Add capabilities for automatic type conversion.

src/include/parser/parse_coerce.h

@@ -0,0 +1,96 @@
+/*-------------------------------------------------------------------------
+ *
+ * parse_coerce.h
+ *
+ *
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ * $Id: parse_coerce.h,v 1.1 1998/05/09 23:31:34 thomas Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PARSE_COERCE_H
+#define PARSE_COERCE_H
+
+typedef enum CATEGORY {
+	INVALID_TYPE,
+	UNKNOWN_TYPE,
+	BOOLEAN_TYPE,
+	STRING_TYPE,
+	NUMERIC_TYPE,
+	DATETIME_TYPE,
+	TIMESPAN_TYPE,
+	GEOMETRIC_TYPE,
+	USER_TYPE,
+	MIXED_TYPE
+} CATEGORY;
+
+
+#define IS_BUILTIN_TYPE(t) \
+		  (((t) == BOOLOID) \
+		|| ((t) == BPCHAROID) \
+		|| ((t) == VARCHAROID) \
+		|| ((t) == TEXTOID) \
+		|| ((t) == CASHOID) \
+		|| ((t) == INT4OID) \
+		|| ((t) == DATETIMEOID) \
+		|| ((t) == FLOAT8OID) \
+		|| ((t) == ABSTIMEOID) \
+		|| ((t) == TIMESTAMPOID) \
+		|| ((t) == RELTIMEOID))
+
+
+/* IS_BINARY_COMPATIBLE()
+ * Check for types with the same underlying binary representation.
+ * This allows us to cheat and directly exchange values without
+ *  going through the trouble of calling a conversion function.
+ */
+#define IS_BINARY_COMPATIBLE(a,b) \
+		  (((a) == BPCHAROID && (b) == TEXTOID) \
+		|| ((a) == BPCHAROID && (b) == VARCHAROID) \
+		|| ((a) == VARCHAROID && (b) == TEXTOID) \
+		|| ((a) == VARCHAROID && (b) == BPCHAROID) \
+		|| ((a) == TEXTOID && (b) == BPCHAROID) \
+		|| ((a) == TEXTOID && (b) == VARCHAROID) \
+		|| ((a) == CASHOID && (b) == INT4OID) \
+		|| ((a) == INT4OID && (b) == CASHOID) \
+		|| ((a) == DATETIMEOID && (b) == FLOAT8OID) \
+		|| ((a) == FLOAT8OID && (b) == DATETIMEOID) \
+		|| ((a) == ABSTIMEOID && (b) == TIMESTAMPOID) \
+		|| ((a) == TIMESTAMPOID && (b) == ABSTIMEOID) \
+		|| ((a) == ABSTIMEOID && (b) == INT4OID) \
+		|| ((a) == INT4OID && (b) == ABSTIMEOID) \
+		|| ((a) == RELTIMEOID && (b) == INT4OID) \
+		|| ((a) == INT4OID && (b) == RELTIMEOID))
+
+/* IS_HIGHER_TYPE()
+ * These types are the most general in each of the type categories.
+ */
+#define IS_HIGHER_TYPE(t) \
+		  (((t) == TEXTOID) \
+		|| ((t) == FLOAT8OID) \
+		|| ((t) == TIMESPANOID) \
+		|| ((t) == DATETIMEOID) \
+		|| ((t) == POLYGONOID))
+
+/* IS_HIGHEST_TYPE()
+ * These types are the most general in each of the type categories.
+ * Since timespan and datetime overload so many functions, let's
+ *  give datetime the preference.
+ * Since text is a generic string type let's leave it out too.
+ */
+#define IS_HIGHEST_TYPE(t) \
+		  (((t) == FLOAT8OID) \
+		|| ((t) == DATETIMEOID) \
+		|| ((t) == TIMESPANOID))
+
+
+extern bool IsPreferredType(CATEGORY category, Oid type);
+extern Oid PreferredType(CATEGORY category, Oid type);
+extern CATEGORY TypeCategory(Oid type);
+
+extern bool can_coerce_type(int nargs, Oid *input_typeids, Oid *func_typeids);
+extern Node *coerce_type(ParseState *pstate, Node *node, Oid inputTypeId, Oid targetTypeId);
+
+#endif							/* PARSE_COERCE_H */