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denoland-deno/js/type_directives.ts
2019-08-22 12:05:01 -04:00

87 lines
2.5 KiB
TypeScript

// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
interface DirectiveInfo {
path: string;
start: number;
end: number;
}
/** Remap the module name based on any supplied type directives passed. */
export function getMappedModuleName(
moduleName: string,
containingFile: string,
typeDirectives?: Record<string, string>
): string {
if (containingFile.endsWith(".d.ts") && !moduleName.endsWith(".d.ts")) {
moduleName = `${moduleName}.d.ts`;
}
if (!typeDirectives) {
return moduleName;
}
if (moduleName in typeDirectives) {
return typeDirectives[moduleName];
}
return moduleName;
}
/** Matches directives that look something like this and parses out the value
* of the directive:
*
* // @deno-types="./foo.d.ts"
*
* [See Diagram](http://bit.ly/31nZPCF)
*/
const typeDirectiveRegEx = /@deno-types\s*=\s*(["'])((?:(?=(\\?))\3.)*?)\1/gi;
/** Matches `import` or `export from` statements and parses out the value of the
* module specifier in the second capture group:
*
* import * as foo from "./foo.js"
* export { a, b, c } from "./bar.js"
*
* [See Diagram](http://bit.ly/2GSkJlF)
*/
const importExportRegEx = /(?:import|export)\s+[\s\S]*?from\s+(["'])((?:(?=(\\?))\3.)*?)\1/;
/** Parses out any Deno type directives that are part of the source code, or
* returns `undefined` if there are not any.
*/
export function parseTypeDirectives(
sourceCode: string | undefined
): Record<string, string> | undefined {
if (!sourceCode) {
return;
}
// collect all the directives in the file and their start and end positions
const directives: DirectiveInfo[] = [];
let maybeMatch: RegExpExecArray | null = null;
while ((maybeMatch = typeDirectiveRegEx.exec(sourceCode))) {
const [matchString, , path] = maybeMatch;
const { index: start } = maybeMatch;
directives.push({
path,
start,
end: start + matchString.length
});
}
if (!directives.length) {
return;
}
// work from the last directive backwards for the next `import`/`export`
// statement
directives.reverse();
const directiveRecords: Record<string, string> = {};
for (const { path, start, end } of directives) {
const searchString = sourceCode.substring(end);
const maybeMatch = importExportRegEx.exec(searchString);
if (maybeMatch) {
const [, , fromPath] = maybeMatch;
directiveRecords[fromPath] = path;
}
sourceCode = sourceCode.substring(0, start);
}
return directiveRecords;
}