/*
 * string.h - Public API for Scheme strings
 *
 *   Copyright (c) 2000-2016  Shiro Kawai  <shiro@acm.org>
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 *   3. Neither the name of the authors nor the names of its contributors
 *      may be used to endorse or promote products derived from this
 *      software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 *   TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* This file is included from gauche.h */

#ifndef GAUCHE_STRING_H
#define GAUCHE_STRING_H

/* [String mutation and MT safety]
 * Scheme String is mutable (unfortunately).  The fields of a string
 * may be altered by another thread while you're reading it.  For MT
 * safety, it is important that we ensure the atomicity in retrieving
 * string length/size and content.
 *
 * It isn't practical to use mutex for every string access, so we use
 * atomicity of pointer dereference and assignments.  The actual string
 * fields are stored in immutable structure, ScmStringBody, and a Scheme
 * string, ScmString, has a pointer to it.  When mutation occurs, a new
 * ScmStringBody is allocated, and the pointer is altered.  So, as far
 * as the client retrieves ScmStringBody first, then use its field values,
 * the client won't see inconsistent state.
 * Alternatively, the client can use Scm_GetStringContent(), which
 * retrieves length, size and char array atomically.
 *
 * We further use an assumption that mutation of strings is rare.
 * So ScmString is allocated with initial body.   The 'body' pointer
 * of ScmString is NULL when it is created, which indicates the initial
 * body is used (this convention allows static definition of ScmString).
 * Once the string is mutated, the 'body' pointer points to a
 * fresh ScmStringBody.  Note that it means the initial content of the
 * string, pointed by initialBody.start, won't be GC-ed as far as the
 * ScmString is alive, even if its content is mutated and the initial
 * content isn't used.   Another reason to avoid string mutations.
 */
/* NB: For the backward compatibility, the string size is 'int'.  We limit
   the length of strings up to min(INT_MAX, SCM_SMALL_INT_MAX).
   Theoretically we can make it bigger; but having such large string in
   flat array is a bad idea.  For the long term, we should have a simple
   string that has the flat multibyte characters,
   and a compound ones that has cord-like structure.
   We'll defer having >2G strings by then.
*/
typedef struct ScmStringBodyRec {
    unsigned int flags;
    unsigned int length;
    unsigned int size;
    const char *start;
} ScmStringBody;

#if SIZEOF_LONG == 4
#define SCM_STRING_MAX_SIZE    SCM_SMALL_INT_MAX
#define SCM_STRING_MAX_LENGTH  SCM_SMALL_INT_MAX
#else /*SIZEOF_LONG > 4*/
#define SCM_STRING_MAX_SIZE    INT_MAX
#define SCM_STRING_MAX_LENGTH  INT_MAX
#endif

struct ScmStringRec {
    SCM_HEADER;
    const ScmStringBody *body;  /* may be NULL if we use initial body. */
    ScmStringBody initialBody;  /* initial body */
};

/* The flag value.  Some of them can be specified at construction time
   (marked 'C').  Some of them are kept in "flags" field of the string body
   (marked 'R). */
enum ScmStringFlags {
    SCM_STRING_IMMUTABLE  = (1L<<0),     /* [C,R] The string is immutable. */
    SCM_STRING_INCOMPLETE = (1L<<1),     /* [C,R] The string is incomplete. */
    SCM_STRING_TERMINATED = (1L<<2),     /* [R] The string content is
                                            NUL-terminated.  This flag is used
                                            internally. */
    SCM_STRING_COPYING = (1L<<16),       /* [C]   Need to copy the content
                                            given to the constructor. */
};
#define SCM_STRING_FLAG_MASK  (0xffff)

SCM_CLASS_DECL(Scm_StringClass);
#define SCM_CLASS_STRING        (&Scm_StringClass)

#define SCM_STRINGP(obj)        SCM_XTYPEP(obj, SCM_CLASS_STRING)
#define SCM_STRING(obj)         ((ScmString*)(obj))
#define SCM_STRING_BODY(obj) \
    ((const ScmStringBody*)(SCM_STRING(obj)->body?SCM_STRING(obj)->body:&SCM_STRING(obj)->initialBody))

/* Accessor macros for string body */
#define SCM_STRING_BODY_LENGTH(body)       ((body)->length)
#define SCM_STRING_BODY_SIZE(body)         ((body)->size)
#define SCM_STRING_BODY_START(body)        ((body)->start)
#define SCM_STRING_BODY_FLAGS(body)        ((body)->flags)

