372 lines
11 KiB
C
372 lines
11 KiB
C
/*
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******************************************************************************
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*
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* Copyright (C) 2009-2011, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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******************************************************************************
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*
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* FILE NAME : icuplug.h
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*
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* Date Name Description
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* 10/29/2009 sl New.
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******************************************************************************
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*/
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/**
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* \file
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* \brief C API: ICU Plugin API
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*
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* <h2>C API: ICU Plugin API</h2>
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*
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* <p>C API allowing run-time loadable modules that extend or modify ICU functionality.</p>
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*
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* <h3>Loading and Configuration</h3>
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*
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* <p>At ICU startup time, the environment variable "ICU_PLUGINS" will be
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* queried for a directory name. If it is not set, the preprocessor symbol
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* "DEFAULT_ICU_PLUGINS" will be checked for a default value.</p>
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*
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* <p>Within the above-named directory, the file "icuplugins##.txt" will be
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* opened, if present, where ## is the major+minor number of the currently
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* running ICU (such as, 44 for ICU 4.4, thus icuplugins44.txt)</p>
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*
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* <p>The configuration file has this format:</p>
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*
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* <ul>
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* <li>Hash (#) begins a comment line</li>
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*
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* <li>Non-comment lines have two or three components:
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* LIBRARYNAME ENTRYPOINT [ CONFIGURATION .. ]</li>
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*
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* <li>Tabs or spaces separate the three items.</li>
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*
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* <li>LIBRARYNAME is the name of a shared library, either a short name if
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* it is on the loader path, or a full pathname.</li>
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*
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* <li>ENTRYPOINT is the short (undecorated) symbol name of the plugin's
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* entrypoint, as above.</li>
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*
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* <li>CONFIGURATION is the entire rest of the line . It's passed as-is to
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* the plugin.</li>
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* </ul>
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*
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* <p>An example configuration file is, in its entirety:</p>
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*
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* \code
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* # this is icuplugins44.txt
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* testplug.dll myPlugin hello=world
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* \endcode
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* <p>Plugins are categorized as "high" or "low" level. Low level are those
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* which must be run BEFORE high level plugins, and before any operations
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* which cause ICU to be 'initialized'. If a plugin is low level but
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* causes ICU to allocate memory or become initialized, that plugin is said
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* to cause a 'level change'. </p>
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*
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* <p>At load time, ICU first queries all plugins to determine their level,
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* then loads all 'low' plugins first, and then loads all 'high' plugins.
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* Plugins are otherwise loaded in the order listed in the configuration file.</p>
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*
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* <h3>Implementing a Plugin</h3>
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* \code
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* U_CAPI UPlugTokenReturn U_EXPORT2
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* myPlugin (UPlugData *plug, UPlugReason reason, UErrorCode *status) {
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* if(reason==UPLUG_REASON_QUERY) {
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* uplug_setPlugName(plug, "Simple Plugin");
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* uplug_setPlugLevel(plug, UPLUG_LEVEL_HIGH);
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* } else if(reason==UPLUG_REASON_LOAD) {
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* ... Set up some ICU things here....
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* } else if(reason==UPLUG_REASON_UNLOAD) {
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* ... unload, clean up ...
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* }
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* return UPLUG_TOKEN;
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* }
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* \endcode
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*
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* <p>The UPlugData* is an opaque pointer to the plugin-specific data, and is
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* used in all other API calls.</p>
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*
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* <p>The API contract is:</p>
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* <ol><li>The plugin MUST always return UPLUG_TOKEN as a return value- to
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* indicate that it is a valid plugin.</li>
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*
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* <li>When the 'reason' parameter is set to UPLUG_REASON_QUERY, the
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* plugin MUST call uplug_setPlugLevel() to indicate whether it is a high
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* level or low level plugin.</li>
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*
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* <li>When the 'reason' parameter is UPLUG_REASON_QUERY, the plugin
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* SHOULD call uplug_setPlugName to indicate a human readable plugin name.</li></ol>
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*
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*
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* \internal ICU 4.4 Technology Preview
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*/
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#ifndef ICUPLUG_H
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#define ICUPLUG_H
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#include "unicode/utypes.h"
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/* === Basic types === */
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#ifndef U_HIDE_INTERNAL_API
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/**
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* @{
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* Opaque structure passed to/from a plugin.
