Add utilities for creating SourceChanges

pkg/analysis_server/lib/utilities/change_builder_core.dart

Index: pkg/analysis_server/lib/utilities/change_builder_core.dart
diff --git a/pkg/analysis_server/lib/utilities/change_builder_core.dart b/pkg/analysis_server/lib/utilities/change_builder_core.dart
new file mode 100644
index 0000000000000000000000000000000000000000..7c69c462dc9940788abe2daf9196ad73928ae2c1
--- /dev/null
+++ b/pkg/analysis_server/lib/utilities/change_builder_core.dart
@@ -0,0 +1,123 @@
+// Copyright (c) 2015, 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 analysis_server.utilities.change_builder_core;
+
+import 'package:analysis_server/src/utilities/change_builder_core.dart';
+import 'package:analysis_server/src/protocol.dart';
+import 'package:analyzer/src/generated/source.dart';
+
+/**
+ * A builder used to build a [SourceChange].
+ *
+ * Clients are not expected to subtype this class.
+ */
+abstract class ChangeBuilder {
+  /**
+   * Initialize a newly created change builder.
+   */
+  factory ChangeBuilder() = ChangeBuilderImpl;
+
+  /**
+   * Return the source change that was built.
+   */
+  SourceChange get sourceChange;
+
+  /**
+   * Use the [buildFileEdit] function to create a collection of edits to the
+   * given [source]. The edits will be added to the source change that is being
+   * built. The [timeStamp] is the time at which the [source] was last modified
+   * and is used by clients to ensure that it is safe to apply the edits.
+   */
+  void addFileEdit(Source source, int timeStamp,
+      void buildFileEdit(FileEditBuilder builder));
+}
+
+/**
+ * A builder used to build a [SourceEdit] as part of a [SourceFileEdit].
+ *
+ * Clients are not expected to subtype this class.
+ */
+abstract class EditBuilder {
+  /**
+   * Add a region of text that is part of the linked edit group with the given
+   * [groupName]. The [buildLinkedEdit] function is used to write the content of
+   * the region of text and to add suggestions for other possible values for
+   * that region.
+   */
+  void addLinkedEdit(
+      String groupName, void buildLinkedEdit(LinkedEditBuilder builder));
+
+  /**
+   * Add the given [string] to the content of the current edit.
+   */
+  void write(String string);
+
+  /**
+   * Add the given [string] to the content of the current edit and then add an
+   * end-of-line marker.
+   */
+  void writeln([String string]);
+}
+
+/**
+ * A builder used to build a [SourceFileEdit] within a [SourceChange].
+ *
+ * Clients are not expected to subtype this class.
+ */
+abstract class FileEditBuilder {
+  /**
+   * Add an insertion of text at the given [offset]. The [offset] is relative to
+   * the original source. The [buildEdit] function is used to write the text to
+   * be inserted. This is fully equivalent to
+   *
+   *     addReplacement(offset, 0, buildEdit);
+   */
+  void addInsertion(int offset, void buildEdit(EditBuilder builder));
+
+  /**
+   * Add the region of text starting at the given [offset] and continuing for
+   * the given [length] to the linked edit group with the given [groupName].
+   * The [offset] is relative to the original source. This is typically used to

[Paul Berry, 2015/05/04 16:00:29]

This seems incorrect to me.  The implementation of addLinkedPosition uses the
offset to populate a Position in a LinkedEditGroup.  According to the API
specification, a LinkedEditGroup is:

A collection of positions that should be linked (edited simultaneously) for the
purposes of updating code after a source change. For example, if a set of edits
introduced a new variable name, the group would contain all of the positions of
the variable name so that if the client wanted to let the user edit the variable
name after the operation, all occurrences of the name could be edited
simultaneously.

So it seems to me that the offset has to be relative to the state of the
document as it will appear after all the edits have been applied.  Otherwise it
couldn't possibly refer to the positions of variable names that have been
introduced.  Am I misunderstanding?

+   * include pre-existing regions of text in a group.
+   */
+  void addLinkedPosition(int offset, int length, String groupName);
+
+  /**
+   * Add a replacement of text starting at the given [offset] and continuing for
+   * the given [length]. The [offset] is relative to the original source. The
+   * [buildEdit] function is used to write the text that will replace the
+   * specified region.
+   */
+  void addReplacement(
+      int offset, int length, void buildEdit(EditBuilder builder));
+}
+
+/**
+ * A builder used to build a [LinkedEdit] region within an edit.
+ *
+ * Clients are not expected to subtype this class.
+ */
+abstract class LinkedEditBuilder {
+  /**
+   * Add the given [value] as a suggestion with the given [kind].
+   */
+  void addSuggestion(LinkedEditSuggestionKind kind, String value);
+
+  /**
+   * Add each of the given [values] as a suggestion with the given [kind].
+   */
+  void addSuggestions(LinkedEditSuggestionKind kind, Iterable<String> values);
+
+  /**
+   * Add the given [string] to the content of the current edit.
+   */
+  void write(String string);
+
+  /**
+   * Add the given [string] to the content of the current edit and then add an
+   * end-of-line marker.
+   */
+  void writeln([String string]);
+}