*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.81 2002/08/31 22:10:46 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.82 2002/09/01 02:27:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "utils/syscache.h"
-Oid DemoteType(Oid inType);
-Oid PromoteTypeToNext(Oid inType);
-
static Oid PreferredType(CATEGORY category, Oid type);
-static Node *build_func_call(Oid funcid, Oid rettype, List *args);
-static Oid find_coercion_function(Oid targetTypeId, Oid sourceTypeId,
- bool isExplicit);
+static bool find_coercion_pathway(Oid targetTypeId, Oid sourceTypeId,
+ bool isExplicit,
+ Oid *funcid);
static Oid find_typmod_coercion_function(Oid typeId);
+static Node *build_func_call(Oid funcid, Oid rettype, List *args);
-/* coerce_type()
- * Convert a function argument to a different type.
+/*
+ * coerce_type()
+ * Convert a function argument to a different type.
+ *
+ * The caller should already have determined that the coercion is possible;
+ * see can_coerce_type.
*/
Node *
coerce_type(ParseState *pstate, Node *node, Oid inputTypeId,
Oid targetTypeId, int32 atttypmod, bool isExplicit)
{
Node *result;
+ Oid funcId;
if (targetTypeId == inputTypeId ||
node == NULL)
/* assume can_coerce_type verified that implicit coercion is okay */
result = node;
}
- else if (IsBinaryCompatible(inputTypeId, targetTypeId))
+ else if (find_coercion_pathway(targetTypeId, inputTypeId, isExplicit,
+ &funcId))
{
- /*
- * We don't really need to do a conversion, but we do need to
- * attach a RelabelType node so that the expression will be seen
- * to have the intended type when inspected by higher-level code.
- *
- * Also, domains may have value restrictions beyond the base type
- * that must be accounted for.
- */
- result = coerce_type_constraints(pstate, node, targetTypeId, true);
- /*
- * XXX could we label result with exprTypmod(node) instead of
- * default -1 typmod, to save a possible length-coercion later?
- * Would work if both types have same interpretation of typmod,
- * which is likely but not certain (wrong if target is a domain,
- * in any case).
- */
- result = (Node *) makeRelabelType(result, targetTypeId, -1);
+ if (OidIsValid(funcId))
+ {
+ /*
+ * Generate an expression tree representing run-time application
+ * of the conversion function. If we are dealing with a domain
+ * target type, the conversion function will yield the base type.
+ */
+ Oid baseTypeId = getBaseType(targetTypeId);
+
+ result = build_func_call(funcId, baseTypeId, makeList1(node));
+
+ /*
+ * If domain, test against domain constraints and relabel with
+ * domain type ID
+ */
+ if (targetTypeId != baseTypeId)
+ {
+ result = coerce_type_constraints(pstate, result,
+ targetTypeId, true);
+ result = (Node *) makeRelabelType(result, targetTypeId, -1);
+ }
+
+ /*
+ * If the input is a constant, apply the type conversion function
+ * now instead of delaying to runtime. (We could, of course, just
+ * leave this to be done during planning/optimization; but it's a
+ * very frequent special case, and we save cycles in the rewriter
+ * if we fold the expression now.)
+ *
+ * Note that no folding will occur if the conversion function is
+ * not marked 'immutable'.
+ *
+ * HACK: if constant is NULL, don't fold it here. This is needed
+ * by make_subplan(), which calls this routine on placeholder
+ * Const nodes that mustn't be collapsed. (It'd be a lot cleaner
+ * to make a separate node type for that purpose...)
+ */
+ if (IsA(node, Const) &&
+ !((Const *) node)->constisnull)
+ result = eval_const_expressions(result);
+ }
+ else
+ {
+ /*
+ * We don't need to do a physical conversion, but we do need to
+ * attach a RelabelType node so that the expression will be seen
+ * to have the intended type when inspected by higher-level code.
+ *
+ * Also, domains may have value restrictions beyond the base type
+ * that must be accounted for.
+ */
+ result = coerce_type_constraints(pstate, node,
+ targetTypeId, true);
+ /*
+ * XXX could we label result with exprTypmod(node) instead of
+ * default -1 typmod, to save a possible length-coercion later?
+ * Would work if both types have same interpretation of typmod,
+ * which is likely but not certain (wrong if target is a domain,
+ * in any case).
