1 files changed, 157 insertions, 0 deletions
diff --git a/WWW/Library/Implementation/HTHistory.c b/WWW/Library/Implementation/HTHistory.c
new file mode 100644
index 00000000..726380a6
--- /dev/null
+++ b/WWW/Library/Implementation/HTHistory.c
@@ -0,0 +1,157 @@
+#include "HTUtils.h"
+#include "tcp.h"		/* for standard io */
+
+#include "HTHistory.h"
+
+#include "LYLeaks.h"
+
+static HTList * history;	/* List of visited anchors */
+
+
+/*				Navigation
+**				==========
+*/
+
+/*		Record the jump to an anchor
+**		----------------------------
+*/
+
+void HTHistory_record
+  ARGS1 (HTAnchor *,destination)
+{
+  if (destination) {
+    if (! history)
+      history = HTList_new();
+    HTList_addObject (history, destination);
+  }
+}
+
+/*		Go back in history (find the last visited node)
+**		------------------
+*/
+
+HTAnchor * HTHistory_backtrack
+  NOARGS  /* FIXME: Should we add a `sticky' option ? */
+{
+  if (HTHistory_canBacktrack())
+    HTList_removeLastObject(history);
+  return(HTAnchor *)HTList_lastObject(history); /* is Home if can't backtrack */
+}
+
+BOOL HTHistory_canBacktrack
+  NOARGS
+{
+  return (HTList_objectAt (history, 1) != NULL);
+}
+
+/*		Browse through references in the same parent node
+**		-------------------------------------------------
+**
+**	Take the n-th child's link after or before the one we took to get here.
+**	Positive offset means go towards most recently added children.
+*/
+
+HTAnchor * HTHistory_moveBy
+ ARGS1 (int,offset)
+{
+  HTAnchor * last = (HTAnchor *)HTList_objectAt (history, 1);
+  if (! last)
+    return NULL;  /* No last visited node */
+  if (last != (HTAnchor *) last->parent) {  /* Was a child */
+    HTList * kids = last->parent->children;
+    int i = HTList_indexOf (kids, last); 
+    HTAnchor * nextOne = (HTAnchor *)HTList_objectAt (kids, i - offset);
+    if (nextOne) {
+      HTAnchor * destination = HTAnchor_followMainLink (nextOne);
+      if (destination) {
+	HTList_removeLastObject (history);
+	HTList_removeLastObject (history);
+	HTList_addObject (history, nextOne);
+	HTList_addObject (history, destination);
+      }
+      return destination;
+    } else {
+      if (TRACE) fprintf(stderr, 
+      		"HTHistory_moveBy: offset by %+d goes out of list %p.\n",
+		offset, (void*)kids);
+      return NULL;
+    }
+  } else {  /* Was a parent */
+    return NULL;  /* FIXME we could possibly follow the next link... */
+  }
+}
+
+BOOL HTHistory_canMoveBy
+ ARGS1 (int,offset)
+{
+  HTAnchor * last = (HTAnchor *)HTList_objectAt (history, 1);
+  if (! last)
+    return NO;  /* No last visited node */
+  if (last != (HTAnchor *) last->parent) {  /* Was a child */
+    HTList * kids = last->parent->children;
+    int i = HTList_indexOf (kids, last); 
+    return (HTList_objectAt (kids, i - offset) != NULL);
+  } else {  /* Was a parent */
+    return NO;  /* FIXME we could possibly follow the next link... */
+  }
+}
+
+
+/*				Retrieval
+**				=========
+*/
+
+/*		Read numbered visited anchor (1 is the oldest)
+**		----------------------------
+*/
+
+HTAnchor * HTHistory_read
+  ARGS1 (int,number)
+{
+  return (HTAnchor *)HTList_objectAt(history, HTList_count (history) - number);
+}
+
+
+/*		Recall numbered visited anchor (1 is the oldest)
+**		------------------------------
+**	This reads the anchor and stores it again in the list, except if last.
+*/
+
+HTAnchor * HTHistory_recall
+  ARGS1 (int,number)
+{
+  HTAnchor * destination =
+    (HTAnchor *)HTList_objectAt (history, HTList_count (history) - number);
+  if (destination && destination != (HTAnchor *)HTList_lastObject (history))
+    HTList_addObject (history, destination);
+  return destination;
+}
+
+/*		Number of Anchors stored
+**		------------------------
+**
+**	This is needed in order to check the validity of certain commands
+**	for menus, etc.
+(not needed for now. Use canBacktrack, etc.)
+int HTHistory_count
+  NOARGS
+{
+  return HTList_count (history);
+}
+*/
+
+/*		Change last history entry
+**		-------------------------
+**
+**	Sometimes we load a node by one anchor but leave by a different
+**	one, and it is the one we left from which we want to remember.
+*/
+
+void HTHistory_leavingFrom
+  ARGS1 (HTAnchor *,anchor)
+{
+  if (HTList_removeLastObject (history))
+    HTList_addObject (history, anchor);
+  else
+    if (TRACE) fprintf(stderr, "HTHistory_leavingFrom: empty history !\n");
+}