216 lines
8.5 KiB
C
216 lines
8.5 KiB
C
/*
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*******************************************************************************
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* *
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* COPYRIGHT: *
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* (C) Copyright International Business Machines Corporation, 1999 *
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* Licensed Material - Program-Property of IBM - All Rights Reserved. *
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* US Government Users Restricted Rights - Use, duplication, or disclosure *
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* restricted by GSA ADP Schedule Contract with IBM Corp. *
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* *
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*******************************************************************************
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* file name: udata.h
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* encoding: US-ASCII
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* tab size: 8 (not used)
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* indentation:4
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*
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* created on: 1999oct25
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* created by: Markus W. Scherer
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*/
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#ifndef __UDATA_H__
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#define __UDATA_H__
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#include "utypes.h"
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/**
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* Information about data memory.
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* This structure may grow in the future, indicated by the
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* <code>size</code> field.
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*
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* <p>The platform data property fields help determine if a data
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* file can be efficiently used on a given machine.
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* The particular fields are of importance only if the data
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* is affected by the properties - if there is integer data
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* with word sizes > 1 byte, char* text, or UChar* text.</p>
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*
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* <p>The implementation for the <code>udata_open[Choice]()</code>
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* functions may reject data based on the value in <code>isBigEndian</code>.
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* No other field is used by the <code>udata</code> API implementation.</p>
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*
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* <p>The <code>dataFormat</code> may be used to identify
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* the kind of data, e.g. a converter table.</p>
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*
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* <p>The <code>formatVersion</code> field should be used to
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* make sure that the format can be interpreted.
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* I may be a good idea to check only for the one or two highest
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* of the version elements to allow the data memory to
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* get more or somewhat rearranged contents, for as long
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* as the using code can still interpret the older contents.</p>
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*
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* <p>The <code>dataVersion</code> field is intended to be a
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* common place to store the source version of the data;
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* for data from the Unicode character database, this could
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* reflect the Unicode version.</p>
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*/
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typedef struct {
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/** @memo sizeof(UDataInfo) */
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uint16_t size;
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/** @memo unused, set to 0 */
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uint16_t reservedWord;
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/* platform data properties */
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/** @memo 0 for little-endian machine, 1 for big-endian */
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uint8_t isBigEndian;
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/** @memo see U_CHARSET_FAMILY values in utypes.h */
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uint8_t charsetFamily;
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/** @memo sizeof(UChar), one of { 1, 2, 4 } */
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uint8_t sizeofUChar;
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/** @memo unused, set to 0 */
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uint8_t reservedByte;
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/** @memo data format identifier */
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uint8_t dataFormat[4];
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/** @memo versions: [0] major [1] minor [2] milli [3] micro */
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uint8_t formatVersion[4];
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uint8_t dataVersion[4];
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} UDataInfo;
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/* API for reading data -----------------------------------------------------*/
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/**
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* Forward declaration of the data memory type.
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*/
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typedef struct UDataMemory UDataMemory;
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/**
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* Callback function for udata_openChoice().
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* @param context parameter passed into <code>udata_openChoice()</code>.
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* @param type The type of the data as passed into <code>udata_openChoice()</code>.
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* It may be <code>NULL</code>.
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* @param name The name of the data as passed into <code>udata_openChoice()</code>.
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* @param pInfo A pointer to the <code>UDataInfo</code> structure
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* of data that has been loaded and will be returned
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* by <code>udata_openChoice()</code> if this function
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* returns <code>TRUE</code>.
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* @return TRUE if the current data memory is acceptable
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*/
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typedef bool_t
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UDataMemoryIsAcceptable(void *context,
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const char *type, const char *name,
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UDataInfo *pInfo);
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/**
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* Convenience function.
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* This function works the same as <code>udata_openChoice</code>
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* except that any data that matches the type and name
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* is assumed to be acceptable.
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*/
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U_CAPI UDataMemory * U_EXPORT2
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udata_open(const char *path, const char *type, const char *name,
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UErrorCode *pErrorCode);
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/**
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* Data loading function.
