1 files changed, 61 insertions, 0 deletions
diff --git a/src/parser.rs b/src/parser.rs
new file mode 100644
index 0000000..2f65180
--- /dev/null
+++ b/src/parser.rs
@@ -0,0 +1,61 @@
+use nom::{
+    branch::alt,
+    bytes::complete::{is_not, tag},
+    character::complete::{multispace0, multispace1},
+    combinator::{eof, map, value},
+    error::ParseError,
+    sequence::delimited,
+    sequence::tuple,
+    Finish, IResult,
+};
+use std::str::FromStr;
+
+#[derive(Clone)]
+pub enum Command {
+    Whitespace,
+    Exit,
+    GitInit(String),
+}
+
+impl FromStr for Command {
+    // the error must be owned as well
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match command_parser(s).finish() {
+            Ok((remaining, command)) => {
+                if remaining.trim().is_empty() {
+                    Ok(command)
+                } else {
+                    Err(s.trim().to_owned())
+                }
+            }
+            Err(_) => Err(s.trim().to_owned()),
+        }
+    }
+}
+
+fn command_parser(input: &str) -> IResult<&str, Command> {
+    alt((
+        value(Command::Exit, eof),
+        value(Command::Whitespace, tuple((multispace1, eof))),
+        value(Command::Exit, ws(tag("exit"))),
+        map(
+            ws(tuple((tag("git-init"), multispace1, not_space))),
+            |(_, _, repo_name)| Command::GitInit(repo_name.to_owned()),
+        ),
+    ))(input)
+}
+
+/// A combinator that takes a parser `inner` and produces a parser that also consumes both leading and
+/// trailing whitespace, returning the output of `inner`.
+fn ws<'a, F, O, E: ParseError<&'a str>>(inner: F) -> impl FnMut(&'a str) -> IResult<&'a str, O, E>
+where
+    F: FnMut(&'a str) -> IResult<&'a str, O, E>,
+{
+    delimited(multispace0, inner, multispace0)
+}
+
+fn not_space(s: &str) -> IResult<&str, &str> {
+    is_not(" \t\r\n")(s)
+}