1 files changed, 152 insertions, 0 deletions
diff --git a/vanilla/node_modules/estree-walker/src/sync.js b/vanilla/node_modules/estree-walker/src/sync.js
new file mode 100644
index 0000000..171fb36
--- /dev/null
+++ b/vanilla/node_modules/estree-walker/src/sync.js
@@ -0,0 +1,152 @@
+import { WalkerBase } from './walker.js';
+
+/**
+ * @typedef { import('estree').Node} Node
+ * @typedef { import('./walker.js').WalkerContext} WalkerContext
+ * @typedef {(
+ *    this: WalkerContext,
+ *    node: Node,
+ *    parent: Node | null,
+ *    key: string | number | symbol | null | undefined,
+ *    index: number | null | undefined
+ * ) => void} SyncHandler
+ */
+
+export class SyncWalker extends WalkerBase {
+	/**
+	 *
+	 * @param {SyncHandler} [enter]
+	 * @param {SyncHandler} [leave]
+	 */
+	constructor(enter, leave) {
+		super();
+
+		/** @type {boolean} */
+		this.should_skip = false;
+
+		/** @type {boolean} */
+		this.should_remove = false;
+
+		/** @type {Node | null} */
+		this.replacement = null;
+
+		/** @type {WalkerContext} */
+		this.context = {
+			skip: () => (this.should_skip = true),
+			remove: () => (this.should_remove = true),
+			replace: (node) => (this.replacement = node)
+		};
+
+		/** @type {SyncHandler | undefined} */
+		this.enter = enter;
+
+		/** @type {SyncHandler | undefined} */
+		this.leave = leave;
+	}
+
+	/**
+	 * @template {Node} Parent
+	 * @param {Node} node
+	 * @param {Parent | null} parent
+	 * @param {keyof Parent} [prop]
+	 * @param {number | null} [index]
+	 * @returns {Node | null}
+	 */
+	visit(node, parent, prop, index) {
+		if (node) {
+			if (this.enter) {
+				const _should_skip = this.should_skip;
+				const _should_remove = this.should_remove;
+				const _replacement = this.replacement;
+				this.should_skip = false;
+				this.should_remove = false;
+				this.replacement = null;
+
+				this.enter.call(this.context, node, parent, prop, index);
+
+				if (this.replacement) {
+					node = this.replacement;
+					this.replace(parent, prop, index, node);
+				}
+
+				if (this.should_remove) {
+					this.remove(parent, prop, index);
+				}
+
+				const skipped = this.should_skip;
+				const removed = this.should_remove;
+
+				this.should_skip = _should_skip;
+				this.should_remove = _should_remove;
+				this.replacement = _replacement;
+
+				if (skipped) return node;
+				if (removed) return null;
+			}
+
+			/** @type {keyof Node} */
+			let key;
+
+			for (key in node) {
+				/** @type {unknown} */
+				const value = node[key];
+
+				if (value && typeof value === 'object') {
+					if (Array.isArray(value)) {
+						const nodes = /** @type {Array<unknown>} */ (value);
+						for (let i = 0; i < nodes.length; i += 1) {
+							const item = nodes[i];
+							if (isNode(item)) {
+								if (!this.visit(item, node, key, i)) {
+									// removed
+									i--;
+								}
+							}
+						}
+					} else if (isNode(value)) {
+						this.visit(value, node, key, null);
+					}
+				}
+			}
+
+			if (this.leave) {
+				const _replacement = this.replacement;
+				const _should_remove = this.should_remove;
+				this.replacement = null;
+				this.should_remove = false;
+
+				this.leave.call(this.context, node, parent, prop, index);
+
+				if (this.replacement) {
+					node = this.replacement;
+					this.replace(parent, prop, index, node);
+				}
+
+				if (this.should_remove) {
+					this.remove(parent, prop, index);
+				}
+
+				const removed = this.should_remove;
+
+				this.replacement = _replacement;
+				this.should_remove = _should_remove;
+
+				if (removed) return null;
+			}
+		}
+
+		return node;
+	}
+}
+
+/**
+ * Ducktype a node.
+ *
+ * @param {unknown} value
+ * @returns {value is Node}
+ */
+function isNode(value) {
+	return (
+		value !== null && typeof value === 'object' && 'type' in value && typeof value.type === 'string'
+	);
+}