mirror of
https://github.com/zen-browser/pdf.js.git
synced 2025-07-09 01:35:43 +02:00
Replace the webpack+acorn transform with a Babel plugin
This commit converts the pdfjsdev-loader transform into a Babel plugin, to skip a AST->string->AST round-trip. Before this commit, the webpack build process was: 1. Babel parses the code 2. Babel transforms the AST 3. Babel generates the code 4. Acorn parses the code 5. pdfjsdev-loader transforms the AST 6. @javascript-obfuscator/escodegen generates the code 7. Webpack parses the file 8. Webpack concatenates the files After this commit, it is reduced to: 1. Babel parses the code 2. Babel transforms the AST 3. babel-plugin-pdfjs-preprocessor transforms the AST 4. Babel generates the code 5. Webpack parses the file 6. Webpack concatenates the files This change improves the build time by ~25% (tested on MacBook Air M2): - `gulp lib`: 3.4s to 2.6s - `gulp dist`: 36s to 29s - `gulp generic`: 5.5s to 4.0s - `gulp mozcentral`: 4.7s to 3.2s The new Babel plugin doesn't support the `saveComments` option of pdfjsdev-loader, and it just always discards comments. Even though pdfjsdev-loader supported multiple values for that option, it was effectively ignored due to `acorn` dropping comments by default.
This commit is contained in:
Nicolò Ribaudo
parent
f5bb9bc21b
commit
f724ae98a1
16 changed files with 287 additions and 479 deletions
464
external/builder/babel-plugin-pdfjs-preprocessor.mjs
vendored
464
external/builder/babel-plugin-pdfjs-preprocessor.mjs
vendored
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@ -1,347 +1,241 @@
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import * as acorn from "acorn";
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import escodegen from "@javascript-obfuscator/escodegen";
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import { types as t, transformSync } from "@babel/core";
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import fs from "fs";
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import path from "path";
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import { join as joinPaths } from "path";
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import vm from "vm";
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const PDFJS_PREPROCESSOR_NAME = "PDFJSDev";
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const ROOT_PREFIX = "$ROOT/";
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const ACORN_ECMA_VERSION = 2022;
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function isLiteral(obj, value) {
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return obj.type === "Literal" && obj.value === value;
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}
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function isPDFJSPreprocessor(obj) {
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return obj.type === "Identifier" && obj.name === PDFJS_PREPROCESSOR_NAME;
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}
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function evalWithDefines(code, defines, loc) {
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function evalWithDefines(code, defines) {
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if (!code || !code.trim()) {
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throw new Error("No JavaScript expression given");
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}
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return vm.runInNewContext(code, defines, { displayErrors: false });
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}
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function handlePreprocessorAction(ctx, actionName, args, loc) {
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function handlePreprocessorAction(ctx, actionName, args, path) {
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try {
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let arg;
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const arg = args[0];
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switch (actionName) {
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case "test":
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arg = args[0];
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if (!arg || arg.type !== "Literal" || typeof arg.value !== "string") {
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if (!t.isStringLiteral(arg)) {
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throw new Error("No code for testing is given");
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}
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const isTrue = !!evalWithDefines(arg.value, ctx.defines);
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return { type: "Literal", value: isTrue, loc };
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return !!evalWithDefines(arg.value, ctx.defines);
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case "eval":
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arg = args[0];
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if (!arg || arg.type !== "Literal" || typeof arg.value !== "string") {
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if (!t.isStringLiteral(arg)) {
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throw new Error("No code for eval is given");
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}
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const result = evalWithDefines(arg.value, ctx.defines);
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if (
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typeof result === "boolean" ||
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typeof result === "string" ||
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typeof result === "number"
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typeof result === "number" ||
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typeof result === "object"
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) {
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return { type: "Literal", value: result, loc };
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}
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if (typeof result === "object") {
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const parsedObj = acorn.parse("(" + JSON.stringify(result) + ")", {
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ecmaVersion: ACORN_ECMA_VERSION,
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});
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parsedObj.body[0].expression.loc = loc;
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return parsedObj.body[0].expression;
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return result;
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}
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break;
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case "json":
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arg = args[0];
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if (!arg || arg.type !== "Literal" || typeof arg.value !== "string") {
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if (!t.isStringLiteral(arg)) {
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throw new Error("Path to JSON is not provided");
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}
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let jsonPath = arg.value;
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if (jsonPath.indexOf(ROOT_PREFIX) === 0) {
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jsonPath = path.join(
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if (jsonPath.startsWith(ROOT_PREFIX)) {
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jsonPath = joinPaths(
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ctx.rootPath,
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jsonPath.substring(ROOT_PREFIX.length)
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);
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}
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const jsonContent = fs.readFileSync(jsonPath).toString();
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const parsedJSON = acorn.parse("(" + jsonContent + ")", {
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ecmaVersion: ACORN_ECMA_VERSION,
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});
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parsedJSON.body[0].expression.loc = loc;
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return parsedJSON.body[0].expression;
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return JSON.parse(fs.readFileSync(jsonPath, "utf8"));
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}
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throw new Error("Unsupported action");
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} catch (e) {
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throw new Error(
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throw path.buildCodeFrameError(
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"Could not process " +
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PDFJS_PREPROCESSOR_NAME +
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"." +
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actionName +
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" at " +
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JSON.stringify(loc) +
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"\n" +
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e.name +
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": " +
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e.message
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);
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}
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}
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function postprocessNode(ctx, node) {
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switch (node.type) {
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case "ExportNamedDeclaration":
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case "ImportDeclaration":
