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+/*-------------------------------------------------------------------------
+ *
+ * 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). They don't support being toasted, either.
+ *
+ * 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.
+ *
+ * In addition, arrays are a major user of the "expanded object" TOAST
+ * infrastructure. This allows a varlena array to be converted to a
+ * separate representation that may include "deconstructed" Datum/isnull
+ * arrays holding the elements.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, 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"
+#include "utils/expandeddatum.h"
+
+/* avoid including execnodes.h here */
+struct ExprState;
+struct ExprContext;
+
+
+/*
+ * Maximum number of array subscripts (arbitrary limit)
+ */
+#define MAXDIM 6
+
+/*
+ * 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 ArrayType
+{
+ 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;
+
+/*
+ * An expanded array is contained within a private memory context (as
+ * all expanded objects must be) and has a control structure as below.
+ *
+ * The expanded array might contain a regular "flat" array if that was the
+ * original input and we've not modified it significantly. Otherwise, the
+ * contents are represented by Datum/isnull arrays plus dimensionality and
+ * type information. We could also have both forms, if we've deconstructed
+ * the original array for access purposes but not yet changed it. For pass-
+ * by-reference element types, the Datums would point into the flat array in
+ * this situation. Once we start modifying array elements, new pass-by-ref
+ * elements are separately palloc'd within the memory context.
+ */
+#define EA_MAGIC 689375833 /* ID for debugging crosschecks */
+
+typedef struct ExpandedArrayHeader
+{
+ /* Standard header for expanded objects */
+ ExpandedObjectHeader hdr;
+
+ /* Magic value identifying an expanded array (for debugging only) */
+ int ea_magic;
+
+ /* Dimensionality info (always valid) */
+ int ndims; /* # of dimensions */
+ int *dims; /* array dimensions */
+ int *lbound; /* index lower bounds for each dimension */
+
+ /* Element type info (always valid) */
+ Oid element_type; /* element type OID */
+ int16 typlen; /* needed info about element datatype */
+ bool typbyval;
+ char typalign;
+
+ /*
+ * If we have a Datum-array representation of the array, it's kept here;
+ * else dvalues/dnulls are NULL. The dvalues and dnulls arrays are always
+ * palloc'd within the object private context, but may change size from
+ * time to time. For pass-by-ref element types, dvalues entries might
+ * point either into the fstartptr..fendptr area, or to separately
+ * palloc'd chunks. Elements should always be fully detoasted, as they
+ * are in the standard flat representation.
+ *
+ * Even when dvalues is valid, dnulls can be NULL if there are no null
+ * elements.
+ */
+ Datum *dvalues; /* array of Datums */
+ bool *dnulls; /* array of is-null flags for Datums */
+ int dvalueslen; /* allocated length of above arrays */
+ int nelems; /* number of valid entries in above arrays */
+
+ /*
+ * flat_size is the current space requirement for the flat equivalent of
+ * the expanded array, if known; otherwise it's 0. We store this to make
+ * consecutive calls of get_flat_size cheap.
+ */
+ Size flat_size;
+
+ /*
+ * fvalue points to the flat representation if it is valid, else it is
+ * NULL. If we have or ever had a flat representation then
+ * fstartptr/fendptr point to the start and end+1 of its data area; this
+ * is so that we can tell which Datum pointers point into the flat
+ * representation rather than being pointers to separately palloc'd data.
+ */
+ ArrayType *fvalue; /* must be a fully detoasted array */
+ char *fstartptr; /* start of its data area */
+ char *fendptr; /* end+1 of its data area */
+} ExpandedArrayHeader;
+
+/*
+ * Functions that can handle either a "flat" varlena array or an expanded
+ * array use this union to work with their input. Don't refer to "flt";
+ * instead, cast to ArrayType. This struct nominally requires 8-byte
+ * alignment on 64-bit, but it's often used for an ArrayType having 4-byte
+ * alignment. UBSan complains about referencing "flt" in such cases.
