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udata.h File Reference


Compounds

struct  UDataInfo

Typedefs

typedef struct UDataMemory UDataMemory
Forward declaration of the data memory type.

typedef bool_t UDataMemoryIsAcceptable (void *context, const char *type, const char *name, UDataInfo *pInfo)
Callback function for udata_openChoice(). More...


Functions

U_CAPI UDataMemory* U_EXPORT2 udata_open (const char *path, const char *type, const char *name, UErrorCode *pErrorCode)
Convenience function. More...

U_CAPI UDataMemory* U_EXPORT2 udata_openChoice (const char *path, const char *type, const char *name, UDataMemoryIsAcceptable *isAcceptable, void *context, UErrorCode *pErrorCode)
Data loading function. More...

U_CAPI void U_EXPORT2 udata_close (UDataMemory *pData)
Close the data memory. More...

U_CAPI const void* U_EXPORT2 udata_getMemory (UDataMemory *pData)
Get the pointer to the actual data inside the data memory. More...

U_CAPI void U_EXPORT2 udata_getInfo (UDataMemory *pData, UDataInfo *pInfo)
Get the information from the data memory header. More...


Typedef Documentation

typedef struct UDataMemory UDataMemory

Forward declaration of the data memory type.

typedef bool_t UDataMemoryIsAcceptable(void *context, const char *type, const char *name, UDataInfo *pInfo)

Callback function for udata_openChoice().

Parameters:
context   parameter passed into udata_openChoice().
type   The type of the data as passed into udata_openChoice(). It may be NULL.
name   The name of the data as passed into udata_openChoice().
pInfo   A pointer to the UDataInfo structure of data that has been loaded and will be returned by udata_openChoice() if this function returns TRUE.
Returns:
TRUE if the current data memory is acceptable
Stable:

Function Documentation

U_CAPI UDataMemory *U_EXPORT2 udata_open (const char * path, const char * type, const char * name, UErrorCode * pErrorCode)

Convenience function.

This function works the same as udata_openChoice except that any data that matches the type and name is assumed to be acceptable.

Stable:

U_CAPI UDataMemory *U_EXPORT2 udata_openChoice (const char * path, const char * type, const char * name, UDataMemoryIsAcceptable * isAcceptable, void * context, 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.

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).

The data is always preceded by a header that includes a UDataInfo structure. The caller's isAcceptable() 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.

If path==NULL, then ICU data is loaded. Otherwise, it is separated into a basename and a basename-less path string. If the path string is empty, then u_getDataDirectory() is set in its place. When data is loaded from files or DLLs (shared libraries) and may be stored in common files, then the data finding is roughly as follows:

If the basename is empty, then only the last two options are attempted. Otherwise, it serves as a name for a common data file or as a basename (collection name) prefix for individual files.

Parameters:
path   Specifies an absolute path and/or a basename for the finding of the data in the file system. NULL for ICU data.
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 NULL or empty.
name   A string that specifies the name of the data.
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 udata_openChoice() will return with an error.
context   Arbitrary parameter to be passed into isAcceptable.
pErrorCode   An ICU UErrorCode parameter. It must not be NULL.
Returns:
A pointer (handle) to a data memory object, or NULL if an error occurs. Call udata_getMemory() to get a pointer to the actual data.
Stable:

U_CAPI void U_EXPORT2 udata_close (UDataMemory * pData)

Close the data memory.

This function must be called to allow the system to release resources associated with this data memory.

Stable:

U_CAPI const void *U_EXPORT2 udata_getMemory (UDataMemory * pData)

Get the pointer to the actual data inside the data memory.

The data is read-only.

Stable:

U_CAPI void U_EXPORT2 udata_getInfo (UDataMemory * pData, UDataInfo * pInfo)

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 udata_getMemory() returns.

Parameters:
pData   pointer to the data memory object
pInfo   pointer to a UDataInfo object; its size field must be set correctly, typically to sizeof(UDataInfo).

*pInfo will be filled with the UDataInfo structure in the data memory object. If this structure is smaller than pInfo->size, then the size will be adjusted and only part of the structure will be filled.
Stable:

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