support default imports, side effect imports and namespace imports

Author: Feiyang1

repo-scripts/size-analysis/bundle-analysis.ts

@@ -74,6 +74,12 @@ enum Mode {
   Local = 'local'
 }
 
+enum SpecialImport {
+  Default = 'default import',
+  Sizeeffect = 'side effect import',
+  Namespace = 'namespace import'
+}
+
 export async function run({
   input,
   bundler,
@@ -392,15 +398,23 @@ async function analyzeBundleWithBundler(
 
 function createEntryFileContent(bundleDefinition: BundleDefinition): string {
   const contentArray = [];
+  // cache used symbols. Used to avoid symbol collision when multiple modules export symbols with the same name.
+  const symbolsCache = new Set<string>();
   for (const dep of bundleDefinition.dependencies) {
     for (const imp of dep.imports) {
       if (typeof imp === 'string') {
-        contentArray.push(`export {${imp}} from '${dep.packageName}';`);
+        contentArray.push(
+          ...createImportExport(imp, dep.packageName, symbolsCache)
+        );
       } else {
-        // Import object
+        // submodule imports
         for (const subImp of imp.imports) {
           contentArray.push(
-            `export {${subImp}} from '${dep.packageName}/${imp.path}';`
+            ...createImportExport(
+              subImp,
+              `${dep.packageName}/${imp.path}`,
+              symbolsCache
+            )
           );
         }
       }
@@ -410,6 +424,58 @@ function createEntryFileContent(bundleDefinition: BundleDefinition): string {
   return contentArray.join('\n');
 }
 
+function createImportExport(
+  symbol: string,
+  modulePath: string,
+  symbolsCache: Set<string>
+): string[] {
+  const contentArray = [];
+
+  switch (symbol) {
+    case SpecialImport.Default:
+      contentArray.push(
+        `import * as ${createSymbolName('default_import', symbolsCache)}`
+      );
+      break;
+    case SpecialImport.Namespace:
+      contentArray.push(
+        `import * as ${createSymbolName('namespace', symbolsCache)}`
+      );
+      break;
+    case SpecialImport.Sizeeffect:
+      contentArray.push(`import '${modulePath}';`);
+      break;
+    default:
+      // named imports
+      const nameToUse = createSymbolName(symbol, symbolsCache);
+
+      if (nameToUse !== symbol) {
+        contentArray.push(
+          `export {${symbol} as ${nameToUse}} from '${modulePath}';`
+        );
+      } else {
+        contentArray.push(`export {${symbol}} from '${modulePath}';`);
+      }
+  }
+
+  return contentArray;
+}
+
+/**
+ * In case a symbol with the same name is already imported from another module, we need to give this symbol another name
+ * using "originalname as anothername" syntax, otherwise it returns the original symbol name.
+ */
+function createSymbolName(symbol: string, symbolsCache: Set<string>): string {
+  let nameToUse = symbol;
+  const max = 100;
+  while (symbolsCache.has(nameToUse)) {
+    nameToUse = `${symbol}_${Math.floor(Math.random() * max)}`;
+  }
+
+  symbolsCache.add(nameToUse);
+  return nameToUse;
+}
+
 interface BundleAnalysis {
   name: string; // the bundle name defined in the bundle definition
   results: BundleAnalysisResult[];

repo-scripts/size-analysis/bundle-definition-examples/bundle-definition-1.json

@@ -1,6 +1,7 @@
 [
     {
         "name": "test",
+        "desecription": "",
         "dependencies": [
             {
                 "packageName": "@firebase/app",
@@ -19,5 +20,45 @@
                 ]
             }
         ]
+    },
+    {
+        "name": "test2",
+        "description": "default imports and side effect imports",
+        "dependencies": [
+            {
+                "packageName": "@firebase/app",
+                "versionOrTag": "latest",
+                "imports": [
+                    "default import"
+                ]
+            },
+            {
+                "packageName": "@firebase/firestore",
+                "versionOrTag": "latest",
+                "imports": [
+                    "side effect import"
+                ]
+            }
+        ]
+    },
+    {
+        "name": "test3",
+        "description": "symbols with the same name",
+        "dependencies": [
+            {
+                "packageName": "@firebase/firestore",
+                "versionOrTag": "exp",
+                "imports": [
+                    "ref"
+                ]
+            },
+            {
+                "packageName": "@firebase/storage",
+                "versionOrTag": "exp",
+                "imports": [
+                    "ref"
+                ]
+            }
+        ]
     }
 ]