The Tor Browser: toolkit/devtools/pretty-fast/pretty-fast.js@b8a032363ba2 (annotated)

toolkit/devtools/pretty-fast/pretty-fast.js@b8a032363ba2 (annotated)

toolkit/devtools/pretty-fast/pretty-fast.js

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /*
  * Copyright 2013 Mozilla Foundation and contributors
  * Licensed under the New BSD license. See LICENSE.md or:
  * http://opensource.org/licenses/BSD-2-Clause
  */
 (function (root, factory) {
   if (typeof define === 'function' && define.amd) {
     define(factory);
   } else if (typeof exports === 'object') {
     module.exports = factory();
   } else {
     root.prettyFast = factory();
   }
 }(this, function () {
   "use strict";
   var acorn = this.acorn || require("acorn/acorn");
   var sourceMap = this.sourceMap || require("source-map");
   var SourceNode = sourceMap.SourceNode;
   // If any of these tokens are seen before a "[" token, we know that "[" token
   // is the start of an array literal, rather than a property access.
   //
   // The only exception is "}", which would need to be disambiguated by
   // parsing. The majority of the time, an open bracket following a closing
   // curly is going to be an array literal, so we brush the complication under
   // the rug, and handle the ambiguity by always assuming that it will be an
   // array literal.
   var PRE_ARRAY_LITERAL_TOKENS = {
     "typeof": true,
     "void": true,
     "delete": true,
     "case": true,
     "do": true,
     "=": true,
     "in": true,
     "{": true,
     "*": true,
     "/": true,
     "%": true,
     "else": true,
     ";": true,
     "++": true,
     "--": true,
     "+": true,
     "-": true,
     "~": true,
     "!": true,
     ":": true,
     "?": true,
     ">>": true,
     ">>>": true,
     "<<": true,
     "||": true,
     "&&": true,
     "<": true,
     ">": true,
     "<=": true,
     ">=": true,
     "instanceof": true,
     "&": true,
     "^": true,
     "|": true,
     "==": true,
     "!=": true,
     "===": true,
     "!==": true,
     ",": true,
     "}": true
   };
   /**
    * Determines if we think that the given token starts an array literal.
    *
    * @param Object token
    *        The token we want to determine if it is an array literal.
    * @param Object lastToken
    *        The last token we added to the pretty printed results.
    *
    * @returns Boolean
    *          True if we believe it is an array literal, false otherwise.
    */
   function isArrayLiteral(token, lastToken) {
     if (token.type.type != "[") {
       return false;
     }
     if (!lastToken) {
       return true;
     }
     if (lastToken.type.isAssign) {
       return true;
     }
     return !!PRE_ARRAY_LITERAL_TOKENS[lastToken.type.keyword || lastToken.type.type];
   }
   // If any of these tokens are followed by a token on a new line, we know that
   // ASI cannot happen.
   var PREVENT_ASI_AFTER_TOKENS = {
     // Binary operators
     "*": true,
     "/": true,
     "%": true,
     "+": true,
     "-": true,
     "<<": true,
     ">>": true,
     ">>>": true,
     "<": true,
     ">": true,
     "<=": true,
     ">=": true,
     "instanceof": true,
     "in": true,
     "==": true,
     "!=": true,
     "===": true,
     "!==": true,
     "&": true,
     "^": true,
     "|": true,
     "&&": true,
     "||": true,
     ",": true,
     ".": true,
     "=": true,
     "*=": true,
     "/=": true,
     "%=": true,
     "+=": true,
     "-=": true,
     "<<=": true,
     ">>=": true,
     ">>>=": true,
     "&=": true,
     "^=": true,
     "|=": true,
     // Unary operators
     "delete": true,
     "void": true,
     "typeof": true,
     "~": true,
     "!": true,
     "new": true,
     // Function calls and grouped expressions
     "(": true
   };
   // If any of these tokens are on a line after the token before it, we know
   // that ASI cannot happen.
   var PREVENT_ASI_BEFORE_TOKENS = {
     // Binary operators
     "*": true,
     "/": true,
     "%": true,
     "<<": true,
     ">>": true,
     ">>>": true,
     "<": true,
     ">": true,
     "<=": true,
     ">=": true,
     "instanceof": true,
     "in": true,
     "==": true,
     "!=": true,
     "===": true,
     "!==": true,
     "&": true,
     "^": true,
     "|": true,
     "&&": true,
     "||": true,
     ",": true,
     ".": true,
     "=": true,
     "*=": true,
     "/=": true,
     "%=": true,
     "+=": true,
     "-=": true,
     "<<=": true,
     ">>=": true,
     ">>>=": true,
     "&=": true,
     "^=": true,
     "|=": true,
     // Function calls
     "(": true
   };
   /**
    * Determines if Automatic Semicolon Insertion (ASI) occurs between these
    * tokens.