+ */
+ result = (Node *) makeRelabelType(result, targetTypeId, -1);
+ }
}
else if (typeInheritsFrom(inputTypeId, targetTypeId))
{
}
else
{
- /*
- * Otherwise, find the appropriate type conversion function
- * (caller should have determined that there is one), and generate
- * an expression tree representing run-time application of the
- * conversion function.
- *
- * For domains, we use the coercion function for the base type.
- */
- Oid baseTypeId = getBaseType(targetTypeId);
- Oid funcId;
-
- funcId = find_coercion_function(baseTypeId,
- getBaseType(inputTypeId),
- isExplicit);
- if (!OidIsValid(funcId))
- elog(ERROR, "coerce_type: no conversion function from '%s' to '%s'",
- format_type_be(inputTypeId), format_type_be(targetTypeId));
-
- result = build_func_call(funcId, baseTypeId, makeList1(node));
-
- /*
- * If domain, test against domain constraints and relabel with
- * domain type ID
- */
- if (targetTypeId != baseTypeId)
- {
- result = coerce_type_constraints(pstate, result, targetTypeId,
- true);
- result = (Node *) makeRelabelType(result, targetTypeId, -1);
- }
-
- /*
- * If the input is a constant, apply the type conversion function
- * now instead of delaying to runtime. (We could, of course, just
- * leave this to be done during planning/optimization; but it's a
- * very frequent special case, and we save cycles in the rewriter
- * if we fold the expression now.)
- *
- * Note that no folding will occur if the conversion function is not
- * marked 'iscachable'.
- *
- * HACK: if constant is NULL, don't fold it here. This is needed by
- * make_subplan(), which calls this routine on placeholder Const
- * nodes that mustn't be collapsed. (It'd be a lot cleaner to
- * make a separate node type for that purpose...)
- */
- if (IsA(node, Const) &&
- !((Const *) node)->constisnull)
- result = eval_const_expressions(result);
+ /* If we get here, caller blew it */
+ elog(ERROR, "coerce_type: no conversion function from %s to %s",
+ format_type_be(inputTypeId), format_type_be(targetTypeId));
+ result = NULL; /* keep compiler quiet */
}
return result;
}
-/* can_coerce_type()
- * Can input_typeids be coerced to func_typeids?
- *
- * There are a few types which are known apriori to be convertible.
- * We will check for those cases first, and then look for possible
- * conversion functions.
+/*
+ * can_coerce_type()
+ * Can input_typeids be coerced to func_typeids?
*
* We must be told whether this is an implicit or explicit coercion
* (explicit being a CAST construct, explicit function call, etc).
* We will accept a wider set of coercion cases for an explicit coercion.
- *
- * Notes:
- * This uses the same mechanism as the CAST() SQL construct in gram.y.
*/
bool
can_coerce_type(int nargs, Oid *input_typeids, Oid *func_typeids,
}
/*
- * one of the known-good transparent conversions? then drop
- * through...
+ * If pg_cast shows that we can coerce, accept. This test now
+ * covers both binary-compatible and coercion-function cases.
*/
- if (IsBinaryCompatible(inputTypeId, targetTypeId))
+ if (find_coercion_pathway(targetTypeId, inputTypeId, isExplicit,
+ &funcId))
continue;
/*
- * If input is a class type that inherits from target, no problem
+ * If input is a class type that inherits from target, accept
*/
if (typeInheritsFrom(inputTypeId, targetTypeId))
continue;
/*
- * Else, try for run-time conversion using functions: look for a
- * single-argument function named with the target type name and
- * accepting the source type.
- *
- * If either type is a domain, use its base type instead.
+ * Else, cannot coerce at this argument position
*/
- funcId = find_coercion_function(getBaseType(targetTypeId),
- getBaseType(inputTypeId),
- isExplicit);
- if (!OidIsValid(funcId))
- return false;
+ return false;
}
return true;
}
+
+/*
+ * Create an expression tree to enforce the constraints (if any)
+ * that should be applied by the type. Currently this is only
+ * interesting for domain types.
