1 files changed, 173 insertions, 0 deletions
diff --git a/src/backend/utils/mmgr/oset.c b/src/backend/utils/mmgr/oset.c
new file mode 100644
index 00000000000..478fe1516ab
--- /dev/null
+++ b/src/backend/utils/mmgr/oset.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * oset.c--
+ *    Fixed format ordered set definitions.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/utils/mmgr/Attic/oset.c,v 1.1.1.1 1996/07/09 06:22:09 scrappy Exp $
+ *
+ * NOTE
+ *    XXX This is a preliminary implementation which lacks fail-fast
+ *    XXX validity checking of arguments.
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "c.h"
+
+#include "utils/memutils.h"	/* where declarations of this file goes */
+
+static Pointer OrderedElemGetBase(OrderedElem elem);
+static void OrderedElemInit(OrderedElem elem, OrderedSet set);
+static void OrderedElemPush(OrderedElem elem);
+static void OrderedElemPushHead(OrderedElem elem);
+
+/*
+ * OrderedElemGetBase --
+ *	Returns base of enclosing structure.
+ */
+static Pointer
+OrderedElemGetBase(OrderedElem elem)
+{
+    if (elem == (OrderedElem) NULL)
+	return (Pointer) NULL;
+    
+    return ((Pointer)((char*)(elem) - (elem)->set->offset));
+}
+
+/*
+ * OrderedSetInit --
+ */
+void
+OrderedSetInit(OrderedSet set, Offset offset)
+{
+    set->head = (OrderedElem)&set->dummy;
+    set->dummy = NULL;
+    set->tail = (OrderedElem)&set->head;
+    set->offset = offset;
+}
+
+/*
+ * OrderedElemInit --
+ */
+static void
+OrderedElemInit(OrderedElem elem, OrderedSet set)
+{
+    elem->set = set;
+    /* mark as unattached */
+    elem->next = NULL;
+    elem->prev = NULL;
+}
+
+/*
+ * OrderedSetContains --
+ *	True iff ordered set contains given element.
+ */
+bool
+OrderedSetContains(OrderedSet set, OrderedElem elem)
+{
+    return ((bool)(elem->set == set && (elem->next || elem->prev)));
+}
+
+/*
+ * OrderedSetGetHead --
+ */
+Pointer
+OrderedSetGetHead(OrderedSet set)
+{
+    register OrderedElem	elem;
+    
+    elem = set->head;
+    if (elem->next) {
+	return (OrderedElemGetBase(elem));
+    }
+    return (NULL);
+}
+
+/*
+ * OrderedSetGetTail --
+ */
+Pointer
+OrderedSetGetTail(OrderedSet set)
+{
+    register OrderedElem	elem;
+    
+    elem = set->tail;
+    if (elem->prev) {
+	return (OrderedElemGetBase(elem));
+    }
+    return (NULL);
+}
+
+/*
+ * OrderedElemGetPredecessor --
+ */
+Pointer
+OrderedElemGetPredecessor(OrderedElem elem)
+{
+    elem = elem->prev;
+    if (elem->prev) {
+	return (OrderedElemGetBase(elem));
+    }
+    return (NULL);
+}
+
+/*
+ * OrderedElemGetSuccessor --
+ */
+Pointer
+OrderedElemGetSuccessor(OrderedElem elem)
+{
+    elem = elem->next;
+    if (elem->next) {
+	return (OrderedElemGetBase(elem));
+    }
+    return (NULL);
+}
+
+/*
+ * OrderedElemPop --
+ */
+void 
+OrderedElemPop(OrderedElem elem)
+{
+    elem->next->prev = elem->prev;
+    elem->prev->next = elem->next;
+    /* assignments used only for error detection */
+    elem->next = NULL;
+    elem->prev = NULL;
+}
+
+/*
+ * OrderedElemPushInto --
+ */
+void
+OrderedElemPushInto(OrderedElem elem, OrderedSet set)
+{
+    OrderedElemInit(elem, set);
+    OrderedElemPush(elem);
+}
+
+/*
+ * OrderedElemPush --
+ */
+static void
+OrderedElemPush(OrderedElem elem)
+{
+    OrderedElemPushHead(elem);
+}
+
+/*
+ * OrderedElemPushHead --
+ */
+static void
+OrderedElemPushHead(OrderedElem elem)
+{
+    elem->next = elem->set->head;
+    elem->prev = (OrderedElem)&elem->set->head;
+    elem->next->prev = elem;
+    elem->prev->next = elem;
+}
+