    *
    * @param Object token
    *        The current token.
    * @param Object lastToken
    *        The last token we added to the pretty printed results.
    *
    * @returns Boolean
    *          True if we believe ASI occurs.
    */
   function isASI(token, lastToken) {
     if (!lastToken) {
       return false;
     }
     if (token.startLoc.line === lastToken.startLoc.line) {
       return false;
     }
     if (PREVENT_ASI_AFTER_TOKENS[lastToken.type.type || lastToken.type.keyword]) {
       return false;
     }
     if (PREVENT_ASI_BEFORE_TOKENS[token.type.type || token.type.keyword]) {
       return false;
     }
     return true;
   }
   /**
    * Determine if we have encountered a getter or setter.
    *
    * @param Object token
    *        The current token. If this is a getter or setter, it would be the
    *        property name.
    * @param Object lastToken
    *        The last token we added to the pretty printed results. If this is a
    *        getter or setter, it would be the `get` or `set` keyword
    *        respectively.
    * @param Array stack
    *        The stack of open parens/curlies/brackets/etc.
    *
    * @returns Boolean
    *          True if this is a getter or setter.
    */
   function isGetterOrSetter(token, lastToken, stack) {
     return stack[stack.length - 1] == "{"
       && lastToken
       && lastToken.type.type == "name"
       && (lastToken.value == "get" || lastToken.value == "set")
       && token.type.type == "name";
   }
   /**
    * Determine if we should add a newline after the given token.
    *
    * @param Object token
    *        The token we are looking at.
    * @param Array stack
    *        The stack of open parens/curlies/brackets/etc.
    *
    * @returns Boolean
    *          True if we should add a newline.
    */
   function isLineDelimiter(token, stack) {
     if (token.isArrayLiteral) {
       return true;
     }
     var ttt = token.type.type;
     var top = stack[stack.length - 1];
     return ttt == ";" && top != "("
       || ttt == "{"
       || ttt == "," && top != "("
       || ttt == ":" && (top == "case" || top == "default");
   }
   /**
    * Append the necessary whitespace to the result after we have added the given
    * token.
    *
    * @param Object token
    *        The token that was just added to the result.
    * @param Function write
    *        The function to write to the pretty printed results.
    * @param Array stack
    *        The stack of open parens/curlies/brackets/etc.
    *
    * @returns Boolean
    *          Returns true if we added a newline to result, false in all other
    *          cases.
    */
   function appendNewline(token, write, stack) {
     if (isLineDelimiter(token, stack)) {
       write("\n", token.startLoc.line, token.startLoc.column);
       return true;
     }
     return false;
   }
   /**
    * Determines if we need to add a space between the last token we added and
    * the token we are about to add.
    *
    * @param Object token
    *        The token we are about to add to the pretty printed code.
    * @param Object lastToken
    *        The last token added to the pretty printed code.
    */
   function needsSpaceAfter(token, lastToken) {
     if (lastToken) {
       if (lastToken.type.isLoop) {
         return true;
       }
       if (lastToken.type.isAssign) {
         return true;
       }
       if (lastToken.type.binop != null) {
         return true;
       }
       var ltt = lastToken.type.type;
       if (ltt == "?") {
         return true;
       }
       if (ltt == ":") {
         return true;
       }
       if (ltt == ",") {
         return true;
       }
       if (ltt == ";") {
         return true;
       }
       var ltk = lastToken.type.keyword;
       if (ltk != null) {
         if (ltk == "break" || ltk == "continue") {
           return token.type.type != ";";
         }
         if (ltk != "debugger"
             && ltk != "null"
             && ltk != "true"
             && ltk != "false"
             && ltk != "this"
             && ltk != "default") {
           return true;
         }
       }
       if (ltt == ")" && (token.type.type != ")"
                          && token.type.type != "]"
                          && token.type.type != ";"
                          && token.type.type != ",")) {
         return true;
       }
     }
     if (token.type.isAssign) {
       return true;
     }
     if (token.type.binop != null) {
       return true;
     }
     if (token.type.type == "?") {
       return true;
     }
     return false;
   }
   /**
    * Add the required whitespace before this token, whether that is a single
    * space, newline, and/or the indent on fresh lines.
