icuSources/common/unicode/udata.h

   1 /*
   2 ******************************************************************************
   3 *
   4 *   Copyright (C) 1999-2003, International Business Machines
   5 *   Corporation and others.  All Rights Reserved.
   6 *
   7 ******************************************************************************
   8 *   file name:  udata.h
   9 *   encoding:   US-ASCII
  10 *   tab size:   8 (not used)
  11 *   indentation:4
  12 *
  13 *   created on: 1999oct25
  14 *   created by: Markus W. Scherer
  15 */
  16
  17 #ifndef __UDATA_H__
  18 #define __UDATA_H__
  19
  20 #include "unicode/utypes.h"
  21
  22 U_CDECL_BEGIN
  23
  24 /**
  25  * \file
  26  * \brief C API: Data loading interface
  27  *
  28  * <h2>Information about data loading interface</h2>
  29  *
  30  * This API is used to find and efficiently load data for ICU and applications
  31  * using ICU. It provides an abstract interface that specifies a data type and
  32  * name to find and load the data. Normally this API is used by other ICU APIs
  33  * to load required data out of the ICU data library, but it can be used to
  34  * load data out of other places.
  35  *
  36  * See the User Guide Data Management chapter.
  37  */
  38
  39 /**
  40  * UDataInfo contains the properties about the requested data.
  41  * This is meta data.
  42  *
  43  * <p>This structure may grow in the future, indicated by the
  44  * <code>size</code> field.</p>
  45  *
  46  * <p>The platform data property fields help determine if a data
  47  * file can be efficiently used on a given machine.
  48  * The particular fields are of importance only if the data
  49  * is affected by the properties - if there is integer data
  50  * with word sizes > 1 byte, char* text, or UChar* text.</p>
  51  *
  52  * <p>The implementation for the <code>udata_open[Choice]()</code>
  53  * functions may reject data based on the value in <code>isBigEndian</code>.
  54  * No other field is used by the <code>udata</code> API implementation.</p>
  55  *
  56  * <p>The <code>dataFormat</code> may be used to identify
  57  * the kind of data, e.g. a converter table.</p>
  58  *
  59  * <p>The <code>formatVersion</code> field should be used to
  60  * make sure that the format can be interpreted.
  61  * I may be a good idea to check only for the one or two highest
  62  * of the version elements to allow the data memory to
  63  * get more or somewhat rearranged contents, for as long
  64  * as the using code can still interpret the older contents.</p>
  65  *
  66  * <p>The <code>dataVersion</code> field is intended to be a
  67  * common place to store the source version of the data;
  68  * for data from the Unicode character database, this could
  69  * reflect the Unicode version.</p>
  70  * @stable ICU 2.0
  71  */
  72 typedef struct {
  73     /** @memo sizeof(UDataInfo)
  74      *  @stable ICU 2.0 */
  75     uint16_t size;
  76
  77     /** @memo unused, set to 0
  78      *  @stable ICU 2.0*/
  79     uint16_t reservedWord;
  80
  81     /* platform data properties */
  82     /** @memo 0 for little-endian machine, 1 for big-endian
  83      *  @stable ICU 2.0 */
  84     uint8_t isBigEndian;
  85
  86     /** @memo see U_CHARSET_FAMILY values in utypes.h
  87      *  @stable ICU 2.0*/
  88     uint8_t charsetFamily;
  89
  90     /** @memo sizeof(UChar), one of { 1, 2, 4 }
  91      *  @stable ICU 2.0*/
  92     uint8_t sizeofUChar;
  93
  94     /** @memo unused, set to 0
  95      *  @stable ICU 2.0*/
  96     uint8_t reservedByte;
  97
  98     /** @memo data format identifier
  99      *  @stable ICU 2.0*/
 100     uint8_t dataFormat[4];
 101
 102     /** @memo versions: [0] major [1] minor [2] milli [3] micro
 103      *  @stable ICU 2.0*/
 104     uint8_t formatVersion[4];
 105
 106     /** @memo versions: [0] major [1] minor [2] milli [3] micro
 107      *  @stable ICU 2.0*/
 108     uint8_t dataVersion[4];
 109 } UDataInfo;
 110
 111 /* API for reading data -----------------------------------------------------*/
 112
 113 /**
 114  * Forward declaration of the data memory type.
 115  * @stable ICU 2.0
 116  */
 117 typedef struct UDataMemory UDataMemory;
 118
 119 /**
 120  * Callback function for udata_openChoice().
 121  * @param context parameter passed into <code>udata_openChoice()</code>.
 122  * @param type The type of the data as passed into <code>udata_openChoice()</code>.
