From 08c5e770fcd8d985830c6b34b138fca6b5ce8855 Mon Sep 17 00:00:00 2001
From: ddovod <ddovod@gmail.com>
Date: Tue, 28 Aug 2018 09:10:47 +0300
Subject: [PATCH 1/6] adding 3 more options for completion scoring

---
 .gitmodules                              |  3 ++
 CMakeLists.txt                           |  3 ++
 src/completion_matcher.h                 | 10 +++++++
 src/config.h                             |  6 +++-
 src/fts_match.cc                         | 20 +++++++++++++
 src/fts_match.h                          | 13 ++++++++
 src/fuzzy_match.cc                       |  9 ++++++
 src/fuzzy_match.h                        |  7 +++--
 src/messages/text_document_completion.cc | 25 +++++++++++-----
 src/prefix_match.cc                      | 38 ++++++++++++++++++++++++
 src/prefix_match.h                       | 14 +++++++++
 third_party/lib_fts                      |  1 +
 12 files changed, 138 insertions(+), 11 deletions(-)
 create mode 100644 src/completion_matcher.h
 create mode 100644 src/fts_match.cc
 create mode 100644 src/fts_match.h
 create mode 100644 src/prefix_match.cc
 create mode 100644 src/prefix_match.h
 create mode 160000 third_party/lib_fts

diff --git a/.gitmodules b/.gitmodules
index 211365bfa..0172f592e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -19,3 +19,6 @@
 [submodule "third_party/reproc"]
 	path = third_party/reproc
 	url = https://github.com/DaanDeMeyer/reproc.git
+[submodule "third_party/lib_fts"]
+	path = third_party/lib_fts
+	url = https://github.com/forrestthewoods/lib_fts.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5c54eae41..5b5c0c3a4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -156,6 +156,7 @@ target_include_directories(cquery PRIVATE
   third_party/pugixml/src
   third_party/rapidjson/include
   third_party/sparsepp
+  third_party/lib_fts/code
 )
 
 ### Install
@@ -304,6 +305,8 @@ target_sources(cquery PRIVATE
   src/file_contents.cc
   src/file_types.cc
   src/fuzzy_match.cc
+  src/fts_match.cc
+  src/prefix_match.cc
   src/iindexer.cc
   src/import_manager.cc
   src/import_pipeline.cc
diff --git a/src/completion_matcher.h b/src/completion_matcher.h
new file mode 100644
index 000000000..d773d512e
--- /dev/null
+++ b/src/completion_matcher.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <string_view.h>
+
+class CompletionMatcher {
+ public:
+  // virtual ~CompletionMatcher() = default; // don't know why but it crashed if I uncomment this like, investigating
+  virtual int Match(std::string_view text) = 0;
+  virtual int MinScore() const = 0;
+};
diff --git a/src/config.h b/src/config.h
index 3867ffe5c..99d98aae7 100644
--- a/src/config.h
+++ b/src/config.h
@@ -156,6 +156,9 @@ struct Config {
     // For example, to hide all files in a /CACHE/ folder, use ".*/CACHE/.*"
     std::vector<std::string> includeBlacklist;
     std::vector<std::string> includeWhitelist;
+
+    //
+    std::string matcherType = "cqueryMatcher";
   };
   Completion completion;
 
@@ -261,7 +264,8 @@ MAKE_REFLECT_STRUCT(Config::Completion,
                     includeMaxPathSize,
                     includeSuffixWhitelist,
                     includeBlacklist,
-                    includeWhitelist);
+                    includeWhitelist,
+                    matcherType);
 MAKE_REFLECT_STRUCT(Config::Formatting, enabled)
 MAKE_REFLECT_STRUCT(Config::Diagnostics,
                     blacklist,
diff --git a/src/fts_match.cc b/src/fts_match.cc
new file mode 100644
index 000000000..c10c526ba
--- /dev/null
+++ b/src/fts_match.cc
@@ -0,0 +1,20 @@
+#include "fts_match.h"
+
+#define FTS_FUZZY_MATCH_IMPLEMENTATION 1
+#include <fts_fuzzy_match.h>
+
+FtsMatcher::FtsMatcher(std::string_view pattern) {
+  original_pattern = pattern;
+}
+
+int FtsMatcher::Match(std::string_view text) {
+  int result = 0;
+  if (fts::fuzzy_match(original_pattern.data(), text.data(), result)) {
+    return result;
+  }
+  return MinScore();
+}
+
+int FtsMatcher::MinScore() const {
+  return -100000;
+}
diff --git a/src/fts_match.h b/src/fts_match.h
new file mode 100644
index 000000000..d98fcad7b
--- /dev/null
+++ b/src/fts_match.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include "completion_matcher.h"
+
+class FtsMatcher : public CompletionMatcher {
+ public:
+  FtsMatcher(std::string_view pattern);
+  int Match(std::string_view text) override;
+  int MinScore() const override;
+
+ private:
+  std::string_view original_pattern;
+};
diff --git a/src/fuzzy_match.cc b/src/fuzzy_match.cc
index 6e271665d..6f8670a57 100644
--- a/src/fuzzy_match.cc
+++ b/src/fuzzy_match.cc
@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <algorithm>
 #include <vector>
+#include "lex_utils.h"
 
 enum CharClass { Other, Lower, Upper };
 enum CharRole { None, Tail, Head };
@@ -73,6 +74,7 @@ int FuzzyMatcher::MatchScore(int i, int j, bool last) {
 }
 
