Initial revision

1 files changed, 158 insertions, 0 deletions

diff --git a/zwgc/xrevstack.c b/zwgc/xrevstack.c
new file mode 100644
index 0000000..fb196fc
--- /dev/null
+++ b/zwgc/xrevstack.c
@@ -0,0 +1,158 @@
+#include "X_gram.h"
+#include "zwgc.h"
+#include <stdio.h>
+
+x_gram *bottom_gram=NULL;
+static x_gram *top_gram=NULL;
+
+#ifdef DEBUG
+void print_gram_list(str)
+char *str;
+{
+   x_gram *gram;
+   char buf[80];
+
+   if (zwgc_debug) {
+      printf("----- From function %s: Top of tree\n",str);
+      if (top_gram) 
+	if (top_gram->above) 
+	  printf("Tree munged: something above top_gram\n");
+      for (gram=top_gram;gram;gram=gram->below) {
+	 strncpy(buf,gram->text,63);
+	 buf[63]='\0';
+	 printf("wid %lx txt: %s\n",(long) gram->w,buf);
+      }
+      if (bottom_gram) 
+	if (bottom_gram->below) 
+	  printf("Tree munged: something below bottom_gram\n");
+      printf("----- Bottom of tree\n");
+   }
+}
+#endif
+
+void pull_to_top(gram)
+x_gram *gram;
+{
+   if (gram==top_gram) {
+      /* already here */
+      return;
+   } else if (top_gram==NULL) {
+      /* no grams at all.  Make gram both top and bottom */
+      top_gram=gram;
+      bottom_gram=gram;
+   } else if (gram==bottom_gram) {
+      /* bottom gram is special case */
+      bottom_gram=bottom_gram->above;
+      bottom_gram->below=NULL;
+      top_gram->above=gram;
+      gram->below=top_gram;
+      top_gram=gram;
+   } else {
+      /* normal case of a gram in the middle */
+      gram->above->below=gram->below;
+      gram->below->above=gram->above;
+      top_gram->above=gram;
+      gram->below=top_gram;
+      gram->above=NULL;
+      top_gram=gram;
+   }
+#ifdef DEBUG
+   print_gram_list("pull_to_top");
+#endif
+}
+
+void push_to_bottom(gram)
+x_gram *gram;
+{
+   if (gram==bottom_gram) {
+      /* already here */
+      return;
+   } else if (bottom_gram==NULL) {
+      /* no grams at all.  Make gram both top and bottom */
+      gram->above=NULL;
+      gram->below=NULL;
+      top_gram=gram;
+      bottom_gram=gram;
+   } else if (gram==top_gram) {
+      /* top gram is special case */
+      top_gram=top_gram->below;
+      top_gram->above=NULL;
+      bottom_gram->below=gram;
+      gram->above=bottom_gram;
+      bottom_gram=gram;
+   } else {
+      /* normal case of a gram in the middle */
+      gram->above->below=gram->below;
+      gram->below->above=gram->above;
+      bottom_gram->below=gram;
+      gram->above=bottom_gram;
+      gram->below=NULL;
+      bottom_gram=gram;
+   }
+#ifdef DEBUG
+   print_gram_list("push_to_bottom");
+#endif
+}
+
+void unlink_gram(gram)
+x_gram *gram;
+{
+   if (top_gram==bottom_gram) {
+      /* the only gram in the stack */
+      top_gram=NULL;
+      bottom_gram=NULL;
+   } else if (gram==top_gram) {
+      top_gram=gram->below;
+      top_gram->above=NULL;
+   } else if (gram==bottom_gram) {
+      bottom_gram=gram->above;
+      bottom_gram->below=NULL;
+   } else {
+      gram->above->below=gram->below;
+      gram->below->above=gram->above;
+   }
+#ifdef DEBUG
+   print_gram_list("unlink_gram");
+#endif
+}
+
+#ifdef notdef
+void add_to_top(gram)
+x_gram *gram;
+{
+   if (top_gram==NULL) {
+      gram->above=NULL;
+      gram->below=NULL;
+      top_gram=gram;
+      bottom_gram=gram;
+   } else {
+      top_gram->above=gram;
+      gram->above=NULL;
+      gram->below=top_gram;
+      top_gram=gram;
+   }
+#ifdef DEBUG
+   print_gram_list("add_to_top");
+#endif
+}
+#endif
+
+void add_to_bottom(gram)
+x_gram *gram;
+{
+   if (bottom_gram==NULL) {
+      gram->above=NULL;
+      gram->below=NULL;
+      top_gram=gram;
+      bottom_gram=gram;
+   } else {
+      bottom_gram->below=gram;
+      gram->above=bottom_gram;
+      gram->below=NULL;
+      bottom_gram=gram;
+   }
+#ifdef DEBUG
+   print_gram_list("add_to_bottom");
+#endif
+}
+