text: /*-------------------------------------------------------------------------
   *
   * array.h
   *	  Declarations for Postgres arrays.
   *
   * A standard varlena array has the following internal structure:
   *	  <vl_len_>		- standard varlena header word
   *	  <ndim>		- number of dimensions of the array
   *	  <dataoffset>	- offset to stored data, or 0 if no nulls bitmap
   *	  <elemtype>	- element type OID
   *	  <dimensions>	- length of each array axis (C array of int)
   *	  <lower bnds>	- lower boundary of each dimension (C array of int)
   *	  <null bitmap> - bitmap showing locations of nulls (OPTIONAL)
   *	  <actual data> - whatever is the stored data
   *
   * The <dimensions> and <lower bnds> arrays each have ndim elements.
   *
   * The <null bitmap> may be omitted if the array contains no NULL elements.
   * If it is absent, the <dataoffset> field is zero and the offset to the
   * stored data must be computed on-the-fly.  If the bitmap is present,
   * <dataoffset> is nonzero and is equal to the offset from the array start
   * to the first data element (including any alignment padding).  The bitmap
   * follows the same conventions as tuple null bitmaps, ie, a 1 indicates
   * a non-null entry and the LSB of each bitmap byte is used first.
   *
   * The actual data starts on a MAXALIGN boundary.  Individual items in the
   * array are aligned as specified by the array element type.  They are
   * stored in row-major order (last subscript varies most rapidly).
   *
   * NOTE: it is important that array elements of toastable datatypes NOT be
   * toasted, since the tupletoaster won't know they are there.  (We could
   * support compressed toasted items; only out-of-line items are dangerous.
   * However, it seems preferable to store such items uncompressed and allow
   * the toaster to compress the whole array as one input.)
   *
   *
   * The OIDVECTOR and INT2VECTOR datatypes are storage-compatible with
   * generic arrays, but they support only one-dimensional arrays with no
   * nulls (and no null bitmap).
   *
   * There are also some "fixed-length array" datatypes, such as NAME and
   * POINT.  These are simply a sequence of a fixed number of items each
   * of a fixed-length datatype, with no overhead; the item size must be
   * a multiple of its alignment requirement, because we do no padding.
   * We support subscripting on these types, but array_in() and array_out()
   * only work with varlena arrays.
   *
   *
   * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   * src/include/utils/array.h
   *
   *-------------------------------------------------------------------------
   */
  #ifndef ARRAY_H
  #define ARRAY_H
  
  #include "fmgr.h"
  
  /*
   * Arrays are varlena objects, so must meet the varlena convention that
   * the first int32 of the object contains the total object size in bytes.
   * Be sure to use VARSIZE() and SET_VARSIZE() to access it, though!
   *
   * CAUTION: if you change the header for ordinary arrays you will also
   * need to change the headers for oidvector and int2vector!
   */
  typedef struct
  {
  	int32		vl_len_;		/* varlena header (do not touch directly!) */
  	int			ndim;			/* # of dimensions */
  	int32		dataoffset;		/* offset to data, or 0 if no bitmap */
  	Oid			elemtype;		/* element type OID */
  } ArrayType;
  
  /*
   * working state for accumArrayResult() and friends
   * note that the input must be scalars (legal array elements)
   */
  typedef struct ArrayBuildState
  {
  	MemoryContext mcontext;		/* where all the temp stuff is kept */
  	Datum	   *dvalues;		/* array of accumulated Datums */
  	bool	   *dnulls;			/* array of is-null flags for Datums */
  	int			alen;			/* allocated length of above arrays */
  	int			nelems;			/* number of valid entries in above arrays */
  	Oid			element_type;	/* data type of the Datums */
  	int16		typlen;			/* needed info about datatype */
  	bool		typbyval;
  	char		typalign;
  	bool		private_cxt;	/* use private memory context */
  } ArrayBuildState;
  