 123  *             It may be <code>NULL</code>.
 124  * @param name The name of the data as passed into <code>udata_openChoice()</code>.
 125  * @param pInfo A pointer to the <code>UDataInfo</code> structure
 126  *              of data that has been loaded and will be returned
 127  *              by <code>udata_openChoice()</code> if this function
 128  *              returns <code>TRUE</code>.
 129  * @return TRUE if the current data memory is acceptable
 130  * @stable ICU 2.0
 131  */
 132 typedef UBool U_CALLCONV
 133 UDataMemoryIsAcceptable(void *context,
 134                         const char *type, const char *name,
 135                         const UDataInfo *pInfo);
 136
 137
 138 /**
 139  * Convenience function.
 140  * This function works the same as <code>udata_openChoice</code>
 141  * except that any data that matches the type and name
 142  * is assumed to be acceptable.
 143  * @param path Specifies an absolute path and/or a basename for the
 144  *             finding of the data in the file system.
 145  *             <code>NULL</code> for ICU data.
 146  * @param type A string that specifies the type of data to be loaded.
 147  *             For example, resource bundles are loaded with type "res",
 148  *             conversion tables with type "cnv".
 149  *             This may be <code>NULL</code> or empty.
 150  * @param name A string that specifies the name of the data.
 151  * @param pErrorCode An ICU UErrorCode parameter. It must not be <code>NULL</code>.
 152  * @return A pointer (handle) to a data memory object, or <code>NULL</code>
 153  *         if an error occurs. Call <code>udata_getMemory()</code>
 154  *         to get a pointer to the actual data.
 155  *
 156  * @see udata_openChoice
 157  * @stable ICU 2.0
 158  */
 159 U_CAPI UDataMemory * U_EXPORT2
 160 udata_open(const char *path, const char *type, const char *name,
 161            UErrorCode *pErrorCode);
 162
 163 /**
 164  * Data loading function.
 165  * This function is used to find and load efficiently data for
 166  * ICU and applications using ICU.
 167  * It provides an abstract interface that allows to specify a data
 168  * type and name to find and load the data.
 169  *
 170  * <p>The implementation depends on platform properties and user preferences
 171  * and may involve loading shared libraries (DLLs), mapping
 172  * files into memory, or fopen()/fread() files.
 173  * It may also involve using static memory or database queries etc.
 174  * Several or all data items may be combined into one entity
 175  * (DLL, memory-mappable file).</p>
 176  *
 177  * <p>The data is always preceded by a header that includes
 178  * a <code>UDataInfo</code> structure.
 179  * The caller's <code>isAcceptable()</code> function is called to make
 180  * sure that the data is useful. It may be called several times if it
 181  * rejects the data and there is more than one location with data
 182  * matching the type and name.</p>
 183  *
 184  * <p>If <code>path==NULL</code>, then ICU data is loaded.
 185  * Otherwise, it is separated into a basename and a basename-less directory string.
 186  * The basename is used as the data package name, and the directory is
 187  * logically prepended to the ICU data directory string.</p>
 188  *
 189  * <p>For details about ICU data loading see the User Guide
 190  * Data Management chapter. (http://oss.software.ibm.com/icu/userguide/icudata.html)</p>
 191  *
 192  * @param path Specifies an absolute path and/or a basename for the
 193  *             finding of the data in the file system.
 194  *             <code>NULL</code> for ICU data.
 195  * @param type A string that specifies the type of data to be loaded.
 196  *             For example, resource bundles are loaded with type "res",
 197  *             conversion tables with type "cnv".
 198  *             This may be <code>NULL</code> or empty.
 199  * @param name A string that specifies the name of the data.
 200  * @param isAcceptable This function is called to verify that loaded data
 201  *                     is useful for the client code. If it returns FALSE
 202  *                     for all data items, then <code>udata_openChoice()</code>
 203  *                     will return with an error.
 204  * @param context Arbitrary parameter to be passed into isAcceptable.
 205  * @param pErrorCode An ICU UErrorCode parameter. It must not be <code>NULL</code>.
 206  * @return A pointer (handle) to a data memory object, or <code>NULL</code>
 207  *         if an error occurs. Call <code>udata_getMemory()</code>
 208  *         to get a pointer to the actual data.
 209  * @stable ICU 2.0
 210  */
 211 U_CAPI UDataMemory * U_EXPORT2
 212 udata_openChoice(const char *path, const char *type, const char *name,
 213                  UDataMemoryIsAcceptable *isAcceptable, void *context,
 214                  UErrorCode *pErrorCode);
 215
 216 /**
 217  * Close the data memory.
