On type formatting

src/Analysis/Engine/Impl/Infrastructure/TextBuilder.cs

@@ -0,0 +1,59 @@
+// Python Tools for Visual Studio
+// Copyright(c) Microsoft Corporation
+// All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the License); you may not use
+// this file except in compliance with the License. You may obtain a copy of the
+// License at http://www.apache.org/licenses/LICENSE-2.0
+//
+// THIS CODE IS PROVIDED ON AN  *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS
+// OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY
+// IMPLIED WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+// MERCHANTABLITY OR NON-INFRINGEMENT.
+//
+// See the Apache Version 2.0 License for specific language governing
+// permissions and limitations under the License.
+
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Microsoft.PythonTools.Analysis.Infrastructure {
+    internal class TextBuilder {
+        private readonly List<string> _segments = new List<string>();
+
+        public override string ToString() {
+            IEnumerable<string> seq = _segments;
+            if (IsLastWhitespace()) {
+                // Don't mutate when producing the string.
+                seq = _segments.Take(_segments.Count - 1);
+            }
+            return string.Concat(seq);
+        }
+
+        public void Append(string s) => _segments.Add(s);
+
+        public void Append(object o) => _segments.Add(o.ToString());
+
+        /// <summary>
+        /// "Soft" append a space to the text. If the most recent appended item
+        /// was whitespace, then nothing is added.
+        /// </summary>
+        /// <param name="count">How many spaces to append.</param>
+        /// <param name="allowLeading">True if spacing can be appended as the first item.</param>
+        public void SoftAppendSpace(int count = 1, bool allowLeading = false) {
+            if (_segments.Count == 0 && !allowLeading) {
+                return;
+            }
+
+            if (IsLastWhitespace()) {
+                count--;
+            }
+
+            for (var i = 0; i < count; i++) {
+                _segments.Add(" ");
+            }
+        }
+
+        private bool IsLastWhitespace() => _segments.Count != 0 && string.IsNullOrWhiteSpace(_segments.Last());
+    }
+}

src/Analysis/Engine/Test/LanguageServerTests.cs

@@ -992,6 +992,19 @@ public async Task ParseAndAnalysisDiagnostics() {
             );
         }
 
+        [TestMethod, Priority(0)]
+        public async Task OnTypeFormatting() {
+            var s = await CreateServer();
+
+            var mod = await AddModule(s, "def foo  ( ) :\n    x = a + b\n    x+= 1");
+
+            // Extended tests for line formatting are in LineFormatterTests.
+            // These just verify that the language server formats and returns something correct.
+            await AssertLineFormat(s, mod, 1, "\n", "def foo():", new SourceLocation(1, 1), new SourceLocation(1, 15));
+            await AssertLineFormat(s, mod, 2, "\n", "x = a + b", new SourceLocation(2, 5), new SourceLocation(2, 14));
+            await AssertLineFormat(s, mod, 3, "\n", "x += 1", new SourceLocation(3, 5), new SourceLocation(3, 10));
+        }
+
         class GetAllExtensionProvider : ILanguageServerExtensionProvider {
             public Task<ILanguageServerExtension> CreateAsync(IPythonLanguageServer server, IReadOnlyDictionary<string, object> properties, CancellationToken cancellationToken) {
                 return Task.FromResult<ILanguageServerExtension>(new GetAllExtension((Server)server, properties));
@@ -1185,6 +1198,22 @@ public static async Task AssertReferences(Server s, TextDocumentIdentifier docum
             refs.Select(r => $"{r._kind ?? ReferenceKind.Reference};{r.range}").Should().Contain(contains).And.NotContain(excludes);
         }
 
+        public static async Task AssertLineFormat(Server s, TextDocumentIdentifier document, int line, string ch, string newText, SourceLocation start, SourceLocation end) {
+            var edits = await s.DocumentOnTypeFormatting(new DocumentOnTypeFormattingParams {
+                textDocument = document,
+                ch = ch,
+                position = new SourceLocation(line+1, 1)
+            }, CancellationToken.None);
+
+            edits.Should().OnlyContain(new TextEdit {
+                newText = newText,
+                range = new Range {
+                    start = start,
+                    end = end
+                }
+            });
+        }
+
         public Task<ILanguageServerExtension> CreateAsync(IPythonLanguageServer server, IReadOnlyDictionary<string, object> properties, CancellationToken cancellationToken) => throw new NotImplementedException();
     }