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udata.h (16006B)

---

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
*
*   Copyright (C) 1999-2014, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*   file name:  udata.h
*   encoding:   UTF-8
*   tab size:   8 (not used)
*   indentation:4
*
*   created on: 1999oct25
*   created by: Markus W. Scherer
*/

#ifndef __UDATA_H__
#define __UDATA_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API
#include "unicode/localpointer.h"
#endif   // U_SHOW_CPLUSPLUS_API

U_CDECL_BEGIN

/**
* \file
* \brief C API: Data loading interface
*
* <h2>Information about data loading interface</h2>
*
* This API is used to find and efficiently load data for ICU and applications
* using ICU. It provides an abstract interface that specifies a data type and
* name to find and load the data. Normally this API is used by other ICU APIs
* to load required data out of the ICU data library, but it can be used to
* load data out of other places.
*
* See the User Guide Data Management chapter.
*/

#ifndef U_HIDE_INTERNAL_API
/**
* Character used to separate package names from tree names 
* @internal ICU 3.0
*/
#define U_TREE_SEPARATOR '-'

/**
* String used to separate package names from tree names 
* @internal ICU 3.0
*/
#define U_TREE_SEPARATOR_STRING "-"

/**
* Character used to separate parts of entry names
* @internal ICU 3.0
*/
#define U_TREE_ENTRY_SEP_CHAR '/'

/**
* String used to separate parts of entry names
* @internal ICU 3.0
*/
#define U_TREE_ENTRY_SEP_STRING "/"

/**
* Alias for standard ICU data 
* @internal ICU 3.0
*/
#define U_ICUDATA_ALIAS "ICUDATA"

#endif /* U_HIDE_INTERNAL_API */

/**
* UDataInfo contains the properties about the requested data.
* This is meta data.
*
* <p>This structure may grow in the future, indicated by the
* <code>size</code> field.</p>
*
* <p>ICU data must be at least 8-aligned, and should be 16-aligned.
* The UDataInfo struct begins 4 bytes after the start of the data item,
* so it is 4-aligned.
*
* <p>The platform data property fields help determine if a data
* file can be efficiently used on a given machine.
* The particular fields are of importance only if the data
* is affected by the properties - if there is integer data
* with word sizes > 1 byte, char* text, or UChar* text.</p>
*
* <p>The implementation for the <code>udata_open[Choice]()</code>
* functions may reject data based on the value in <code>isBigEndian</code>.
* No other field is used by the <code>udata</code> API implementation.</p>
*
* <p>The <code>dataFormat</code> may be used to identify
* the kind of data, e.g. a converter table.</p>
*
* <p>The <code>formatVersion</code> field should be used to
* make sure that the format can be interpreted.
* It may be a good idea to check only for the one or two highest
* of the version elements to allow the data memory to
* get more or somewhat rearranged contents, for as long
* as the using code can still interpret the older contents.</p>
*
* <p>The <code>dataVersion</code> field is intended to be a
* common place to store the source version of the data;
* for data from the Unicode character database, this could
* reflect the Unicode version.</p>
*
* @stable ICU 2.0
*/
typedef struct {
   /** sizeof(UDataInfo)
    *  @stable ICU 2.0 */
   uint16_t size;

   /** unused, set to 0 
    *  @stable ICU 2.0*/
   uint16_t reservedWord;

   /* platform data properties */
   /** 0 for little-endian machine, 1 for big-endian
    *  @stable ICU 2.0 */
   uint8_t isBigEndian;

   /** see U_CHARSET_FAMILY values in utypes.h 
    *  @stable ICU 2.0*/
   uint8_t charsetFamily;

   /** sizeof(UChar), one of { 1, 2, 4 } 
    *  @stable ICU 2.0*/
   uint8_t sizeofUChar;

   /** unused, set to 0 
    *  @stable ICU 2.0*/
   uint8_t reservedByte;

   /** data format identifier 
    *  @stable ICU 2.0*/
   uint8_t dataFormat[4];

   /** versions: [0] major [1] minor [2] milli [3] micro 
    *  @stable ICU 2.0*/
   uint8_t formatVersion[4];

   /** versions: [0] major [1] minor [2] milli [3] micro 
    *  @stable ICU 2.0*/
   uint8_t dataVersion[4];
} UDataInfo;

/* API for reading data -----------------------------------------------------*/

/**
* Forward declaration of the data memory type.
* @stable ICU 2.0
*/
typedef struct UDataMemory UDataMemory;

/**
* Callback function for udata_openChoice().
* @param context parameter passed into <code>udata_openChoice()</code>.
* @param type The type of the data as passed into <code>udata_openChoice()</code>.
*             It may be <code>NULL</code>.
* @param name The name of the data as passed into <code>udata_openChoice()</code>.
* @param pInfo A pointer to the <code>UDataInfo</code> structure
*              of data that has been loaded and will be returned
*              by <code>udata_openChoice()</code> if this function
*              returns <code>true</code>.
* @return true if the current data memory is acceptable
* @stable ICU 2.0
*/
typedef UBool U_CALLCONV
UDataMemoryIsAcceptable(void *context,
                       const char *type, const char *name,
                       const UDataInfo *pInfo);


