feat(estree-ast-utils): add joinArrayExpression util (#377)

Author: fraxken

.changeset/purple-emus-appear.md

@@ -0,0 +1,5 @@
+---
+"@nodesecure/estree-ast-utils": minor
+---
+
+Implement a new joinArrayExpression utility

workspaces/estree-ast-utils/README.md

@@ -33,7 +33,7 @@ You can provide a custom `externalIdentifierLookup` function to enable the utili
 ---
 
 <details>
-<summary>arrayExpressionToString(node: ESTree.Node | null): IterableIterator< string ></summary>
+<summary>arrayExpressionToString(node: ESTree.Node | null, options?: ArrayExpressionToStringOptions): IterableIterator< string ></summary>
 
 Transforms an ESTree `ArrayExpression` into an iterable of literal values.
 
@@ -43,6 +43,37 @@ Transforms an ESTree `ArrayExpression` into an iterable of literal values.
 
 will yield `"foo"`, then `"bar"`.
 
+```ts
+export interface ArrayExpressionToStringOptions extends DefaultOptions {
+  /**
+   * When enabled, resolves the char code of the literal value.
+   *
+   * @default true
+   * @example
+   * [65, 66] // => ['A', 'B']
+   */
+  resolveCharCode?: boolean;
+}
+```
+
+</details>
+
+<details>
+<summary>joinArrayExpression(node: ESTree.Node | null, options?: DefaultOptions): string | null</summary>
+
+Compute simple ArrayExpression that are using a CallExpression `join()`
+
+```js
+{
+  host: [
+    ["goo", "g", "gle"].join(""),
+    "com"
+  ].join(".")
+}
+```
+
+Will return `google.com`
+
 </details>
 
 <details>

workspaces/estree-ast-utils/src/arrayExpression.ts

@@ -0,0 +1,126 @@
+// Import Third-party Dependencies
+import type { ESTree } from "meriyah";
+
+// Import Internal Dependencies
+import {
+  type DefaultOptions,
+  noop
+} from "./options.js";
+import {
+  isNode,
+  isCallExpression,
+  isLiteral
+} from "./utils/is.js";
+import {
+  getMemberExpressionIdentifier
+} from "./getMemberExpressionIdentifier.js";
+
+export interface ArrayExpressionToStringOptions extends DefaultOptions {
+  /**
+   * When enabled, resolves the char code of the literal value.
+   *
+   * @default true
+   * @example
+   * [65, 66] // => ['A', 'B']
+   */
+  resolveCharCode?: boolean;
+}
+
+export function* arrayExpressionToString(
+  node: ESTree.Node | null,
+  options: ArrayExpressionToStringOptions = {}
+): IterableIterator<string> {
+  const {
+    externalIdentifierLookup = noop,
+    resolveCharCode = true
+  } = options;
+
+  if (!isNode(node) || node.type !== "ArrayExpression") {
+    return;
+  }
+
+  for (const row of node.elements) {
+    if (row === null) {
+      continue;
+    }
+
+    switch (row.type) {
+      case "Literal": {
+        if (
+          row.value === ""
+        ) {
+          continue;
+        }
+
+        if (resolveCharCode) {
+          const value = Number(row.value);
+          yield Number.isNaN(value) ?
+            String(row.value) :
+            String.fromCharCode(value);
+        }
+        else {
+          yield String(row.value);
+        }
+
+        break;
+      }
+      case "Identifier": {
+        const identifier = externalIdentifierLookup(row.name);
+        if (identifier !== null) {
+          yield identifier;
+        }
+        break;
+      }
+      case "CallExpression": {
+        const value = joinArrayExpression(row, {
+          externalIdentifierLookup
+        });
+        if (value !== null) {
+          yield value;
+        }
+        break;
+      }
+    }
+  }
+}
+
+export function joinArrayExpression(
+  node: ESTree.Node | null,
+  options: DefaultOptions = {}
+): string | null {
+  if (!isCallExpression(node)) {
+    return null;
+  }
+
+  if (
+    node.arguments.length !== 1 ||
+    (
+      node.callee.type !== "MemberExpression" ||
+      node.callee.object.type !== "ArrayExpression"
+    )
+  ) {
+    return null;
+  }
+
+  const id = Array.from(
+    getMemberExpressionIdentifier(node.callee)
+  ).join(".");
+  if (
+    id !== "join" ||
+    !isLiteral(node.arguments[0])
+  ) {
+    return null;
+  }
+
+  const separator = node.arguments[0].value;
+
+  const iter = arrayExpressionToString(
+    node.callee.object,
+    {
+      ...options,
+      resolveCharCode: false
+    }
+  );
+
+  return [...iter].join(separator);
+}

workspaces/estree-ast-utils/src/arrayExpressionToString.ts

@@ -2,7 +2,7 @@
 import type { ESTree } from "meriyah";
 
 // Import Internal Dependencies
-import { arrayExpressionToString } from "./arrayExpressionToString.js";
+import { arrayExpressionToString } from "./arrayExpression.js";
 import {
   type DefaultOptions,
   noop

workspaces/estree-ast-utils/src/concatBinaryExpression.ts

@@ -3,6 +3,7 @@ export * from "./getCallExpressionIdentifier.js";
 export * from "./getVariableDeclarationIdentifiers.js";
 export * from "./getCallExpressionArguments.js";
 export * from "./concatBinaryExpression.js";
-export * from "./arrayExpressionToString.js";
+export * from "./arrayExpression.js";
 export * from "./extractLogicalExpression.js";
+export * from "./utils/is.js";
 export type { DefaultOptions } from "./options.js";

workspaces/estree-ast-utils/src/index.ts

@@ -0,0 +1,35 @@
+// Import Third-party Dependencies
+import type { ESTree } from "meriyah";
+
+export type Literal<T> = ESTree.Literal & {
+  value: T;
+};
+
+export type RegExpLiteral<T> = ESTree.RegExpLiteral & {
+  value: T;
+};
+
+export function isNode(
+  value: any
+): value is ESTree.Node {
+  return (
+    value !== null &&
+    typeof value === "object" &&
+    "type" in value &&
+    typeof value.type === "string"
+  );
+}
+
+export function isCallExpression(
+  node: any
+): node is ESTree.CallExpression {
+  return isNode(node) && node.type === "CallExpression";
+}
+
+export function isLiteral(
+  node: any
+): node is Literal<string> {
+  return isNode(node) &&
+    node.type === "Literal" &&
+    typeof node.value === "string";
+}