Adds esprima-based preprocessor.

external/builder/preprocessor2.js

@@ -0,0 +1,266 @@
+/* jshint node:true */
+
+'use strict';
+
+var esprima = require('esprima');
+var escodegen = require('escodegen');
+var vm = require('vm');
+var fs = require('fs');
+var path = require('path');
+
+var PDFJS_PREPROCESSOR_NAME = 'PDFJSDev';
+var ROOT_PREFIX = '$ROOT/';
+
+function isLiteral(obj, value) {
+  return obj.type === 'Literal' && obj.value === value;
+}
+
+function isPDFJSPreprocessor(obj) {
+  return obj.type === 'Identifier' &&
+         obj.name === PDFJS_PREPROCESSOR_NAME;
+}
+
+function evalWithDefines(code, defines, loc) {
+  if (!code || !code.trim()) {
+    throw new Error('No JavaScript expression given');
+  }
+  return vm.runInNewContext(code, defines, {displayErrors: false});
+}
+
+function handlePreprocessorAction(ctx, actionName, args, loc) {
+  try {
+    var arg;
+    switch (actionName) {
+      case 'test':
+        arg = args[0];
+        if (!arg || arg.type !== 'Literal' ||
+            typeof arg.value !== 'string') {
+          throw new Error('No code for testing is given');
+        }
+        var isTrue = !!evalWithDefines(arg.value, ctx.defines);
+        return {type: 'Literal', value: isTrue, loc: loc};
+      case 'eval':
+        arg = args[0];
+        if (!arg || arg.type !== 'Literal' ||
+            typeof arg.value !== 'string') {
+          throw new Error('No code for eval is given');
+        }
+        var result = evalWithDefines(arg.value, ctx.defines);
+        if (typeof result === 'boolean' || typeof result === 'string' ||
+            typeof result === 'number') {
+          return {type: 'Literal', value: result, loc: loc};
+        }
+        if (typeof result === 'object') {
+          var parsedObj = esprima.parse('(' + JSON.stringify(result) + ')');
+          parsedObj.body[0].expression.loc = loc;
+          return parsedObj.body[0].expression;
+        }
+        break;
+      case 'json':
+        arg = args[0];
+        if (!arg || arg.type !== 'Literal' ||
+            typeof arg.value !== 'string') {
+          throw new Error('Path to JSON is not provided');
+        }
+        var jsonPath = arg.value;
+        if (jsonPath.indexOf(ROOT_PREFIX) === 0) {
+          jsonPath = path.join(ctx.rootPath,
+                               jsonPath.substring(ROOT_PREFIX.length));
+        }
+        var jsonContent = fs.readFileSync(jsonPath).toString();
+        var parsedJSON = esprima.parse('(' +jsonContent + ')');
+        parsedJSON.body[0].expression.loc = loc;
+        return parsedJSON.body[0].expression;
+    }
+    throw new Error('Unsupported action');
+  } catch (e) {
+    throw new Error('Could not process ' + PDFJS_PREPROCESSOR_NAME + '.' +
+                    actionName + ' at ' + JSON.stringify(loc) + '\n' +
+                    e.name + ': ' + e.message);
+  }
+}
+
+function postprocessNode(ctx, node) {
+  switch (node.type) {
+    case 'IfStatement':
+      if (isLiteral(node.test, true)) {
+        // if (true) stmt1; => stmt1
+        return node.consequent;
+      } else if (isLiteral(node.test, false)) {
+        // if (false) stmt1; else stmt2; => stmt2
+        return node.alternate || {type: 'EmptyStatement', loc: node.loc};
+      }
+      break;
+    case 'ConditionalExpression':
+      if (isLiteral(node.test, true)) {
+        // true ? stmt1 : stmt2 => stmt1
+        return node.consequent;
+      } else if (isLiteral(node.test, false)) {
+        // false ? stmt1 : stmt2 => stmt2
+        return node.alternate;
+      }
+      break;
+    case 'UnaryExpression':
+      if (node.operator === 'typeof' &&
+          isPDFJSPreprocessor(node.argument)) {
+        // typeof PDFJSDev => 'object'
+        return {type: 'Literal', value: 'object', loc: node.loc};
+      }
+      if (node.operator === '!' &&
+          node.argument.type === 'Literal' &&
+          typeof node.argument.value === 'boolean') {
+        // !true => false,  !false => true
+        return {type: 'Literal', value: !node.argument.value, loc: node.loc};
+      }
+      break;
+    case 'LogicalExpression':
+      switch (node.operator) {
+        case '&&':
+          if (isLiteral(node.left, true)) {
+            return node.right;
+          }
+          if (isLiteral(node.left, false)) {
+            return node.left;
