before, after, and between callbacks to fancier traversing

ljharb · Sep 4, 2010 · 5662b6f · 5662b6f
1 parent f22580a
commit 5662b6f
Showing 1 changed file with 29 additions and 5 deletions.
diff --git a/lib/traverse.js b/lib/traverse.js
@@ -43,7 +43,7 @@ function Traverse (refObj) {
     // get() is deprecated, use .value
     this.get = function () { return this.value };
 
-    this.map = function (f) {
+    this.map = function (cb) {
         var self = this;
 
         var path = [];
@@ -52,12 +52,18 @@ function Traverse (refObj) {
         return this;
 
         function walk (node) {
+            var before = null;
+            var after = null;
+            var between = null;
+
             var state = {
                 node : node,
                 path : [].concat(path),
                 parent : parents.slice(-1)[0],
                 key : path.slice(-1)[0],
                 isRoot : node === self.value,
+                level : path.length,
+                circular : null,
                 update : function (x) {
                     if (state.isRoot) {
                         self.value = x;
@@ -67,8 +73,12 @@ function Traverse (refObj) {
                     }
                     state.node = x;
                 },
-                level : path.length,
-                circular : null
+                before : function (f) { before = f },
+                after : function (f) { after = f },
+                between : function (f, acc) {
+                    between = f;
+                    between._acc = acc;
+                }
             };
 
             if (typeof node == 'object' && node !== null) {
@@ -85,20 +95,34 @@ function Traverse (refObj) {
             state.notLeaf = !state.isLeaf;
             state.notRoot = !state.isRoot;
 
+            if (before) before.call(state, node);
+
             // use return values to update if defined
-            var ret = f.call(state, node);
+            var ret = cb.call(state, node);
             if (ret !== undefined && state.update) state.update(ret);
 
             if (typeof state.node == 'object'
             && state.node !== null && !state.circular) {
                 parents.push(state);
-                Object.keys(state.node).forEach(function (key) {
+                Object.keys(state.node).forEach(function (key, i) {
                     path.push(key);
                     walk(state.node[key]);
+
+                    if (i == 0 && between && between._acc === undefined) {
+                        between._acc = state.node[key]
+                    }
+                    else if (between) {
+                        between._acc = between.call(
+                            state, between._acc, state.node[key]
+                        );
+                    }
+
                     path.pop();
                 });
                 parents.pop();
             }
+
+            if (after) after.call(state, node);
         }
     };