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* use the APIs to access it.
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* @internal ICU 4.4 Technology Preview
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*/
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struct UPlugData;
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typedef struct UPlugData UPlugData;
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/** @} */
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/**
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* Random Token to identify a valid ICU plugin. Plugins must return this
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* from the entrypoint.
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* @internal ICU 4.4 Technology Preview
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*/
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#define UPLUG_TOKEN 0x54762486
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/**
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* Max width of names, symbols, and configuration strings
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* @internal ICU 4.4 Technology Preview
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*/
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#define UPLUG_NAME_MAX 100
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/**
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* Return value from a plugin entrypoint.
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* Must always be set to UPLUG_TOKEN
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* @see UPLUG_TOKEN
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* @internal ICU 4.4 Technology Preview
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*/
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typedef uint32_t UPlugTokenReturn;
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/**
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* Reason code for the entrypoint's call
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* @internal ICU 4.4 Technology Preview
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*/
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typedef enum {
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UPLUG_REASON_QUERY = 0, /**< The plugin is being queried for info. **/
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UPLUG_REASON_LOAD = 1, /**< The plugin is being loaded. **/
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UPLUG_REASON_UNLOAD = 2, /**< The plugin is being unloaded. **/
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UPLUG_REASON_COUNT /**< count of known reasons **/
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} UPlugReason;
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/**
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* Level of plugin loading
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* INITIAL: UNKNOWN
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* QUERY: INVALID -> { LOW | HIGH }
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* ERR -> INVALID
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* @internal ICU 4.4 Technology Preview
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*/
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typedef enum {
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UPLUG_LEVEL_INVALID = 0, /**< The plugin is invalid, hasn't called uplug_setLevel, or can't load. **/
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UPLUG_LEVEL_UNKNOWN = 1, /**< The plugin is waiting to be installed. **/
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UPLUG_LEVEL_LOW = 2, /**< The plugin must be called before u_init completes **/
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UPLUG_LEVEL_HIGH = 3, /**< The plugin can run at any time. **/
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UPLUG_LEVEL_COUNT /**< count of known reasons **/
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} UPlugLevel;
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/**
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* Entrypoint for an ICU plugin.
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* @param plug the UPlugData handle.
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* @param status the plugin's extended status code.
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* @return A valid plugin must return UPLUG_TOKEN
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* @internal ICU 4.4 Technology Preview
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*/
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typedef UPlugTokenReturn (U_EXPORT2 UPlugEntrypoint) (
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UPlugData *plug,
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UPlugReason reason,
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UErrorCode *status);
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/* === Needed for Implementing === */
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/**
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* Request that this plugin not be unloaded at cleanup time.
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* This is appropriate for plugins which cannot be cleaned up.
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* @see u_cleanup()
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* @param plug plugin
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* @param dontUnload set true if this plugin can't be unloaded
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void U_EXPORT2
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uplug_setPlugNoUnload(UPlugData *plug, UBool dontUnload);
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/**
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* Set the level of this plugin.
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* @param plug plugin data handle
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* @param level the level of this plugin
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void U_EXPORT2
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uplug_setPlugLevel(UPlugData *plug, UPlugLevel level);
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/**
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* Get the level of this plugin.
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* @param plug plugin data handle
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* @return the level of this plugin
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI UPlugLevel U_EXPORT2
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uplug_getPlugLevel(UPlugData *plug);
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/**
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* Get the lowest level of plug which can currently load.
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* For example, if UPLUG_LEVEL_LOW is returned, then low level plugins may load
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* if UPLUG_LEVEL_HIGH is returned, then only high level plugins may load.
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* @return the lowest level of plug which can currently load
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI UPlugLevel U_EXPORT2
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uplug_getCurrentLevel(void);
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/**
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* Get plug load status
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* @return The error code of this plugin's load attempt.