+          }
+          break;
+        case '||':
+          if (isLiteral(node.left, true)) {
+            return node.left;
+          }
+          if (isLiteral(node.left, false)) {
+            return node.right;
+          }
+          break;
+      }
+      break;
+    case 'BinaryExpression':
+      switch (node.operator) {
+        case '==':
+        case '===':
+        case '!=':
+        case '!==':
+          if (node.left.type === 'Literal' &&
+              node.right.type === 'Literal' &&
+              typeof node.left.value === typeof node.right.value) {
+             // folding two literals == and != check
+             switch (typeof node.left.value) {
+               case 'string':
+               case 'boolean':
+               case 'number':
+                 var equal = node.left.value === node.right.value;
+                 return {
+                   type: 'Literal',
+                   value: (node.operator[0] === '=') === equal,
+                   loc: node.loc
+                 };
+             }
+          }
+          break;
+      }
+      break;
+    case 'CallExpression':
+      if (node.callee.type === 'MemberExpression' &&
+          isPDFJSPreprocessor(node.callee.object) &&
+          node.callee.property.type === 'Identifier') {
+        // PDFJSDev.xxxx(arg1, arg2, ...) => tranform
+        var action = node.callee.property.name;
+        return handlePreprocessorAction(ctx, action,
+                                        node.arguments, node.loc);
+      }
+      break;
+    case 'BlockStatement':
+      var subExpressionIndex = 0;
+      while (subExpressionIndex < node.body.length) {
+        if (node.body[subExpressionIndex].type === 'EmptyStatement') {
+          // Removing empty statements from the blocks.
+          node.body.splice(subExpressionIndex, 1);
+          continue;
+        }
+        if (node.body[subExpressionIndex].type === 'BlockStatement') {
+          // Block statements inside a block are moved to the parent one.
+          var subChildren = node.body[subExpressionIndex].body;
+          Array.prototype.splice.apply(node.body,
+            [subExpressionIndex, 1].concat(subChildren));
+          subExpressionIndex += subChildren.length;
+          continue;
+        }
+        subExpressionIndex++;
+      }
+      break;
+  }
+  return node;
+}
+
+function fixComments(ctx, node) {
+  if (!ctx.saveComments) {
+    return;
+  }
+  // Fixes double comments in the escodegen output.
+  delete node.trailingComments;
+  // Removes jshint and other service comments.
+  if (node.leadingComments) {
+    var i = 0;
+    while (i < node.leadingComments.length) {
+      var type = node.leadingComments[i].type;
+      var value = node.leadingComments[i].value;
+      if (type === 'Block' &&
+          /^\s*(globals|jshint|falls through|umdutils)\b/.test(value)) {
+        node.leadingComments.splice(i, 1);
+        continue;
+      }
+      i++;
+    }
+  }
+}
+
+function traverseTree(ctx, node) {
+  // generic node processing
+  for (var i in node) {
+    var child = node[i];
+    if (typeof child === 'object' && child !== null && child.type) {
+      var result = traverseTree(ctx, child);
+      if (result !== child) {
+        node[i] = result;
+      }
+    } else if (Array.isArray(child)) {
+      child.forEach(function (childItem, index) {
+        if (typeof childItem === 'object' && childItem !== null &&
+            childItem.type) {
+          var result = traverseTree(ctx, childItem);
+          if (result !== childItem) {
+            child[index] = result;
+          }
+        }
+      });
+    }
+  }
+
+  node = postprocessNode(ctx, node) || node;
+
+  fixComments(ctx, node);
+  return node;
+}
+
+function preprocessPDFJSCode(ctx, code) {
+  var saveComments = !!ctx.saveComments;
+  var format = ctx.format || {
+    indent: {
+      style: '  ',
+      adjustMultilineComment: saveComments,
+    }
+  };
+  var parseComment = {
+    loc: true,
+    attachComment: saveComments
+  };
+  var codegenOptions = {
+    format: format,
+    comment: saveComments,
+    parse: esprima.parse
+  };
+  var syntax = esprima.parse(code, parseComment);
+  traverseTree(ctx, syntax);
+  return escodegen.generate(syntax, codegenOptions);
+}
+
+exports.preprocessPDFJSCode = preprocessPDFJSCode;