#define SCM_STRING_BODY_HAS_FLAG(body, flag) \
    (SCM_STRING_BODY_FLAGS(body)&(flag))
#define SCM_STRING_BODY_INCOMPLETE_P(body)   \
    SCM_STRING_BODY_HAS_FLAG(body, SCM_STRING_INCOMPLETE)
#define SCM_STRING_BODY_IMMUTABLE_P(body)    \
    SCM_STRING_BODY_HAS_FLAG(body, SCM_STRING_IMMUTABLE)
#define SCM_STRING_BODY_SINGLE_BYTE_P(body) \
    (SCM_STRING_BODY_SIZE(body)==SCM_STRING_BODY_LENGTH(body))

/* This is MT-safe, for string immutability won't change */
#define SCM_STRING_IMMUTABLE_P(obj)  \
    SCM_STRING_BODY_IMMUTABLE_P(SCM_STRING_BODY(obj))

#define SCM_STRING_NULL_P(obj) \
    (SCM_STRING_BODY_SIZE(SCM_STRING_BODY(obj)) == 0)

/* Macros for backward compatibility.  Use of these are deprecated,
   since they are not MT-safe.  Use SCM_STRING_BODY_* macros or
   Scm_GetString* API. */
#define SCM_STRING_LENGTH(obj)  (SCM_STRING_BODY(obj)->length)
#define SCM_STRING_SIZE(obj)    (SCM_STRING_BODY(obj)->size)
#define SCM_STRING_START(obj)   (SCM_STRING_BODY(obj)->start)
#define SCM_STRING_INCOMPLETE_P(obj)  \
    (SCM_STRING_BODY_INCOMPLETE_P(SCM_STRING_BODY(obj)))
#define SCM_STRING_SINGLE_BYTE_P(obj) \
    (SCM_STRING_SIZE(obj)==SCM_STRING_LENGTH(obj))


/* OBSOLETED.  Kept for backward compatibility */
#define SCM_MAKSTR_INCOMPLETE  SCM_STRING_INCOMPLETE
#define SCM_MAKSTR_IMMUTABLE   SCM_STRING_IMMUTABLE
#define SCM_MAKSTR_COPYING     SCM_STRING_COPYING

/*
 * Constructors
 */

SCM_EXTERN ScmObj  Scm_MakeString(const char *str,
                                  ScmSmallInt size, ScmSmallInt len,
                                  int flags);
SCM_EXTERN ScmObj  Scm_MakeFillString(ScmSmallInt len, ScmChar fill);
SCM_EXTERN ScmObj  Scm_CopyStringWithFlags(ScmString *str, int flags, int mask);

#define SCM_MAKE_STR(cstr) \
    Scm_MakeString(cstr, -1, -1, 0)
#define SCM_MAKE_STR_COPYING(cstr) \
    Scm_MakeString(cstr, -1, -1, SCM_STRING_COPYING)
#define SCM_MAKE_STR_IMMUTABLE(cstr) \
    Scm_MakeString(cstr, -1, -1, SCM_STRING_IMMUTABLE)

#define Scm_CopyString(str) \
    Scm_CopyStringWithFlags(str, 0, SCM_STRING_IMMUTABLE)

/*
 * C String extraction
 */

SCM_EXTERN char*   Scm_GetString(ScmString *str);
SCM_EXTERN const char* Scm_GetStringConst(ScmString *str);
SCM_EXTERN const char* Scm_GetStringConstUnsafe(ScmString *str);
SCM_EXTERN const char* Scm_GetStringContent(ScmString *str,
                                            unsigned int *psize,
                                            unsigned int *plen,
                                            unsigned int *pflags);

#define SCM_STRING_CONST_CSTRING(obj) Scm_GetStringConst(SCM_STRING(obj))
#define SCM_STRING_CONST_CSTRING_SAFE(obj) Scm_GetStringConstSafe(SCM_STRING(obj))

/*
 * Conversions
 */

SCM_EXTERN ScmObj Scm_CStringArrayToList(const char **array,
                                         int size, int flags);
SCM_EXTERN const char **Scm_ListToConstCStringArray(ScmObj lis,
                                                    int errp);
SCM_EXTERN char **Scm_ListToCStringArray(ScmObj lis, int errp,
                                         void *(*alloc)(size_t));

SCM_EXTERN ScmObj  Scm_StringCompleteToIncomplete(ScmString *str);
SCM_EXTERN ScmObj  Scm_StringIncompleteToComplete(ScmString *str,
                                                  int handling,
                                                  ScmChar substitute);

SCM_EXTERN ScmObj  Scm_StringToList(ScmString *str);
SCM_EXTERN ScmObj  Scm_ListToString(ScmObj chars);

/*
 * Comparisons
 */

SCM_EXTERN int     Scm_StringEqual(ScmString *x, ScmString *y);
SCM_EXTERN int     Scm_StringCmp(ScmString *x, ScmString *y);
SCM_EXTERN int     Scm_StringCiCmp(ScmString *x, ScmString *y);

