[#232] Format from elixir project dir (#239)

Make it so that if there is a `.formatter.exs` file somewhere in the
parent directories, then Apheleia will run `mix format` from there
instead of the current directory.

Close #232

1 files changed, 22 insertions, 0 deletions

diff --git a/scripts/formatters/apheleia-mix b/scripts/formatters/apheleia-mix
new file mode 100755
index 0000000..d2038e1
--- /dev/null
+++ b/scripts/formatters/apheleia-mix
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+# This function prints the name of the current directory if it
+# contains a file or directory named after the first argument, or the
+# parent directory if it contains such a file, or the parent's parent,
+# and so on. If no such file is found it returns nonzero.
+# https://unix.stackexchange.com/a/22215
+find_upwards() {
+    fname="$1"
+
+    path="${PWD}"
+    while [[ -n "${path}" && ! -e "${path}/${fname}" ]]; do
+        path="${path%/*}"
+    done
+    [[ -n "${path}" ]] && echo "${path}"
+}
+
+if dir="$(find_upwards .formatter.exs)"; then
+    cd -- "${dir}" || exit
+fi
+
+exec mix "$@"