Refactor script position calculation

src/js/messages.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // -------------------------------------------------------------------
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
@@ skipping 196 matching lines @@
 }
 
 
 // Returns the source code line containing the given source
 // position, or the empty string if the position is invalid.
 function GetSourceLine(message) {
   var script = %MessageGetScript(message);
   var start_position = %MessageGetStartPosition(message);
   var location = script.locationFromPosition(start_position, true);
   if (location == null) return "";
-  return location.sourceText();
+  return location.sourceText;
 }
 
 
 /**
  * Find a line number given a specific source position.
  * @param {number} position The source position.
  * @return {number} 0 if input too small, -1 if input too large,
        else the line number.
  */
 function ScriptLineFromPosition(position) {
-  var lower = 0;
-  var upper = this.lineCount() - 1;
-  var line_ends = this.line_ends;
-
-  // We'll never find invalid positions so bail right away.
-  if (position > line_ends[upper]) {
-    return -1;
-  }
-
-  // This means we don't have to safe-guard indexing line_ends[i - 1].
-  if (position <= line_ends[0]) {
-    return 0;
-  }
-
-  // Binary search to find line # from position range.
-  while (upper >= 1) {
-    var i = (lower + upper) >> 1;
-
-    if (position > line_ends[i]) {
-      lower = i + 1;
-    } else if (position <= line_ends[i - 1]) {
-      upper = i - 1;
-    } else {
-      return i;
-    }
-  }
-
-  return -1;
+  var info = %ScriptPositionInfo(this, position, false);
+  return (info == null) ? -1 : info.line;
 }
 
 
 /**
  * Get information on a specific source position.
+ * Returns an object with the following following properties:
+ *   script     : script object for the source
+ *   line       : source line number
+ *   column     : source column within the line
+ *   position   : position within the source
+ *   sourceText : a string containing the current line
  * @param {number} position The source position
  * @param {boolean} include_resource_offset Set to true to have the resource
  *     offset added to the location
- * @return {SourceLocation}
- *     If line is negative or not in the source null is returned.
+ * @return If line is negative or not in the source null is returned.
  */
 function ScriptLocationFromPosition(position,
                                     include_resource_offset) {
-  var line = this.lineFromPosition(position);
-  if (line == -1) return null;
-
-  // Determine start, end and column.
-  var line_ends = this.line_ends;
-  var start = line == 0 ? 0 : line_ends[line - 1] + 1;
-  var end = line_ends[line];
-  if (end > 0 && %_StringCharAt(this.source, end - 1) === '\r') {
-    end--;
-  }
-  var column = position - start;
-
-  // Adjust according to the offset within the resource.
-  if (include_resource_offset) {
-    line += this.line_offset;
-    if (line == this.line_offset) {
-      column += this.column_offset;
-    }
-  }
-
-  return new SourceLocation(this, position, line, column, start, end);
+  return %ScriptPositionInfo(this, position, !!include_resource_offset);
 }
 
 
 /**
  * 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.
+ * @return If line is negative or not in the source null is returned.
  */
 function ScriptLocationFromLine(opt_line, opt_column, opt_offset_position) {
   // 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, false);
   } else {
     // Find the line where the offset position is located.
     var offset_line = this.lineFromPosition(offset_position);
 
     if (offset_line == -1 || offset_line + line >= this.lineCount()) {
       return null;
     }
 
     return this.locationFromPosition(
-        this.line_ends[offset_line + line - 1] + 1 + column);  // line > 0 here.
+        %ScriptLineStartPosition(this, offset_line + line) + column);
   }
 }
 
 
 /**
  * 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
@@ skipping 13 matching lines @@
   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 line_ends = this.line_ends;
-  var from_position = from_line == 0 ? 0 : line_ends[from_line - 1] + 1;
-  var to_position = to_line == 0 ? 0 : line_ends[to_line - 1] + 1;
+  var from_position = %ScriptLineStartPosition(this, from_line);
+  var to_position = %ScriptLineStartPosition(this, to_line);
 
   // 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);
+                         from_position, to_position);
 }
 
 
 function ScriptSourceLine(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 line_ends = this.line_ends;
-  var start = line == 0 ? 0 : line_ends[line - 1] + 1;
-  var end = line_ends[line];
+  var start = %ScriptLineStartPosition(this, line);
+  var end = %ScriptLineEndPosition(this, line);
   return %_Call(StringSubstring, this.source, start, end);
 }
 
 
 /**
  * Returns the number of source lines.
  * @return {number}
  *     Number of source lines.
  */
 function ScriptLineCount() {
   // Return number of source lines.
-  return this.line_ends.length;
+  return %ScriptLineCount(this);
 }
 
 
-/**
- * Returns the position of the nth line end.
- * @return {number}
- *     Zero-based position of the nth line end in the script.
- */
-function ScriptLineEnd(n) {
-  return this.line_ends[n];
-}
-
-
 /**
  * If sourceURL comment is available returns sourceURL comment contents.
  * Otherwise, script name is returned. See
  * http://fbug.googlecode.com/svn/branches/firebug1.1/docs/ReleaseNotes_1.1.txt
  * and Source Map Revision 3 proposal for details on using //# sourceURL and
  * deprecated //@ sourceURL comment to identify scripts that don't have name.
  *
  * @return {?string} script name if present, value for //# sourceURL comment or
  * deprecated //@ sourceURL comment otherwise.
  */
 function ScriptNameOrSourceURL() {
   if (this.source_url) return this.source_url;
   return this.name;
 }
 
 
 utils.SetUpLockedPrototype(Script, [
     "source",
     "name",
     "source_url",
     "source_mapping_url",
-    "line_ends",
     "line_offset",
     "column_offset"
   ], [
     "lineFromPosition", ScriptLineFromPosition,
     "locationFromPosition", ScriptLocationFromPosition,
     "locationFromLine", ScriptLocationFromLine,
     "sourceSlice", ScriptSourceSlice,
     "sourceLine", ScriptSourceLine,
     "lineCount", ScriptLineCount,
     "nameOrSourceURL", ScriptNameOrSourceURL,
-    "lineEnd", ScriptLineEnd
   ]
 );
 
 
 /**
- * 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;
-}
-
-
-/**
- * Get the source text for a SourceLocation
- * @return {String}
- *     Source text for this location.
- */
-function SourceLocationSourceText() {
-  return %_Call(StringSubstring, this.script.source, this.start, this.end);
-}
-
-
-utils.SetUpLockedPrototype(SourceLocation,
-  ["script", "position", "line", "column", "start", "end"],
-  ["sourceText", SourceLocationSourceText]
-);
-
-
-/**
  * 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[.
@@ skipping 526 matching lines @@
 utils.Export(function(to) {
   to.ErrorToString = ErrorToString;
   to.MakeError = MakeError;
   to.MakeRangeError = MakeRangeError;
   to.MakeSyntaxError = MakeSyntaxError;
   to.MakeTypeError = MakeTypeError;
   to.MakeURIError = MakeURIError;
 });
 
 });