  /*
   * working state for accumArrayResultArr() and friends
   * note that the input must be arrays, and the same array type is returned
   */
  typedef struct ArrayBuildStateArr
  {
  	MemoryContext mcontext;		/* where all the temp stuff is kept */
  	char	   *data;			/* accumulated data */
  	bits8	   *nullbitmap;		/* bitmap of is-null flags, or NULL if none */
  	int			abytes;			/* allocated length of "data" */
  	int			nbytes;			/* number of bytes used so far */
  	int			aitems;			/* allocated length of bitmap (in elements) */
  	int			nitems;			/* total number of elements in result */
  	int			ndims;			/* current dimensions of result */
  	int			dims[MAXDIM];
  	int			lbs[MAXDIM];
  	Oid			array_type;		/* data type of the arrays */
  	Oid			element_type;	/* data type of the array elements */
  	bool		private_cxt;	/* use private memory context */
  } ArrayBuildStateArr;
  
  /*
   * working state for accumArrayResultAny() and friends
   * these functions handle both cases
   */
  typedef struct ArrayBuildStateAny
  {
  	/* Exactly one of these is not NULL: */
  	ArrayBuildState *scalarstate;
  	ArrayBuildStateArr *arraystate;
  } ArrayBuildStateAny;
  
  /*
   * structure to cache type metadata needed for array manipulation
   */
  typedef struct ArrayMetaState
  {
  	Oid			element_type;
  	int16		typlen;
  	bool		typbyval;
  	char		typalign;
  	char		typdelim;
  	Oid			typioparam;
  	Oid			typiofunc;
  	FmgrInfo	proc;
  } ArrayMetaState;
  
  /*
   * private state needed by array_map (here because caller must provide it)
   */
  typedef struct ArrayMapState
  {
  	ArrayMetaState inp_extra;
  	ArrayMetaState ret_extra;
  } ArrayMapState;
  
  /* ArrayIteratorData is private in arrayfuncs.c */
  typedef struct ArrayIteratorData *ArrayIterator;
  
  /*
   * fmgr macros for array objects
   */
  #define DatumGetArrayTypeP(X)		  ((ArrayType *) PG_DETOAST_DATUM(X))
  #define DatumGetArrayTypePCopy(X)	  ((ArrayType *) PG_DETOAST_DATUM_COPY(X))
  #define PG_GETARG_ARRAYTYPE_P(n)	  DatumGetArrayTypeP(PG_GETARG_DATUM(n))
  #define PG_GETARG_ARRAYTYPE_P_COPY(n) DatumGetArrayTypePCopy(PG_GETARG_DATUM(n))
  #define PG_RETURN_ARRAYTYPE_P(x)	  PG_RETURN_POINTER(x)
  
  /*
   * Access macros for array header fields.
   *
   * ARR_DIMS returns a pointer to an array of array dimensions (number of
   * elements along the various array axes).
   *
   * ARR_LBOUND returns a pointer to an array of array lower bounds.
   *
   * That is: if the third axis of an array has elements 5 through 8, then
   * ARR_DIMS(a)[2] == 4 and ARR_LBOUND(a)[2] == 5.
   *
   * Unlike C, the default lower bound is 1.
   */
  #define ARR_SIZE(a)				VARSIZE(a)
  #define ARR_NDIM(a)				((a)->ndim)
  #define ARR_HASNULL(a)			((a)->dataoffset != 0)
  #define ARR_ELEMTYPE(a)			((a)->elemtype)
  
  #define ARR_DIMS(a) \
  		((int *) (((char *) (a)) + sizeof(ArrayType)))
  #define ARR_LBOUND(a) \
  		((int *) (((char *) (a)) + sizeof(ArrayType) + \
  				  sizeof(int) * ARR_NDIM(a)))
  
  #define ARR_NULLBITMAP(a) \
  		(ARR_HASNULL(a) ? \
  		 (bits8 *) (((char *) (a)) + sizeof(ArrayType) + \
  					2 * sizeof(int) * ARR_NDIM(a)) \
  		 : (bits8 *) NULL)
  
  /*
   * The total array header size (in bytes) for an array with the specified
   * number of dimensions and total number of items.
   */
  #define ARR_OVERHEAD_NONULLS(ndims) \
  		MAXALIGN(sizeof(ArrayType) + 2 * sizeof(int) * (ndims))
  #define ARR_OVERHEAD_WITHNULLS(ndims, nitems) \
  		MAXALIGN(sizeof(ArrayType) + 2 * sizeof(int) * (ndims) + \
  				 ((nitems) + 7) / 8)
  
  #define ARR_DATA_OFFSET(a) \
  		(ARR_HASNULL(a) ? (a)->dataoffset : ARR_OVERHEAD_NONULLS(ARR_NDIM(a)))
  
