377 lines
13 KiB
JavaScript
377 lines
13 KiB
JavaScript
'use strict';
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var acorn = require('acorn');
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var escodegen = require('escodegen');
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var vm = require('vm');
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var fs = require('fs');
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var path = require('path');
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var PDFJS_PREPROCESSOR_NAME = 'PDFJSDev';
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var ROOT_PREFIX = '$ROOT/';
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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' &&
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obj.name === PDFJS_PREPROCESSOR_NAME;
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}
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function evalWithDefines(code, defines, loc) {
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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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try {
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var arg;
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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' ||
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typeof arg.value !== 'string') {
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throw new Error('No code for testing is given');
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}
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var isTrue = !!evalWithDefines(arg.value, ctx.defines);
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return {type: 'Literal', value: isTrue, loc: loc};
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case 'eval':
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arg = args[0];
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if (!arg || arg.type !== 'Literal' ||
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typeof arg.value !== 'string') {
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throw new Error('No code for eval is given');
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}
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var result = evalWithDefines(arg.value, ctx.defines);
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if (typeof result === 'boolean' || typeof result === 'string' ||
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typeof result === 'number') {
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return {type: 'Literal', value: result, loc: loc};
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}
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if (typeof result === 'object') {
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var parsedObj = acorn.parse('(' + JSON.stringify(result) + ')');
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parsedObj.body[0].expression.loc = loc;
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return parsedObj.body[0].expression;
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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' ||
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typeof arg.value !== 'string') {
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throw new Error('Path to JSON is not provided');
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}
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var jsonPath = arg.value;
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if (jsonPath.indexOf(ROOT_PREFIX) === 0) {
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jsonPath = path.join(ctx.rootPath,
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jsonPath.substring(ROOT_PREFIX.length));
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}
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var jsonContent = fs.readFileSync(jsonPath).toString();
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var parsedJSON = acorn.parse('(' + jsonContent + ')');
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parsedJSON.body[0].expression.loc = loc;
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return parsedJSON.body[0].expression;
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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('Could not process ' + PDFJS_PREPROCESSOR_NAME + '.' +
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actionName + ' at ' + JSON.stringify(loc) + '\n' +
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e.name + ': ' + e.message);
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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 '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' &&
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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 (node.operator === '!' &&
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node.argument.type === 'Literal' &&
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typeof node.argument.value === 'boolean') {
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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 (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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// 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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var 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 (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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// PDFJSDev.xxxx(arg1, arg2, ...) => tranform
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var action = node.callee.property.name;
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return handlePreprocessorAction(ctx, action,
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node.arguments, node.loc);
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}
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break;
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case 'BlockStatement':
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var 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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var subChildren = node.body[subExpressionIndex].body;
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Array.prototype.splice.apply(node.body,
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[subExpressionIndex, 1].concat(subChildren));
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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(subExpressionIndex + 1,
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node.body.length - subExpressionIndex - 1);
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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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var block = node.body;
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if (block.body.length > 0 &&
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block.body[block.body.length - 1].type === 'ReturnStatement' &&
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!block.body[block.body.length - 1].argument) {
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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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case 'Program':
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// Checking for a function closure that looks like UMD header.
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node.body.some(function (item, index) {
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// Is it `(function (root, factory) { ? }(this, function (?) {?}));` ?
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if (item.type !== 'ExpressionStatement' ||
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item.expression.type !== 'CallExpression' ||
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item.expression.callee.type !== 'FunctionExpression' ||
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item.expression.callee.params.length !== 2 ||
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item.expression.arguments.length !== 2 ||
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item.expression.arguments[0].type !== 'ThisExpression' ||
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item.expression.arguments[1].type !== 'FunctionExpression') {
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return false;
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}
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var init = item.expression.callee;
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// Is init body looks like
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// `if (?) { ? } else if (typeof exports !== 'undefined') { ? } ...`?
