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pg_include/utils/datum.h

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+/*-------------------------------------------------------------------------
+ *
+ * datum.h
+ *	  POSTGRES Datum (abstract data type) manipulation routines.
+ *
+ * These routines are driven by the 'typbyval' and 'typlen' information,
+ * which must previously have been obtained by the caller for the datatype
+ * of the Datum.  (We do it this way because in most situations the caller
+ * can look up the info just once and use it for many per-datum operations.)
+ *
+ * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/datum.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DATUM_H
+#define DATUM_H
+
+/*
+ * datumGetSize - find the "real" length of a datum
+ */
+extern Size datumGetSize(Datum value, bool typByVal, int typLen);
+
+/*
+ * datumCopy - make a copy of a datum.
+ *
+ * If the datatype is pass-by-reference, memory is obtained with palloc().
+ */
+extern Datum datumCopy(Datum value, bool typByVal, int typLen);
+
+/*
+ * datumFree - free a datum previously allocated by datumCopy, if any.
+ *
+ * Does nothing if datatype is pass-by-value.
+ */
+extern void datumFree(Datum value, bool typByVal, int typLen);
+
+/*
+ * datumIsEqual
+ * return true if two datums of the same type are equal, false otherwise.
+ *
+ * XXX : See comments in the code for restrictions!
+ */
+extern bool datumIsEqual(Datum value1, Datum value2,
+			 bool typByVal, int typLen);
+
+#endif   /* DATUM_H */