  /*
   * Returns a pointer to the actual array data.
   */
  #define ARR_DATA_PTR(a) \
  		(((char *) (a)) + ARR_DATA_OFFSET(a))
  
  
  /*
   * GUC parameter
   */
  extern bool Array_nulls;
  
  /*
   * prototypes for functions defined in arrayfuncs.c
   */
  extern Datum array_in(PG_FUNCTION_ARGS);
  extern Datum array_out(PG_FUNCTION_ARGS);
  extern Datum array_recv(PG_FUNCTION_ARGS);
  extern Datum array_send(PG_FUNCTION_ARGS);
  extern Datum array_eq(PG_FUNCTION_ARGS);
  extern Datum array_ne(PG_FUNCTION_ARGS);
  extern Datum array_lt(PG_FUNCTION_ARGS);
  extern Datum array_gt(PG_FUNCTION_ARGS);
  extern Datum array_le(PG_FUNCTION_ARGS);
  extern Datum array_ge(PG_FUNCTION_ARGS);
  extern Datum btarraycmp(PG_FUNCTION_ARGS);
  extern Datum hash_array(PG_FUNCTION_ARGS);
  extern Datum arrayoverlap(PG_FUNCTION_ARGS);
  extern Datum arraycontains(PG_FUNCTION_ARGS);
  extern Datum arraycontained(PG_FUNCTION_ARGS);
  extern Datum array_ndims(PG_FUNCTION_ARGS);
  extern Datum array_dims(PG_FUNCTION_ARGS);
  extern Datum array_lower(PG_FUNCTION_ARGS);
  extern Datum array_upper(PG_FUNCTION_ARGS);
  extern Datum array_length(PG_FUNCTION_ARGS);
  extern Datum array_cardinality(PG_FUNCTION_ARGS);
  extern Datum array_larger(PG_FUNCTION_ARGS);
  extern Datum array_smaller(PG_FUNCTION_ARGS);
  extern Datum generate_subscripts(PG_FUNCTION_ARGS);
  extern Datum generate_subscripts_nodir(PG_FUNCTION_ARGS);
  extern Datum array_fill(PG_FUNCTION_ARGS);
  extern Datum array_fill_with_lower_bounds(PG_FUNCTION_ARGS);
  extern Datum array_unnest(PG_FUNCTION_ARGS);
  extern Datum array_remove(PG_FUNCTION_ARGS);
  extern Datum array_replace(PG_FUNCTION_ARGS);
  extern Datum width_bucket_array(PG_FUNCTION_ARGS);
  
  extern Datum array_get_element(Datum arraydatum, int nSubscripts, int *indx,
  				  int arraytyplen, int elmlen, bool elmbyval, char elmalign,
  				  bool *isNull);
  extern Datum array_set_element(Datum arraydatum, int nSubscripts, int *indx,
  				  Datum dataValue, bool isNull,
  				  int arraytyplen, int elmlen, bool elmbyval, char elmalign);
  extern Datum array_get_slice(Datum arraydatum, int nSubscripts,
  				int *upperIndx, int *lowerIndx,
  				int arraytyplen, int elmlen, bool elmbyval, char elmalign);
  extern Datum array_set_slice(Datum arraydatum, int nSubscripts,
  				int *upperIndx, int *lowerIndx,
  				Datum srcArrayDatum, bool isNull,
  				int arraytyplen, int elmlen, bool elmbyval, char elmalign);
  
  extern Datum array_ref(ArrayType *array, int nSubscripts, int *indx,
  		  int arraytyplen, int elmlen, bool elmbyval, char elmalign,
  		  bool *isNull);
  extern ArrayType *array_set(ArrayType *array, int nSubscripts, int *indx,
  		  Datum dataValue, bool isNull,
  		  int arraytyplen, int elmlen, bool elmbyval, char elmalign);
  
  extern Datum array_map(FunctionCallInfo fcinfo, Oid inpType, Oid retType,
  		  ArrayMapState *amstate);
  
  extern void array_bitmap_copy(bits8 *destbitmap, int destoffset,
  				  const bits8 *srcbitmap, int srcoffset,
  				  int nitems);
  
