flow like the river

BACK_BACK/node_modules/babylon-walk/src/index.js

@@ -0,0 +1,107 @@
+import * as t from 'babel-types';
+import explode from './explode.js';
+
+export function simple(node, visitors, state) {
+  if (!node) return;
+
+  visitors = explode(visitors);
+
+  (function c(node) {
+    if (!node) return;
+
+    const {enter, exit} = visitors[node.type] || {};
+
+    if (enter) {
+      for (let visitor of enter) {
+        visitor(node, state);
+      }
+    }
+
+    for (let key of t.VISITOR_KEYS[node.type] || []) {
+      let subNode = node[key];
+      if (Array.isArray(subNode)) {
+        for (let subSubNode of subNode) {
+          c(subSubNode);
+        }
+      } else {
+        c(subNode);
+      }
+    }
+
+    if (exit) {
+      for (let visitor of exit) {
+        visitor(node, state);
+      }
+    }
+  })(node);
+}
+
+export function ancestor(node, visitors, state) {
+  if (!node) return;
+
+  visitors = explode(visitors);
+  let ancestors = [];
+
+  (function c(node) {
+    if (!node) return;
+
+    const {enter, exit} = visitors[node.type] || {};
+
+    let isNew = node != ancestors[ancestors.length - 1];
+    if (isNew) ancestors.push(node);
+
+    if (enter) {
+      for (let visitor of enter) {
+        visitor(node, state || ancestors, ancestors);
+      }
+    }
+
+    for (let key of t.VISITOR_KEYS[node.type] || []) {
+      let subNode = node[key];
+      if (Array.isArray(subNode)) {
+        for (let subSubNode of subNode) {
+          c(subSubNode);
+        }
+      } else {
+        c(subNode);
+      }
+    }
+
+    if (exit) {
+      for (let visitor of exit) {
+        visitor(node, state || ancestors, ancestors);
+      }
+    }
+
+    if (isNew) ancestors.pop();
+  })(node);
+}
+
+export function recursive(node, visitors, state) {
+  if (!node) return;
+
+  visitors = explode(visitors);
+
+  (function c(node) {
+    if (!node) return;
+
+    const {enter} = visitors[node.type] || {};
+
+    if (enter && enter.length) {
+      for (let visitor of enter) {
+        visitor(node, state, c);
+      }
+    } else {
+      for (let key of t.VISITOR_KEYS[node.type] || []) {
+        let subNode = node[key];
+        if (Array.isArray(subNode)) {
+          for (let subSubNode of subNode) {
+            c(subSubNode);
+          }
+        } else {
+          c(subNode);
+        }
+      }
+    }
+  })(node);
+}