add ci files for check the repo structure

Author: Qinghao Shi

.circleci/config.yml

@@ -7,14 +7,15 @@ jobs:
   build:
     docker:
       - image: mbedos/mbed-os-env:stable
-    working_directory: ~/repo
     steps:
       - checkout:
-          path: work/sinppet/TESTS
-      - run: mv work/sinppet/TESTS/mbed-os.lib work/
-      - run: git clone https://github.com/ARMmbed/mbed-os.git work/mbed-os
+          path: sinppet/TESTS
+      - run: |
+          cd sinppet/TESTS
+          python3 .circleci/repo_checks.py
+      - run: mv sinppet/TESTS/mbed-os.lib .
+      - run: git clone https://github.com/ARMmbed/mbed-os.git mbed-os
       - run: |
-          cd work
           mbed config root .
           mbed update
           mbed add https://github.com/c1728p9/AudioPlayer

.circleci/repo_checks.py

@@ -0,0 +1,67 @@
+"""
+Copyright (c) 2016-2020 ARM Limited. All rights reserved.
+
+SPDX-License-Identifier: Apache-2.0
+
+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
+
+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 
+"""
+
+from pathlib import Path
+import glob
+import os.path
+import sys
+
+level2_set= set()
+dup_set = set()
+
+
+def main():
+    for filepath in Path('.').rglob('main.cpp'):
+        level2dir=os.path.basename(os.path.dirname(filepath))
+        level1dir=os.path.basename(os.path.dirname(os.path.dirname(filepath)))
+        level0dir=os.path.dirname(os.path.dirname(os.path.dirname(filepath)))
+        
+        # check if length of folder name less then 34 
+        if len(level2dir) > 34 :
+            sys.stderr.write("ERROR: Snippet '{}' length of {} is {} exceed the requirement of 34".format(filepath,level2dir,len(level2dir)))
+            sys.exit(1)
+
+        # check if folder level less than 2 
+        if level1dir == '':
+            sys.stderr.write("ERROR: Snippet '{}' has only one level of folder, but 2 is required".format(filepath))
+            sys.exit(1) 
+
+        # check if folder level more than 2 
+        if level0dir !=  '':
+            sys.stderr.write("ERROR: Snippet '{}' has more than two level of folders, but 2 is required".format(filepath))
+            sys.exit(1) 
+
+        if level2dir not in level2_set:
+            level2_set.add(level2dir)
+        else:
+            dup_set.add(level2dir)
+
+    # check duplicated level2 folder names
+    if len(dup_set) > 0 :
+        for filepath in Path('.').rglob('main.cpp'):
+            level2dir=os.path.basename(os.path.dirname(filepath))
+            if level2dir in dup_set:
+                sys.stderr.write("ERROR level2 name '{}' in path '{}' is has a duplicated with others".format(level2dir,filepath))
+        sys.exit(1)
+
+
+    print("All checks PASSED")
+
+
+if __name__ == "__main__":
+    main()

README.md

@@ -1,2 +1,12 @@
 # Mbed OS Docs-Only Examples
-This repository contains example applications that currently only exist in the Mbed OS docs.
+This repository contains example applications snippets that currently only exist in the Mbed OS docs.
+
+## Contributions
+
+Contribute the the example folder need to following bellow requirements
+- Every individual example snippet need to contain a compile-able `main.cpp` and placed into one folder with all required files.
+- The path to the folder has to be in the 2 level folder structure `Repo_ROOT/<Level1>/<Level2>/main.cpp` we recommend to following our conventions: `Repo_ROOT/Category_Topic/Module_Example`
+- A `README.md` file in the snippet folder is optional, the main instruction and explanatory documents should be contributed to [mbed-os-docs](https://github.com/ARMmbed/mbed-os-5-docs). 
+- the `Level2` folder name, e.g. `<Module_Example>`, need to be unique to any other `Level2` folder in this repository and contains no more than 34 characters.
+- The CI on this repository will check on the above criteria and also make sure the snippets able to be built 
+