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if (
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node.source &&
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node.source.type === "Literal" &&
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ctx.map &&
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ctx.map[node.source.value]
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) {
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const newValue = ctx.map[node.source.value];
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node.source.value = node.source.raw = newValue;
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}
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break;
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case "IfStatement":
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if (isLiteral(node.test, true)) {
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// if (true) stmt1; => stmt1
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return node.consequent;
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} else if (isLiteral(node.test, false)) {
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// if (false) stmt1; else stmt2; => stmt2
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return node.alternate || { type: "EmptyStatement", loc: node.loc };
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}
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break;
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case "ConditionalExpression":
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if (isLiteral(node.test, true)) {
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// true ? stmt1 : stmt2 => stmt1
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return node.consequent;
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} else if (isLiteral(node.test, false)) {
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// false ? stmt1 : stmt2 => stmt2
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return node.alternate;
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}
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break;
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case "UnaryExpression":
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if (node.operator === "typeof" && isPDFJSPreprocessor(node.argument)) {
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// typeof PDFJSDev => 'object'
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return { type: "Literal", value: "object", loc: node.loc };
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}
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if (
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node.operator === "!" &&
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node.argument.type === "Literal" &&
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typeof node.argument.value === "boolean"
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) {
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// !true => false, !false => true
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return { type: "Literal", value: !node.argument.value, loc: node.loc };
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}
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break;
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case "LogicalExpression":
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switch (node.operator) {
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case "&&":
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if (isLiteral(node.left, true)) {
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return node.right;
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}
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if (isLiteral(node.left, false)) {
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return node.left;
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}
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break;
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case "||":
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if (isLiteral(node.left, true)) {
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return node.left;
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}
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if (isLiteral(node.left, false)) {
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return node.right;
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}
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break;
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}
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break;
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case "BinaryExpression":
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switch (node.operator) {
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case "==":
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case "===":
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case "!=":
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case "!==":
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if (
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node.left.type === "Literal" &&
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node.right.type === "Literal" &&
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typeof node.left.value === typeof node.right.value
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) {
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// folding two literals == and != check
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switch (typeof node.left.value) {
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case "string":
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case "boolean":
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case "number":
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const equal = node.left.value === node.right.value;
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return {
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type: "Literal",
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value: (node.operator[0] === "=") === equal,
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loc: node.loc,
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};
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}
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}
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break;
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}
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break;
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case "CallExpression":
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if (
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node.callee.type === "MemberExpression" &&
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isPDFJSPreprocessor(node.callee.object) &&
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node.callee.property.type === "Identifier"
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) {
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// PDFJSDev.xxxx(arg1, arg2, ...) => transform
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const action = node.callee.property.name;
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return handlePreprocessorAction(ctx, action, node.arguments, node.loc);
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}
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// require('string')
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if (
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node.callee.type === "Identifier" &&
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node.callee.name === "require" &&
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node.arguments.length === 1 &&
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node.arguments[0].type === "Literal" &&
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ctx.map &&
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ctx.map[node.arguments[0].value]
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) {
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const requireName = node.arguments[0];
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requireName.value = requireName.raw = ctx.map[requireName.value];
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}
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break;
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case "BlockStatement":
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let subExpressionIndex = 0;
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while (subExpressionIndex < node.body.length) {
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switch (node.body[subExpressionIndex].type) {
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case "EmptyStatement":
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// Removing empty statements from the blocks.
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node.body.splice(subExpressionIndex, 1);
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continue;
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case "BlockStatement":
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// Block statements inside a block are moved to the parent one.
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const subChildren = node.body[subExpressionIndex].body;
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Array.prototype.splice.apply(node.body, [
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subExpressionIndex,
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1,
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...subChildren,
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]);
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subExpressionIndex += Math.max(subChildren.length - 1, 0);
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continue;
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case "ReturnStatement":
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case "ThrowStatement":
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// Removing dead code after return or throw.