/**
* Convenience function.
* This function works the same as <code>udata_openChoice</code>
* except that any data that matches the type and name
* is assumed to be acceptable.
* @param path Specifies an absolute path and/or a basename for the
*             finding of the data in the file system.
*             <code>NULL</code> for ICU data.
* @param type A string that specifies the type of data to be loaded.
*             For example, resource bundles are loaded with type "res",
*             conversion tables with type "cnv".
*             This may be <code>NULL</code> or empty.
* @param name A string that specifies the name of the data.
* @param pErrorCode An ICU UErrorCode parameter. It must not be <code>NULL</code>.
* @return A pointer (handle) to a data memory object, or <code>NULL</code>
*         if an error occurs. Call <code>udata_getMemory()</code>
*         to get a pointer to the actual data.
*
* @see udata_openChoice
* @stable ICU 2.0
*/
U_CAPI UDataMemory * U_EXPORT2
udata_open(const char *path, const char *type, const char *name,
          UErrorCode *pErrorCode);

/**
* Data loading function.
* This function is used to find and load efficiently data for
* ICU and applications using ICU.
* It provides an abstract interface that allows to specify a data
* type and name to find and load the data.
*
* <p>The implementation depends on platform properties and user preferences
* and may involve loading shared libraries (DLLs), mapping
* files into memory, or fopen()/fread() files.
* It may also involve using static memory or database queries etc.
* Several or all data items may be combined into one entity
* (DLL, memory-mappable file).</p>
*
* <p>The data is always preceded by a header that includes
* a <code>UDataInfo</code> structure.
* The caller's <code>isAcceptable()</code> function is called to make
* sure that the data is useful. It may be called several times if it
* rejects the data and there is more than one location with data
* matching the type and name.</p>
*
* <p>If <code>path==NULL</code>, then ICU data is loaded.
* Otherwise, it is separated into a basename and a basename-less directory string.
* The basename is used as the data package name, and the directory is
* logically prepended to the ICU data directory string.</p>
*
* <p>For details about ICU data loading see the User Guide
* Data Management chapter. (https://unicode-org.github.io/icu/userguide/icu_data/)</p>
*
* @param path Specifies an absolute path and/or a basename for the
*             finding of the data in the file system.
*             <code>NULL</code> for ICU data.
* @param type A string that specifies the type of data to be loaded.
*             For example, resource bundles are loaded with type "res",
*             conversion tables with type "cnv".
*             This may be <code>NULL</code> or empty.
* @param name A string that specifies the name of the data.
* @param isAcceptable This function is called to verify that loaded data
*                     is useful for the client code. If it returns false
*                     for all data items, then <code>udata_openChoice()</code>
*                     will return with an error.
* @param context Arbitrary parameter to be passed into isAcceptable.
* @param pErrorCode An ICU UErrorCode parameter. It must not be <code>NULL</code>.
* @return A pointer (handle) to a data memory object, or <code>NULL</code>
*         if an error occurs. Call <code>udata_getMemory()</code>
*         to get a pointer to the actual data.
* @stable ICU 2.0
*/
U_CAPI UDataMemory * U_EXPORT2
udata_openChoice(const char *path, const char *type, const char *name,
                UDataMemoryIsAcceptable *isAcceptable, void *context,
                UErrorCode *pErrorCode);

/**
* Close the data memory.
* This function must be called to allow the system to
* release resources associated with this data memory.
* @param pData The pointer to data memory object
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
udata_close(UDataMemory *pData);

/**
* Get the pointer to the actual data inside the data memory.
* The data is read-only.
*
* ICU data must be at least 8-aligned, and should be 16-aligned.
*
* @param pData The pointer to data memory object
* @stable ICU 2.0
*/
U_CAPI const void * U_EXPORT2
udata_getMemory(UDataMemory *pData);

/**
* Get the information from the data memory header.
* This allows to get access to the header containing
* platform data properties etc. which is not part of
* the data itself and can therefore not be accessed
* via the pointer that <code>udata_getMemory()</code> returns.
*
* @param pData pointer to the data memory object
* @param pInfo pointer to a UDataInfo object;
*              its <code>size</code> field must be set correctly,
*              typically to <code>sizeof(UDataInfo)</code>.
*
* <code>*pInfo</code> will be filled with the UDataInfo structure
* in the data memory object. If this structure is smaller than
* <code>pInfo->size</code>, then the <code>size</code> will be
* adjusted and only part of the structure will be filled.
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
udata_getInfo(UDataMemory *pData, UDataInfo *pInfo);

