pass current path to enter/leave callbacks

.travis.yml

@@ -0,0 +1,7 @@
+language: node_js
+node_js:
+  - "node"
+notifications:
+  email: false
+script:
+  - npm test

lib/__test__/traverse.test.js

@@ -0,0 +1,81 @@
+import assert from 'assert'
+
+import traverse from '../traverse'
+
+describe('traverse', () => {
+    it('should pass the current path to enter and leave', () => {
+        const ast = {
+            type: 'Apply',
+            op: 'add',
+            args: [{
+                type: 'Number',
+                value: '5',
+            }, {
+                type: 'Identifier',
+                name: 'a',
+            }]
+        }
+
+        let enterPath = []
+        let leavePath = []
+
+        traverse(ast, {
+            enter(node, path) {
+                if (node.value === '5') {
+                    enterPath = path
+                }
+            },
+            leave(node, path) {
+                if (node.name === 'a') {
+                    leavePath = path
+                }
+            }
+        })
+
+        assert.deepEqual(enterPath, ['args', 0])
+        assert.deepEqual(leavePath, ['args', 1])
+    })
+
+    it('should pass the current path to enter and leave', () => {
+        const ast = {
+            type: 'Apply',
+            op: 'add',
+            args: [{
+                type: 'Apply',
+                op: 'add',
+                args: [
+                    {
+                        type: 'Number',
+                        value: '5',
+                    },
+                    {
+                        type: 'Number',
+                        value: '10',
+                    },
+                ],
+            }, {
+                type: 'Identifier',
+                name: 'a',
+            }]
+        }
+
+        let enterPath = []
+        let leavePath = []
+
+        traverse(ast, {
+            enter(node, path) {
+                if (node.value === '5') {
+                    enterPath = path
+                }
+            },
+            leave(node, path) {
+                if (node.value === '10') {
+                    leavePath = path
+                }
+            }
+        })
+
+        assert.deepEqual(enterPath, ['args', 0, 'args', 0])
+        assert.deepEqual(leavePath, ['args', 0, 'args', 1])
+    })
+})

lib/traverse.js

@@ -2,48 +2,51 @@
  * traverse - walk all of the nodes in a tree.
  */
 
-function traverse(node, {enter = () => {}, leave = () => {}}) {
+function traverse(node, {enter = () => {}, leave = () => {}}, path = []) {
     switch (node.type) {
         // regular non-leaf nodes
         case 'Apply':
-            enter(node)
-            node.args.forEach((arg) => traverse(arg, {enter, leave}))
-            leave(node)
+            enter(node, path)
+            node.args.forEach((arg, index) =>
+                traverse(arg, {enter, leave}, [...path, 'args', index]))
+            leave(node, path)
             break
 
         // leaf nodes
         case 'Identifier':
         case 'Number':
         case 'Ellipsis':
-            enter(node)
-            leave(node)
+            enter(node, path)
+            leave(node, path)
             break
 
         // irregular non-leaf nodes
         case 'Parentheses':
-            enter(node)
-            traverse(node.body, {enter, leave})
-            leave(node)
+            enter(node, path)
+            traverse(node.body, {enter, leave}, [...path, 'body'])
+            leave(node, path)
             break
 
         case 'List':
         case 'Sequence':
-            enter(node)
-            node.items.forEach((item) => traverse(item, {enter, leave}))
-            leave(node)
+            enter(node, path)
+            node.items.forEach((item, index) =>
+                traverse(item, {enter, leave}, [...path, 'items', index]))
+            leave(node, path)
             break
 
         case 'System':
-            enter(node)
-            node.relations.forEach((rel) => traverse(rel, { enter, leave }))
-            leave(node)
+            enter(node, path)
+            node.relations.forEach((rel, index) =>
+                traverse(rel, {enter, leave}, [...path, 'relations', index]))
+            leave(node, path)
             break
 
         case 'Placeholder':
             // TODO(kevinb) handle children of the placeholder
             // e.g. we there might #a_0 could match x_0, y_0, z_0, etc.
-            enter(node)
-            leave(node)
+            enter(node, path)
+            leave(node, path)
             break
 
         default:

package.json

@@ -1,11 +1,11 @@
 {
   "name": "math-traverse",
-  "version": "0.2.1",
+  "version": "0.2.2",
   "description": "Library for traversing and replacing nodes in a math-ast AST",
   "main": "dist/math-traverse.js",
   "scripts": {
     "prepublish": "webpack",
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "jest"
   },
   "repository": "git+https://github.com/semantic-math/math-traverse.git",
   "author": "Kevin Barabash <[email protected]>",
@@ -16,8 +16,17 @@
   "homepage": "https://github.com/semantic-math/math-traverse#readme",
   "devDependencies": {
     "babel-core": "^6.24.1",
+    "babel-jest": "^20.0.3",
     "babel-loader": "^7.0.0",
+    "babel-polyfill": "^6.23.0",
     "babel-preset-es2015": "^6.24.1",
+    "jest": "^20.0.4",
     "webpack": "^2.4.1"
+  },
+  "jest": {
+    "setupTestFrameworkScriptFile": "<rootDir>/node_modules/babel-polyfill/dist/polyfill.js",
+    "transform": {
+      "^.+\\.jsx?$": "babel-jest"
+    }
   }
 }