Add cleaning of python files to 'clean' action.

When python files are cleaned, we will clear out all the .pyc, .pyo
files, and any __pycache__ directories.

common

@@ -28,6 +28,23 @@ function bool() {
 }
 
 
+##
+# Trim leading and trailing whitespace from a string.
+#
+# @param $1     String to trim
+function trim() {
+    local var="$1"
+
+    # remove leading whitespace characters
+    var="${var#"${var%%[![:space:]]*}"}"
+
+    # remove trailing whitespace characters
+    var="${var%"${var##*[![:space:]]}"}"
+
+    echo -n "$var"
+}
+
+
 ##
 # Read a configuration parameter from the project's config.
 #

common.python

@@ -75,11 +75,17 @@ function python_active() {
         files="$(config -e lint_python_files '*.py')"
     elif [[ "$action" == 'docs' ]] ; then
         files="$(config -e docs_python_files '*.py')"
+    elif [[ "$action" == 'clean' ]] ; then
+        files="$(config -e docs_python_files '*.py')"
+        files="$files $(config -e lint_python_files '*.py') "
+        files="$files $(config -e test_python_files '*_test.py')"
     else
         # Unrecognised type
         return 1
     fi
 
+    files="$(trim "$files")"
+
     if [[ -n "$files" ]] ; then
         return 0
     fi
@@ -221,6 +227,39 @@ function python_run_docs() {
     docs_total=$(( docs_total+1 ))
 }
 
+function python_run_clean() {
+    local files=''
+    local lastdir=''
+    local thisdir
+
+    files="$(config -e docs_python_files '*.py')"
+    files="$files $(config -e lint_python_files '*.py') "
+    files="$files $(config -e test_python_files '*_test.py')"
+
+    lastdir=''
+    for file in $files ; do
+        file="./$file"
+        if [[ "${file: -3}" == '.py' ]] ; then
+            if [[ -f "${file//.py/.pyc}" ]] ; then
+                rm "${file//.py/.pyc}"
+            fi
+            if [[ -f "${file//.py/.pyo}" ]] ; then
+                rm "${file//.py/.pyo}"
+            fi
+
+            # Only check each directory once.
+            if [[ "${file:0:${#lastdir} + 1}" != "${lastdir}/" ]] || \
+               [[ "${file:${#lastdir} + 1}" =~ / ]] ; then
+                thisdir="$(dirname "$file")"
+                if [[ -d "${thisdir}/__pycache__" ]] ; then
+                    rmtree "${thisdir:-THISDIR_NOT_SET}/__pycache__"
+                fi
+                lastdir="$thisdir"
+            fi
+        fi
+    done
+}
+
 
 function python_process_test() {
     : # Nothing to do