+ */
+Node *
+coerce_type_constraints(ParseState *pstate, Node *arg,
+ Oid typeId, bool applyTypmod)
+{
+ char *notNull = NULL;
+ int32 typmod = -1;
+
+ for (;;)
+ {
+ HeapTuple tup;
+ Form_pg_type typTup;
+
+ tup = SearchSysCache(TYPEOID,
+ ObjectIdGetDatum(typeId),
+ 0, 0, 0);
+ if (!HeapTupleIsValid(tup))
+ elog(ERROR, "coerce_type_constraints: failed to lookup type %u",
+ typeId);
+ typTup = (Form_pg_type) GETSTRUCT(tup);
+
+ /* Test for NOT NULL Constraint */
+ if (typTup->typnotnull && notNull == NULL)
+ notNull = pstrdup(NameStr(typTup->typname));
+
+ /* TODO: Add CHECK Constraints to domains */
+
+ if (typTup->typtype != 'd')
+ {
+ /* Not a domain, so done */
+ ReleaseSysCache(tup);
+ break;
+ }
+
+ Assert(typmod < 0);
+
+ typeId = typTup->typbasetype;
+ typmod = typTup->typtypmod;
+ ReleaseSysCache(tup);
+ }
+
+ /*
+ * If domain applies a typmod to its base type, do length coercion.
+ */
+ if (applyTypmod && typmod >= 0)
+ arg = coerce_type_typmod(pstate, arg, typeId, typmod);
+
+ /*
+ * Only need to add one NOT NULL check regardless of how many
+ * domains in the stack request it. The topmost domain that
+ * requested it is used as the constraint name.
+ */
+ if (notNull)
+ {
+ ConstraintTest *r = makeNode(ConstraintTest);
+
+ r->arg = arg;
+ r->testtype = CONSTR_TEST_NOTNULL;
+ r->name = notNull;
+ r->check_expr = NULL;
+
+ arg = (Node *) r;
+ }
+
+ return arg;
+}
+
+
/* coerce_type_typmod()
* Force a value to a particular typmod, if meaningful and possible.
*
* The caller must have already ensured that the value is of the correct
* type, typically by applying coerce_type.
*
- * If the target column type possesses a function named for the type
- * and having parameter signature (columntype, int4), we assume that
- * the type requires coercion to its own length and that the said
- * function should be invoked to do that.
- *
- * "bpchar" (ie, char(N)) and "numeric" are examples of such types.
- *
- * This mechanism may seem pretty grotty and in need of replacement by
- * something in pg_cast, but since typmod is only interesting for datatypes
- * that have special handling in the grammar, there's not really much
- * percentage in making it any easier to apply such coercions ...
- *
* NOTE: this does not need to work on domain types, because any typmod
* coercion for a domain is considered to be part of the type coercion
- * needed to produce the domain value in the first place.
+ * needed to produce the domain value in the first place. So, no getBaseType.
*/
Node *
coerce_type_typmod(ParseState *pstate, Node *node,
} /* TypeCategory() */
-/* IsBinaryCompatible()
- * Check if two types are binary-compatible.
- *
- * This notion allows us to cheat and directly exchange values without
- * going through the trouble of calling a conversion function.
- *
- * XXX This should be moved to system catalog lookups
- * to allow for better type extensibility.
- */
-
-#define TypeIsTextGroup(t) \
- ((t) == TEXTOID || \
- (t) == BPCHAROID || \
- (t) == VARCHAROID)
-
-/* Notice OidGroup is a subset of Int4GroupA */
-#define TypeIsOidGroup(t) \
- ((t) == OIDOID || \
- (t) == REGPROCOID || \
- (t) == REGPROCEDUREOID || \
- (t) == REGOPEROID || \
- (t) == REGOPERATOROID || \
- (t) == REGCLASSOID || \
- (t) == REGTYPEOID)
-
-/*
- * INT4 is binary-compatible with many types, but we don't want to allow
- * implicit coercion directly between, say, OID and AbsTime. So we subdivide
- * the categories.
