add glob support

Author: Ian Sibner

README.markdown

@@ -36,14 +36,25 @@ https://github.com/heroku/heroku-buildpack-ruby
 https://github.com/Lostmyname/heroku-buildpack-post-build-clean
 ```
 
-The `.slug-post-clean` file supports single-file and single-directory
-declarations only, e.g.:
+The `.slug-post-clean` file supports single-file and single-directory patterns, **as well as glob patterns**, e.g.:
 
 ```
 some_huge_file.psd
 some/nested/directory
 why_does_this_app_even_contain_a.tiff
+your_frontend/build/*.map
 ```
 
-I might expand it to support file globs, but for the moment it's not
-necessary and the testing implications give me the willies.
+Glob patterns are expanded using Bash syntax - not with a third-party library such as [node-glob](https://github.com/isaacs/node-glob). You can see what your glob matches from  `bash` with this command:
+
+```bash
+ls -d1 your/glob/pattern/*
+```
+
+## Testing
+
+The `bin/compile` script does all the heavy lifting for this package. It takes a single argument, $BUILD_DIR, the directory of your app. If you want to test it out locally and make sure your app still runs after the post-build cleanup, you can copy `bin/compile` into your app directory and run:
+
+```bash
+chmod +x compile; ./compile .
+```

bin/compile

@@ -17,15 +17,29 @@ if [[ ! -f "${CLEAN_FILES}" ]]; then
   exit 1
 fi
 
+function remove_file_or_dir {
+  if [[ -f "$1" ]]; then
+    echo "Removing file $1 from slug"
+    rm -f $1
+  elif [[ -d "$1" ]]; then
+    echo "Removing directory $1 from slug"
+    rm -rf $1
+  else
+    echo "Location $1 not found - ignoring"
+  fi
+}
+
+export -f remove_file_or_dir
+
 while read file; do
   [[ ! -n "${file}" ]] && continue
 
-  if [[ -f "${file}" ]]; then
-    echo "Removing file ${file} from slug"
-    rm -f ${file}
-  elif [[ -d "${file}" ]]; then
-    echo "Removing directory ${file} from slug"
-    rm -rf ${file}
+  if [[ -f "${file}" || -d "${file}" ]]; then
+    # Target is a file or directory, remove it
+    remove_file_or_dir ${file}
+  elif ls -d $(echo $file) &> /dev/null; then
+    # target is a glob, expand it and remove everything it matches
+    ls -d1 $(echo $file) | while read line; do remove_file_or_dir $line; done
   else
     echo "Location ${file} not found - ignoring"
   fi