Add clang-tidy and check script and fix the warnings under count directory

Author: SYaoJun

.clang-tidy

@@ -0,0 +1,36 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+---
+Checks: |
+  clang-diagnostic-*,
+  clang-analyzer-*,
+  -clang-analyzer-alpha*,
+  google-*,
+  modernize-*,
+  -modernize-avoid-c-arrays,
+  -modernize-use-trailing-return-type,
+  -modernize-use-nodiscard,
+
+CheckOptions:
+  - key:             google-readability-braces-around-statements.ShortStatementLines
+    value:           '1'
+  - key:             google-readability-function-size.StatementThreshold
+    value:           '800'
+  - key:             google-readability-namespace-comments.ShortNamespaceLines
+    value:           '10'
+  - key:             google-readability-namespace-comments.SpacesBeforeComments
+    value:           '2'

.pre-commit-config.yaml

@@ -0,0 +1,29 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# To use this, install the python package `pre-commit` and
+# run once `pre-commit install`. This will setup a git pre-commit-hook
+# that is executed on each commit and will report the linting problems.
+# To run all hooks on all files use `pre-commit run -a`
+
+repos:
+  - repo: https://github.com/pocc/pre-commit-hooks
+    rev: v1.3.5
+    hooks:
+      - id: clang-tidy
+        args: ['--quiet', '-p=build/compile_commands.json', '--config-file=.clang-tidy']
+        types_or: [c++, c]

count/include/count_min_impl.hpp

@@ -74,7 +74,7 @@ uint64_t count_min_sketch<W,A>::get_seed() const {
 
 template<typename W, typename A>
 double count_min_sketch<W,A>::get_relative_error() const {
-  return exp(1.0) / double(_num_buckets);
+  return exp(1.0) / static_cast<double>(_num_buckets);
 }
 
 template<typename W, typename A>
@@ -449,8 +449,9 @@ string<A> count_min_sketch<W,A>::to_string() const {
   // count the number of used entries in the sketch
   uint64_t num_nonzero = 0;
   for (const auto entry: _sketch_array) {
-    if (entry != static_cast<W>(0.0))
+    if (entry != static_cast<W>(0.0)){
       ++num_nonzero;
+    }
   }
 
   // Using a temporary stream for implementation here does not comply with AllocatorAwareContainer requirements.