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Merge pull request #10 from Polymer/ns-reexport
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Support namespace member re-exporting, excluding references, and cleanups
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@justinfagnani
justinfagnani authored Jun 2, 2017
2 parents 1392a53 + 5df7050 commit 86f5c9b
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Showing 2 changed files with 217 additions and 42 deletions.
207 changes: 171 additions & 36 deletions src/html2js.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -50,9 +50,26 @@ export interface JsExport {
}

export interface JsModule {
/**
* Package-relative URL of the converted JS module.
*/
url: string;

/**
* Converted source of the JS module.
*/
source: string;

/**
* Set of exported names.
*/
exports: Set<string>;

/**
* Map of module URL (ie, polymer-element.js) to imported references
* (ie, Element). This map is used to rewrite import statements to
* only include what's used in an importing module.
*/
importedReferences: Map<string, Set<string>>;
}

Expand All @@ -66,7 +83,8 @@ export interface ModuleIndex {
modules: Map<string, JsModule>;

/**
* Map of namespaced id to module URL + exported name
* Map of namespaced id (ie, Polymer.Element) to module URL
* (ie, polymeer-element.js) + exported name (ie, Element).
*/
namespacedExports: Map<string, JsExport>;
}
Expand All @@ -87,29 +105,60 @@ export async function convertPackage() {
}

const analysis = await analyzer.analyzePackage();
// TODO(justinfagnani): These setting are only good for Polymer core and should be
// extracted into a config file
const converter = new AnalysisConverter(analysis, {
excludes: ['lib/utils/boot.html'],
excludes: [
'lib/utils/boot.html',
'lib/elements/dom-module.html',
],
referenceExcludes: ['Polymer.DomModule'],
});
const results = await converter.convert();
for (const [jsUrl, newSource] of results) {
const outPath = path.resolve(outDir, jsUrl);
const jsDir = path.dirname(outPath);
// console.log(`writing ${outPath}`);
mkdirp.sync(jsDir);
// console.log(`created dir ${jsDir}`);
await fs.writeFile(outPath, newSource);

try {
const results = await converter.convert();
for (const [jsUrl, newSource] of results!) {
const outPath = path.resolve(outDir, jsUrl);
const jsDir = path.dirname(outPath);
// console.log(`writing ${outPath}`);
mkdirp.sync(jsDir);
// console.log(`created dir ${jsDir}`);
await fs.writeFile(outPath, newSource);
}
} catch (e) {
console.log('error in conversion');
console.error(e);
}
}

interface AnalysisConverterOptions {
/**
* Files to exclude from conversion (ie lib/utils/boot.html). Imports
* to these files are also excluded.
*/
excludes?: string[];

/**
* Namespace references (ie, Polymer.DomModule) to "exclude"" be replacing
* the entire reference with `undefined`.
*
* These references would normally be rewritten to module imports, but in some
* cases they are accessed without importing. The presumption is that access
* is guarded by a conditional and replcing with `undefined` will safely
* fail the guard.
*/
referenceExcludes?: string[];
}

/**
* Converts an entire Analysis object.
*/
export class AnalysisConverter {

analysis: Analysis;
options: AnalysisConverterOptions;
_excludes: Set<string>;
_referenceExcludes: Set<string>;

modules = new Map<string, JsModule>();
namespacedExports = new Map<string, JsExport>();
Expand All @@ -118,6 +167,7 @@ export class AnalysisConverter {
this.analysis = analysis;
this.options = options || {};
this._excludes = new Set(this.options.excludes);
this._referenceExcludes = new Set(this.options.referenceExcludes);
}

async convert(): Promise<Map<string, string>> {
Expand Down Expand Up @@ -162,6 +212,9 @@ export class AnalysisConverter {
}
}

/**
* Converts a Document and its dependencies.
*/
class DocumentConverter {

jsUrl: string;
Expand All @@ -188,6 +241,8 @@ class DocumentConverter {
if (scripts.size === 0) {
this.program = jsc.program([]);
} else if (scripts.size > 1) {
// TODO(justinfagnani): better warning wording, plus actionable reccomendation or
// decide on some default handling of multiple scripts.
console.log('multiple scripts');
return;
} else {
Expand All @@ -197,11 +252,21 @@ class DocumentConverter {
}
}