/*
 * Accessors and modifiers
 */

SCM_EXTERN ScmChar Scm_StringRef(ScmString *str,
                                 ScmSmallInt k,
                                 int range_error);
SCM_EXTERN int     Scm_StringByteRef(ScmString *str,
                                     ScmSmallInt k,
                                     int range_error);
SCM_EXTERN ScmObj  Scm_Substring(ScmString *x,
                                 ScmSmallInt start,
                                 ScmSmallInt end,
                                 int byterange);
SCM_EXTERN ScmObj  Scm_StringReplaceBody(ScmString *x, const ScmStringBody *b);

/*
 * Concatenation
 */

SCM_EXTERN ScmObj  Scm_StringAppend2(ScmString *x, ScmString *y);
SCM_EXTERN ScmObj  Scm_StringAppendC(ScmString *x, const char *s,
                                     ScmSmallInt size, ScmSmallInt len);
SCM_EXTERN ScmObj  Scm_StringAppend(ScmObj strs);
SCM_EXTERN ScmObj  Scm_StringJoin(ScmObj strs, ScmString *delim, int grammer);


/* grammer spec for StringJoin (see SRFI-13) */
enum {
    SCM_STRING_JOIN_INFIX,
    SCM_STRING_JOIN_STRICT_INFIX,
    SCM_STRING_JOIN_SUFFIX,
    SCM_STRING_JOIN_PREFIX
};

/*
 * Searching
 */

/* Note: On 1.0 release, let StringSplitByChar have limit arg.  For 0.9.x
   series we use a separate Scm_StringSplitByCharWithLimit in order to keep
   ABI compatibility. */
SCM_EXTERN ScmObj  Scm_StringSplitByChar(ScmString *str, ScmChar ch);
SCM_EXTERN ScmObj  Scm_StringSplitByCharWithLimit(ScmString *str, ScmChar ch,
                                                  int limit);
SCM_EXTERN ScmObj  Scm_StringScan(ScmString *s1, ScmString *s2, int retmode);
SCM_EXTERN ScmObj  Scm_StringScanChar(ScmString *s1, ScmChar ch, int retmode);
SCM_EXTERN ScmObj  Scm_StringScanRight(ScmString *s1, ScmString *s2, int retmode);
SCM_EXTERN ScmObj  Scm_StringScanCharRight(ScmString *s1, ScmChar ch, int retmode);

/* "retmode" argument for string scan */
enum {
    SCM_STRING_SCAN_INDEX,      /* return index */
    SCM_STRING_SCAN_BEFORE,     /* return substring of s1 before s2 */
    SCM_STRING_SCAN_AFTER,      /* return substring of s1 after s2 */
    SCM_STRING_SCAN_BEFORE2,    /* return substr of s1 before s2 and rest */
    SCM_STRING_SCAN_AFTER2,     /* return substr of s1 up to s2 and rest */
    SCM_STRING_SCAN_BOTH        /* return substr of s1 before and after s2 */
};

/*
 * Miscellaneous
 */
SCM_EXTERN int     Scm_MBLen(const char *str, const char *stop);

/* INTERNAL */
SCM_EXTERN const char *Scm_StringPosition(ScmString *str, ScmSmallInt k); /*DEPRECATED*/
SCM_EXTERN const char *Scm_StringBodyPosition(const ScmStringBody *str, ScmSmallInt k);
SCM_EXTERN ScmObj  Scm_MaybeSubstring(ScmString *x, ScmObj start, ScmObj end);

/*
 * Static initializer
 */
/* You can allocate a constant string statically, if you calculate
   the length by yourself.  These macros are mainly used in machine-
   generated code.
   SCM_DEFINE_STRING_CONST can be used to define a static string,
   and SCM_STRING_CONST_INITIALIZER can be used inside static array
   of strings. */

#define SCM_STRING_CONST_INITIALIZER(str, len, siz)             \
    { { SCM_CLASS_STATIC_TAG(Scm_StringClass) }, NULL,          \
      { SCM_STRING_IMMUTABLE|SCM_STRING_TERMINATED, (len), (siz), (str) } }

#define SCM_DEFINE_STRING_CONST(name, str, len, siz)            \
    ScmString name = SCM_STRING_CONST_INITIALIZER(str, len, siz)

