Refactor code for determining line position in a source file....

src/messages.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 84 matching lines @@
   apply_non_function:           "Function.prototype.apply was called on %0, which is a %1 and not a function",
   apply_wrong_args:             "Function.prototype.apply: Arguments list has wrong type",
   invalid_in_operator_use:      "Cannot use 'in' operator to search for '%0' in %1",
   instanceof_function_expected: "Expecting a function in instanceof check, but got %0",
   instanceof_nonobject_proto:   "Function has non-object prototype '%0' in instanceof check",
   null_to_object:               "Cannot convert null to object",
   // RangeError
   invalid_array_length:         "Invalid array length",
   invalid_array_apply_length:   "Function.prototype.apply supports only up to 1024 arguments",
   stack_overflow:               "Maximum call stack size exceeded",
-  apply_overflow:               "Function.prototype.apply cannot support %0 arguments", 
+  apply_overflow:               "Function.prototype.apply cannot support %0 arguments",
   // SyntaxError
   unable_to_parse:              "Parse error",
   duplicate_regexp_flag:        "Duplicate RegExp flag %0",
   unrecognized_regexp_flag:     "Unrecognized RegExp flag %0",
   invalid_regexp:               "Invalid RegExp pattern /%0/",
   illegal_break:                "Illegal break statement",
   illegal_continue:             "Illegal continue statement",
   illegal_return:               "Illegal return statement",
   error_loading_debugger:       "Error loading debugger %0",
   no_input_to_regexp:           "No input to %0",
@@ skipping 105 matching lines @@
   return MakeGenericError($EvalError, type, args);
 }
 
 
 function MakeError(type, args) {
   return MakeGenericError($Error, type, args);
 }
 
 
 /**
- * Initialize the cached source information in a script. Currently all line
- * end positions are cached.
- */
-Script.prototype.initSourceInfo_ = function () {
-  // Just return if initialized.
-  if (this.lineEnds_) return;
-
-  // Collect all line endings.
-  this.lineEnds_ = [];
-  for (var i = 0; i < this.source.length; i++) {
-    var current = this.source.charAt(i);
-    if (current == '\n') {
-      this.lineEnds_.push(i);
-    }
-  }
-
-  // If the script does not end with a line ending add the final end position
-  // as just past the last line ending.
-  if (this.lineEnds_[this.lineEnds_.length - 1] != this.source.length - 1) {
-    this.lineEnds_.push(this.source.length);
-  }
-};
-
-
-/**
  * Get information on a specific source position.
  * @param {number} position The source position
  * @return {SourceLocation}
  *     If line is negative or not in the source null is returned.
  */
 Script.prototype.locationFromPosition = function (position) {
-  // Make sure source info has been initialized.
-  this.initSourceInfo_();
-
   var lineCount = this.lineCount();
   var line = -1;
-  if (position <= this.lineEnds_[0]) {
+  if (position <= this.line_ends[0]) {
     line = 0;
   } else {
     for (var i = 1; i < lineCount; i++) {
-      if (this.lineEnds_[i - 1] < position && position <= this.lineEnds_[i]) {
+      if (this.line_ends[i - 1] < position && position <= this.line_ends[i]) {
         line = i;
         break;
       }
     }
   }
 
   if (line == -1) return null;
 
   // Determine start, end and column.
-  var start = line == 0 ? 0 : this.lineEnds_[line - 1] + 1;
-  var end = this.lineEnds_[line];
+  var start = line == 0 ? 0 : this.line_ends[line - 1] + 1;
+  var end = this.line_ends[line];
   if (end > 0 && this.source.charAt(end - 1) == '\r') end--;
   var column = position - start;
 
   // Adjust according to the offset within the resource.
   line += this.line_offset;
   if (line == this.line_offset) {
     column += this.column_offset;
   }
 
   return new SourceLocation(this, position, line, column, start, end);
 };
 
 
 /**
  * Get information on a specific source line and column possibly offset by a
  * fixed source position. This function is used to find a source position from
  * a line and column position. The fixed source position offset is typically
  * used to find a source position in a function based on a line and column in
  * the source for the function alone. The offset passed will then be the
  * start position of the source for the function within the full script source.
  * @param {number} opt_line The line within the source. Default value is 0
  * @param {number} opt_column The column in within the line. Default value is 0
  * @param {number} opt_offset_position The offset from the begining of the
  *     source from where the line and column calculation starts. Default value is 0
  * @return {SourceLocation}
  *     If line is negative or not in the source null is returned.
  */
 Script.prototype.locationFromLine = function (opt_line, opt_column, opt_offset_position) {
-  // Make soure source info has been initialized.
-  this.initSourceInfo_();
-
   // Default is the first line in the script. Lines in the script is relative
   // to the offset within the resource.
   var line = 0;
   if (!IS_UNDEFINED(opt_line)) {
     line = opt_line - this.line_offset;
   }
 
   // Default is first column. If on the first line add the offset within the
   // resource.
   var column = opt_column || 0;
   if (line == 0) {
     column -= this.column_offset
   }
 
   var offset_position = opt_offset_position || 0;
   if (line < 0 || column < 0 || offset_position < 0) return null;
   if (line == 0) {
     return this.locationFromPosition(offset_position + column);
   } else {
     // Find the line where the offset position is located
     var lineCount = this.lineCount();
     var offset_line;
     for (var i = 0; i < lineCount; i++) {
-      if (offset_position <= this.lineEnds_[i]) {
+      if (offset_position <= this.line_ends[i]) {
         offset_line = i;
         break;
       }
     }
     if (offset_line + line >= lineCount) return null;
-    return this.locationFromPosition(this.lineEnds_[offset_line + line - 1] + 1 + column);  // line > 0 here.
+    return this.locationFromPosition(this.line_ends[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.  
+  // 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;
+  var from_position = from_line == 0 ? 0 : this.line_ends[from_line - 1] + 1;
+  var to_position = to_line == 0 ? 0 : this.line_ends[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.  
+
+  // 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 the source line.
+  var start = line == 0 ? 0 : this.line_ends[line - 1] + 1;
+  var end = this.line_ends[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;
+  // Return number of source lines.
+  return this.line_ends.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. 
+ * 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;
@@ skipping 226 matching lines @@
     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', []);