[elpa] externals/trie 81268ae 012/111: Added functions for pushing things onto dictree and trie stacks

[Stefan Monnier]

branch: externals/trie
commit 81268ae9cab8f151c5fbf1621e847242b2ecde7a
Author: Toby Cubitt <toby-predictive@dr-qubit.org>
Commit: tsc25 <toby-predictive@dr-qubit.org>

    Added functions for pushing things onto dictree and trie stacks
---
 trie.el | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/trie.el b/trie.el
index 139b004..aa41fef 100644
--- a/trie.el
+++ b/trie.el
@@ -333,9 +333,9 @@ If START or END is negative, it counts from the end."
   ;; Return t if NODE is a trie--node, nil otherwise.
   ;; Have to define this ourselves, because we created a defstruct
   ;; without any identifying tags (i.e. (:type vector)) for efficiency.
-  `(or (trie--node-data-p ,node)
-       (and (vectorp ,node)
-           (= (length ,node) 2)
+  `(and (vectorp ,node)
+       (= (length ,node) 2)
+       (or (trie--node-data-p ,node)
            (trie--p (trie--node-subtree ,node)))))
 
 
@@ -396,6 +396,7 @@ If START or END is negative, it counts from the end."
                        (funcall stack-createfun
                                 (trie--node-subtree (trie--root trie))
                                 reverse)))))
+             (pushed '())
              ))
            (:constructor
             trie--completion-stack-create
@@ -408,9 +409,11 @@ If START or END is negative, it counts from the end."
              (stack-emptyfun (trie--stack-emptyfun trie))
              (store (trie--completion-stack-construct-store
                      trie prefix reverse))
+             (pushed '())
              ))
            (:copier nil))
-  reverse stack-createfun stack-popfun stack-emptyfun store)
+  reverse predicatefun stack-createfun stack-popfun stack-emptyfun
+  store pushed)
 
 
 (defun trie--completion-stack-construct-store (trie prefix reverse)
@@ -438,9 +441,8 @@ If START or END is negative, it counts from the end."
   ;; Recursively push children of the node at the head of STACK onto the front
   ;; of STACK, until a data node is reached.
 
-  ;; nothing to do if stack is empty or first element isn't a trie node
-  (when (and (not (trie-stack-empty-p stack))
-            (trie--node-p (trie-stack-first stack)))
+  ;; nothing to do if stack is empty
+  (unless (trie-stack-empty-p stack)
     (let ((node (funcall (trie--stack-stack-popfun stack)
                         (cdar (trie--stack-store stack))))
          (seq (caar (trie--stack-store stack))))
@@ -871,21 +873,29 @@ it is better to use one of those instead."
 (defun trie-stack-pop (trie-stack)
   "Pop the first element from TRIE-STACK.
 Returns nil if the stack is empty."
-  (let ((first (pop (trie--stack-store trie-stack))))
-    (when first
-      (trie--stack-repopulate trie-stack)
-      first)))
+  ;; if elements have been pushed onto the stack, pop those first
+  (if (trie--stack-pushed trie-stack)
+      (pop (trie--stack-pushed trie-stack))
+    ;; otherwise, pop first element from trie-stack and repopulate it
+    (let ((first (pop (trie--stack-store trie-stack))))
+      (when first
+       (trie--stack-repopulate trie-stack)
+       first))))
 
 
 (defun trie-stack-push (element trie-stack)
   "Push ELEMENT onto TRIE-STACK."
-  (push element (trie--stack-store trie-stack)))
+  (push element (trie--stack-pushed trie-stack)))
 
 
 (defun trie-stack-first (trie-stack)
   "Return the first element from TRIE-STACK, without removing it
 from the stack. Returns nil if the stack is empty."
-  (car (trie--stack-store trie-stack)))
+  ;; if elements have been pushed onto the stack, return first of those
+  (if (trie--stack-pushed trie-stack)
+      (car (trie--stack-pushed trie-stack))
+    ;; otherwise, return first element from trie-stack
+    (car (trie--stack-store trie-stack))))
 
 
 (defalias 'trie-stack-p 'trie--stack-p
@@ -894,7 +904,8 @@ from the stack. Returns nil if the stack is empty."
 
 (defun trie-stack-empty-p (trie-stack)
   "Return t if TRIE-STACK is empty, nil otherwise."
-  (null (trie--stack-store trie-stack)))
+  (and (null (trie--stack-store trie-stack))
+       (null (trie--stack-pushed trie-stack))))