/*
 * DStrings
 *   Auxiliary structure to construct a string of unknown length.
 *   This is not an ScmObj.   See string.c for details.
 */
#define SCM_DSTRING_INIT_CHUNK_SIZE 32

typedef struct ScmDStringChunkRec {
    int bytes;                  /* actual bytes stored in this chunk.
                                   Note that this is set when the next
                                   chunk is allocated. */
    char data[SCM_DSTRING_INIT_CHUNK_SIZE]; /* variable length, indeed. */
} ScmDStringChunk;

typedef struct ScmDStringChainRec {
    struct ScmDStringChainRec *next;
    ScmDStringChunk *chunk;
} ScmDStringChain;

struct ScmDStringRec {
    ScmDStringChunk init;       /* initial chunk */
    ScmDStringChain *anchor;    /* chain of extra chunks */
    ScmDStringChain *tail;      /* current chunk */
    char *current;              /* current ptr */
    char *end;                  /* end of current chunk */
    int lastChunkSize;          /* size of the last chunk */
    int length;                 /* # of chars written */
};

SCM_EXTERN void        Scm_DStringInit(ScmDString *dstr);
SCM_EXTERN int         Scm_DStringSize(ScmDString *dstr);
SCM_EXTERN ScmObj      Scm_DStringGet(ScmDString *dstr, int flags);
SCM_EXTERN const char *Scm_DStringGetz(ScmDString *dstr);
SCM_EXTERN const char *Scm_DStringPeek(ScmDString *dstr, int *size, int *len);
SCM_EXTERN void        Scm_DStringPutz(ScmDString *dstr, const char *str,
                                       int siz);
SCM_EXTERN void        Scm_DStringAdd(ScmDString *dstr, ScmString *str);
SCM_EXTERN void        Scm_DStringPutb(ScmDString *dstr, char byte);
SCM_EXTERN void        Scm_DStringPutc(ScmDString *dstr, ScmChar ch);

#define SCM_DSTRING_SIZE(dstr)    Scm_DStringSize(dstr);

#define SCM_DSTRING_PUTB(dstr, byte)                                     \
    do {                                                                 \
        if ((dstr)->current >= (dstr)->end) Scm__DStringRealloc(dstr, 1);\
        *(dstr)->current++ = (char)(byte);                               \
        (dstr)->length = -1;    /* may be incomplete */                  \
    } while (0)

#define SCM_DSTRING_PUTC(dstr, ch)                      \
    do {                                                \
        ScmChar ch_DSTR = (ch);                         \
        ScmDString *d_DSTR = (dstr);                    \
        int siz_DSTR = SCM_CHAR_NBYTES(ch_DSTR);        \
        if (d_DSTR->current + siz_DSTR > d_DSTR->end)   \
            Scm__DStringRealloc(d_DSTR, siz_DSTR);      \
        SCM_CHAR_PUT(d_DSTR->current, ch_DSTR);         \
        d_DSTR->current += siz_DSTR;                    \
        if (d_DSTR->length >= 0) d_DSTR->length++;      \
    } while (0)

SCM_EXTERN void Scm__DStringRealloc(ScmDString *dstr, int min_incr);

/*
 * Utility.  Returns NUL-terminated string (SRC doesn't need to be
 * NUL-terminated, but must be longer than SIZE).
 */
SCM_EXTERN char *Scm_StrdupPartial(const char *src, size_t size);

/*
 * String pointers (WILL BE OBSOLETED)
 */

/* Efficient way to access string from Scheme */
typedef struct ScmStringPointerRec {
    SCM_HEADER;
    int length;
    int size;
    const char *start;
    int index;
    const char *current;
} ScmStringPointer;

SCM_CLASS_DECL(Scm_StringPointerClass);
#define SCM_CLASS_STRING_POINTER  (&Scm_StringPointerClass)
#define SCM_STRING_POINTERP(obj)  SCM_XTYPEP(obj, SCM_CLASS_STRING_POINTER)
#define SCM_STRING_POINTER(obj)   ((ScmStringPointer*)obj)

SCM_EXTERN ScmObj Scm_MakeStringPointer(ScmString *src, ScmSmallInt index,
                                        ScmSmallInt start, ScmSmallInt end);
SCM_EXTERN ScmObj Scm_StringPointerRef(ScmStringPointer *sp);
SCM_EXTERN ScmObj Scm_StringPointerNext(ScmStringPointer *sp);
SCM_EXTERN ScmObj Scm_StringPointerPrev(ScmStringPointer *sp);
SCM_EXTERN ScmObj Scm_StringPointerSet(ScmStringPointer *sp,
                                       ScmSmallInt index);
SCM_EXTERN ScmObj Scm_StringPointerSubstring(ScmStringPointer *sp, int beforep);
SCM_EXTERN ScmObj Scm_StringPointerCopy(ScmStringPointer *sp);
SCM_EXTERN void   Scm_StringPointerDump(ScmStringPointer *sp);

#endif /* GAUCHE_STRING_H */

