128 lines
6.7 KiB
JavaScript
128 lines
6.7 KiB
JavaScript
import fs from "fs/promises";
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import path from "path";
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// NOTE: this should be updated if this loader file is moved.
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const PACKAGE_ROOT = path.normalize(path.join(__dirname, "../../.."));
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const TEMPLATE_FOLDER = path.join(__dirname, "templates");
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const TEMPLATES_ESM_FOLDER = path.normalize(path.join(__dirname, "../../dist/esm/build/templates"));
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/**
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* Load the entrypoint file from the ESM directory and performs string
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* replacements of the template variables specified in the `replacements`
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* argument.
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*
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* For non-string replacements, the template should use the
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* `declare const ${key}: ${type}` syntax. to ensure that the type is correct
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* and the typescript can compile. You may have to use `@ts-expect-error` to
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* handle replacement values that are related to imports.
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*
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* @param entrypoint the entrypoint to load
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* @param replacements string replacements to perform
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* @param injections code injections to perform
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* @param imports optional imports to insert or set to null
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* @returns the loaded file with the replacements
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*/ export async function loadEntrypoint(entrypoint, replacements, injections, imports) {
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const filepath = path.resolve(path.join(TEMPLATES_ESM_FOLDER, `${entrypoint}.js`));
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let file = await fs.readFile(filepath, "utf8");
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// Update the relative imports to be absolute. This will update any relative
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// imports to be relative to the root of the `next` package.
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let count = 0;
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file = file.replaceAll(/from "(\..*)"|import "(\..*)"/g, function(_, fromRequest, importRequest) {
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count++;
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const relative = path.relative(PACKAGE_ROOT, path.resolve(TEMPLATE_FOLDER, fromRequest ?? importRequest))// Ensure that we use linux style path separators for node.
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.replace(/\\/g, "/");
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// Verify that the relative import is relative to the `next` package. This
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// will catch cases where the constants at the top of the file were not
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// updated after the file was moved.
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if (!relative.startsWith("next/")) {
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throw new Error(`Invariant: Expected relative import to start with "next/", found "${relative}"`);
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}
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return fromRequest ? `from ${JSON.stringify(relative)}` : `import ${JSON.stringify(relative)}`;
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});
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// Verify that at least one import was replaced. It's the case today where
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// every template file has at least one import to update, so this ensures that
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// we don't accidentally remove the import replacement code or use the wrong
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// template file.
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if (count === 0) {
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throw new Error("Invariant: Expected to replace at least one import");
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}
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const replaced = new Set();
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// Replace all the template variables with the actual values. If a template
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// variable is missing, throw an error.
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file = file.replaceAll(new RegExp(`${Object.keys(replacements).map((k)=>`"${k}"`).join("|")}`, "g"), (match)=>{
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const key = JSON.parse(match);
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if (!(key in replacements)) {
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throw new Error(`Invariant: Unexpected template variable ${key}`);
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}
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replaced.add(key);
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return JSON.stringify(replacements[key]);
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});
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// Check to see if there's any remaining template variables.
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let matches = file.match(/VAR_[A-Z_]+/g);
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if (matches) {
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throw new Error(`Invariant: Expected to replace all template variables, found ${matches.join(", ")}`);
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}
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// Check to see if any template variable was provided but not used.
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if (replaced.size !== Object.keys(replacements).length) {
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// Find the difference between the provided replacements and the replaced
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// template variables. This will let us notify the user of any template
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// variables that were not used but were provided.
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const difference = Object.keys(replacements).filter((key)=>!replaced.has(key));
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throw new Error(`Invariant: Expected to replace all template variables, missing ${difference.join(", ")} in template`);
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}
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// Replace the injections.
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const injected = new Set();
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if (injections) {
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// Track all the injections to ensure that we're not missing any.
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file = file.replaceAll(new RegExp(`// INJECT:(${Object.keys(injections).join("|")})`, "g"), (_, key)=>{
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if (!(key in injections)) {
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throw new Error(`Invariant: Unexpected injection ${key}`);
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}
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injected.add(key);
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return `const ${key} = ${injections[key]}`;
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});
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}
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// Check to see if there's any remaining injections.
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matches = file.match(/\/\/ INJECT:[A-Za-z0-9_]+/g);
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if (matches) {
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throw new Error(`Invariant: Expected to inject all injections, found ${matches.join(", ")}`);
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}
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// Check to see if any injection was provided but not used.
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if (injected.size !== Object.keys(injections ?? {}).length) {
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// Find the difference between the provided injections and the injected
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// injections. This will let us notify the user of any injections that were
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// not used but were provided.
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const difference = Object.keys(injections ?? {}).filter((key)=>!injected.has(key));
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throw new Error(`Invariant: Expected to inject all injections, missing ${difference.join(", ")} in template`);
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}
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// Replace the optional imports.
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const importsAdded = new Set();
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if (imports) {
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// Track all the imports to ensure that we're not missing any.
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file = file.replaceAll(new RegExp(`// OPTIONAL_IMPORT:(\\* as )?(${Object.keys(imports).join("|")})`, "g"), (_, asNamespace = "", key)=>{
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if (!(key in imports)) {
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throw new Error(`Invariant: Unexpected optional import ${key}`);
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}
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importsAdded.add(key);
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if (imports[key]) {
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return `import ${asNamespace}${key} from ${JSON.stringify(imports[key])}`;
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} else {
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return `const ${key} = null`;
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}
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});
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}
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// Check to see if there's any remaining imports.
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matches = file.match(/\/\/ OPTIONAL_IMPORT:(\* as )?[A-Za-z0-9_]+/g);
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if (matches) {
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throw new Error(`Invariant: Expected to inject all imports, found ${matches.join(", ")}`);
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}
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// Check to see if any import was provided but not used.
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if (importsAdded.size !== Object.keys(imports ?? {}).length) {
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// Find the difference between the provided imports and the injected
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// imports. This will let us notify the user of any imports that were
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// not used but were provided.
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const difference = Object.keys(imports ?? {}).filter((key)=>!importsAdded.has(key));
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throw new Error(`Invariant: Expected to inject all imports, missing ${difference.join(", ")} in template`);
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}
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return file;
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}
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//# sourceMappingURL=load-entrypoint.js.map
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