 218  * This function must be called to allow the system to
 219  * release resources associated with this data memory.
 220  * @param pData The pointer to data memory object
 221  * @stable ICU 2.0
 222  */
 223 U_CAPI void U_EXPORT2
 224 udata_close(UDataMemory *pData);
 225
 226 /**
 227  * Get the pointer to the actual data inside the data memory.
 228  * The data is read-only.
 229  * @param pData The pointer to data memory object
 230  * @stable ICU 2.0
 231  */
 232 U_CAPI const void * U_EXPORT2
 233 udata_getMemory(UDataMemory *pData);
 234
 235 /**
 236  * Get the information from the data memory header.
 237  * This allows to get access to the header containing
 238  * platform data properties etc. which is not part of
 239  * the data itself and can therefore not be accessed
 240  * via the pointer that <code>udata_getMemory()</code> returns.
 241  *
 242  * @param pData pointer to the data memory object
 243  * @param pInfo pointer to a UDataInfo object;
 244  *              its <code>size</code> field must be set correctly,
 245  *              typically to <code>sizeof(UDataInfo)</code>.
 246  *
 247  * <code>*pInfo</code> will be filled with the UDataInfo structure
 248  * in the data memory object. If this structure is smaller than
 249  * <code>pInfo->size</code>, then the <code>size</code> will be
 250  * adjusted and only part of the structure will be filled.
 251  * @stable ICU 2.0
 252  */
 253 U_CAPI void U_EXPORT2
 254 udata_getInfo(UDataMemory *pData, UDataInfo *pInfo);
 255
 256 /**
 257  * This function bypasses the normal ICU data loading process and
 258  * allows you to force ICU's system data to come out of a user-specified
 259  * area in memory.
 260  *
 261  * The format of this data is that of the icu common data file, as is
 262  * generated by the pkgdata tool with mode=common or mode=dll.
 263  * You can read in a whole common mode file and pass the address to the start of the
 264  * data, or (with the appropriate link options) pass in the pointer to
 265  * the data that has been loaded from a dll by the operating system,
 266  * as shown in this code:
 267  *
 268  *       extern const  char U_IMPORT U_ICUDATA_ENTRY_POINT [];
 269  *        // U_ICUDATA_ENTRY_POINT is same as entry point specified to pkgdata tool
 270  *       UErrorCode  status = U_ZERO_ERROR;
 271  *
 272  *       udata_setCommonData(&U_ICUDATA_ENTRY_POINT, &status);
 273  *
 274  * Warning: ICU must NOT have even attempted to access its data yet
 275  * when this call is made, or U_USING_DEFAULT_WARNING code will
 276  * be returned. Be careful of UnicodeStrings in static initialization which
 277  * may attempt to load a converter (use the UNICODE_STRING(x) macro instead).
 278  *
 279  * Also note that it is important that the declaration be as above. The entry point
 280  * must not be declared as an extern void*.
 281  *
 282  * This function has no effect on application (non ICU) data.  See udata_setAppData()
 283  * for similar functionality for application data.
 284  *
 285  * @param data pointer to ICU common data
 286  * @param err outgoing error status <code>U_USING_DEFAULT_WARNING, U_UNSUPPORTED_ERROR</code>
 287  * @stable ICU 2.0
 288  */
 289
 290 U_CAPI void U_EXPORT2
 291 udata_setCommonData(const void *data, UErrorCode *err);
 292
 293
 294 /**
 295  * This function bypasses the normal ICU data loading process for application-specific
 296  * data and allows you to force the it to come out of a user-specified
 297  * pointer.
 298  *
 299  * The format of this data is that of the icu common data file, like 'icudt26l.dat'
 300  * or the corresponding shared library (DLL) file.
 301  * The application must read in or otherwise construct an image of the data and then
 302  * pass the address of it to this function.
 303  *
 304  *
 305  * Warning:  setAppData will set a U_USING_DEFAULT_WARNING code if
 306  *           data with the specifed path that has already been opened, or
 307  *           if setAppData with the same path has already been called.
 308  *           Any such calls to setAppData will have no effect.
 309  *
 310  *
 311  * @param packageName the package name by which the application will refer
 312  *             to (open) this data
 313  * @param data pointer to the data
 314  * @param err outgoing error status <code>U_USING_DEFAULT_WARNING, U_UNSUPPORTED_ERROR</code>
 315  * @see udata_setCommonData
 316  * @stable ICU 2.0
 317  */
 318 U_CAPI void U_EXPORT2
 319 udata_setAppData(const char *packageName, const void *data, UErrorCode *err);
 320
 321 U_CDECL_END
 322
 323 #endif