/**
* This function bypasses the normal ICU data loading process and
* allows you to force ICU's system data to come out of a user-specified
* area in memory.
*
* ICU data must be at least 8-aligned, and should be 16-aligned.
* See https://unicode-org.github.io/icu/userguide/icu_data
*
* The format of this data is that of the icu common data file, as is
* generated by the pkgdata tool with mode=common or mode=dll.
* You can read in a whole common mode file and pass the address to the start of the
* data, or (with the appropriate link options) pass in the pointer to
* the data that has been loaded from a dll by the operating system,
* as shown in this code:
*
*       extern const char U_IMPORT U_ICUDATA_ENTRY_POINT [];
*        // U_ICUDATA_ENTRY_POINT is same as entry point specified to pkgdata tool
*       UErrorCode  status = U_ZERO_ERROR;
*
*       udata_setCommonData(&U_ICUDATA_ENTRY_POINT, &status);
*
* It is important that the declaration be as above. The entry point
* must not be declared as an extern void*.
*
* Starting with ICU 4.4, it is possible to set several data packages,
* one per call to this function.
* udata_open() will look for data in the multiple data packages in the order
* in which they were set.
* The position of the linked-in or default-name ICU .data package in the
* search list depends on when the first data item is loaded that is not contained
* in the already explicitly set packages.
* If data was loaded implicitly before the first call to this function
* (for example, via opening a converter, constructing a UnicodeString
* from default-codepage data, using formatting or collation APIs, etc.),
* then the default data will be first in the list.
*
* This function has no effect on application (non ICU) data.  See udata_setAppData()
* for similar functionality for application data.
*
* @param data pointer to ICU common data
* @param err outgoing error status <code>U_USING_DEFAULT_WARNING, U_UNSUPPORTED_ERROR</code>
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
udata_setCommonData(const void *data, UErrorCode *err);


/**
* This function bypasses the normal ICU data loading process for application-specific
* data and allows you to force the it to come out of a user-specified
* pointer.
*
* ICU data must be at least 8-aligned, and should be 16-aligned.
* See https://unicode-org.github.io/icu/userguide/icu_data
*
* The format of this data is that of the icu common data file, like 'icudt26l.dat'
* or the corresponding shared library (DLL) file.
* The application must read in or otherwise construct an image of the data and then
* pass the address of it to this function.
*
*
* Warning:  setAppData will set a U_USING_DEFAULT_WARNING code if
*           data with the specified path that has already been opened, or
*           if setAppData with the same path has already been called.
*           Any such calls to setAppData will have no effect.
*
*
* @param packageName the package name by which the application will refer
*             to (open) this data
* @param data pointer to the data
* @param err outgoing error status <code>U_USING_DEFAULT_WARNING, U_UNSUPPORTED_ERROR</code>
* @see udata_setCommonData
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
udata_setAppData(const char *packageName, const void *data, UErrorCode *err);

/**
* Possible settings for udata_setFileAccess()
* @see udata_setFileAccess
* @stable ICU 3.4
*/
typedef enum UDataFileAccess {
   /** ICU looks for data in single files first, then in packages. (default) @stable ICU 3.4 */
   UDATA_FILES_FIRST,
   /** An alias for the default access mode. @stable ICU 3.4 */
   UDATA_DEFAULT_ACCESS = UDATA_FILES_FIRST,
   /** ICU only loads data from packages, not from single files. @stable ICU 3.4 */
   UDATA_ONLY_PACKAGES,
   /** ICU loads data from packages first, and only from single files
       if the data cannot be found in a package. @stable ICU 3.4 */
   UDATA_PACKAGES_FIRST,
   /** ICU does not access the file system for data loading. @stable ICU 3.4 */
   UDATA_NO_FILES,
#ifndef U_HIDE_DEPRECATED_API
   /**
    * Number of real UDataFileAccess values.
    * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
    */
   UDATA_FILE_ACCESS_COUNT
#endif  // U_HIDE_DEPRECATED_API
} UDataFileAccess;

/**
* This function may be called to control how ICU loads data. It must be called
* before any ICU data is loaded, including application data loaded with 
* ures/ResourceBundle or udata APIs. This function is not multithread safe.  
* The results of calling it while other threads are loading data are undefined.
* @param access The type of file access to be used
* @param status Error code.
* @see UDataFileAccess
* @stable ICU 3.4 
*/
U_CAPI void U_EXPORT2
udata_setFileAccess(UDataFileAccess access, UErrorCode *status);

U_CDECL_END

#if U_SHOW_CPLUSPLUS_API

U_NAMESPACE_BEGIN

/**
* \class LocalUDataMemoryPointer
* "Smart pointer" class, closes a UDataMemory via udata_close().
* For most methods see the LocalPointerBase base class.
*
* @see LocalPointerBase
* @see LocalPointer
* @stable ICU 4.4
*/
U_DEFINE_LOCAL_OPEN_POINTER(LocalUDataMemoryPointer, UDataMemory, udata_close);

U_NAMESPACE_END

#endif  // U_SHOW_CPLUSPLUS_API

#endif