[clangd] Expose offset <-> LSP position functions, and fix bugs

Summary:
- Moved these functions to SourceCode.h
- added unit tests
- fix off by one in positionToOffset: Offset - 1 in final calculation was wrong
- fixed formatOnType which had an equal and opposite off-by-one
- positionToOffset and offsetToPosition both consistently clamp to beginning/end
  of file when input is out of range
- gave variables more descriptive names
- removed windows line ending fixmes where there is nothing to fix
- elaborated on UTF-8 fixmes

This will conflict with Eric's D41281, but in a pretty easy-to-resolve way.

Reviewers: ioeric

Subscribers: klimek, mgorny, ilya-biryukov, cfe-commits

Differential Revision: https://reviews.llvm.org/D41351

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@321073 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 78 insertions, 0 deletions

diff --git a/unittests/clangd/CMakeLists.txt b/unittests/clangd/CMakeLists.txt
index 2c514e96..36853a17 100644
--- a/unittests/clangd/CMakeLists.txt
+++ b/unittests/clangd/CMakeLists.txt
@@ -18,6 +18,7 @@ add_extra_unittest(ClangdTests
   JSONExprTests.cpp
   TestFS.cpp
   TraceTests.cpp
+  SourceCodeTests.cpp
   SymbolCollectorTests.cpp
   )
 
diff --git a/unittests/clangd/CodeCompleteTests.cpp b/unittests/clangd/CodeCompleteTests.cpp
index ae2fe27a..8ba9ebb3 100644
--- a/unittests/clangd/CodeCompleteTests.cpp
+++ b/unittests/clangd/CodeCompleteTests.cpp
@@ -11,6 +11,7 @@
 #include "Context.h"
 #include "Matchers.h"
 #include "Protocol.h"
+#include "SourceCode.h"
 #include "TestFS.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
diff --git a/unittests/clangd/SourceCodeTests.cpp b/unittests/clangd/SourceCodeTests.cpp
new file mode 100644
index 00000000..bc64276d
--- /dev/null
+++ b/unittests/clangd/SourceCodeTests.cpp
@@ -0,0 +1,76 @@
+//===-- SourceCodeTests.cpp  ------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "SourceCode.h"
+#include "llvm/Support/raw_os_ostream.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace clang{
+namespace clangd {
+void PrintTo(const Position &P, std::ostream *O) {
+  llvm::raw_os_ostream OS(*O);
+  OS << toJSON(P);
+}
+namespace {
+
+MATCHER_P2(Pos, Line, Col, "") {
+  return arg.line == Line && arg.character == Col;
+}
+
+const char File[] = R"(0:0 = 0
+1:0 = 8
+2:0 = 16)";
+
+TEST(SourceCodeTests, PositionToOffset) {
+  // line out of bounds
+  EXPECT_EQ(0u, positionToOffset(File, Position{-1, 2}));
+  // first line
+  EXPECT_EQ(0u, positionToOffset(File, Position{0, -1})); // out of range
+  EXPECT_EQ(0u, positionToOffset(File, Position{0, 0})); // first character
+  EXPECT_EQ(3u, positionToOffset(File, Position{0, 3})); // middle character
+  EXPECT_EQ(6u, positionToOffset(File, Position{0, 6})); // last character
+  EXPECT_EQ(7u, positionToOffset(File, Position{0, 7})); // the newline itself
+  EXPECT_EQ(8u, positionToOffset(File, Position{0, 8})); // out of range
+  // middle line
+  EXPECT_EQ(8u, positionToOffset(File, Position{1, -1})); // out of range
+  EXPECT_EQ(8u, positionToOffset(File, Position{1, 0})); // first character
+  EXPECT_EQ(11u, positionToOffset(File, Position{1, 3})); // middle character
+  EXPECT_EQ(14u, positionToOffset(File, Position{1, 6})); // last character
+  EXPECT_EQ(15u, positionToOffset(File, Position{1, 7})); // the newline itself
+  EXPECT_EQ(16u, positionToOffset(File, Position{1, 8})); // out of range
+  // last line
+  EXPECT_EQ(16u, positionToOffset(File, Position{2, -1})); // out of range
+  EXPECT_EQ(16u, positionToOffset(File, Position{2, 0})); // first character
+  EXPECT_EQ(19u, positionToOffset(File, Position{2, 3})); // middle character
+  EXPECT_EQ(23u, positionToOffset(File, Position{2, 7})); // last character
+  EXPECT_EQ(24u, positionToOffset(File, Position{2, 8})); // EOF
+  EXPECT_EQ(24u, positionToOffset(File, Position{2, 9})); // out of range
+  // line out of bounds
+  EXPECT_EQ(24u, positionToOffset(File, Position{3, 1}));
+}
+
+TEST(SourceCodeTests, OffsetToPosition) {
+  EXPECT_THAT(offsetToPosition(File, 0), Pos(0, 0)) << "start of file";
+  EXPECT_THAT(offsetToPosition(File, 3), Pos(0, 3)) << "in first line";
+  EXPECT_THAT(offsetToPosition(File, 6), Pos(0, 6)) << "end of first line";
+  EXPECT_THAT(offsetToPosition(File, 7), Pos(0, 7)) << "first newline";
+  EXPECT_THAT(offsetToPosition(File, 8), Pos(1, 0)) << "start of second line";
+  EXPECT_THAT(offsetToPosition(File, 11), Pos(1, 3)) << "in second line";
+  EXPECT_THAT(offsetToPosition(File, 14), Pos(1, 6)) << "end of second line";
+  EXPECT_THAT(offsetToPosition(File, 15), Pos(1, 7)) << "second newline";
+  EXPECT_THAT(offsetToPosition(File, 16), Pos(2, 0)) << "start of last line";
+  EXPECT_THAT(offsetToPosition(File, 19), Pos(2, 3)) << "in last line";
+  EXPECT_THAT(offsetToPosition(File, 23), Pos(2, 7)) << "end of last line";
+  EXPECT_THAT(offsetToPosition(File, 24), Pos(2, 8)) << "EOF";
+  EXPECT_THAT(offsetToPosition(File, 25), Pos(2, 8)) << "out of bounds";
+}
+
+} // namespace
+} // namespace clangd
+} // namespace clang