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denoland-deno/cli/js/compiler_bundler.ts
Kitson Kelly 671f0b83be
Bundles can be sync or async based on top level await (#4124)
Previously, bundles always utilised top level await, even if the bundled
modules didn't require top level await.  Now, analysis of the bundle is
done and if none of the bundled modules are asynchronously executed,
then the bundle as a whole will be synchronously executed.

Fixes #4055
Fixes #4123
2020-02-26 17:59:33 +01:00

107 lines
3.9 KiB
TypeScript

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { SYSTEM_LOADER } from "./compiler_bootstrap.ts";
import {
assert,
commonPath,
normalizeString,
CHAR_FORWARD_SLASH
} from "./util.ts";
/** Local state of what the root exports are of a root module. */
let rootExports: string[] | undefined;
/** Take a URL and normalize it, resolving relative path parts. */
function normalizeUrl(rootName: string): string {
const match = /^(\S+:\/{2,3})(.+)$/.exec(rootName);
if (match) {
const [, protocol, path] = match;
return `${protocol}${normalizeString(
path,
false,
"/",
code => code === CHAR_FORWARD_SLASH
)}`;
} else {
return rootName;
}
}
/** Given a root name, contents, and source files, enrich the data of the
* bundle with a loader and re-export the exports of the root name. */
export function buildBundle(
rootName: string,
data: string,
sourceFiles: readonly ts.SourceFile[]
): string {
// when outputting to AMD and a single outfile, TypeScript makes up the module
// specifiers which are used to define the modules, and doesn't expose them
// publicly, so we have to try to replicate
const sources = sourceFiles.map(sf => sf.fileName);
const sharedPath = commonPath(sources);
rootName = normalizeUrl(rootName)
.replace(sharedPath, "")
.replace(/\.\w+$/i, "");
// If one of the modules requires support for top-level-await, TypeScript will
// emit the execute function as an async function. When this is the case we
// need to bubble up the TLA to the instantiation, otherwise we instantiate
// synchronously.
const hasTla = data.match(/execute:\sasync\sfunction\s/);
let instantiate: string;
if (rootExports && rootExports.length) {
instantiate = hasTla
? `const __exp = await __inst("${rootName}");\n`
: `const __exp = __inst_s("${rootName}");\n`;
for (const rootExport of rootExports) {
if (rootExport === "default") {
instantiate += `export default __exp["${rootExport}"];\n`;
} else {
instantiate += `export const ${rootExport} = __exp["${rootExport}"];\n`;
}
}
} else {
instantiate = hasTla
? `await __inst("${rootName}");\n`
: `__inst_s("${rootName}");\n`;
}
return `${SYSTEM_LOADER}\n${data}\n${instantiate}`;
}
/** Set the rootExports which will by the `emitBundle()` */
export function setRootExports(program: ts.Program, rootModule: string): void {
// get a reference to the type checker, this will let us find symbols from
// the AST.
const checker = program.getTypeChecker();
// get a reference to the main source file for the bundle
const mainSourceFile = program.getSourceFile(rootModule);
assert(mainSourceFile);
// retrieve the internal TypeScript symbol for this AST node
const mainSymbol = checker.getSymbolAtLocation(mainSourceFile);
if (!mainSymbol) {
return;
}
rootExports = checker
.getExportsOfModule(mainSymbol)
// .getExportsOfModule includes type only symbols which are exported from
// the module, so we need to try to filter those out. While not critical
// someone looking at the bundle would think there is runtime code behind
// that when there isn't. There appears to be no clean way of figuring that
// out, so inspecting SymbolFlags that might be present that are type only
.filter(
sym =>
sym.flags & ts.SymbolFlags.Class ||
!(
sym.flags & ts.SymbolFlags.Interface ||
sym.flags & ts.SymbolFlags.TypeLiteral ||
sym.flags & ts.SymbolFlags.Signature ||
sym.flags & ts.SymbolFlags.TypeParameter ||
sym.flags & ts.SymbolFlags.TypeAlias ||
sym.flags & ts.SymbolFlags.Type ||
sym.flags & ts.SymbolFlags.Namespace ||
sym.flags & ts.SymbolFlags.InterfaceExcludes ||
sym.flags & ts.SymbolFlags.TypeParameterExcludes ||
sym.flags & ts.SymbolFlags.TypeAliasExcludes
)
)
.map(sym => sym.getName());
}