Represent type-specific length coercion functions as pg_cast entries,

eliminating the former hard-wired convention about their names.  Allow
pg_cast entries to represent both type coercion and length coercion in
a single step --- this is represented by a function that takes an
extra typmod argument, just like a length coercion function.  This
nicely merges the type and length coercion mechanisms into something
at least a little cleaner than we had before.  Make use of the single-
coercion-step behavior to fix integer-to-bit coercion so that coercing
to bit(n) yields the rightmost n bits of the integer instead of the
leftmost n bits.  This should fix recurrent complaints about the odd
behavior of this coercion.  Clean up the documentation of the bit string
functions, and try to put it where people might actually find it.
Also, get rid of the unreliable heuristics in ruleutils.c about whether
to display nested coercion steps; instead require parse_coerce.c to
label them properly in the first place.

1 files changed, 116 insertions, 81 deletions

diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 62361932f98..e9951d839a3 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.104 2004/06/08 20:28:21 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.105 2004/06/16 01:26:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -109,6 +109,11 @@ static void array_insert_slice(int ndim, int *dim, int *lb,
 				   int *st, int *endp, char *srcPtr,
 				   int typlen, bool typbyval, char typalign);
 static int	array_cmp(FunctionCallInfo fcinfo);
+static Datum array_type_length_coerce_internal(ArrayType *src,
+											   int32 desttypmod,
+											   bool isExplicit,
+											   FmgrInfo *fmgr_info);
+
 
 /*---------------------------------------------------------------------
  * array_in :
@@ -1174,82 +1179,6 @@ array_send(PG_FUNCTION_ARGS)
 	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 }
 
-/*-------------------------------------------------------------------------
- * array_length_coerce :
- *		  Apply the element type's length-coercion routine to each element
- *		  of the given array.
- *-------------------------------------------------------------------------
- */
-Datum
-array_length_coerce(PG_FUNCTION_ARGS)
-{
-	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
-	int32		len = PG_GETARG_INT32(1);
-	bool		isExplicit = PG_GETARG_BOOL(2);
-	FmgrInfo   *fmgr_info = fcinfo->flinfo;
-	typedef struct
-	{
-		Oid			elemtype;
-		FmgrInfo	coerce_finfo;
-	} alc_extra;
-	alc_extra  *my_extra;
-	FunctionCallInfoData locfcinfo;
-
-	/* If no typmod is provided, shortcircuit the whole thing */
-	if (len < 0)
-		PG_RETURN_ARRAYTYPE_P(v);
-
-	/*
-	 * We arrange to look up the element type's coercion function only
-	 * once per series of calls, assuming the element type doesn't change
-	 * underneath us.
-	 */
-	my_extra = (alc_extra *) fmgr_info->fn_extra;
-	if (my_extra == NULL)
-	{
-		fmgr_info->fn_extra = MemoryContextAlloc(fmgr_info->fn_mcxt,
-												 sizeof(alc_extra));
-		my_extra = (alc_extra *) fmgr_info->fn_extra;
-		my_extra->elemtype = InvalidOid;
-	}
-
-	if (my_extra->elemtype != ARR_ELEMTYPE(v))
-	{
-		Oid			funcId;
-		int			nargs;
-
-		funcId = find_typmod_coercion_function(ARR_ELEMTYPE(v), &nargs);
-
-		if (OidIsValid(funcId))
-			fmgr_info_cxt(funcId, &my_extra->coerce_finfo, fmgr_info->fn_mcxt);
-		else
-			my_extra->coerce_finfo.fn_oid = InvalidOid;
-		my_extra->elemtype = ARR_ELEMTYPE(v);
-	}
-
-	/*
-	 * If we didn't find a coercion function, return the array unmodified
-	 * (this should not happen in the normal course of things, but might
-	 * happen if this function is called manually).
-	 */
-	if (my_extra->coerce_finfo.fn_oid == InvalidOid)
-		PG_RETURN_ARRAYTYPE_P(v);
-
-	/*
-	 * Use array_map to apply the function to each array element.
-	 *
-	 * Note: we pass isExplicit whether or not the function wants it ...
-	 */
-	MemSet(&locfcinfo, 0, sizeof(locfcinfo));
-	locfcinfo.flinfo = &my_extra->coerce_finfo;
-	locfcinfo.nargs = 3;
-	locfcinfo.arg[0] = PointerGetDatum(v);
-	locfcinfo.arg[1] = Int32GetDatum(len);
-	locfcinfo.arg[2] = BoolGetDatum(isExplicit);
-
-	return array_map(&locfcinfo, ARR_ELEMTYPE(v), ARR_ELEMTYPE(v));
-}
-
 /*-----------------------------------------------------------------------------
  * array_dims :
  *		  returns the dimensions of the array pointed to by "v", as a "text"
@@ -2879,6 +2808,9 @@ array_insert_slice(int ndim,
  * array_type_coerce -- allow explicit or assignment coercion from
  * one array type to another.
  *
+ * array_type_length_coerce -- the same, for cases where both type and length
+ * coercion are done by a single function on the element type.
+ *
  * Caller should have already verified that the source element type can be
  * coerced into the target element type.
  */
@@ -2886,8 +2818,30 @@ Datum
 array_type_coerce(PG_FUNCTION_ARGS)
 {
 	ArrayType  *src = PG_GETARG_ARRAYTYPE_P(0);
-	Oid			src_elem_type = ARR_ELEMTYPE(src);
 	FmgrInfo   *fmgr_info = fcinfo->flinfo;
+
+	return array_type_length_coerce_internal(src, -1, false, fmgr_info);
+}
+
+Datum
+array_type_length_coerce(PG_FUNCTION_ARGS)
+{
+	ArrayType  *src = PG_GETARG_ARRAYTYPE_P(0);
+	int32		desttypmod = PG_GETARG_INT32(1);
+	bool		isExplicit = PG_GETARG_BOOL(2);
+	FmgrInfo   *fmgr_info = fcinfo->flinfo;
+
+	return array_type_length_coerce_internal(src, desttypmod,
+											 isExplicit, fmgr_info);
+}
+
+static Datum
+array_type_length_coerce_internal(ArrayType *src,
+								  int32 desttypmod,
+								  bool isExplicit,
+								  FmgrInfo *fmgr_info)
+{
+	Oid			src_elem_type = ARR_ELEMTYPE(src);
 	typedef struct
 	{
 		Oid			srctype;
@@ -2946,7 +2900,8 @@ array_type_coerce(PG_FUNCTION_ARGS)
 		{
 			/* should never happen, but check anyway */
 			elog(ERROR, "no conversion function from %s to %s",
-			format_type_be(src_elem_type), format_type_be(tgt_elem_type));
+				 format_type_be(src_elem_type),
+				 format_type_be(tgt_elem_type));
 		}
 		if (OidIsValid(funcId))
 			fmgr_info_cxt(funcId, &my_extra->coerce_finfo, fmgr_info->fn_mcxt);
@@ -2962,24 +2917,104 @@ array_type_coerce(PG_FUNCTION_ARGS)
 	 */
 	if (my_extra->coerce_finfo.fn_oid == InvalidOid)
 	{
-		ArrayType  *result = DatumGetArrayTypePCopy(PG_GETARG_DATUM(0));
+		ArrayType  *result;
 