- */
-#define TypeIsInt4GroupA(t) \
- ((t) == INT4OID || \
- TypeIsOidGroup(t))
-
-#define TypeIsInt4GroupB(t) \
- ((t) == INT4OID || \
- (t) == ABSTIMEOID)
-
-#define TypeIsInt4GroupC(t) \
- ((t) == INT4OID || \
- (t) == RELTIMEOID)
-
-#define TypeIsInetGroup(t) \
- ((t) == INETOID || \
- (t) == CIDROID)
-
-#define TypeIsBitGroup(t) \
- ((t) == BITOID || \
- (t) == VARBITOID)
-
-
-static bool
-DirectlyBinaryCompatible(Oid type1, Oid type2)
-{
- HeapTuple tuple;
- bool result;
-
- if (type1 == type2)
- return true;
-
- tuple = SearchSysCache(CASTSOURCETARGET, type1, type2, 0, 0);
- if (HeapTupleIsValid(tuple))
- {
- Form_pg_cast caststruct;
-
- caststruct = (Form_pg_cast) GETSTRUCT(tuple);
- result = caststruct->castfunc == InvalidOid && caststruct->castimplicit;
- ReleaseSysCache(tuple);
- }
- else
- result = false;
-
- return result;
-}
-
-
-bool
-IsBinaryCompatible(Oid type1, Oid type2)
-{
- if (DirectlyBinaryCompatible(type1, type2))
- return true;
- /*
- * Perhaps the types are domains; if so, look at their base types
- */
- if (OidIsValid(type1))
- type1 = getBaseType(type1);
- if (OidIsValid(type2))
- type2 = getBaseType(type2);
- if (DirectlyBinaryCompatible(type1, type2))
- return true;
- return false;
-}
-
-
/* IsPreferredType()
* Check if this type is a preferred type.
* XXX This should be moved to system catalog lookups
break;
case (NUMERIC_TYPE):
- if (TypeIsOidGroup(type))
+ if (type == OIDOID ||
+ type == REGPROCOID ||
+ type == REGPROCEDUREOID ||
+ type == REGOPEROID ||
+ type == REGOPERATOROID ||
+ type == REGCLASSOID ||
+ type == REGTYPEOID)
result = OIDOID;
else if (type == NUMERICOID)
result = NUMERICOID;
return result;
} /* PreferredType() */
-/*
- * find_coercion_function
- * Look for a coercion function between two types.
+
+/* IsBinaryCompatible()
+ * Check if two types are binary-compatible.
*
- * A coercion function must be named after (the internal name of) its
- * result type, and must accept exactly the specified input type. We
- * also require it to be defined in the same namespace as its result type.
- * Furthermore, unless we are doing explicit coercion the function must
- * be marked as usable for implicit coercion --- this allows coercion
- * functions to be provided that aren't implicitly invokable.
+ * This notion allows us to cheat and directly exchange values without
+ * going through the trouble of calling a conversion function.
*
- * This routine is also used to look for length-coercion functions, which
- * are similar but accept a second argument. secondArgType is the type
- * of the second argument (normally INT4OID), or InvalidOid if we are
- * looking for a regular coercion function.
+ * As of 7.3, binary compatibility isn't hardwired into the code anymore.
+ * We consider two types binary-compatible if there is an implicit,
+ * no-function-needed pg_cast entry. NOTE that we assume that such
+ * entries are symmetric, ie, it doesn't matter which type we consider
+ * source and which target. (cf. checks in opr_sanity regression test)
+ */
+bool
+IsBinaryCompatible(Oid type1, Oid type2)
+{
+ HeapTuple tuple;
+ Form_pg_cast castForm;
+ bool result;
+
+ /* Fast path if same type */
+ if (type1 == type2)
+ return true;
+
+ /* Perhaps the types are domains; if so, look at their base types */
+ if (OidIsValid(type1))
+ type1 = getBaseType(type1);
+ if (OidIsValid(type2))
+ type2 = getBaseType(type2);
+
+ /* Somewhat-fast path if same base type */
+ if (type1 == type2)
+ return true;
+
+ /* Else look in pg_cast */
+ tuple = SearchSysCache(CASTSOURCETARGET,
+ ObjectIdGetDatum(type1),
+ ObjectIdGetDatum(type2),
+ 0, 0);
+ if (!HeapTupleIsValid(tuple))
+ return false; /* no cast */
+ castForm = (Form_pg_cast) GETSTRUCT(tuple);
+
+ result = (castForm->castfunc == InvalidOid) && castForm->castimplicit;
+
+ ReleaseSysCache(tuple);
+
+ return result;
+}
+
+
+/*
+ * find_coercion_pathway
+ * Look for a coercion pathway between two types.
*
- * If a function is found, return its pg_proc OID; else return InvalidOid.
+ * If we find a matching entry in pg_cast, return TRUE, and set *funcid
+ * to the castfunc value (which may be InvalidOid for a binary-compatible
+ * coercion).