 FuzzyMatcher::FuzzyMatcher(std::string_view pattern) {
+  original_pattern = pattern;
   CalculateRoles(pattern, pat_role, &pat_set);
   size_t n = 0;
   for (size_t i = 0; i < pattern.size(); i++)
@@ -85,6 +87,9 @@ FuzzyMatcher::FuzzyMatcher(std::string_view pattern) {
 }
 
 int FuzzyMatcher::Match(std::string_view text) {
+  if (!CaseFoldingSubsequenceMatch(original_pattern, text).first) {
+    return MinScore();
+  }
   int n = int(text.size());
   if (n > kMaxText)
     return kMinScore + 1;
@@ -123,6 +128,10 @@ int FuzzyMatcher::Match(std::string_view text) {
   return ret;
 }
 
+int FuzzyMatcher::MinScore() const {
+  return kMinScore;
+}
+
 TEST_SUITE("fuzzy_match") {
   bool Ranks(std::string_view pat, std::vector<const char*> texts) {
     FuzzyMatcher fuzzy(pat);
diff --git a/src/fuzzy_match.h b/src/fuzzy_match.h
index 336815b72..925b5c578 100644
--- a/src/fuzzy_match.h
+++ b/src/fuzzy_match.h
@@ -4,8 +4,9 @@
 
 #include <limits.h>
 #include <string>
+#include "completion_matcher.h"
 
-class FuzzyMatcher {
+class FuzzyMatcher : public CompletionMatcher {
  public:
   constexpr static int kMaxPat = 100;
   constexpr static int kMaxText = 200;
@@ -14,9 +15,11 @@ class FuzzyMatcher {
   constexpr static int kMinScore = INT_MIN / 4;
 
   FuzzyMatcher(std::string_view pattern);
-  int Match(std::string_view text);
+  int Match(std::string_view text) override;
+  int MinScore() const override;
 
  private:
+  std::string_view original_pattern;
   std::string pat;
   std::string_view text;
   int pat_set, text_set;
diff --git a/src/messages/text_document_completion.cc b/src/messages/text_document_completion.cc
index 7cd8a252b..2d7edb2ba 100644
--- a/src/messages/text_document_completion.cc
+++ b/src/messages/text_document_completion.cc
@@ -1,11 +1,14 @@
 #include "clang_complete.h"
 #include "code_complete_cache.h"
 #include "fuzzy_match.h"
+#include "fts_match.h"
+#include "prefix_match.h"
 #include "include_complete.h"
 #include "message_handler.h"
 #include "queue_manager.h"
 #include "timer.h"
 #include "working_files.h"
+#include "config.h"
 
 #include "lex_utils.h"
 
@@ -221,17 +224,23 @@ void FilterAndSortCompletionResponse(
       item.filterText = item.label;
   }
 
