/*
**********************************************************************
*   Copyright (C) 1999-2003, International Business Machines
*   Corporation and others.  All Rights Reserved.
**********************************************************************
*
*   uconv_cnv.h:
*   defines all the low level conversion functions
*   T_UnicodeConverter_{to,from}Unicode_$ConversionType
*
* Modification History:
*
*   Date        Name        Description
*   05/09/00    helena      Added implementation to handle fallback mappings.
*   06/29/2000  helena      Major rewrite of the callback APIs.
*/

#ifndef UCNV_CNV_H
#define UCNV_CNV_H

#include "unicode/utypes.h"
#include "unicode/ucnv.h"
#include "unicode/ucnv_err.h"

U_CDECL_BEGIN

/* this is used in fromUnicode DBCS tables as an "unassigned" marker */
#define missingCharMarker 0xFFFF

/*
 * #define missingUCharMarker 0xfffe
 *
 * commented out because there are actually two values used in toUnicode tables:
 * U+fffe "unassigned"
 * U+ffff "illegal"
 */

/** Forward declaration, see ucnv_bld.h */
struct UConverterSharedData;
typedef struct UConverterSharedData UConverterSharedData;

/* function types for UConverterImpl ---------------------------------------- */

/* struct with arguments for UConverterLoad and ucnv_load() */
typedef struct {
    int32_t size;               /* sizeof(UConverterLoadArgs) */
    int32_t nestedLoads;        /* count nested ucnv_load() calls */
    int32_t reserved;           /* reserved - for good alignment of the pointers */
    uint32_t options;
    const char *pkg, *name;
} UConverterLoadArgs;

typedef void (*UConverterLoad) (UConverterSharedData *sharedData,
                                UConverterLoadArgs *pArgs,
                                const uint8_t *raw, UErrorCode *pErrorCode);
typedef void (*UConverterUnload) (UConverterSharedData *sharedData);

typedef void (*UConverterOpen) (UConverter *cnv, const char *name, const char *locale,uint32_t options, UErrorCode *pErrorCode);
typedef void (*UConverterClose) (UConverter *cnv);

typedef enum UConverterResetChoice {
    UCNV_RESET_BOTH,
    UCNV_RESET_TO_UNICODE,
    UCNV_RESET_FROM_UNICODE
} UConverterResetChoice;

typedef void (*UConverterReset) (UConverter *cnv, UConverterResetChoice choice);

/*
 * Converter implementation function(s) for ucnv_toUnicode().
 * If the toUnicodeWithOffsets function pointer is NULL,
 * then the toUnicode function will be used and the offsets will be set to -1.
 *
 * Must maintain state across buffers. Use toUBytes[toULength] for partial input
 * sequences; it will be checked in ucnv.c at the end of the input stream
 * to detect truncated input.
 * Some converters may need additional detection and may then set U_TRUNCATED_CHAR_FOUND.
 *
 * The toUnicodeWithOffsets must write exactly as many offset values as target
 * units. Write offset values of -1 for when the source index corresponding to
 * the output unit is not known (e.g., the character started in an earlier buffer).
 * The pArgs->offsets pointer need not be moved forward.
 *
 * At function return, either one of the following conditions must be true:
 * - U_BUFFER_OVERFLOW_ERROR and the target is full: target==targetLimit
 * - another error code with toUBytes[toULength] set to the offending input
 * - no error, and the source is consumed: source==sourceLimit
 *
 * The ucnv.c code will handle the end of the input (reset)
 * (reset, and truncation detection) and callbacks.
 */
typedef void (*UConverterToUnicode) (UConverterToUnicodeArgs *, UErrorCode *);

/*
 * Same rules as for UConverterToUnicode.
 * A lead surrogate is kept in fromUChar32 across buffers, and if an error
 * occurs, then the offending input code point must be put into fromUChar32
 * as well.
 */
typedef void (*UConverterFromUnicode) (UConverterFromUnicodeArgs *, UErrorCode *);

/*
 * Converter implementation function for ucnv_getNextUChar().
 * If the function pointer is NULL, then the toUnicode function will be used.
 *
 * Will be called at a character boundary (toULength==0).
 * May return with
 * - U_INDEX_OUTOFBOUNDS_ERROR if there was no output for the input
 *   (the return value will be ignored)
 * - U_TRUNCATED_CHAR_FOUND or another error code (never U_BUFFER_OVERFLOW_ERROR!)
 *   with toUBytes[toULength] set to the offending input
 *   (the return value will be ignored)
 * - return UCNV_GET_NEXT_UCHAR_USE_TO_U, without moving the source pointer,
 *   to indicate that the ucnv.c code shall call the toUnicode function instead
 * - return a real code point result
 *
 * Unless UCNV_GET_NEXT_UCHAR_USE_TO_U is returned, the source bytes must be consumed.
 *
 * The ucnv.c code will handle the end of the input (reset)
 * (except for truncation detection!) and callbacks.
 */
typedef UChar32 (*UConverterGetNextUChar) (UConverterToUnicodeArgs *, UErrorCode *);

typedef void (*UConverterGetStarters)(const UConverter* converter,
                                      UBool starters[256],
                                      UErrorCode *pErrorCode);

/* If this function pointer is null or if the function returns null
 * the name field in static data struct should be returned by 
 * ucnv_getName() API function
 */
typedef const char * (*UConverterGetName) (const UConverter *cnv);

/**
 * Write the codepage substitution character.
 * If this function is not set, then ucnv_cbFromUWriteSub() writes
 * the substitution character from UConverter.
 * For stateful converters, it is typically necessary to handle this
 * specificially for the converter in order to properly maintain the state.
 */
typedef void (*UConverterWriteSub) (UConverterFromUnicodeArgs *pArgs, int32_t offsetIndex, UErrorCode *pErrorCode);

