Add util for joining and splitting words

rups/src/proto/mod.rs

@@ -8,6 +8,8 @@ pub mod client;
 /// "Server-bound" implies commands RECEIVED and DECODED by the server. The client implementation
 /// must use the same messages to ENCODE and SEND.
 pub mod server;
+/// Utilities for encoding and decoding packets.
+pub mod util;
 
 /// Macro that implements the list of "words" in the NUT network protocol.
 macro_rules! impl_words {

rups/src/proto/util.rs

@@ -0,0 +1,41 @@
+/// Splits a sentence (line) into a `Vec<String>`, minding quotation marks
+/// for words with spaces in them.
+///
+/// Returns `None` if the sentence cannot be split safely (usually unbalanced quotation marks).
+pub fn split_sentence<T: AsRef<str>>(sentence: T) -> Option<Vec<String>> {
+    shell_words::split(sentence.as_ref()).ok()
+}
+
+/// Joins a collection of words (`&str`) into one sentence string,
+/// adding quotation marks for words with spaces in them.
+pub fn join_sentence<I, S>(words: I) -> String
+where
+    I: IntoIterator<Item = S>,
+    S: AsRef<str>,
+{
+    shell_words::join(words)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_split() {
+        assert_eq!(
+            split_sentence("AbC dEf GHi"),
+            Some(vec!["AbC".into(), "dEf".into(), "GHi".into()])
+        );
+        assert_eq!(
+            split_sentence("\"AbC dEf\" GHi"),
+            Some(vec!["AbC dEf".into(), "GHi".into()])
+        );
+        assert_eq!(split_sentence("\"AbC dEf GHi"), None);
+    }
+
+    #[test]
+    fn test_join() {
+        assert_eq!(join_sentence(vec!["AbC", "dEf", "GHi"]), "AbC dEf GHi",);
+        assert_eq!(join_sentence(vec!["AbC dEf", "GHi"]), "'AbC dEf' GHi",);
+        assert_eq!(join_sentence(vec!["\"AbC dEf", "GHi"]), "'\"AbC dEf' GHi",);
+    }
+}