class WalkerBase {constructor() { WalkerBase.prototype.__init.call(this);WalkerBase.prototype.__init2.call(this);WalkerBase.prototype.__init3.call(this);WalkerBase.prototype.__init4.call(this); }
	 __init() {this.should_skip = false;}
	 __init2() {this.should_remove = false;}
	 __init3() {this.replacement = null;}

	 __init4() {this.context = {
		skip: () => (this.should_skip = true),
		remove: () => (this.should_remove = true),
		replace: (node) => (this.replacement = node)
	};}

	 replace(parent, prop, index, node) {
		if (parent) {
			if (index !== null) {
				parent[prop][index] = node;
			} else {
				parent[prop] = node;
			}
		}
	}

	 remove(parent, prop, index) {
		if (parent) {
			if (index !== null) {
				parent[prop].splice(index, 1);
			} else {
				delete parent[prop];
			}
		}
	}
}

class SyncWalkerClass extends WalkerBase {
	
	

	constructor(walker) {
		super();
		this.enter = walker.enter;
		this.leave = walker.leave;
	}

	 visit(
		node,
		parent,
		enter,
		leave,
		prop,
		index
	) {
		if (node) {
			if (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;

				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;
			}

			for (const key in node) {
				const value = (node )[key];

				if (typeof value !== "object") {
					continue;
				} else if (Array.isArray(value)) {
					for (let i = 0; i < value.length; i += 1) {
						if (value[i] !== null && typeof value[i].type === 'string') {
							if (!this.visit(value[i], node, enter, leave, key, i)) {
								// removed
								i--;
							}
						}
					}
				} else if (value !== null && typeof value.type === "string") {
					this.visit(value, node, enter, leave, key, null);
				}
			}

			if (leave) {
				const _replacement = this.replacement;
				const _should_remove = this.should_remove;
				this.replacement = null;
				this.should_remove = false;

				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;
	}
}

class AsyncWalkerClass extends WalkerBase {
	
	

	constructor(walker) {
		super();
		this.enter = walker.enter;
		this.leave = walker.leave;
	}

	 async visit(
		node,
		parent,
		enter,
		leave,
		prop,
		index
	) {
		if (node) {
			if (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;

				await 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;
			}

			for (const key in node) {
				const value = (node )[key];

				if (typeof value !== "object") {
					continue;
				} else if (Array.isArray(value)) {
					for (let i = 0; i < value.length; i += 1) {
						if (value[i] !== null && typeof value[i].type === 'string') {
							if (!(await this.visit(value[i], node, enter, leave, key, i))) {
								// removed
								i--;
							}
						}
					}
				} else if (value !== null && typeof value.type === "string") {
					await this.visit(value, node, enter, leave, key, null);
				}
			}

			if (leave) {
				const _replacement = this.replacement;
				const _should_remove = this.should_remove;
				this.replacement = null;
				this.should_remove = false;

				await 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;
	}
}

function walk(ast, walker) {
	const instance = new SyncWalkerClass(walker);
	return instance.visit(ast, null, walker.enter, walker.leave);
}

async function asyncWalk(
	ast,
	walker
) {
	const instance = new AsyncWalkerClass(walker);
	return await instance.visit(ast, null, walker.enter, walker.leave);
}

export { walk, asyncWalk };