/**
 * For converter-specific safeClone processing
 * If this function is not set, then ucnv_safeClone assumes that the converter has no private data that changes
 * after the converter is done opening.
 * If this function is set, then it is called just after a memcpy() of
 * converter data to the new, empty converter, and is expected to set up
 * the initial state of the converter.  It is not expected to increment the
 * reference counts of the standard data types such as the shared data.
 */
typedef UConverter * (*UConverterSafeClone) (const UConverter   *cnv, 
                                             void               *stackBuffer,
                                             int32_t            *pBufferSize, 
                                             UErrorCode         *status);

/**
 * Fills the set of Unicode code points that can be converted by an ICU converter.
 * The API function ucnv_getUnicodeSet() clears the USet before calling
 * the converter's getUnicodeSet() implementation; the converter should only
 * add the appropriate code points to allow recursive use.
 * For example, the ISO-2022-JP converter will call each subconverter's
 * getUnicodeSet() implementation to consecutively add code points to
 * the same USet, which will result in a union of the sets of all subconverters.
 *
 * For more documentation, see ucnv_getUnicodeSet() in ucnv.h.
 */
typedef void (*UConverterGetUnicodeSet) (const UConverter *cnv,
                                         USet *set,
                                         UConverterUnicodeSet which,
                                         UErrorCode *pErrorCode);

UBool CONVERSION_U_SUCCESS (UErrorCode err);

/**
 * UConverterImpl contains all the data and functions for a converter type.
 * Its function pointers work much like a C++ vtable.
 * Many converter types need to define only a subset of the functions;
 * when a function pointer is NULL, then a default action will be performed.
 *
 * Every converter type must implement toUnicode, fromUnicode, and getNextUChar,
 * otherwise the converter may crash.
 * Every converter type that has variable-length codepage sequences should
 * also implement toUnicodeWithOffsets and fromUnicodeWithOffsets for
 * correct offset handling.
 * All other functions may or may not be implemented - it depends only on
 * whether the converter type needs them.
 *
 * When open() fails, then close() will be called, if present.
 */
struct UConverterImpl {
    UConverterType type;

    UConverterLoad load;
    UConverterUnload unload;

    UConverterOpen open;
    UConverterClose close;
    UConverterReset reset;

    UConverterToUnicode toUnicode;
    UConverterToUnicode toUnicodeWithOffsets;
    UConverterFromUnicode fromUnicode;
    UConverterFromUnicode fromUnicodeWithOffsets;
    UConverterGetNextUChar getNextUChar;

    UConverterGetStarters getStarters;
    UConverterGetName getName;
    UConverterWriteSub writeSub;
    UConverterSafeClone safeClone;
    UConverterGetUnicodeSet getUnicodeSet;
};

extern const UConverterSharedData
    _MBCSData, _Latin1Data,
    _UTF8Data, _UTF16BEData, _UTF16LEData, _UTF32BEData, _UTF32LEData,
    _ISO2022Data, 
    _LMBCSData1,_LMBCSData2, _LMBCSData3, _LMBCSData4, _LMBCSData5, _LMBCSData6,
    _LMBCSData8,_LMBCSData11,_LMBCSData16,_LMBCSData17,_LMBCSData18,_LMBCSData19,
    _HZData,_ISCIIData, _SCSUData, _ASCIIData,
    _UTF7Data, _Bocu1Data, _UTF16Data, _UTF32Data, _CESU8Data, _IMAPData;

U_CDECL_END

/** Always use fallbacks from codepage to Unicode */
#define TO_U_USE_FALLBACK(useFallback) TRUE
#define UCNV_TO_U_USE_FALLBACK(cnv) TRUE

/** Use fallbacks from Unicode to codepage when cnv->useFallback or for private-use code points */
#define IS_PRIVATE_USE(c) ((uint32_t)((c)-0xe000)<0x1900 || (uint32_t)((c)-0xf0000)<0x20000)
#define FROM_U_USE_FALLBACK(useFallback, c) ((useFallback) || IS_PRIVATE_USE(c))
#define UCNV_FROM_U_USE_FALLBACK(cnv, c) FROM_U_USE_FALLBACK((cnv)->useFallback, c)

/**
 * Magic number for ucnv_getNextUChar(), returned by a
 * getNextUChar() implementation to indicate to use the converter's toUnicode()
 * instead of the native function.
 * @internal
 */
#define UCNV_GET_NEXT_UCHAR_USE_TO_U -9

U_CFUNC void
ucnv_getCompleteUnicodeSet(const UConverter *cnv,
                   USet *set,
                   UConverterUnicodeSet which,
                   UErrorCode *pErrorCode);

U_CFUNC void
ucnv_getNonSurrogateUnicodeSet(const UConverter *cnv,
                               USet *set,
                               UConverterUnicodeSet which,
                               UErrorCode *pErrorCode);

U_CFUNC void
ucnv_fromUWriteBytes(UConverter *cnv,
                     const char *bytes, int32_t length,
                     char **target, const char *targetLimit,
                     int32_t **offsets,
                     int32_t sourceIndex,
                     UErrorCode *pErrorCode);
U_CFUNC void
ucnv_toUWriteUChars(UConverter *cnv,
                    const UChar *uchars, int32_t length,
                    UChar **target, const UChar *targetLimit,
                    int32_t **offsets,
                    int32_t sourceIndex,
                    UErrorCode *pErrorCode);

U_CFUNC void
ucnv_toUWriteCodePoint(UConverter *cnv,
                       UChar32 c,
                       UChar **target, const UChar *targetLimit,
                       int32_t **offsets,
                       int32_t sourceIndex,
                       UErrorCode *pErrorCode);

#endif /* UCNV_CNV */