/**
* Returns the HTML Imports of a document, except imports to documents
* specifically excluded in the AnalysisConverter.
*
* Note: Imports that are not found are not returned by the analyzer.
*/
getHtmlImports() {
return Array.from(this.document.getFeatures({kind: 'html-import'}))
.filter((f: Import) => !this.analysisConverter._excludes.has(f.url));
}

/**
* Adds an export to this module's metadata and to the AnalysisConverter's
* namespacedExports index.
*/
addExport(namespaceName: string, name: string) {
this.module.exports.add(name);
this.analysisConverter.namespacedExports.set(namespaceName, {
Expand All @@ -216,7 +281,10 @@ class DocumentConverter {
this.rewriteNamespacedReferences();
this.addJsImports();

// Replace namespace assignments with exports
let localNamespaceName: string|undefined;

// Walk through all top-level statements and replace namespace assignments
// with module exports.
while (this.currentStatementIndex < this.program.body.length) {
const statement = this.program.body[this.currentStatementIndex] as Statement;
const exported = getExport(statement, 'Polymer');
Expand All @@ -230,7 +298,7 @@ class DocumentConverter {
} else if (value.type === 'Identifier') {
// An 'export' of the form:
// Polymer.Foo = Foo;
// TODO: generalize to handle namespaces and other declarations
// TODO(justinfagnani): generalize to handle namespaces and other declarations
const localName = value as Identifier;

const features = this.document.getFeatures({id: namespaceName});
Expand Down Expand Up @@ -260,24 +328,47 @@ class DocumentConverter {
this.currentStatementIndex--;
} else {
// Not a namespace, fallback to a named export
// We could probably do better for referenced declarations
// We could probably do better for referenced declarations, ie move the export
// to the declaration
const exportedName = jsc.identifier(namespace[namespace.length - 1]) as Identifier;
this.program.body[this.currentStatementIndex] = jsc.exportNamedDeclaration(
null, // declaration
[jsc.exportSpecifier(localName, exportedName)]);
this.addExport(namespaceName, exportedName.name);
}
} else if (isDeclaration(value)) {
// TODO (justinfagnani): remove this case? Is it used?
// TODO (justinfagnani): remove this case? Is it used? Add a test
this.program.body[this.currentStatementIndex] = jsc.exportDeclaration(
false, // default
value);
} else {
const name = namespace[namespace.length - 1];
this.program.body[this.currentStatementIndex] = jsc.exportNamedDeclaration(
jsc.variableDeclaration(
'const',
[jsc.variableDeclarator(jsc.identifier(name), value)]
));
this.addExport(namespaceName, name);
}
} else if (this.isNamespace(statement) && statement.type === 'VariableDeclaration') {
// Local namespace declaration, like:
// /** @namespace */ const Foo = {};
// Set the localNamespacename so we can rewrite internal references
const declarator = statement.declarations[0];
if (declarator.id.type === 'Identifier') {
localNamespaceName = declarator.id.name;
}
} else if (localNamespaceName) {
const namespaceAssignment = getExport(statement, localNamespaceName);

if (namespaceAssignment !== undefined) {
const {namespace, value} = namespaceAssignment;
const name = namespace[namespace.length - 1];
const namespaceName = namespace.join('.');

this.program.body[this.currentStatementIndex] = jsc.exportNamedDeclaration(
jsc.variableDeclaration(
'let',
'const',
[jsc.variableDeclarator(jsc.identifier(name), value)]
));
this.addExport(namespaceName, name);
Expand All @@ -286,6 +377,8 @@ class DocumentConverter {
this.currentStatementIndex++;
}

this.rewriteLocalNamespacedReferences(localNamespaceName);

this.module.source = escodegen.generate(this.program, {
comment: true,
format: {
Expand All @@ -298,8 +391,10 @@ class DocumentConverter {
}) + '\n';
}

