From c83b9eab7717b254d396d919cc5468141dac569e Mon Sep 17 00:00:00 2001
From: Jacob Dufault <jacobdufault@gmail.com>
Date: Sat, 29 Jul 2017 21:13:22 -0700
Subject: [PATCH] Fix issue when buffer contents do not get synced properly
 near start of file

---
 src/lex_utils.cc     | 19 ++++++++++++++++---
 src/working_files.cc | 10 ++++++++--
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/src/lex_utils.cc b/src/lex_utils.cc
index 112743d1..a2ed2e69 100644
--- a/src/lex_utils.cc
+++ b/src/lex_utils.cc
@@ -17,7 +17,7 @@ int GetOffsetForPosition(lsPosition position, const std::string& content) {
     ++offset;
   }
 
-  return std::min<int>(offset + position.character, content.size() - 1);
+  return std::min<int>(offset + position.character, content.size());
 }
 
 lsPosition CharPos(const std::string& search, char character, int character_offset) {
@@ -211,10 +211,23 @@ bool SubstringMatch(const std::string& search, const std::string& content) {
 
 TEST_SUITE("Offset");
 
-TEST_CASE("over range") {
+TEST_CASE("past end") {
   std::string content = "foo";
   int offset = GetOffsetForPosition(lsPosition(10, 10), content);
-  REQUIRE(offset < content.size());
+  REQUIRE(offset <= content.size());
+}
+
+TEST_CASE("in middle of content") {
+  std::string content = "abcdefghijk";
+  for (int i = 0; i < content.size(); ++i) {
+    int offset = GetOffsetForPosition(lsPosition(0, i), content);
+    REQUIRE(i == offset);
+  }
+}
+
+TEST_CASE("at end of content") {
+  REQUIRE(GetOffsetForPosition(lsPosition(0, 0), "") == 0);
+  REQUIRE(GetOffsetForPosition(lsPosition(0, 1), "a") == 1);
 }
 
 TEST_SUITE_END();
diff --git a/src/working_files.cc b/src/working_files.cc
index 8fea96a4..736c747a 100644
--- a/src/working_files.cc
+++ b/src/working_files.cc
@@ -308,24 +308,30 @@ void WorkingFiles::OnChange(const Ipc_TextDocumentDidChange::Params& change) {
   }
 
   file->version = change.textDocument.version;
+  // std::cerr << "!!!!!!!!!!!!!!!!!!!!!!!!!" << std::endl;
   //std::cerr << "VERSION " << change.textDocument.version << std::endl;
 
   for (const Ipc_TextDocumentDidChange::lsTextDocumentContentChangeEvent& diff : change.contentChanges) {
-    //std::cerr << "Applying rangeLength=" << diff.rangeLength;
-
+    // std::cerr << "|" << file->buffer_content << "|" << std::endl;
     // If range or rangeLength are emitted we replace everything, per the spec.
     if (diff.rangeLength == -1) {
       file->buffer_content = diff.text;
       file->OnBufferContentUpdated();
+      // std::cerr << "-> Replacing entire content";
     }
     else {
       int start_offset = GetOffsetForPosition(diff.range.start, file->buffer_content);
+      // std::cerr << "-> Applying diff start=" << diff.range.start.ToString() << ", end=" << diff.range.end.ToString() << ", start_offset=" << start_offset << std::endl;
       file->buffer_content.replace(file->buffer_content.begin() + start_offset,
         file->buffer_content.begin() + start_offset + diff.rangeLength,
         diff.text);
       file->OnBufferContentUpdated();
     }
+
+    // std::cerr << "|" << file->buffer_content << "|" << std::endl;
   }
+  // std::cerr << "!!!!!!!!!!!!!!!!!!!!!!!!!" << std::endl;
+
   //std::cerr << std::endl << std::endl << "--------" << file->content << "--------" << std::endl << std::endl;
 }