blob: 9f150482c6da354adbbad9753a12a306b4bf432c [file] [log] [blame]
// Copyright (c) 2014, 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.
library source_span.span;
import 'location.dart';
import 'span_mixin.dart';
/// A class that describes a segment of source text.
abstract class SourceSpan implements Comparable<SourceSpan> {
/// The start location of this span.
final SourceLocation start;
/// The end location of this span, exclusive.
final SourceLocation end;
/// The source text for this span.
final String text;
/// The URL of the source (typically a file) of this span.
/// This may be null, indicating that the source URL is unknown or
/// unavailable.
final Uri sourceUrl;
/// The length of this span, in characters.
final int length;
/// Creates a new span from [start] to [end] (exclusive) containing [text].
/// [start] and [end] must have the same source URL and [start] must come
/// before [end]. [text] must have a number of characters equal to the
/// distance between [start] and [end].
factory SourceSpan(SourceLocation start, SourceLocation end, String text) =>
new SourceSpanBase(start, end, text);
/// Creates a new span that's the union of [this] and [other].
/// The two spans must have the same source URL and may not be disjoint.
/// [text] is computed by combining [this.text] and [other.text].
SourceSpan union(SourceSpan other);
/// Compares two spans.
/// [other] must have the same source URL as [this]. This orders spans by
/// [start] then [length].
int compareTo(SourceSpan other);
/// Formats [message] in a human-friendly way associated with this span.
/// [color] may either be a [String], a [bool], or `null`. If it's a string,
/// it indicates an ANSII terminal color escape that should be used to
/// highlight the span's text. If it's `true`, it indicates that the text
/// should be highlighted using the default color. If it's `false` or `null`,
/// it indicates that the text shouldn't be highlighted.
String message(String message, {color});
/// A base class for source spans with [start], [end], and [text] known at
/// construction time.
class SourceSpanBase extends SourceSpanMixin {
final SourceLocation start;
final SourceLocation end;
final String text;
SourceSpanBase(this.start, this.end, this.text) {
if (end.sourceUrl != start.sourceUrl) {
throw new ArgumentError("Source URLs \"${start.sourceUrl}\" and "
" \"${end.sourceUrl}\" don't match.");
} else if (end.offset < start.offset) {
throw new ArgumentError('End $end must come after start $start.');
} else if (text.length != start.distance(end)) {
throw new ArgumentError('Text "$text" must be ${start.distance(end)} '
'characters long.');