source_span 1.2.3

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source_span is a library for tracking locations in source code. It's designed to provide a standard representation for source code locations and spans so that disparate packages can easily pass them among one another, and to make it easy to generate human-friendly messages associated with a given piece of code.

The most commonly-used class is the package's namesake, SourceSpan. It represents a span of characters in some source file, and is often attached to an object that has been parsed to indicate where it was parsed from. It provides access to the text of the span via SourceSpan.text and can be used to produce human-friendly messages using SourceSpan.message().

When parsing code from a file, SourceFile is useful. Not only does it provide an efficient means of computing line and column numbers, SourceFile.span() returns special FileSpans that are able to provide more context for their error messages.


  • Fix a bug where a point span at the end of a file without a trailing newline would be printed incorrectly.


  • Allow SourceSpanException.message, SourceSpanFormatException.source, and SourceSpanWithContext.context to be overridden in strong mode.


  • Fix the declared type of FileSpan.start and FileSpan.end. In 1.2.0 these were mistakenly changed from FileLocation to SourceLocation.


  • Deprecated: Extending SourceLocation directly is deprecated. Instead, extend the new SourceLocationBase class or mix in the new SourceLocationMixin mixin.

  • Dramatically improve the performance of FileLocation.


  • Optimize getLine() in SourceFile when repeatedly called.


  • Fixed another case in which FileSpan.union could throw an exception for external implementations of FileSpan.


  • Eliminated dart2js warning about overriding ==, but not hashCode.


  • FileSpan.compareTo, FileSpan.==, FileSpan.union, and FileSpan.expand no longer throw exceptions for external implementations of FileSpan.

  • FileSpan.hashCode now fully agrees with FileSpan.==.


  • Fixed validation in SourceSpanWithContext to allow multiple occurrences of text within context.


  • Fixed FileSpan's context to include the full span text, not just the first line of it.


  • Added SourceSpanWithContext: a span that also includes the full line of text that contains the span.


  • Cleanup equality operator to accept any Object rather than just a SourceLocation.


  • Avoid unintentionally allocating extra objects for internal FileSpan operations.

  • Ensure that SourceSpan.operator== works on arbitrary Objects.


  • Use a more compact internal representation for FileSpan.


This package was extracted from the source_maps package, but the API has many differences. Among them:

  • Span has been renamed to SourceSpan and Location has been renamed to SourceLocation to clarify their purpose and maintain consistency with the package name. Likewise, SpanException is now SourceSpanException and SpanFormatException is not SourceSpanFormatException.

  • FixedSpan and FixedLocation have been rolled into the Span and Location classes, respectively.

  • SourceFile is more aggressive about validating its arguments. Out-of-bounds lines, columns, and offsets will now throw errors rather than be silently clamped.

  • SourceSpan.sourceUrl, SourceLocation.sourceUrl, and SourceFile.url now return Uri objects rather than Strings. The constructors allow either Strings or Uris.

  • Span.getLocationMessage and SourceFile.getLocationMessage are now SourceSpan.message and SourceFile.message, respectively. Rather than taking both a useColor and a color parameter, they now take a single color parameter that controls both whether and which color is used.

  • Span.isIdentifier has been removed. This property doesn't make sense outside of a source map context.

  • SourceFileSegment has been removed. This class wasn't widely used and was inconsistent in its choice of which parameters were considered relative and which absolute.

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  source_span: ^1.2.3

2. Install it

You can install packages from the command line:

with pub:

$ pub get

Alternatively, your editor might support pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:source_span/source_span.dart';
Version Uploaded Documentation Archive
1.4.1 Jul 18, 2018 Go to the documentation of source_span 1.4.1 Download source_span 1.4.1 archive
1.4.0 May 17, 2017 Go to the documentation of source_span 1.4.0 Download source_span 1.4.0 archive
1.3.1 Jan 7, 2017 Go to the documentation of source_span 1.3.1 Download source_span 1.3.1 archive
1.3.0 Nov 8, 2016 Go to the documentation of source_span 1.3.0 Download source_span 1.3.0 archive
1.2.4 Oct 21, 2016 Go to the documentation of source_span 1.2.4 Download source_span 1.2.4 archive
1.2.3 Jun 9, 2016 Go to the documentation of source_span 1.2.3 Download source_span 1.2.3 archive
1.2.2 Mar 2, 2016 Go to the documentation of source_span 1.2.2 Download source_span 1.2.2 archive
1.2.1 Sep 30, 2015 Go to the documentation of source_span 1.2.1 Download source_span 1.2.1 archive
1.2.0 Sep 2, 2015 Go to the documentation of source_span 1.2.0 Download source_span 1.2.0 archive
1.1.6 Sep 2, 2015 Go to the documentation of source_span 1.1.6 Download source_span 1.1.6 archive

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Package Constraint Resolved Available
Direct dependencies
Dart SDK >=0.8.10+6 <2.0.0