-  // Fuzzy match and remove awful candidates.
-  FuzzyMatcher fuzzy(complete_text);
+  // Match and remove awful candidates.
+  std::unique_ptr<CompletionMatcher> matcher;
+  if (g_config->completion.matcherType == "cqueryMatcher") {
+    matcher = std::make_unique<FuzzyMatcher>(complete_text);
+  } else if (g_config->completion.matcherType == "ftsMatcher") {
+    matcher = std::make_unique<FtsMatcher>(complete_text);
+  } else if (g_config->completion.matcherType == "caseSensitivePrefixMatcher") {
+    matcher = std::make_unique<PrefixMatcher>(complete_text, true);
+  } else if (g_config->completion.matcherType == "caseInsensitivePrefixMatcher") {
+    matcher = std::make_unique<PrefixMatcher>(complete_text, false);
+  }
   for (auto& item : items) {
-    item.score_ =
-        CaseFoldingSubsequenceMatch(complete_text, *item.filterText).first
-            ? fuzzy.Match(*item.filterText)
-            : FuzzyMatcher::kMinScore;
+    item.score_ = matcher->Match(*item.filterText);
   }
   items.erase(std::remove_if(items.begin(), items.end(),
-                             [](const lsCompletionItem& item) {
-                               return item.score_ <= FuzzyMatcher::kMinScore;
+                             [&matcher](const lsCompletionItem& item) {
+                               return item.score_ <= matcher->MinScore();
                              }),
               items.end());
   std::sort(items.begin(), items.end(),
diff --git a/src/prefix_match.cc b/src/prefix_match.cc
new file mode 100644
index 000000000..878b2bc98
--- /dev/null
+++ b/src/prefix_match.cc
@@ -0,0 +1,38 @@
+#include "prefix_match.h"
+
+#include <algorithm>
+
+namespace {
+    bool StartsWith(std::string_view text, std::string_view prefix) {
+      return text.find(prefix) == 0;
+    }
+
+    bool StartsWithIgnoreCase(std::string_view text, std::string_view prefix) {
+      auto min_length = std::min(text.size(), prefix.size());
+      if (min_length == 0) {
+        return false;
+      }
+      return std::equal(
+          text.begin(), text.begin() + min_length,
+          prefix.begin(), prefix.begin() + min_length,
+          [](char ch1, char ch2) { return std::toupper(ch1) == std::toupper(ch2); }
+          );
+    }
+}
+
+PrefixMatcher::PrefixMatcher(std::string_view pattern, bool case_sensitive) {
+  original_pattern = pattern;
+  this->case_sensitive = case_sensitive;
+}
+
+int PrefixMatcher::Match(std::string_view text) {
+  if (case_sensitive) {
+    return ::StartsWith(text, original_pattern) ? 1 : MinScore();
+  } else {
+    return ::StartsWithIgnoreCase(text, original_pattern) ? 1 : MinScore();
+  }
+}
+
+int PrefixMatcher::MinScore() const {
+  return -1;
+}
diff --git a/src/prefix_match.h b/src/prefix_match.h
new file mode 100644
index 000000000..b23503e7e
--- /dev/null
+++ b/src/prefix_match.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "completion_matcher.h"
+
+class PrefixMatcher : public CompletionMatcher {
+ public:
+  PrefixMatcher(std::string_view pattern, bool case_sensitive);
+  int Match(std::string_view text) override;
+  int MinScore() const override;
+
+ private:
+  std::string_view original_pattern;
+  bool case_sensitive;
+};
diff --git a/third_party/lib_fts b/third_party/lib_fts
new file mode 160000
index 000000000..80f3f8c52
--- /dev/null
+++ b/third_party/lib_fts
@@ -0,0 +1 @@
+Subproject commit 80f3f8c52db53428247e741b9efe2cde9667050c

From db1bf88d262b758771e8d2df8f34bcb2bb3b7302 Mon Sep 17 00:00:00 2001
From: davidd <davidd@zeptolab.com>
Date: Tue, 28 Aug 2018 10:32:07 +0300
Subject: [PATCH 2/6] fixing compilation issues

---
 src/fts_match.cc    | 3 +++
 src/prefix_match.cc | 1 +
 2 files changed, 4 insertions(+)

diff --git a/src/fts_match.cc b/src/fts_match.cc
index c10c526ba..147d3e5db 100644
--- a/src/fts_match.cc
+++ b/src/fts_match.cc
@@ -1,7 +1,10 @@
 #include "fts_match.h"
 
 #define FTS_FUZZY_MATCH_IMPLEMENTATION 1
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
 #include <fts_fuzzy_match.h>
+#pragma clang diagnostic pop
 
 FtsMatcher::FtsMatcher(std::string_view pattern) {
   original_pattern = pattern;
diff --git a/src/prefix_match.cc b/src/prefix_match.cc
index 878b2bc98..a80a81231 100644
--- a/src/prefix_match.cc
+++ b/src/prefix_match.cc
@@ -1,6 +1,7 @@
 #include "prefix_match.h"
 
 #include <algorithm>
+#include <cctype>
 
 namespace {
     bool StartsWith(std::string_view text, std::string_view prefix) {

From 40a2f8ace2234ec6a2d6d2af7c263ddde7b113f1 Mon Sep 17 00:00:00 2001
From: ddovod <ddovod@gmail.com>
Date: Sat, 1 Sep 2018 21:46:04 +0300
Subject: [PATCH 3/6] adding virtual dtor to CompletionMatcher

---
 src/completion_matcher.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/completion_matcher.h b/src/completion_matcher.h
index d773d512e..d69c47742 100644
--- a/src/completion_matcher.h
+++ b/src/completion_matcher.h
@@ -4,7 +4,7 @@
 
 class CompletionMatcher {
  public:
-  // virtual ~CompletionMatcher() = default; // don't know why but it crashed if I uncomment this like, investigating
+  virtual ~CompletionMatcher() = default;
   virtual int Match(std::string_view text) = 0;
   virtual int MinScore() const = 0;
 };

