Add more support for exported imports in tree shaking

build/lib/treeshaking.js

@@ -254,6 +254,7 @@ function markNodes(languageService, options) {
     }
     const black_queue = [];
     const gray_queue = [];
+    const export_import_queue = [];
     const sourceFilesLoaded = {};
     function enqueueTopLevelModuleStatements(sourceFile) {
         sourceFile.forEachChild((node) => {
@@ -270,6 +271,11 @@ function markNodes(languageService, options) {
                     setColor(node, 2 /* Black */);
                     enqueueImport(node, node.moduleSpecifier.text);
                 }
+                if (node.exportClause && ts.isNamedExports(node.exportClause)) {
+                    for (const exportSpecifier of node.exportClause.elements) {
+                        export_import_queue.push(exportSpecifier);
+                    }
+                }
                 return;
             }
             if (ts.isExpressionStatement(node)
@@ -448,6 +454,22 @@ function markNodes(languageService, options) {
         };
         node.forEachChild(loop);
     }
+    while (export_import_queue.length > 0) {
+        const node = export_import_queue.shift();
+        if (nodeOrParentIsBlack(node)) {
+            continue;
+        }
+        const symbol = node.symbol;
+        if (!symbol) {
+            continue;
+        }
+        const aliased = checker.getAliasedSymbol(symbol);
+        if (aliased.declarations && aliased.declarations.length > 0) {
+            if (nodeOrParentIsBlack(aliased.declarations[0]) || nodeOrChildIsBlack(aliased.declarations[0])) {
+                setColor(node, 2 /* Black */);
+            }
+        }
+    }
 }
 function nodeIsInItsOwnDeclaration(nodeSourceFile, node, symbol) {
     for (let i = 0, len = symbol.declarations.length; i < len; i++) {
@@ -539,6 +561,21 @@ function generateResult(languageService, shakeLevel) {
                     }
                 }
             }
+            if (ts.isExportDeclaration(node)) {
+                if (node.exportClause && node.moduleSpecifier && ts.isNamedExports(node.exportClause)) {
+                    let survivingExports = [];
+                    for (const exportSpecifier of node.exportClause.elements) {
+                        if (getColor(exportSpecifier) === 2 /* Black */) {
+                            survivingExports.push(exportSpecifier.getFullText(sourceFile));
+                        }
+                    }
+                    const leadingTriviaWidth = node.getLeadingTriviaWidth();
+                    const leadingTrivia = sourceFile.text.substr(node.pos, leadingTriviaWidth);
+                    if (survivingExports.length > 0) {
+                        return write(`${leadingTrivia}export {${survivingExports.join(',')} } from${node.moduleSpecifier.getFullText(sourceFile)};`);
+                    }
+                }
+            }
             if (shakeLevel === 2 /* ClassMembers */ && (ts.isClassDeclaration(node) || ts.isInterfaceDeclaration(node)) && nodeOrChildIsBlack(node)) {
                 let toWrite = node.getFullText();
                 for (let i = node.members.length - 1; i >= 0; i--) {

build/lib/treeshaking.ts

@@ -336,6 +336,7 @@ function markNodes(languageService: ts.LanguageService, options: ITreeShakingOpt
 
 	const black_queue: ts.Node[] = [];
 	const gray_queue: ts.Node[] = [];
+	const export_import_queue: ts.Node[] = [];
 	const sourceFilesLoaded: { [fileName: string]: boolean } = {};
 
 	function enqueueTopLevelModuleStatements(sourceFile: ts.SourceFile): void {
@@ -356,6 +357,11 @@ function markNodes(languageService: ts.LanguageService, options: ITreeShakingOpt
 					setColor(node, NodeColor.Black);
 					enqueueImport(node, node.moduleSpecifier.text);
 				}
+				if (node.exportClause && ts.isNamedExports(node.exportClause)) {
+					for (const exportSpecifier of node.exportClause.elements) {
+						export_import_queue.push(exportSpecifier);
+					}
+				}
 				return;
 			}
 
@@ -566,6 +572,23 @@ function markNodes(languageService: ts.LanguageService, options: ITreeShakingOpt
 		};
 		node.forEachChild(loop);
 	}
+
+	while (export_import_queue.length > 0) {
+		const node = export_import_queue.shift()!;
+		if (nodeOrParentIsBlack(node)) {
+			continue;
+		}
+		const symbol: ts.Symbol | undefined = (<any>node).symbol;
+		if (!symbol) {
+			continue;
+		}
+		const aliased = checker.getAliasedSymbol(symbol);
+		if (aliased.declarations && aliased.declarations.length > 0) {
+			if (nodeOrParentIsBlack(aliased.declarations[0]) || nodeOrChildIsBlack(aliased.declarations[0])) {
+				setColor(node, NodeColor.Black);
+			}
+		}
+	}
 }
 
 function nodeIsInItsOwnDeclaration(nodeSourceFile: ts.SourceFile, node: ts.Node, symbol: ts.Symbol): boolean {
@@ -667,6 +690,22 @@ function generateResult(languageService: ts.LanguageService, shakeLevel: ShakeLe
 				}
 			}
 
+			if (ts.isExportDeclaration(node)) {
+				if (node.exportClause && node.moduleSpecifier && ts.isNamedExports(node.exportClause)) {
+					let survivingExports: string[] = [];
+					for (const exportSpecifier of node.exportClause.elements) {
+						if (getColor(exportSpecifier) === NodeColor.Black) {
+							survivingExports.push(exportSpecifier.getFullText(sourceFile));
+						}
+					}
+					const leadingTriviaWidth = node.getLeadingTriviaWidth();
+					const leadingTrivia = sourceFile.text.substr(node.pos, leadingTriviaWidth);
+					if (survivingExports.length > 0) {
+						return write(`${leadingTrivia}export {${survivingExports.join(',')} } from${node.moduleSpecifier.getFullText(sourceFile)};`);
+					}
+				}
+			}
+
 			if (shakeLevel === ShakeLevel.ClassMembers && (ts.isClassDeclaration(node) || ts.isInterfaceDeclaration(node)) && nodeOrChildIsBlack(node)) {
 				let toWrite = node.getFullText();
 				for (let i = node.members.length - 1; i >= 0; i--) {