Change to accommade Angular plugin and finalize removal of dependency to analysis_server

pkg/analyzer_plugin/lib/src/utilities/completion/replacement_range.dart

+// Copyright (c) 2017, 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/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/standard_ast_factory.dart';
+import 'package:analyzer/dart/ast/token.dart';
+import 'package:analyzer/src/dart/ast/token.dart';
+import 'package:analyzer_plugin/src/utilities/completion/completion_target.dart';
+
+/**
+ * Utility class for computing the code completion replacement range
+ */
+class ReplacementRange {
+  int offset;
+  int length;
+
+  ReplacementRange(this.offset, this.length);
+
+  factory ReplacementRange.compute(int requestOffset, CompletionTarget target) {
+    bool isKeywordOrIdentifier(Token token) =>
+        token.type.isKeyword || token.type == TokenType.IDENTIFIER;
+
+    //TODO(danrubel) Ideally this needs to be pushed down into the contributors
+    // but that implies that each suggestion can have a different
+    // replacement offsent/length which would mean an API change
+
+    var entity = target.entity;
+    Token token = entity is AstNode ? entity.beginToken : entity;
+    if (token != null && requestOffset < token.offset) {
+      token = token.previous;
+    }
+    if (token != null) {
+      if (requestOffset == token.offset && !isKeywordOrIdentifier(token)) {
+        // If the insertion point is at the beginning of the current token
+        // and the current token is not an identifier
+        // then check the previous token to see if it should be replaced
+        token = token.previous;
+      }
+      if (token != null && isKeywordOrIdentifier(token)) {
+        if (token.offset <= requestOffset && requestOffset <= token.end) {
+          // Replacement range for typical identifier completion
+          return new ReplacementRange(token.offset, token.length);
+        }
+      }
+      if (token is StringToken) {
+        SimpleStringLiteral uri =
+            astFactory.simpleStringLiteral(token, token.lexeme);
+        Keyword keyword = token.previous?.keyword;
+        if (keyword == Keyword.IMPORT ||
+            keyword == Keyword.EXPORT ||
+            keyword == Keyword.PART) {
+          int start = uri.contentsOffset;
+          var end = uri.contentsEnd;
+          if (start <= requestOffset && requestOffset <= end) {
+            // Replacement range for import URI
+            return new ReplacementRange(start, end - start);
+          }
+        }
+      }
+    }
+    return new ReplacementRange(requestOffset, 0);
+  }
+}