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI UErrorCode U_EXPORT2
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uplug_getPlugLoadStatus(UPlugData *plug);
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/**
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* Set the human-readable name of this plugin.
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* @param plug plugin data handle
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* @param name the name of this plugin. The first UPLUG_NAME_MAX characters willi be copied into a new buffer.
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void U_EXPORT2
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uplug_setPlugName(UPlugData *plug, const char *name);
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/**
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* Get the human-readable name of this plugin.
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* @param plug plugin data handle
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* @return the name of this plugin
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI const char * U_EXPORT2
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uplug_getPlugName(UPlugData *plug);
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/**
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* Return the symbol name for this plugin, if known.
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* @param plug plugin data handle
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* @return the symbol name, or NULL
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI const char * U_EXPORT2
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uplug_getSymbolName(UPlugData *plug);
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/**
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* Return the library name for this plugin, if known.
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* @param plug plugin data handle
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* @param status error code
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* @return the library name, or NULL
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI const char * U_EXPORT2
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uplug_getLibraryName(UPlugData *plug, UErrorCode *status);
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/**
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* Return the library used for this plugin, if known.
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* Plugins could use this to load data out of their
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* @param plug plugin data handle
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* @return the library, or NULL
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void * U_EXPORT2
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uplug_getLibrary(UPlugData *plug);
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/**
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* Return the plugin-specific context data.
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* @param plug plugin data handle
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* @return the context, or NULL if not set
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void * U_EXPORT2
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uplug_getContext(UPlugData *plug);
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/**
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* Set the plugin-specific context data.
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* @param plug plugin data handle
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* @param context new context to set
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void U_EXPORT2
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uplug_setContext(UPlugData *plug, void *context);
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/**
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* Get the configuration string, if available.
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* The string is in the platform default codepage.
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* @param plug plugin data handle
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* @return configuration string, or else null.
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI const char * U_EXPORT2
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uplug_getConfiguration(UPlugData *plug);
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/**
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* Return all currently installed plugins, from newest to oldest
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* Usage Example:
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* \code
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* UPlugData *plug = NULL;
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* while(plug=uplug_nextPlug(plug)) {
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* ... do something with 'plug' ...
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* }
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* \endcode
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* Not thread safe- do not call while plugs are added or removed.
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* @param prior pass in 'NULL' to get the first (most recent) plug,
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* otherwise pass the value returned on a prior call to uplug_nextPlug
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* @return the next oldest plugin, or NULL if no more.
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI UPlugData* U_EXPORT2
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uplug_nextPlug(UPlugData *prior);
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/**
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* Inject a plugin as if it were loaded from a library.
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* This is useful for testing plugins.
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* Note that it will have a 'NULL' library pointer associated
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* with it, and therefore no llibrary will be closed at cleanup time.
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* Low level plugins may not be able to load, as ordering can't be enforced.
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* @param entrypoint entrypoint to install
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* @param config user specified configuration string, if available, or NULL.
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* @param status error result
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* @return the new UPlugData associated with this plugin, or NULL if error.
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI UPlugData* U_EXPORT2
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uplug_loadPlugFromEntrypoint(UPlugEntrypoint *entrypoint, const char *config, UErrorCode *status);
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/**
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* Inject a plugin from a library, as if the information came from a config file.
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* Low level plugins may not be able to load, and ordering can't be enforced.
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* @param libName DLL name to load
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* @param sym symbol of plugin (UPlugEntrypoint function)
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* @param config configuration string, or NULL
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* @param status error result
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* @return the new UPlugData associated with this plugin, or NULL if error.
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI UPlugData* U_EXPORT2
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uplug_loadPlugFromLibrary(const char *libName, const char *sym, const char *config, UErrorCode *status);
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/**
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* Remove a plugin.
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* Will request the plugin to be unloaded, and close the library if needed
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* @param plug plugin handle to close
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* @param status error result
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* @internal ICU 4.4 Technology Preview
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*/
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U_CAPI void U_EXPORT2
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uplug_removePlug(UPlugData *plug, UErrorCode *status);
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#endif /* U_HIDE_INTERNAL_API */
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#endif
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