blob: 5d0dee930ac25d98b39061ced5e35fb3367cb29c [file] [log] [blame]
// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'package:analyzer/src/generated/java_engine.dart';
import 'package:analyzer/src/generated/source.dart';
/**
* The location of a character represented as a line and column pair.
*/
// ignore: deprecated_member_use
class CharacterLocation extends LineInfo_Location {
// TODO(brianwilkerson) Replace the body of this class with the body of
// LineInfo_Location and remove LineInfo_Location.
/**
* Initialize a newly created location to represent the location of the
* character at the given [lineNumber] and [columnNumber].
*/
CharacterLocation(int lineNumber, int columnNumber)
: super(lineNumber, columnNumber);
}
/**
* Information about line and column information within a source file.
*/
class LineInfo {
/**
* A list containing the offsets of the first character of each line in the
* source code.
*/
final List<int> lineStarts;
/**
* The zero-based [lineStarts] index resulting from the last call to
* [getLocation].
*/
int _previousLine = 0;
/**
* Initialize a newly created set of line information to represent the data
* encoded in the given list of [lineStarts].
*/
LineInfo(this.lineStarts) {
if (lineStarts == null) {
throw new ArgumentError("lineStarts must be non-null");
} else if (lineStarts.length < 1) {
throw new ArgumentError("lineStarts must be non-empty");
}
}
/**
* Initialize a newly created set of line information corresponding to the
* given file [content].
*/
factory LineInfo.fromContent(String content) =>
new LineInfo(StringUtilities.computeLineStarts(content));
/**
* The number of lines.
*/
int get lineCount => lineStarts.length;
/**
* Return the location information for the character at the given [offset].
*
* A future version of this API will return a [CharacterLocation] rather than
// ignore: deprecated_member_use
* a [LineInfo_Location].
*/
// ignore: deprecated_member_use
LineInfo_Location getLocation(int offset) {
var min = 0;
var max = lineStarts.length - 1;
// Subsequent calls to [getLocation] are often for offsets near each other.
// To take advantage of that, we cache the index of the line start we found
// when this was last called. If the current offset is on that line or
// later, we'll skip those early indices completely when searching.
if (offset >= lineStarts[_previousLine]) {
min = _previousLine;
// Before kicking off a full binary search, do a quick check here to see
// if the new offset is on that exact line.
if (min == lineStarts.length - 1 || offset < lineStarts[min + 1]) {
return new CharacterLocation(min + 1, offset - lineStarts[min] + 1);
}
}
// Binary search to fine the line containing this offset.
while (min < max) {
var midpoint = (max - min + 1) ~/ 2 + min;
if (lineStarts[midpoint] > offset) {
max = midpoint - 1;
} else {
min = midpoint;
}
}
_previousLine = min;
return new CharacterLocation(min + 1, offset - lineStarts[min] + 1);
}
/**
* Return the offset of the first character on the line with the given
* [lineNumber].
*/
int getOffsetOfLine(int lineNumber) {
if (lineNumber < 0 || lineNumber >= lineCount) {
throw new ArgumentError(
'Invalid line number: $lineNumber; must be between 0 and ${lineCount - 1}');
}
return lineStarts[lineNumber];
}
/**
* Return the offset of the first character on the line following the line
* containing the given [offset].
*/
int getOffsetOfLineAfter(int offset) {
return getOffsetOfLine(getLocation(offset).lineNumber);
}
}