From 4d53c1d06a4fd936a59906cd9eeaf1411086eec6 Mon Sep 17 00:00:00 2001
From: ddovod <ddovod@gmail.com>
Date: Sat, 1 Sep 2018 21:48:02 +0300
Subject: [PATCH 4/6] using string utilities from utils.h

---
 src/prefix_match.cc | 19 +------------------
 src/utils.cc        |  6 ++++++
 src/utils.h         |  3 ++-
 3 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/src/prefix_match.cc b/src/prefix_match.cc
index 878b2bc98..621db8fbe 100644
--- a/src/prefix_match.cc
+++ b/src/prefix_match.cc
@@ -1,25 +1,8 @@
 #include "prefix_match.h"
 
+#include "utils.h"
 #include <algorithm>
 
-namespace {
-    bool StartsWith(std::string_view text, std::string_view prefix) {
-      return text.find(prefix) == 0;
-    }
-
-    bool StartsWithIgnoreCase(std::string_view text, std::string_view prefix) {
-      auto min_length = std::min(text.size(), prefix.size());
-      if (min_length == 0) {
-        return false;
-      }
-      return std::equal(
-          text.begin(), text.begin() + min_length,
-          prefix.begin(), prefix.begin() + min_length,
-          [](char ch1, char ch2) { return std::toupper(ch1) == std::toupper(ch2); }
-          );
-    }
-}
-
 PrefixMatcher::PrefixMatcher(std::string_view pattern, bool case_sensitive) {
   original_pattern = pattern;
   this->case_sensitive = case_sensitive;
diff --git a/src/utils.cc b/src/utils.cc
index 1a07b980a..575a19b8d 100644
--- a/src/utils.cc
+++ b/src/utils.cc
@@ -79,6 +79,12 @@ bool StartsWith(std::string_view value, std::string_view start) {
   return std::equal(start.begin(), start.end(), value.begin());
 }
 
+bool StartsWithIgnoreCase(std::string_view value, std::string_view start) {
+  if (start.size() > value.size())
+    return false;
+  return std::equal(start.begin(), start.end(), value.begin(), [](char ch1, char ch2) { return std::toupper(ch1) == std::toupper(ch2); });
+}
+
 bool AnyStartsWith(const std::vector<std::string>& values,
                    const std::string& start) {
   return std::any_of(
diff --git a/src/utils.h b/src/utils.h
index d0f044f99..62a809292 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -24,6 +24,7 @@ uint64_t HashUsr(std::string_view s);
 
 // Returns true if |value| starts/ends with |start| or |ending|.
 bool StartsWith(std::string_view value, std::string_view start);
+bool StartsWithIgnoreCase(std::string_view value, std::string_view start);
 bool EndsWith(std::string_view value, std::string_view ending);
 bool AnyStartsWith(const std::vector<std::string>& values,
                    const std::string& start);
@@ -146,4 +147,4 @@ bool IsWindowsAbsolutePath(const std::string& path);
 
 bool IsDirectory(const std::string& path);
 
-size_t HashArguments(const std::vector<std::string>& args);
\ No newline at end of file
+size_t HashArguments(const std::vector<std::string>& args);

From a4ef8032b8ed6ec2b9d04ed6d055211b273ef9d4 Mon Sep 17 00:00:00 2001
From: ddovod <ddovod@gmail.com>
Date: Sat, 1 Sep 2018 21:48:34 +0300
Subject: [PATCH 5/6] adding some docs

---
 src/config.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/config.h b/src/config.h
index 99d98aae7..d90a6c331 100644
--- a/src/config.h
+++ b/src/config.h
@@ -157,7 +157,12 @@ struct Config {
     std::vector<std::string> includeBlacklist;
     std::vector<std::string> includeWhitelist;
 
-    //
+    // Matcher type to filter completion candidates.
+    // Available matchers are:
+    // "cqueryMatcher":                        default cquery fuzzy matching algorithm
+    // "ftsMatcher":                           fuzzy matching algorithm powered by
+    // lib_fts "caseSensitivePrefixMatcher":   simple case sensitive prefix
+    // matcher "caseInsensitivePrefixMatcher": simple case insensitive prefix
     std::string matcherType = "cqueryMatcher";
   };
   Completion completion;

From 2ea4bdfb7db0925380d0833bacb613c54c939fcd Mon Sep 17 00:00:00 2001
From: ddovod <ddovod@gmail.com>
Date: Sat, 1 Sep 2018 21:48:50 +0300
Subject: [PATCH 6/6] disabling clang-format on third-party libs

---
 third_party/.clang-format | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 third_party/.clang-format

diff --git a/third_party/.clang-format b/third_party/.clang-format
new file mode 100644
index 000000000..ef2ae21fa
--- /dev/null
+++ b/third_party/.clang-format
@@ -0,0 +1,4 @@
+---
+DisableFormat: true
+SortIncludes: false
+...