/**
* Convert dependencies first, so we know what exports they have.
*/
convertDependencies() {
// DFS to convert dependencies, so we know what exports they have
const htmlImports = this.getHtmlImports();
for (const htmlImport of htmlImports) {
const jsUrl = htmlUrlToJs(htmlImport.url, this.document.url);
Expand Down Expand Up @@ -327,23 +422,28 @@ class DocumentConverter {
const memberPath = getMemberPath(path.node);
if (memberPath) {
const memberName = memberPath.join('.');
const moduleExport = analysisConverter.namespacedExports.get(memberName);
if (moduleExport) {
// Store the imported reference to we can add it to the import statement
const moduleJsUrl = htmlUrlToJs(moduleExport.url, baseUrl);
let moduleImportedNames = importedReferences.get(moduleJsUrl);
if (moduleImportedNames === undefined) {
moduleImportedNames = new Set<string>();
importedReferences.set(moduleJsUrl, moduleImportedNames);
}
moduleImportedNames.add(moduleExport.name);

// replace the member expression
if (moduleExport.name === '*') {
const jsModule = analysisConverter.modules.get(moduleExport.url)!;
path.replace(jsc.identifier(getModuleId(jsModule.url)));
} else {
path.replace(jsc.identifier(moduleExport.name));
if (analysisConverter._referenceExcludes.has(memberName)) {
path.replace(jsc.identifier('undefined'));
} else {
const moduleExport = analysisConverter.namespacedExports.get(memberName);
if (moduleExport) {
// Store the imported reference to we can add it to the import statement
const moduleJsUrl = htmlUrlToJs(moduleExport.url, baseUrl);
let moduleImportedNames = importedReferences.get(moduleJsUrl);
if (moduleImportedNames === undefined) {
moduleImportedNames = new Set<string>();
importedReferences.set(moduleJsUrl, moduleImportedNames);
}
moduleImportedNames.add(moduleExport.name);

// replace the member expression
if (moduleExport.name === '*') {
const jsModule = analysisConverter.modules.get(moduleExport.url)!;
path.replace(jsc.identifier(getModuleId(jsModule.url)));
} else {
path.replace(jsc.identifier(moduleExport.name));
}
}
}
}
Expand All @@ -352,6 +452,38 @@ class DocumentConverter {
});
}

/**
* Rewrites local references to a namespace member, ie:
*
* const NS = {
* foo() {}
* }
* NS.foo();
*
* to:
*
* export foo() {}
* foo();
*/
rewriteLocalNamespacedReferences(localNamespaceName?: string) {
if (localNamespaceName === undefined) {
return;
}
astTypes.visit(this.program, {
visitMemberExpression(path: any) {
const memberPath = getMemberPath(path.node);
if (memberPath && memberPath[0] === localNamespaceName) {
path.replace(path.node.property);
}
// do not visit rest of member expression
return false;
}
});
}

/**
* Injects JS imports at the top of the program.
*/
addJsImports() {
const htmlImports = this.getHtmlImports();
const baseUrl = this.document.url;
Expand Down Expand Up @@ -417,7 +549,7 @@ class DocumentConverter {

// Replace original namespace statement with new exports
const nsIndex = this.program.body.indexOf(statement);
this.program.body.splice(nsIndex, 1, ...exports.map((e) => e.node));
this.program.body.splice(nsIndex, 1, ...exports.map((e) => e.node as Statement));
this.currentStatementIndex += exports.length - 1;

exports.forEach((e) => {
Expand All @@ -441,6 +573,9 @@ class DocumentConverter {

}

/**
* Returns export declarations for each of a namespace objects members.
*/
function getNamespaceExports(namespace: ObjectExpression) {
const exports: {name: string, node: Node}[] = [];

Expand All @@ -451,7 +586,7 @@ function getNamespaceExports(namespace: ObjectExpression) {
name,
node: jsc.exportNamedDeclaration(
jsc.variableDeclaration(
'let',
'const',
[jsc.variableDeclarator(key, value)]))
});
} else if (value.type === 'FunctionExpression') {
Expand All @@ -465,13 +600,13 @@ function getNamespaceExports(namespace: ObjectExpression) {
func.body,
func.generator
))
})
});
} else if (value.type === 'ArrowFunctionExpression') {
exports.push({
name,
node: jsc.exportNamedDeclaration(
jsc.variableDeclaration(
'let',
'const',
[jsc.variableDeclarator(key, value)]
))
});
Expand Down
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