    *
    * @param Object token
    *        The token we are about to add to the pretty printed code.
    * @param Object lastToken
    *        The last token we added to the pretty printed code.
    * @param Boolean addedNewline
    *        Whether we added a newline after adding the last token to the pretty
    *        printed code.
    * @param Function write
    *        The function to write pretty printed code to the result SourceNode.
    * @param Object options
    *        The options object.
    * @param Number indentLevel
    *        The number of indents deep we are.
    * @param Array stack
    *        The stack of open curlies, brackets, etc.
    */
   function prependWhiteSpace(token, lastToken, addedNewline, write, options,
                              indentLevel, stack) {
     var ttk = token.type.keyword;
     var ttt = token.type.type;
     var newlineAdded = addedNewline;
     var ltt = lastToken ? lastToken.type.type : null;
     // Handle whitespace and newlines after "}" here instead of in
     // `isLineDelimiter` because it is only a line delimiter some of the
     // time. For example, we don't want to put "else if" on a new line after
     // the first if's block.
     if (lastToken && ltt == "}") {
       if (ttk == "while" && stack[stack.length - 1] == "do") {
         write(" ",
               lastToken.startLoc.line,
               lastToken.startLoc.column);
       } else if (ttk == "else" ||
                  ttk == "catch" ||
                  ttk == "finally") {
         write(" ",
               lastToken.startLoc.line,
               lastToken.startLoc.column);
       } else if (ttt != "(" &&
                  ttt != ";" &&
                  ttt != "," &&
                  ttt != ")" &&
                  ttt != ".") {
         write("\n",
               lastToken.startLoc.line,
               lastToken.startLoc.column);
         newlineAdded = true;
       }
     }
     if (isGetterOrSetter(token, lastToken, stack)) {
       write(" ",
             lastToken.startLoc.line,
             lastToken.startLoc.column);
     }
     if (ttt == ":" && stack[stack.length - 1] == "?") {
       write(" ",
             lastToken.startLoc.line,
             lastToken.startLoc.column);
     }
     if (lastToken && ltt != "}" && ttk == "else") {
       write(" ",
             lastToken.startLoc.line,
             lastToken.startLoc.column);
     }
     function ensureNewline() {
       if (!newlineAdded) {
         write("\n",
               lastToken.startLoc.line,
               lastToken.startLoc.column);
         newlineAdded = true;
       }
     }
     if (isASI(token, lastToken)) {
       ensureNewline();
     }
     if (decrementsIndent(ttt, stack)) {
       ensureNewline();
     }
     if (newlineAdded) {
       if (ttk == "case" || ttk == "default") {
         write(repeat(options.indent, indentLevel - 1),
               token.startLoc.line,
               token.startLoc.column);
       } else {
         write(repeat(options.indent, indentLevel),
               token.startLoc.line,
               token.startLoc.column);
       }
     } else if (needsSpaceAfter(token, lastToken)) {
       write(" ",
             lastToken.startLoc.line,
             lastToken.startLoc.column);
     }
   }
   /**
    * Repeat the `str` string `n` times.
    *
    * @param String str
    *        The string to be repeated.
    * @param Number n
    *        The number of times to repeat the string.
    *
    * @returns String
    *          The repeated string.
    */
   function repeat(str, n) {
     var result = "";
     while (n > 0) {
       if (n & 1) {
         result += str;
       }
       n >>= 1;
       str += str;
     }
     return result;
   }
   /**
    * Make sure that we output the escaped character combination inside string literals
    * instead of various problematic characters.
    */
   var sanitize = (function () {
     var escapeCharacters = {
       // Backslash
       "\\": "\\\\",
       // Newlines
       "\n": "\\n",
       // Carriage return
       "\r": "\\r",
       // Tab
       "\t": "\\t",
       // Vertical tab
       "\v": "\\v",
       // Form feed
       "\f": "\\f",
       // Null character
       "\0": "\\0",
       // Single quotes
       "'": "\\'"
     };
     var regExpString = "("
       + Object.keys(escapeCharacters)
               .map(function (c) { return escapeCharacters[c]; })
               .join("|")
       + ")";
     var escapeCharactersRegExp = new RegExp(regExpString, "g");
     return function(str) {
       return str.replace(escapeCharactersRegExp, function (_, c) {
         return escapeCharacters[c];
       });
     }
   }());
   /**
    * Add the given token to the pretty printed results.
    *
    * @param Object token
    *        The token to add.
    * @param Function write
    *        The function to write pretty printed code to the result SourceNode.
    * @param Object options
    *        The options object.
    */
   function addToken(token, write, options) {
     if (token.type.type == "string") {
       write("'" + sanitize(token.value) + "'",
             token.startLoc.line,
             token.startLoc.column);
     } else {
       write(String(token.value != null ? token.value : token.type.type),
             token.startLoc.line,
             token.startLoc.column);
     }
   }
   /**
    * Returns true if the given token type belongs on the stack.
    */
   function belongsOnStack(token) {
     var ttt = token.type.type;
     var ttk = token.type.keyword;
     return ttt == "{"
       || ttt == "("
       || ttt == "["
       || ttt == "?"
       || ttk == "do"
       || ttk == "case"
       || ttk == "default";
   }
   /**
    * Returns true if the given token should cause us to pop the stack.
    */
   function shouldStackPop(token, stack) {
     var ttt = token.type.type;
     var ttk = token.type.keyword;
     var top = stack[stack.length - 1];
     return ttt == "]"
       || ttt == ")"
       || ttt == "}"
       || (ttt == ":" && (top == "case" || top == "default" || top == "?"))
       || (ttk == "while" && top == "do");
   }
   /**
    * Returns true if the given token type should cause us to decrement the
    * indent level.
    */
   function decrementsIndent(tokenType, stack) {
     return tokenType == "}"
       || (tokenType == "]" && stack[stack.length - 1] == "[\n")
   }
   /**
    * Returns true if the given token should cause us to increment the indent
    * level.
    */
   function incrementsIndent(token) {
     return token.type.type == "{" || token.isArrayLiteral;
   }
   /**
    * Add a comment to the pretty printed code.
    *
    * @param Function write
    *        The function to write pretty printed code to the result SourceNode.
    * @param Number indentLevel
    *        The number of indents deep we are.
    * @param Object options
    *        The options object.
    * @param Boolean block
    *        True if the comment is a multiline block style comment.
    * @param String text
    *        The text of the comment.
    * @param Number line
    *        The line number to comment appeared on.
    * @param Number column
    *        The column number the comment appeared on.
    */
   function addComment(write, indentLevel, options, block, text, line, column) {
     var indentString = repeat(options.indent, indentLevel);
     write(indentString, line, column);
     if (block) {
       write("/*");
       write(text
             .split(new RegExp("/\n" + indentString + "/", "g"))
             .join("\n" + indentString));
       write("*/");
     } else {
       write("//");
       write(text);
     }
     write("\n");
   }
   /**
    * The main function.
    *
    * @param String input
    *        The ugly JS code we want to pretty print.
    * @param Object options
    *        The options object. Provides configurability of the pretty
    *        printing. Properties:
    *          - url: The URL string of the ugly JS code.
    *          - indent: The string to indent code by.
    *
    * @returns Object
    *          An object with the following properties:
    *            - code: The pretty printed code string.
    *            - map: A SourceMapGenerator instance.
    */
   return function prettyFast(input, options) {
     // The level of indents deep we are.
     var indentLevel = 0;
     // We will accumulate the pretty printed code in this SourceNode.
     var result = new SourceNode();
     /**
      * Write a pretty printed string to the result SourceNode.
      *
      * We buffer our writes so that we only create one mapping for each line in
      * the source map. This enhances performance by avoiding extraneous mapping
      * serialization, and flattening the tree that
      * `SourceNode#toStringWithSourceMap` will have to recursively walk. When
      * timing how long it takes to pretty print jQuery, this optimization
      * brought the time down from ~390 ms to ~190ms!
      *
      * @param String str
      *        The string to be added to the result.
      * @param Number line
      *        The line number the string came from in the ugly source.
      * @param Number column
      *        The column number the string came from in the ugly source.
      */
     var write = (function () {
       var buffer = [];
       var bufferLine = -1;
       var bufferColumn = -1;
       return function write(str, line, column) {
         if (line != null && bufferLine === -1) {
           bufferLine = line;
         }
         if (column != null && bufferColumn === -1) {
           bufferColumn = column;
         }
         buffer.push(str);
         if (str == "\n") {
           var lineStr = "";
           for (var i = 0, len = buffer.length; i < len; i++) {
             lineStr += buffer[i];
           }
           result.add(new SourceNode(bufferLine, bufferColumn, options.url, lineStr));
           buffer.splice(0, buffer.length);
           bufferLine = -1;
           bufferColumn = -1;
         }
       }
     }());
     // Whether or not we added a newline on after we added the last token.
     var addedNewline = false;
     // The current token we will be adding to the pretty printed code.
     var token;
     // Shorthand for token.type.type, so we don't have to repeatedly access
     // properties.
     var ttt;
     // Shorthand for token.type.keyword, so we don't have to repeatedly access
     // properties.
     var ttk;
     // The last token we added to the pretty printed code.
     var lastToken;
     // Stack of token types/keywords that can affect whether we want to add a
     // newline or a space. We can make that decision based on what token type is
     // on the top of the stack. For example, a comma in a parameter list should
     // be followed by a space, while a comma in an object literal should be
     // followed by a newline.
     //
     // Strings that go on the stack:
     //
     //   - "{"
     //   - "("
     //   - "["
     //   - "[\n"
     //   - "do"
     //   - "?"
     //   - "case"
     //   - "default"
     //
     // The difference between "[" and "[\n" is that "[\n" is used when we are
     // treating "[" and "]" tokens as line delimiters and should increment and
     // decrement the indent level when we find them.
     var stack = [];
     // Acorn's tokenizer will always yield comments *before* the token they
     // follow (unless the very first thing in the source is a comment), so we
     // have to queue the comments in order to pretty print them in the correct
     // location. For example, the source file:
     //
     //     foo
     //     // a
     //     // b
     //     bar
     //
     // When tokenized by acorn, gives us the following token stream:
     //
     //     [ '// a', '// b', foo, bar ]
     var commentQueue = [];
     var getToken = acorn.tokenize(input, {
       locations: true,
       sourceFile: options.url,
       onComment: function (block, text, start, end, startLoc, endLoc) {
         if (lastToken) {
           commentQueue.push({
             block: block,
             text: text,
             line: startLoc.line,
             column: startLoc.column
           });
         } else {
           addComment(write, indentLevel, options, block, text, startLoc.line,
                      startLoc.column);
           addedNewline = true;
         }
       }
     });
     while (true) {
       token = getToken();
       ttk = token.type.keyword;
       ttt = token.type.type;
       if (ttt == "eof") {
         if (!addedNewline) {
           write("\n");
         }
         break;
       }
       token.isArrayLiteral = isArrayLiteral(token, lastToken);
       if (belongsOnStack(token)) {
         if (token.isArrayLiteral) {
           stack.push("[\n");
         } else {
           stack.push(ttt || ttk);
         }
       }
       if (decrementsIndent(ttt, stack)) {
         indentLevel--;
       }
       prependWhiteSpace(token, lastToken, addedNewline, write, options,
                         indentLevel, stack);
       addToken(token, write, options);
       addedNewline = appendNewline(token, write, stack);
       if (shouldStackPop(token, stack)) {
         stack.pop();
       }
       if (incrementsIndent(token)) {
         indentLevel++;
       }
       // Acorn's tokenizer re-uses tokens, so we have to copy the last token on
       // every iteration. We follow acorn's lead here, and reuse the lastToken
       // object the same way that acorn reuses the token object. This allows us
       // to avoid allocations and minimize GC pauses.
       if (!lastToken) {
         lastToken = { startLoc: {}, endLoc: {} };
       }
       lastToken.start = token.start;
       lastToken.end = token.end;
       lastToken.startLoc.line = token.startLoc.line;
       lastToken.startLoc.column = token.startLoc.column;
       lastToken.endLoc.line = token.endLoc.line;
       lastToken.endLoc.column = token.endLoc.column;
       lastToken.type = token.type;
       lastToken.value = token.value;
       lastToken.isArrayLiteral = token.isArrayLiteral;
       // Apply all the comments that have been queued up.
       if (commentQueue.length) {
         if (!addedNewline) {
           write("\n");
         }
         for (var i = 0, n = commentQueue.length; i < n; i++) {
           var comment = commentQueue[i];
           addComment(write, indentLevel, options, comment.block, comment.text,
                      comment.line, comment.column);
         }
         addedNewline = true;
         commentQueue.splice(0, commentQueue.length);
       }
     }
     return result.toStringWithSourceMap({ file: options.url });
   };
 }.bind(this)));