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node.body.splice(
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subExpressionIndex + 1,
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node.body.length - subExpressionIndex - 1
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function babelPluginPDFJSPreprocessor(babel, ctx) {
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return {
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name: "babel-plugin-pdfjs-preprocessor",
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manipulateOptions({ parserOpts }) {
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parserOpts.attachComment = false;
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},
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visitor: {
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"ExportNamedDeclaration|ImportDeclaration": ({ node }) => {
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if (node.source && ctx.map?.[node.source.value]) {
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node.source.value = ctx.map[node.source.value];
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}
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},
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"IfStatement|ConditionalExpression": {
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exit(path) {
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const { node } = path;
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if (t.isBooleanLiteral(node.test)) {
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// if (true) stmt1; => stmt1
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// if (false) stmt1; else stmt2; => stmt2
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path.replaceWith(
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node.test.value === true
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? node.consequent
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: node.alternate || t.emptyStatement()
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);
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break;
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}
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subExpressionIndex++;
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}
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break;
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case "FunctionDeclaration":
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case "FunctionExpression":
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const block = node.body;
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if (
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block.body.length > 0 &&
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block.body.at(-1).type === "ReturnStatement" &&
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!block.body.at(-1).argument
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) {
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// Function body ends with return without arg -- removing it.
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block.body.pop();
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}
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break;
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}
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return node;
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}
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function fixComments(ctx, node) {
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if (!ctx.saveComments) {
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return;
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}
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// Fixes double comments in the escodegen output.
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delete node.trailingComments;
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// Removes ESLint and other service comments.
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if (node.leadingComments) {
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const CopyrightRegExp = /\bcopyright\b/i;
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const BlockCommentRegExp = /^\s*(globals|eslint|falls through)\b/;
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const LineCommentRegExp = /^\s*eslint\b/;
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let i = 0;
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while (i < node.leadingComments.length) {
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const type = node.leadingComments[i].type;
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const value = node.leadingComments[i].value;
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|
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if (ctx.saveComments === "copyright") {
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// Remove all comments, except Copyright notices and License headers.
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if (!(type === "Block" && CopyrightRegExp.test(value))) {
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node.leadingComments.splice(i, 1);
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continue;
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}
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} else if (
|
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(type === "Block" && BlockCommentRegExp.test(value)) ||
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(type === "Line" && LineCommentRegExp.test(value))
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) {
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node.leadingComments.splice(i, 1);
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continue;
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}
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i++;
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}
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}
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}
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function traverseTree(ctx, node) {
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// generic node processing
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for (const i in node) {
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const child = node[i];
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if (typeof child === "object" && child !== null && child.type) {
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const result = traverseTree(ctx, child);
|
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if (result !== child) {
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node[i] = result;
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}
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} else if (Array.isArray(child)) {
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child.forEach(function (childItem, index) {
|
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if (
|
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typeof childItem === "object" &&
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childItem !== null &&
