1 files changed, 87 insertions, 0 deletions
diff --git a/@linaria/packages/shaker/src/Visitors.ts b/@linaria/packages/shaker/src/Visitors.ts
new file mode 100644
index 0000000..0228d4a
--- /dev/null
+++ b/@linaria/packages/shaker/src/Visitors.ts
@@ -0,0 +1,87 @@
+import { types as t } from '@babel/core';
+import type { Identifier, Node, VisitorKeys } from '@babel/types';
+import { warn } from '@linaria/logger';
+import { peek } from '@linaria/babel-preset';
+import GraphBuilderState from './GraphBuilderState';
+import identifierHandlers from './identifierHandlers';
+import type { Visitor, Visitors } from './types';
+
+import { visitors as core } from './langs/core';
+
+const visitors: Visitors = {
+  Identifier<TParent extends Node>(
+    this: GraphBuilderState,
+    node: Identifier,
+    parent: TParent | null,
+    parentKey: VisitorKeys[TParent['type']] | null,
+    listIdx: number | null = null
+  ) {
+    if (!parent || !parentKey) {
+      return;
+    }
+
+    const handler = identifierHandlers[`${parent.type}:${parentKey}`];
+
+    if (typeof handler === 'function') {
+      handler(this, node, parent, parentKey, listIdx);
+      return;
+    }
+
+    if (handler === 'keep') {
+      return;
+    }
+
+    if (handler === 'declare') {
+      const kindOfDeclaration = this.meta.get('kind-of-declaration');
+      this.scope.declare(node, kindOfDeclaration === 'var', null);
+      return;
+    }
+
+    if (handler === 'refer') {
+      const declaration = this.scope.addReference(node);
+      // Let's check that it's not a global variable
+      if (declaration) {
+        // usage of a variable depends on its declaration
+        this.graph.addEdge(node, declaration);
+
+        const context = peek(this.context);
+        if (context === 'lval') {
+          // This is an identifier in the left side of an assignment expression and a variable value depends on that.
+          this.graph.addEdge(declaration, node);
+        }
+      }
+
+      return;
+    }
+
+    /*
+     * There is an unhandled identifier.
+     * This case should be added to ./identifierHandlers.ts
+     */
+    warn(
+      'evaluator:shaker',
+      'Unhandled identifier',
+      node.name,
+      parent.type,
+      parentKey,
+      listIdx
+    );
+  },
+
+  ...core,
+};
+
+const isKeyOfVisitors = (type: string): type is keyof Visitors =>
+  type in visitors;
+
+export function getVisitors<TNode extends Node>(node: TNode): Visitor<TNode>[] {
+  const aliases = t.ALIAS_KEYS[node.type] || [];
+  const aliasVisitors = aliases
+    .map((type) => (isKeyOfVisitors(type) ? visitors[type] : null))
+    .filter((i) => i) as Visitor<TNode>[];
+  return [...aliasVisitors, visitors[node.type] as Visitor<TNode>].filter(
+    (v) => v
+  );
+}
+
+export default visitors;