  extern ArrayType *construct_array(Datum *elems, int nelems,
  				Oid elmtype,
  				int elmlen, bool elmbyval, char elmalign);
  extern ArrayType *construct_md_array(Datum *elems,
  				   bool *nulls,
  				   int ndims,
  				   int *dims,
  				   int *lbs,
  				   Oid elmtype, int elmlen, bool elmbyval, char elmalign);
  extern ArrayType *construct_empty_array(Oid elmtype);
  extern void deconstruct_array(ArrayType *array,
  				  Oid elmtype,
  				  int elmlen, bool elmbyval, char elmalign,
  				  Datum **elemsp, bool **nullsp, int *nelemsp);
  extern bool array_contains_nulls(ArrayType *array);
  
  extern ArrayBuildState *initArrayResult(Oid element_type,
  				MemoryContext rcontext, bool subcontext);
  extern ArrayBuildState *accumArrayResult(ArrayBuildState *astate,
  				 Datum dvalue, bool disnull,
  				 Oid element_type,
  				 MemoryContext rcontext);
  extern Datum makeArrayResult(ArrayBuildState *astate,
  				MemoryContext rcontext);
  extern Datum makeMdArrayResult(ArrayBuildState *astate, int ndims,
  				  int *dims, int *lbs, MemoryContext rcontext, bool release);
  
  extern ArrayBuildStateArr *initArrayResultArr(Oid array_type, Oid element_type,
  				   MemoryContext rcontext, bool subcontext);
  extern ArrayBuildStateArr *accumArrayResultArr(ArrayBuildStateArr *astate,
  					Datum dvalue, bool disnull,
  					Oid array_type,
  					MemoryContext rcontext);
  extern Datum makeArrayResultArr(ArrayBuildStateArr *astate,
  				   MemoryContext rcontext, bool release);
  
  extern ArrayBuildStateAny *initArrayResultAny(Oid input_type,
  				   MemoryContext rcontext, bool subcontext);
  extern ArrayBuildStateAny *accumArrayResultAny(ArrayBuildStateAny *astate,
  					Datum dvalue, bool disnull,
  					Oid input_type,
  					MemoryContext rcontext);
  extern Datum makeArrayResultAny(ArrayBuildStateAny *astate,
  				   MemoryContext rcontext, bool release);
  
  extern ArrayIterator array_create_iterator(ArrayType *arr, int slice_ndim, ArrayMetaState *mstate);
  extern bool array_iterate(ArrayIterator iterator, Datum *value, bool *isnull);
  extern void array_free_iterator(ArrayIterator iterator);
  
  /*
   * prototypes for functions defined in arrayutils.c
   */
  
  extern int	ArrayGetOffset(int n, const int *dim, const int *lb, const int *indx);
  extern int	ArrayGetOffset0(int n, const int *tup, const int *scale);
  extern int	ArrayGetNItems(int ndim, const int *dims);
  extern void mda_get_range(int n, int *span, const int *st, const int *endp);
  extern void mda_get_prod(int n, const int *range, int *prod);
  extern void mda_get_offset_values(int n, int *dist, const int *prod, const int *span);
  extern int	mda_next_tuple(int n, int *curr, const int *span);
  extern int32 *ArrayGetIntegerTypmods(ArrayType *arr, int *n);
  
  /*
   * prototypes for functions defined in array_userfuncs.c
   */
  extern Datum array_append(PG_FUNCTION_ARGS);
  extern Datum array_prepend(PG_FUNCTION_ARGS);
  extern Datum array_cat(PG_FUNCTION_ARGS);
  
  extern ArrayType *create_singleton_array(FunctionCallInfo fcinfo,
  					   Oid element_type,
  					   Datum element,
  					   bool isNull,
  					   int ndims);
  
  extern Datum array_agg_transfn(PG_FUNCTION_ARGS);
  extern Datum array_agg_finalfn(PG_FUNCTION_ARGS);
  extern Datum array_agg_array_transfn(PG_FUNCTION_ARGS);
  extern Datum array_agg_array_finalfn(PG_FUNCTION_ARGS);
  
  extern Datum array_offset(PG_FUNCTION_ARGS);
  extern Datum array_offset_start(PG_FUNCTION_ARGS);
  extern Datum array_offsets(PG_FUNCTION_ARGS);
  
  /*
   * prototypes for functions defined in array_typanalyze.c
   */
  extern Datum array_typanalyze(PG_FUNCTION_ARGS);
  
  #endif   /* ARRAY_H */
  