feat: Add minor performance improvements.

avocadowastaken · Jul 30, 2021 · ea7ef45 · ea7ef45
1 parent 6a8026b
commit ea7ef45
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Showing 4 changed files with 34 additions and 17 deletions.
diff --git a/lib/internal/DependencyTree.js b/lib/internal/DependencyTree.js
@@ -86,11 +86,10 @@ class DependencyTree {
     this.nodeModule = nodeModule;
 
     /**
-     * @type {Map<string, Dependency>}
-     * @readonly
+     * @type {null | Map<string, Dependency>}
      * @protected
      */
-    this.items = new Map();
+    this.items = null;
 
     /**
      * @type {Map<string, Array<import('@babel/types').Statement>>}
@@ -295,8 +294,9 @@ class DependencyTree {
   }
 
   /** @returns {Map<string, Dependency>} */
-  get dependencies() {
-    if (!this.items.size) {
+  getDependencies() {
+    if (!this.items) {
+      this.items = new Map();
       for (const dependency of this.collectDependencies()) {
         this.items.set(dependency.id, dependency);
       }
@@ -309,7 +309,7 @@ class DependencyTree {
    * @param {import("@babel/types").ImportSpecifier | import("@babel/types").ImportDefaultSpecifier | import("@babel/types").ImportNamespaceSpecifier} node
    * @returns {null | import("@babel/types").ImportDeclaration}
    */
-  process(node) {
+  findReplacement(node) {
     const { types: t } = this.babel;
 
     if (t.isImportNamespaceSpecifier(node)) {
@@ -323,7 +323,7 @@ class DependencyTree {
       ? node.imported.name
       : node.imported.value;
 
-    const dependency = this.dependencies.get(moduleName);
+    const dependency = this.getDependencies().get(moduleName);
 
     if (dependency) {
       const localName = t.identifier(node.local.name);

diff --git a/lib/internal/PluginOptions.js b/lib/internal/PluginOptions.js
@@ -58,8 +58,20 @@ class PluginOptions {
    * @protected
    */
   constructor(modules) {
+    /**
+     * @type {Map<string, NodeModule>}
+     * @protected
+     */
     this.modules = modules;
   }
+
+  /**
+   * @param {string} id
+   * @returns {undefined | NodeModule}
+   */
+  findNodeModule(id) {
+    return this.modules.get(id);
+  }
 }
 
 module.exports = PluginOptions;
diff --git a/lib/plugin.js b/lib/plugin.js
@@ -16,23 +16,29 @@ module.exports = function plugin(babel) {
         if (!specifiers.length || importKind === "type") return;
 
         const pluginOptions = PluginOptions.parse(opts);
-        const nodeModule = pluginOptions.modules.get(source.value);
+        const nodeModule = pluginOptions.findNodeModule(source.value);
         if (!nodeModule) return;
         const tree = DependencyTree.create(nodeModule, babel);
 
+        /** @type {Set<import("@babel/types").Node>} */
+        const removedSpecifiers = new Set();
+
         for (const specifier of specifiers) {
-          const replacement = tree.process(specifier);
+          const replacement = tree.findReplacement(specifier);
 
           if (replacement) {
-            declaration.node.specifiers = declaration.node.specifiers.filter(
-              (x) => x !== specifier
-            );
-
+            removedSpecifiers.add(specifier);
             declaration.insertBefore(replacement);
           }
         }
 
-        if (!declaration.node.specifiers.length) declaration.remove();
+        if (removedSpecifiers.size === declaration.node.specifiers.length) {
+          declaration.remove();
+        } else {
+          declaration.node.specifiers = declaration.node.specifiers.filter(
+            (specifier) => !removedSpecifiers.has(specifier)
+          );
+        }
       },
     },
   };

diff --git a/test/testExports.js b/test/testExports.js
@@ -10,9 +10,8 @@ const DependencyTree = require("../lib/internal/DependencyTree");
  * @returns {unknown[]}
  */
 module.exports = function testExports(id) {
-  const { dependencies } = DependencyTree.create(NodeModule.get(id), babel);
-
-  return Array.from(dependencies.values(), (dependency) => [
+  const tree = DependencyTree.create(NodeModule.get(id), babel);
+  return Array.from(tree.getDependencies().values(), (dependency) => [
     dependency.id,
     dependency.internalID,
     dependency.source,