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if (init.body.type !== 'BlockStatement' ||
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init.body.body.length !== 1 ||
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init.body.body[0].type !== 'IfStatement') {
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return false;
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}
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var initIf = init.body.body[0];
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if (initIf.alternate.type !== 'IfStatement' ||
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initIf.alternate.test.type !== 'BinaryExpression' ||
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initIf.alternate.test.operator !== '!==' ||
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initIf.alternate.test.left.type !== 'UnaryExpression' ||
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initIf.alternate.test.left.operator !== 'typeof' ||
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initIf.alternate.test.left.argument.type !== 'Identifier' ||
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initIf.alternate.test.left.argument.name !== 'exports' ||
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initIf.alternate.test.right.type !== 'Literal' ||
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initIf.alternate.test.right.value !== 'undefined' ||
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initIf.alternate.consequent.type !== 'BlockStatement') {
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return false;
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}
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var commonJsInit = initIf.alternate.consequent;
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// Is commonJsInit `factory(exports, ...)` ?
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if (commonJsInit.body.length !== 1 ||
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commonJsInit.body[0].type !== 'ExpressionStatement' ||
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commonJsInit.body[0].expression.type !== 'CallExpression' ||
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commonJsInit.body[0].expression.callee.type !== 'Identifier') {
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return false;
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}
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var commonJsInitArgs = commonJsInit.body[0].expression.arguments;
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if (commonJsInitArgs.length === 0 ||
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commonJsInitArgs[0].type !== 'Identifier' ||
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commonJsInitArgs[0].name !== 'exports') {
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return false;
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}
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var factory = item.expression.arguments[1];
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// Is factory `function (exports, ....) { ? }` ?
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if (factory.params.length === 0 ||
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factory.params[0].type !== 'Identifier' ||
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factory.params[0].name !== 'exports' ||
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factory.body.type !== 'BlockStatement') {
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return true;
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}
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var factoryParams = factory.params;
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var factoryBody = factory.body;
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// Remove closure and function and replacing parameters with vars.
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node.body.splice(index, 1);
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for (var i = 1, ii = factoryParams.length; i < ii; i++) {
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var varNode = {
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type: 'VariableDeclaration',
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'declarations': [{
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type: 'VariableDeclarator',
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id: factoryParams[i],
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init: commonJsInitArgs[i] || null,
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loc: factoryParams[i].loc
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}],
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kind: 'var'
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};
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node.body.splice(index++, 0, varNode);
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}
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factoryBody.body.forEach(function (item) {
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node.body.splice(index++, 0, item);
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});
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return true;
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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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var CopyrightRegExp = /\bcopyright\b/i;
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var BlockCommentRegExp = /^\s*(globals|eslint|falls through)\b/;
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var LineCommentRegExp = /^\s*eslint\b/;
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var i = 0;
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while (i < node.leadingComments.length) {
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var type = node.leadingComments[i].type;
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var value = node.leadingComments[i].value;
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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 ((type === 'Block' && BlockCommentRegExp.test(value)) ||
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(type === 'Line' && LineCommentRegExp.test(value))) {
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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 (var i in node) {
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var child = node[i];
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if (typeof child === 'object' && child !== null && child.type) {
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var 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 (typeof childItem === 'object' && childItem !== null &&
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childItem.type) {
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var 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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}
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}
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node = postprocessNode(ctx, node) || node;
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fixComments(ctx, node);
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return node;
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}
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function preprocessPDFJSCode(ctx, code) {
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var saveComments = !!ctx.saveComments;
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var format = ctx.format || {
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indent: {
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style: ' ',
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adjustMultilineComment: saveComments,
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}
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};
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var comments;
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var parseComment = {
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locations: true,
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onComments: saveComments || (comments = []),
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sourceType: 'module',
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};
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var codegenOptions = {
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format: format,
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comment: saveComments,
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parse: acorn.parse,
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};
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var syntax = acorn.parse(code, parseComment);
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if (saveComments) {
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escodegen.attachComments(syntax, comments);
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}
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traverseTree(ctx, syntax);
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return escodegen.generate(syntax, codegenOptions);
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}
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exports.preprocessPDFJSCode = preprocessPDFJSCode;
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