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* This function is used to find and load efficiently data for
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* ICU and applications using ICU.
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* It provides an abstract interface that allows to specify a data
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* type and name to find and load the data.
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*
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* <p>The implementation depends on platform properties and user preferences
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* and may involve loading shared libraries (DLLs), mapping
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* files into memory, or fopen()/fread() files.
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* It may also involve using static memory or database queries etc.
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* Several or all data items may be combined into one entity
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* (DLL, memory-mappable file).</p>
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*
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* <p>The data is always preceded by a header that includes
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* a <code>UDataInfo</code> structure.
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* The caller's <code>isAcceptable()</code> function is called to make
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* sure that the data is useful. It may be called several times if it
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* rejects the data and there is more than one location with data
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* matching the type and name.</p>
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*
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* <p>If <code>path==NULL</code>, then ICU data is loaded.
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* Otherwise, it is separated into a basename and a basename-less path string.
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* If the path string is empty, then <code>u_getDataDirectory()</code>
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* is set in its place.
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* When data is loaded from files or DLLs (shared libraries) and
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* may be stored in common files, then the data finding is roughly as follows:
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* <ul>
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* <li>common file at path/basename has entry name_type?</li>
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* <li>common file at basename has entry name_type?</li>
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* <li>separate file at path/basename_name_type?</li>
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* <li>separate file at basename_name_type?</li>
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* <li>separate file at path/name_type?</li>
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* <li>separate file at name_type?</li>
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* </ul>
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* If the basename is empty, then only the last two options are attempted.
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* Otherwise, it serves as a name for a common data file or as a basename
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* (collection name) prefix for individual files.</p>
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*
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* @param path Specifies an absolute path and/or a basename for the
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* finding of the data in the file system.
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* <code>NULL</code> for ICU data.
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* @param type A string that specifies the type of data to be loaded.
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* For example, resource bundles are loaded with type "res",
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* conversion tables with type "cnv".
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* This may be <code>NULL</code> or empty.
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* @param name A string that specifies the name of the data.
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* @param isAcceptable This function is called to verify that loaded data
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* is useful for the client code. If it returns FALSE
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* for all data items, then <code>udata_openChoice()</code>
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* will return with an error.
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* @param context Arbitrary parameter to be passed into isAcceptable.
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* @param pErrorCode An ICU UErrorCode parameter. It must not be <code>NULL</code>.
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* @return A pointer (handle) to a data memory object, or <code>NULL</code>
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* if an error occurs. Call <code>udata_getMemory()</code>
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* to get a pointer to the actual data.
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*/
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U_CAPI UDataMemory * U_EXPORT2
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udata_openChoice(const char *path, const char *type, const char *name,
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UDataMemoryIsAcceptable *isAcceptable, void *context,
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UErrorCode *pErrorCode);
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/**
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* Close the data memory.
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* This function must be called to allow the system to
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* release resources associated with this data memory.
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*/
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U_CAPI void U_EXPORT2
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udata_close(UDataMemory *pData);
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/**
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* Get the pointer to the actual data inside the data memory.
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* The data is read-only.
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*/
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U_CAPI const void * U_EXPORT2
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udata_getMemory(UDataMemory *pData);
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/**
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* Get the information from the data memory header.
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* This allows to get access to the header containing
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* platform data properties etc. which is not part of
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* the data itself and can therefore not be accessed
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* via the pointer that <code>udata_getMemory()</code> returns.
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*
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* @param pData pointer to the data memory object
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* @param pInfo pointer to a UDataInfo object;
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* its <code>size</code> field must be set correctly,
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* typically to <code>sizeof(UDataInfo)</code>.
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*
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* <code>*pInfo</code> will be filled with the UDataInfo structure
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* in the data memory object. If this structure is smaller than
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* <code>pInfo->size</code>, then the <code>size</code> will be
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* adjusted and only part of the structure will be filled.
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*/
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U_CAPI void U_EXPORT2
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udata_getInfo(UDataMemory *pData, UDataInfo *pInfo);
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#endif
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