138 lines
4.2 KiB
TypeScript
138 lines
4.2 KiB
TypeScript
import * as t from "@babel/types";
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import type { TemplateReplacements } from "./options";
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import type { Metadata, Placeholder } from "./parse";
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export default function populatePlaceholders(
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metadata: Metadata,
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replacements: TemplateReplacements,
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): t.File {
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const ast = t.cloneNode(metadata.ast);
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if (replacements) {
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metadata.placeholders.forEach(placeholder => {
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if (
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!Object.prototype.hasOwnProperty.call(replacements, placeholder.name)
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) {
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const placeholderName = placeholder.name;
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throw new Error(
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`Error: No substitution given for "${placeholderName}". If this is not meant to be a
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placeholder you may want to consider passing one of the following options to @babel/template:
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- { placeholderPattern: false, placeholderWhitelist: new Set(['${placeholderName}'])}
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- { placeholderPattern: /^${placeholderName}$/ }`,
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);
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}
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});
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Object.keys(replacements).forEach(key => {
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if (!metadata.placeholderNames.has(key)) {
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throw new Error(`Unknown substitution "${key}" given`);
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}
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});
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}
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// Process in reverse order so AST mutation doesn't change indices that
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// will be needed for later calls to `placeholder.resolve()`.
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metadata.placeholders
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.slice()
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.reverse()
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.forEach(placeholder => {
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try {
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applyReplacement(
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placeholder,
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ast,
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(replacements && replacements[placeholder.name]) || null,
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);
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} catch (e) {
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e.message = `@babel/template placeholder "${placeholder.name}": ${e.message}`;
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throw e;
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}
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});
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return ast;
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}
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function applyReplacement(
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placeholder: Placeholder,
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ast: t.File,
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replacement: any,
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) {
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// Track inserted nodes and clone them if they are inserted more than
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// once to avoid injecting the same node multiple times.
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if (placeholder.isDuplicate) {
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if (Array.isArray(replacement)) {
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replacement = replacement.map(node => t.cloneNode(node));
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} else if (typeof replacement === "object") {
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replacement = t.cloneNode(replacement);
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}
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}
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const { parent, key, index } = placeholder.resolve(ast);
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if (placeholder.type === "string") {
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if (typeof replacement === "string") {
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replacement = t.stringLiteral(replacement);
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}
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if (!replacement || !t.isStringLiteral(replacement)) {
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throw new Error("Expected string substitution");
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}
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} else if (placeholder.type === "statement") {
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if (index === undefined) {
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if (!replacement) {
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replacement = t.emptyStatement();
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} else if (Array.isArray(replacement)) {
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replacement = t.blockStatement(replacement);
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} else if (typeof replacement === "string") {
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replacement = t.expressionStatement(t.identifier(replacement));
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} else if (!t.isStatement(replacement)) {
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replacement = t.expressionStatement(replacement as any);
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}
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} else {
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if (replacement && !Array.isArray(replacement)) {
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if (typeof replacement === "string") {
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replacement = t.identifier(replacement);
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}
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if (!t.isStatement(replacement)) {
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replacement = t.expressionStatement(replacement as any);
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}
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}
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}
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} else if (placeholder.type === "param") {
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if (typeof replacement === "string") {
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replacement = t.identifier(replacement);
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}
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if (index === undefined) throw new Error("Assertion failure.");
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} else {
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if (typeof replacement === "string") {
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replacement = t.identifier(replacement);
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}
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if (Array.isArray(replacement)) {
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throw new Error("Cannot replace single expression with an array.");
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}
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}
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if (index === undefined) {
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t.validate(parent, key, replacement);
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(parent as any)[key] = replacement;
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} else {
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const items: Array<t.Node> = (parent as any)[key].slice();
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if (placeholder.type === "statement" || placeholder.type === "param") {
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if (replacement == null) {
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items.splice(index, 1);
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} else if (Array.isArray(replacement)) {
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items.splice(index, 1, ...replacement);
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} else {
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items[index] = replacement;
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}
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} else {
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items[index] = replacement;
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}
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t.validate(parent, key, items);
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(parent as any)[key] = items;
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}
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}
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