*/
-static Oid
-find_coercion_function(Oid targetTypeId, Oid sourceTypeId, bool isExplicit)
+static bool
+find_coercion_pathway(Oid targetTypeId, Oid sourceTypeId, bool isExplicit,
+ Oid *funcid)
{
- Oid funcid = InvalidOid;
+ bool result = false;
HeapTuple tuple;
+ *funcid = InvalidOid;
+
+ /* Perhaps the types are domains; if so, look at their base types */
+ if (OidIsValid(sourceTypeId))
+ sourceTypeId = getBaseType(sourceTypeId);
+ if (OidIsValid(targetTypeId))
+ targetTypeId = getBaseType(targetTypeId);
+
+ /* Domains are automatically binary-compatible with their base type */
+ if (sourceTypeId == targetTypeId)
+ return true;
+
+ /* Else look in pg_cast */
tuple = SearchSysCache(CASTSOURCETARGET,
ObjectIdGetDatum(sourceTypeId),
ObjectIdGetDatum(targetTypeId),
if (HeapTupleIsValid(tuple))
{
- Form_pg_cast cform = (Form_pg_cast) GETSTRUCT(tuple);
+ Form_pg_cast castForm = (Form_pg_cast) GETSTRUCT(tuple);
- if (isExplicit || cform->castimplicit)
- funcid = cform->castfunc;
+ if (isExplicit || castForm->castimplicit)
+ {
+ *funcid = castForm->castfunc;
+ result = true;
+ }
ReleaseSysCache(tuple);
}
- return funcid;
+ return result;
}
+/*
+ * find_typmod_coercion_function -- does the given type need length coercion?
+ *
+ * If the target type possesses a function named for the type
+ * and having parameter signature (targettype, int4), we assume that
+ * the type requires coercion to its own length and that the said
+ * function should be invoked to do that.
+ *
+ * "bpchar" (ie, char(N)) and "numeric" are examples of such types.
+ *
+ * This mechanism may seem pretty grotty and in need of replacement by
+ * something in pg_cast, but since typmod is only interesting for datatypes
+ * that have special handling in the grammar, there's not really much
+ * percentage in making it any easier to apply such coercions ...
+ */
static Oid
find_typmod_coercion_function(Oid typeId)
{
}
ReleaseSysCache(targetType);
+
return funcid;
}
return (Node *) expr;
}
-
-/*
- * Create an expression tree to enforce the constraints (if any)
- * that should be applied by the type. Currently this is only
- * interesting for domain types.
- */
-Node *
-coerce_type_constraints(ParseState *pstate, Node *arg,
- Oid typeId, bool applyTypmod)
-{
- char *notNull = NULL;
- int32 typmod = -1;
-
- for (;;)
- {
- HeapTuple tup;
- Form_pg_type typTup;
-
- tup = SearchSysCache(TYPEOID,
- ObjectIdGetDatum(typeId),
- 0, 0, 0);
- if (!HeapTupleIsValid(tup))
- elog(ERROR, "coerce_type_constraints: failed to lookup type %u",
- typeId);
- typTup = (Form_pg_type) GETSTRUCT(tup);
-
- /* Test for NOT NULL Constraint */
- if (typTup->typnotnull && notNull == NULL)
- notNull = pstrdup(NameStr(typTup->typname));
-
- /* TODO: Add CHECK Constraints to domains */
-
- if (typTup->typtype != 'd')
- {
- /* Not a domain, so done */
- ReleaseSysCache(tup);
- break;
- }
-
- Assert(typmod < 0);
-
- typeId = typTup->typbasetype;
- typmod = typTup->typtypmod;
- ReleaseSysCache(tup);
- }
-
- /*
- * If domain applies a typmod to its base type, do length coercion.
- */
- if (applyTypmod && typmod >= 0)
- arg = coerce_type_typmod(pstate, arg, typeId, typmod);
-
- /*
- * Only need to add one NOT NULL check regardless of how many
- * domains in the stack request it. The topmost domain that
- * requested it is used as the constraint name.
- */
- if (notNull)
- {
- ConstraintTest *r = makeNode(ConstraintTest);
-
- r->arg = arg;
- r->testtype = CONSTR_TEST_NOTNULL;
- r->name = notNull;
- r->check_expr = NULL;
-
- arg = (Node *) r;
- }
-
- return arg;
-}
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