+ */
+typedef union AnyArrayType
+{
+ ArrayType flt;
+ ExpandedArrayHeader xpn;
+} AnyArrayType;
+
+/*
+ * 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 regular varlena 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)
+
+/* fmgr macros for expanded array objects */
+#define PG_GETARG_EXPANDED_ARRAY(n) DatumGetExpandedArray(PG_GETARG_DATUM(n))
+#define PG_GETARG_EXPANDED_ARRAYX(n, metacache) \
+ DatumGetExpandedArrayX(PG_GETARG_DATUM(n), metacache)
+#define PG_RETURN_EXPANDED_ARRAY(x) PG_RETURN_DATUM(EOHPGetRWDatum(&(x)->hdr))
+
+/* fmgr macros for AnyArrayType (ie, get either varlena or expanded form) */
+#define PG_GETARG_ANY_ARRAY_P(n) DatumGetAnyArrayP(PG_GETARG_DATUM(n))
+
+/*
+ * Access macros for varlena 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))
+
+/*
+ * Macros for working with AnyArrayType inputs. Beware multiple references!
+ */
+#define AARR_NDIM(a) \
+ (VARATT_IS_EXPANDED_HEADER(a) ? \
+ (a)->xpn.ndims : ARR_NDIM((ArrayType *) (a)))
+#define AARR_HASNULL(a) \
+ (VARATT_IS_EXPANDED_HEADER(a) ? \
+ ((a)->xpn.dvalues != NULL ? (a)->xpn.dnulls != NULL : ARR_HASNULL((a)->xpn.fvalue)) : \
+ ARR_HASNULL((ArrayType *) (a)))
+#define AARR_ELEMTYPE(a) \
+ (VARATT_IS_EXPANDED_HEADER(a) ? \
+ (a)->xpn.element_type : ARR_ELEMTYPE((ArrayType *) (a)))
+#define AARR_DIMS(a) \
+ (VARATT_IS_EXPANDED_HEADER(a) ? \
+ (a)->xpn.dims : ARR_DIMS((ArrayType *) (a)))
+#define AARR_LBOUND(a) \
+ (VARATT_IS_EXPANDED_HEADER(a) ? \
+ (a)->xpn.lbound : ARR_LBOUND((ArrayType *) (a)))
+
+
+/*
+ * GUC parameter
+ */
+extern bool Array_nulls;
+
+/*
+ * prototypes for functions defined in arrayfuncs.c
+ */
+extern void CopyArrayEls(ArrayType *array,
+ Datum *values,
+ bool *nulls,
+ int nitems,
+ int typlen,
+ bool typbyval,
+ char typalign,
+ bool freedata);
+
+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,
+ bool *upperProvided, bool *lowerProvided,
+ int arraytyplen, int elmlen, bool elmbyval, char elmalign);
+extern Datum array_set_slice(Datum arraydatum, int nSubscripts,
+ int *upperIndx, int *lowerIndx,
+ bool *upperProvided, bool *lowerProvided,
+ 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(Datum arrayd,
+ struct ExprState *exprstate, struct ExprContext *econtext,
+ 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 ExpandedArrayHeader *construct_empty_expanded_array(Oid element_type,
+ MemoryContext parentcontext,
+ ArrayMetaState *metacache);
+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 ArrayCheckBounds(int ndim, const int *dims, const int *lb);
+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_expanded.c
+ */
+extern Datum expand_array(Datum arraydatum, MemoryContext parentcontext,
+ ArrayMetaState *metacache);
+extern ExpandedArrayHeader *DatumGetExpandedArray(Datum d);
+extern ExpandedArrayHeader *DatumGetExpandedArrayX(Datum d,
+ ArrayMetaState *metacache);
+extern AnyArrayType *DatumGetAnyArrayP(Datum d);
+extern void deconstruct_expanded_array(ExpandedArrayHeader *eah);
+
+#endif /* ARRAY_H */
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