+		result = (ArrayType *) DatumGetPointer(datumCopy(PointerGetDatum(src),
+														 false, -1));
 		ARR_ELEMTYPE(result) = my_extra->desttype;
 		PG_RETURN_ARRAYTYPE_P(result);
 	}
 
 	/*
 	 * Use array_map to apply the function to each array element.
+	 *
+	 * We pass on the desttypmod and isExplicit flags whether or not the
+	 * function wants them.
 	 */
 	MemSet(&locfcinfo, 0, sizeof(locfcinfo));
 	locfcinfo.flinfo = &my_extra->coerce_finfo;
-	locfcinfo.nargs = 1;
+	locfcinfo.nargs = 3;
 	locfcinfo.arg[0] = PointerGetDatum(src);
+	locfcinfo.arg[1] = Int32GetDatum(desttypmod);
+	locfcinfo.arg[2] = BoolGetDatum(isExplicit);
 
 	return array_map(&locfcinfo, my_extra->srctype, my_extra->desttype);
 }
 
 /*
+ * array_length_coerce -- apply the element type's length-coercion routine
+ *		to each element of the given array.
+ */
+Datum
+array_length_coerce(PG_FUNCTION_ARGS)
+{
+	ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
+	int32		desttypmod = PG_GETARG_INT32(1);
+	bool		isExplicit = PG_GETARG_BOOL(2);
+	FmgrInfo   *fmgr_info = fcinfo->flinfo;
+	typedef struct
+	{
+		Oid			elemtype;
+		FmgrInfo	coerce_finfo;
+	} alc_extra;
+	alc_extra  *my_extra;
+	FunctionCallInfoData locfcinfo;
+
+	/* If no typmod is provided, shortcircuit the whole thing */
+	if (desttypmod < 0)
+		PG_RETURN_ARRAYTYPE_P(v);
+
+	/*
+	 * We arrange to look up the element type's coercion function only
+	 * once per series of calls, assuming the element type doesn't change
+	 * underneath us.
+	 */
+	my_extra = (alc_extra *) fmgr_info->fn_extra;
+	if (my_extra == NULL)
+	{
+		fmgr_info->fn_extra = MemoryContextAlloc(fmgr_info->fn_mcxt,
+												 sizeof(alc_extra));
+		my_extra = (alc_extra *) fmgr_info->fn_extra;
+		my_extra->elemtype = InvalidOid;
+	}
+
+	if (my_extra->elemtype != ARR_ELEMTYPE(v))
+	{
+		Oid			funcId;
+
+		funcId = find_typmod_coercion_function(ARR_ELEMTYPE(v));
+
+		if (OidIsValid(funcId))
+			fmgr_info_cxt(funcId, &my_extra->coerce_finfo, fmgr_info->fn_mcxt);
+		else
+			my_extra->coerce_finfo.fn_oid = InvalidOid;
+		my_extra->elemtype = ARR_ELEMTYPE(v);
+	}
+
+	/*
+	 * If we didn't find a coercion function, return the array unmodified
+	 * (this should not happen in the normal course of things, but might
+	 * happen if this function is called manually).
+	 */
+	if (my_extra->coerce_finfo.fn_oid == InvalidOid)
+		PG_RETURN_ARRAYTYPE_P(v);
+
+	/*
+	 * Use array_map to apply the function to each array element.
+	 *
+	 * Note: we pass isExplicit whether or not the function wants it ...
+	 */
+	MemSet(&locfcinfo, 0, sizeof(locfcinfo));
+	locfcinfo.flinfo = &my_extra->coerce_finfo;
+	locfcinfo.nargs = 3;
+	locfcinfo.arg[0] = PointerGetDatum(v);
+	locfcinfo.arg[1] = Int32GetDatum(desttypmod);
+	locfcinfo.arg[2] = BoolGetDatum(isExplicit);
+
+	return array_map(&locfcinfo, ARR_ELEMTYPE(v), ARR_ELEMTYPE(v));
+}
+
+/*
  * accumArrayResult - accumulate one (more) Datum for an array result
  *
  *	astate is working state (NULL on first call)