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childItem.type
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) {
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const result = traverseTree(ctx, childItem);
|
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if (result !== childItem) {
|
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child[index] = result;
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}
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},
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},
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UnaryExpression(path) {
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const { node } = path;
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if (node.operator === "typeof" && isPDFJSPreprocessor(node.argument)) {
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// typeof PDFJSDev => 'object'
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path.replaceWith(t.stringLiteral("object"));
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return;
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}
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});
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}
|
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}
|
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if (node.operator === "!" && t.isBooleanLiteral(node.argument)) {
|
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// !true => false, !false => true
|
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path.replaceWith(t.booleanLiteral(!node.argument.value));
|
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}
|
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},
|
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LogicalExpression: {
|
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exit(path) {
|
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const { node } = path;
|
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if (!t.isBooleanLiteral(node.left)) {
|
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return;
|
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}
|
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|
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node = postprocessNode(ctx, node) || node;
|
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switch (node.operator) {
|
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case "&&":
|
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// true && expr => expr
|
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// false && expr => false
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path.replaceWith(
|
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node.left.value === true ? node.right : node.left
|
||||
);
|
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break;
|
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case "||":
|
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// true || expr => true
|
||||
// false || expr => expr
|
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path.replaceWith(
|
||||
node.left.value === true ? node.left : node.right
|
||||
);
|
||||
break;
|
||||
}
|
||||
},
|
||||
},
|
||||
BinaryExpression: {
|
||||
exit(path) {
|
||||
const { node } = path;
|
||||
switch (node.operator) {
|
||||
case "==":
|
||||
case "===":
|
||||
case "!=":
|
||||
case "!==":
|
||||
if (t.isLiteral(node.left) && t.isLiteral(node.right)) {
|
||||
// folding == and != check that can be statically evaluated
|
||||
const { confident, value } = path.evaluate();
|
||||
if (confident) {
|
||||
path.replaceWith(t.booleanLiteral(value));
|
||||
}
|
||||
}
|
||||
}
|
||||
},
|
||||
},
|
||||
CallExpression(path) {
|
||||
const { node } = path;
|
||||
if (
|
||||
t.isMemberExpression(node.callee) &&
|
||||
isPDFJSPreprocessor(node.callee.object) &&
|
||||
t.isIdentifier(node.callee.property) &&
|
||||
!node.callee.computed
|
||||
) {
|
||||
// PDFJSDev.xxxx(arg1, arg2, ...) => transform
|
||||
const action = node.callee.property.name;
|
||||
const result = handlePreprocessorAction(
|
||||
ctx,
|
||||
action,
|
||||
node.arguments,
|
||||
path
|
||||
);
|
||||
path.replaceWith(t.inherits(t.valueToNode(result), path.node));
|
||||
}
|
||||
|
||||
fixComments(ctx, node);
|
||||
return node;
|
||||
}
|
||||
// require('string')
|
||||
if (
|
||||
t.isIdentifier(node.callee, { name: "require" }) &&
|
||||
node.arguments.length === 1 &&
|
||||
t.isStringLiteral(node.arguments[0]) &&
|
||||
ctx.map?.[node.arguments[0].value]
|
||||
) {
|
||||
const requireName = node.arguments[0];
|
||||
requireName.value = requireName.raw = ctx.map[requireName.value];
|
||||
}
|
||||
},
|
||||
BlockStatement: {
|
||||
// Visit node in post-order so that recursive flattening
|
||||
// of blocks works correctly.
|
||||
exit(path) {
|
||||
const { node } = path;
|
||||
|
||||
function preprocessPDFJSCode(ctx, code) {
|
||||
const format = ctx.format || {
|
||||
indent: {
|
||||
style: " ",
|
||||
let subExpressionIndex = 0;
|
||||
while (subExpressionIndex < node.body.length) {
|
||||
switch (node.body[subExpressionIndex].type) {
|
||||
case "EmptyStatement":
|
||||
// Removing empty statements from the blocks.
|
||||
node.body.splice(subExpressionIndex, 1);
|
||||
continue;
|
||||
case "BlockStatement":
|
||||
// Block statements inside a block are flattened
|
||||
// into the parent one.
|
||||
const subChildren = node.body[subExpressionIndex].body;
|
||||
node.body.splice(subExpressionIndex, 1, ...subChildren);
|
||||
subExpressionIndex += Math.max(subChildren.length - 1, 0);
|
||||
continue;
|
||||
case "ReturnStatement":
|
||||
case "ThrowStatement":
|
||||
// Removing dead code after return or throw.
|
||||
node.body.splice(
|
||||
subExpressionIndex + 1,
|
||||
node.body.length - subExpressionIndex - 1
|
||||
);
|
||||
break;
|
||||
}
|
||||
subExpressionIndex++;
|
||||
}
|
||||
},
|
||||
},
|
||||
Function: {
|
||||
exit(path) {
|
||||
if (!t.isBlockStatement(path.node.body)) {
|
||||
// Arrow function with expression body
|
||||
return;
|
||||
}
|
||||
|
||||
const { body } = path.node.body;
|
||||
if (
|
||||
body.length > 0 &&
|
||||
t.isReturnStatement(body.at(-1), { argument: null })
|
||||
) {
|
||||
// Function body ends with return without arg -- removing it.
|
||||
body.pop();
|
||||
}
|
||||
},
|
||||
},
|
||||
},
|
||||
};
|
||||
const parseOptions = {
|
||||
ecmaVersion: ACORN_ECMA_VERSION,
|
||||
locations: true,
|
||||
sourceFile: ctx.sourceFile,
|
||||
sourceType: "module",
|
||||
};
|
||||
const codegenOptions = {
|
||||
format,
|
||||
parse(input) {
|
||||
return acorn.parse(input, { ecmaVersion: ACORN_ECMA_VERSION });
|
||||
},
|
||||
sourceMap: ctx.sourceMap,
|
||||
sourceMapWithCode: ctx.sourceMap,
|
||||
};
|
||||
const syntax = acorn.parse(code, parseOptions);
|
||||
traverseTree(ctx, syntax);
|
||||
return escodegen.generate(syntax, codegenOptions);
|
||||
}
|
||||
|
||||
export { preprocessPDFJSCode };
|
||||
function preprocessPDFJSCode(ctx, content) {
|
||||
return transformSync(content, {
|
||||
configFile: false,
|
||||
plugins: [[babelPluginPDFJSPreprocessor, ctx]],
|
||||
}).code;
|
||||
}
|
||||
|
||||
export { babelPluginPDFJSPreprocessor, preprocessPDFJSCode };
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue