messages.js.svn-base

Google浏览器V8内核代码

    if (offset_line + line >= lineCount) return null;
    return this.locationFromPosition(this.lineEnds_[offset_line + line - 1] + 1 + column);  // line > 0 here.
  }
}


/**
 * Get a slice of source code from the script. The boundaries for the slice is
 * specified in lines.
 * @param {number} opt_from_line The first line (zero bound) in the slice.
 *     Default is 0
 * @param {number} opt_to_column The last line (zero bound) in the slice (non
 *     inclusive). Default is the number of lines in the script
 * @return {SourceSlice} The source slice or null of the parameters where
 *     invalid
 */
Script.prototype.sourceSlice = function (opt_from_line, opt_to_line) {
  // Make soure source info has been initialized.
  this.initSourceInfo_();

  var from_line = IS_UNDEFINED(opt_from_line) ? this.line_offset : opt_from_line;
  var to_line = IS_UNDEFINED(opt_to_line) ? this.line_offset + this.lineCount() : opt_to_line

  // Adjust according to the offset within the resource.
  from_line -= this.line_offset;
  to_line -= this.line_offset;
  if (from_line < 0) from_line = 0;
  if (to_line > this.lineCount()) to_line = this.lineCount();

  // Check parameters.  
  if (from_line >= this.lineCount() ||
      to_line < 0 ||
      from_line > to_line) {
    return null;
  }

  var from_position = from_line == 0 ? 0 : this.lineEnds_[from_line - 1] + 1;
  var to_position = to_line == 0 ? 0 : this.lineEnds_[to_line - 1] + 1;

  // Return a source slice with line numbers re-adjusted to the resource.
  return new SourceSlice(this, from_line + this.line_offset, to_line + this.line_offset,
                         from_position, to_position);
}


Script.prototype.sourceLine = function (opt_line) {
  // Default is the first line in the script. Lines in the script are relative
  // to the offset within the resource.
  var line = 0;
  if (!IS_UNDEFINED(opt_line)) {
    line = opt_line - this.line_offset;
  }
  
  // Check parameter.  
  if (line < 0 || this.lineCount() <= line) {
    return null;
  }

  // Return the source line.  
  var start = line == 0 ? 0 : this.lineEnds_[line - 1] + 1;
  var end = this.lineEnds_[line];
  return this.source.substring(start, end);
}


/**
 * Returns the number of source lines.
 * @return {number}
 *     Number of source lines.
 */
Script.prototype.lineCount = function() {
  // Make soure source info has been initialized.
  this.initSourceInfo_();

  // Return number of source lines.  
  return this.lineEnds_.length;
};


/**
 * Class for source location. A source location is a position within some
 * source with the following properties:
 *   script   : script object for the source
 *   line     : source line number
 *   column   : source column within the line
 *   position : position within the source
 *   start    : position of start of source context (inclusive)
 *   end      : position of end of source context (not inclusive)
 * Source text for the source context is the character interval [start, end[. In
 * most cases end will point to a newline character. It might point just past
 * the final position of the source if the last source line does not end with a
 * newline character. 
 * @param {Script} script The Script object for which this is a location
 * @param {number} position Source position for the location
 * @param {number} line The line number for the location
 * @param {number} column The column within the line for the location
 * @param {number} start Source position for start of source context
 * @param {number} end Source position for end of source context
 * @constructor
 */
function SourceLocation(script, position, line, column, start, end) {
  this.script = script;
  this.position = position;
  this.line = line;
  this.column = column;
  this.start = start;
  this.end = end;
};


const kLineLengthLimit = 78;

/**
 * Restrict source location start and end positions to make the source slice
 * no more that a certain number of characters wide.
 * @param {number} opt_limit The with limit of the source text with a default
 *     of 78
 * @param {number} opt_before The number of characters to prefer before the
 *     position with a default value of 10 less that the limit
 */
SourceLocation.prototype.restrict = function (opt_limit, opt_before) {
  // Find the actual limit to use.
  var limit;
  var before;
  if (!IS_UNDEFINED(opt_limit)) {
    limit = opt_limit;
  } else {
    limit = kLineLengthLimit;
  }
  if (!IS_UNDEFINED(opt_before)) {
    before = opt_before;
  } else {
    // If no before is specified center for small limits and perfer more source
    // before the the position that after for longer limits.
    if (limit <= 20) {
      before = $Math_floor(limit / 2);
    } else {
      before = limit - 10;
    }
  }
  if (before >= limit) {
    before = limit - 1;
  }

  // If the [start, end[ interval is too big we restrict
  // it in one or both ends. We make sure to always produce
  // restricted intervals of maximum allowed size.
  if (this.end - this.start > limit) {
    var start_limit = this.position - before;
    var end_limit = this.position + limit - before;
    if (this.start < start_limit && end_limit < this.end) {
      this.start = start_limit;
      this.end = end_limit;
    } else if (this.start < start_limit) {
      this.start = this.end - limit;
    } else {
      this.end = this.start + limit;
    }
  }
};


/**
 * Get the source text for a SourceLocation
 * @return {String}
 *     Source text for this location.
 */
SourceLocation.prototype.sourceText = function () {
  return this.script.source.substring(this.start, this.end);
};


/**
 * Class for a source slice. A source slice is a part of a script source with
 * the following properties:
 *   script        : script object for the source
 *   from_line     : line number for the first line in the slice
 *   to_line       : source line number for the last line in the slice
 *   from_position : position of the first character in the slice
 *   to_position   : position of the last character in the slice
 * The to_line and to_position are not included in the slice, that is the lines
 * in the slice are [from_line, to_line[. Likewise the characters in the slice
 * are [from_position, to_position[.
 * @param {Script} script The Script object for the source slice
 * @param {number} from_line
 * @param {number} to_line
 * @param {number} from_position
 * @param {number} to_position
 * @constructor
 */
function SourceSlice(script, from_line, to_line, from_position, to_position) {
  this.script = script;
  this.from_line = from_line;
  this.to_line = to_line;
  this.from_position = from_position;
  this.to_position = to_position;
}


/**
 * Get the source text for a SourceSlice
 * @return {String} Source text for this slice. The last line will include
 *     the line terminating characters (if any)
 */
SourceSlice.prototype.sourceText = function () {
  return this.script.source.substring(this.from_position, this.to_position);
};


// Returns the offset of the given position within the containing
// line.
function GetPositionInLine(message) {
  var location = message.script.locationFromPosition(message.startPos);
  if (location == null) return -1;
  location.restrict();
  return message.startPos - location.start;
};


function ErrorMessage(type, args, startPos, endPos, script, stackTrace) {
  this.startPos = startPos;
  this.endPos = endPos;
  this.type = type;
  this.args = args;
  this.script = script;
  this.stackTrace = stackTrace;
};


function MakeMessage(type, args, startPos, endPos, script, stackTrace) {
  return new ErrorMessage(type, args, startPos, endPos, script, stackTrace);
};


function GetStackTraceLine(recv, fun, pos, isGlobal) {
  try {
    return UnsafeGetStackTraceLine(recv, fun, pos, isGlobal);
  } catch (e) {
    return "<error: " + e + ">";
  }
};


function GetFunctionName(fun, recv) {
  var name = %FunctionGetName(fun);
  if (name) return name;
  for (var prop in recv) {
    if (recv[prop] === fun)
      return prop;
  }
  return "[anonymous]";
};


function UnsafeGetStackTraceLine(recv, fun, pos, isTopLevel) {
  var result = "";
  // The global frame has no meaningful function or receiver
  if (!isTopLevel) {
    // If the receiver is not the global object then prefix the
    // message send
    if (recv !== global)
      result += ToDetailString(recv) + ".";
    result += GetFunctionName(fun, recv);
  }
  if (pos != -1) {
    var script = %FunctionGetScript(fun);
    var file;
    if (script) {
      file = %FunctionGetScript(fun).data;
    }
    if (file) {
      var location = %FunctionGetScript(fun).locationFromPosition(pos);
      if (!isTopLevel) result += "(";
      result += file;
      if (location != null) {
        result += ":" + (location.line + 1) + ":" + (location.column + 1);
      }
      if (!isTopLevel) result += ")";
    }
  }
  return (result) ? "    at " + result : result;
};


// ----------------------------------------------------------------------------
// Error implementation

function DefineError(name) {
  var f = function(msg) {};
  // Store the error function in both the global object
  // and the runtime object. The function is fetched
  // from the runtime object when throwing errors from
  // within the runtime system to avoid strange side
  // effects when overwriting the error functions from
  // user code.
  %AddProperty(global, name, f, DONT_ENUM);
  this['$' + name] = f;
  // Configure the error function.
  // prototype of 'Error' must be as default: new Object().
  if (name != 'Error') %FunctionSetPrototype(f, new $Error());
  %FunctionSetInstanceClassName(f, 'Error');
  f.prototype.name = name;
  f.prototype.constructor = f;
  %SetCode(f, function(m) {
    if (%IsConstructCall()) {
      if (!IS_UNDEFINED(m)) this.message = ToString(m);
    } else {
      return new f(m);
    }
  });
};

$Math.__proto__ = global.Object.prototype;

DefineError('Error');
DefineError('TypeError');
DefineError('RangeError');
DefineError('SyntaxError');
DefineError('ReferenceError');
DefineError('EvalError');
DefineError('URIError');

// Setup extra properties of the Error.prototype object.
$Error.prototype.message = '';

%AddProperty($Error.prototype, 'toString', function() {
  var type = this.type;
  if (type && !this.hasOwnProperty("message")) {
    return this.name + ": " + FormatMessage({ type: type, args: this.arguments });
  }
  var message = this.message;
  return this.name + (message ? (": " + message) : "");
}, DONT_ENUM);


// Boilerplate for exceptions for stack overflows. Used from
// Top::StackOverflow().
const kStackOverflowBoilerplate = MakeRangeError('stack_overflow', []);