Strip trailing whitespace and add a formatting check for it

Author: calcmogul

ci/github/lecture/index.html

@@ -236,10 +236,10 @@ <h1>Resources</h1>
       </section>
     </div>
   </div>
-  <script src="../../../reveal.js/dist/reveal.js"></script> 
-  <script src="../../../reveal.js/plugin/notes/notes.js"></script> 
-  <script src="../../../reveal.js/plugin/markdown/markdown.js"></script> 
-  <script src="../../../reveal.js/plugin/highlight/highlight.js"></script> 
+  <script src="../../../reveal.js/dist/reveal.js"></script>
+  <script src="../../../reveal.js/plugin/notes/notes.js"></script>
+  <script src="../../../reveal.js/plugin/markdown/markdown.js"></script>
+  <script src="../../../reveal.js/plugin/highlight/highlight.js"></script>
   <script src="../../../reveal-init.js"></script>
 </body>
 </html>

ci/intro-to-git/lecture/index.html

@@ -338,10 +338,10 @@ <h1>Resources</h1>
       </section>
     </div>
   </div>
-  <script src="../../../reveal.js/dist/reveal.js"></script> 
-  <script src="../../../reveal.js/plugin/notes/notes.js"></script> 
-  <script src="../../../reveal.js/plugin/markdown/markdown.js"></script> 
-  <script src="../../../reveal.js/plugin/highlight/highlight.js"></script> 
+  <script src="../../../reveal.js/dist/reveal.js"></script>
+  <script src="../../../reveal.js/plugin/notes/notes.js"></script>
+  <script src="../../../reveal.js/plugin/markdown/markdown.js"></script>
+  <script src="../../../reveal.js/plugin/highlight/highlight.js"></script>
   <script src="../../../reveal-init.js"></script>
 </body>
 </html>

ci/intro-to-real-time-software/lecture/index.html

@@ -216,10 +216,10 @@ <h1>Resources</h1>
       </section>
     </div>
   </div>
-  <script src="../../../reveal.js/dist/reveal.js"></script> 
-  <script src="../../../reveal.js/plugin/notes/notes.js"></script> 
-  <script src="../../../reveal.js/plugin/markdown/markdown.js"></script> 
-  <script src="../../../reveal.js/plugin/highlight/highlight.js"></script> 
+  <script src="../../../reveal.js/dist/reveal.js"></script>
+  <script src="../../../reveal.js/plugin/notes/notes.js"></script>
+  <script src="../../../reveal.js/plugin/markdown/markdown.js"></script>
+  <script src="../../../reveal.js/plugin/highlight/highlight.js"></script>
   <script src="../../../reveal-init.js"></script>
 </body>
 </html>

format.py

@@ -5,6 +5,44 @@
 import subprocess
 
 
+def get_linesep(lines):
+    """Returns string containing autodetected line separator for file.
+
+    Keyword arguments:
+    lines -- file contents string
+    """
+    # Find potential line separator
+    pos = lines.find("\n")
+
+    # If a newline character was found and the character preceding it is a
+    # carriage return, assume CRLF line endings. LF line endings are assumed
+    # for empty files.
+    if pos > 0 and lines[pos - 1] == "\r":
+        return "\r\n"
+    else:
+        return "\n"
+
+
+def strip_trailing_whitespace(filename):
+    """Removes trailing whitespace from the file.
+
+    Keyword arguments:
+    filename -- name of file to strip
+    """
+    with open(filename) as input:
+        lines = input.read()
+    linesep = get_linesep(lines)
+
+    output = ""
+    for line in lines.splitlines():
+        line = line[: len(line)].rstrip()
+        output += line + linesep
+
+    if lines != output:
+        with open(filename, "wb") as file:
+            file.write(output.encode())
+
+
 def main():
     # Format HTML
     files = [
@@ -34,6 +72,7 @@ def main():
                 f,
             ]
         )
+        strip_trailing_whitespace(f)
 
     # Format Python
     files = [
@@ -44,6 +83,7 @@ def main():
     ]
     for f in files:
         subprocess.check_output(["python3", "-m", "black", "-q", f])
+        strip_trailing_whitespace(f)
 
 
 if __name__ == "__main__":