string, if available.
* The string is in the platform default codepage.
* @param plug plugin data handle
* @return configuration string, or else null.
* @internal ICU 4.4 Technology Preview
*/
U_CAPI const char * U_EXPORT2
uplug_getConfiguration(UPlugData *plug);
/**
* Return all currently installed plugins, from newest to oldest
* Usage Example:
* \code
* UPlugData *plug = NULL;
* while(plug=uplug_nextPlug(plug)) {
* ... do something with 'plug' ...
* }
* \endcode
* Not thread safe- do not call while plugs are added or removed.
* @param prior pass in 'NULL' to get the first (most recent) plug,
* otherwise pass the value returned on a prior call to uplug_nextPlug
* @return the next oldest plugin, or NULL if no more.
* @internal ICU 4.4 Technology Preview
*/
U_CAPI UPlugData* U_EXPORT2
uplug_nextPlug(UPlugData *prior);
/**
* 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.
* @param entrypoint entrypoint to install
* @param config user specified configuration string, if available, or NULL.
* @param status error result
* @return the new UPlugData associated with this plugin, or NULL if error.
* @internal ICU 4.4 Technology Preview
*/
U_CAPI UPlugData* U_EXPORT2
uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, 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.
* @param libName DLL name to load
* @param sym symbol of plugin (UPlugEntrypoint function)
* @param config configuration string, or NULL
* @param status error result
* @return the new UPlugData associated with this plugin, or NULL if error.
* @internal ICU 4.4 Technology Preview
*/
U_CAPI UPlugData* U_EXPORT2
uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *config, UErrorCode *status);
/**
* Remove a plugin.
* Will request the plugin to be unloaded, and close the library if needed
* @param plug plugin handle to close
* @param status error result
* @internal ICU 4.4 Technology Preview
*/
U_CAPI void U_EXPORT2
uplug_removePlug(UPlugData *plug, UErrorCode *status);
#endif