Move a number of packages and some of pub over to using source_span.

sdk/lib/_internal/pub/lib/src/pubspec.dart

 // Copyright (c) 2012, 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 pub.pubspec;
 
 import 'package:path/path.dart' as path;
-import 'package:source_maps/source_maps.dart';
+import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 
 import 'barback/transformer_config.dart';
 import 'exceptions.dart';
 import 'io.dart';
 import 'package.dart';
 import 'source_registry.dart';
 import 'utils.dart';
 import 'version.dart';
 
@@ skipping 12 matching lines @@
   /// [devDependencies].
   ///
   /// This will be null if this was created using [new Pubspec] or [new
   /// Pubspec.empty].
   final SourceRegistry _sources;
 
   /// The location from which the pubspec was loaded.
   ///
   /// This can be null if the pubspec was created in-memory or if its location
   /// is unknown.
-  Uri get _location => fields.span.sourceUrl == null ? null :
-      Uri.parse(fields.span.sourceUrl);
+  Uri get _location => fields.span.sourceUrl;
 
   /// All pubspec fields.
   ///
   /// This includes the fields from which other properties are derived.
   final YamlMap fields;
 
   /// The package's name.
   String get name {
     if (_name != null) return _name;
 
@@ skipping 197 matching lines @@
 
   /// Returns a Pubspec object for an already-parsed map representing its
   /// contents.
   ///
   /// If [expectedName] is passed and the pubspec doesn't have a matching name
   /// field, this will throw a [PubspecError].
   ///
   /// [location] is the location from which this pubspec was loaded.
   Pubspec.fromMap(Map fields, this._sources, {String expectedName,
       Uri location})
-      : fields = fields is YamlMap ? fields : new YamlMap.wrap(fields,
-          sourceName: location == null ? null : location.toString()) {
+      : fields = fields is YamlMap ? fields :
+            new YamlMap.wrap(fields, sourceUrl: location) {
     // If [expectedName] is passed, ensure that the actual 'name' field exists
     // and matches the expectation.
     if (expectedName == null) return;
     if (name == expectedName) return;
 
     throw new PubspecException('"name" field doesn\'t match expected name '
         '"$expectedName".', this.fields.nodes["name"].span);
   }
 
   /// Parses the pubspec stored at [filePath] whose text is [contents].
   ///
   /// If the pubspec doesn't define a version for itself, it defaults to
   /// [Version.none].
   factory Pubspec.parse(String contents, SourceRegistry sources,
       {String expectedName, Uri location}) {
     if (contents.trim() == '') return new Pubspec.empty();
 
-    var pubspecNode = loadYamlNode(contents, sourceName: location.toString());
+    var pubspecNode = loadYamlNode(contents, sourceUrl: location);
     if (pubspecNode is YamlScalar && pubspecNode.value == null) {
       pubspecNode = new YamlMap();
     } else if (pubspecNode is! YamlMap) {
       throw new PubspecException(
           'The pubspec must be a YAML mapping.', pubspecNode.span);
     }
 
     return new Pubspec.fromMap(pubspecNode, sources,
         expectedName: expectedName, location: location);
   }
@@ skipping 134 matching lines @@
         'appear in both "dependencies" and "dev_dependencies".',
         span);
   }
 
   /// Runs [fn] and wraps any [FormatException] it throws in a
   /// [PubspecException].
   ///
   /// [description] should be a noun phrase that describes whatever's being
   /// parsed or processed by [fn]. [span] should be the location of whatever's
   /// being processed within the pubspec.
-  _wrapFormatException(String description, Span span, fn()) {
+  _wrapFormatException(String description, SourceSpan span, fn()) {
     try {
       return fn();
     } on FormatException catch (e) {
       _error('Invalid $description: ${e.message}', span);
     }
   }
 
   _wrapSpanFormatException(String description, fn()) {
     try {
       return fn();
-    } on SpanFormatException catch (e) {
+    } on SourceSpanFormatException catch (e) {
       _error('Invalid $description: ${e.message}', e.span);
     }
   }
 
   /// Throws a [PubspecException] with the given message.
-  void _error(String message, Span span) {
+  void _error(String message, SourceSpan span) {
     var name;
     try {
       name = this.name;
     } on PubspecException catch (_) {
       // [name] is null.
     }
 
     throw new PubspecException(message, span);
   }
 }
 
 /// The environment-related metadata in the pubspec.
 ///
 /// Corresponds to the data under the "environment:" key in the pubspec.
 class PubspecEnvironment {
   /// The version constraint specifying which SDK versions this package works
   /// with.
   final VersionConstraint sdkVersion;
 
   PubspecEnvironment([VersionConstraint sdk])
       : sdkVersion = sdk != null ? sdk : VersionConstraint.any;
 }
 
 /// An exception thrown when parsing a pubspec.
 ///
 /// These exceptions are often thrown lazily while accessing pubspec properties.
-class PubspecException extends SpanFormatException
+class PubspecException extends SourceSpanFormatException
     implements ApplicationException {
-  PubspecException(String message, Span span)
+  PubspecException(String message, SourceSpan span)
       : super(message, span);
 }
 
 /// Returns whether [uri] is a file URI.
 ///
 /// This is slightly more complicated than just checking if the scheme is
 /// 'file', since relative URIs also refer to the filesystem on the VM.
 bool _isFileUri(Uri uri) => uri.scheme == 'file' || uri.scheme == '';