Initial commit

1 files changed, 77 insertions, 0 deletions

diff --git a/src/commands/parser.rs b/src/commands/parser.rs
new file mode 100644
index 0000000..e75840c
--- /dev/null
+++ b/src/commands/parser.rs
@@ -0,0 +1,77 @@
+
+pub enum ParseResult<'a, T> {
+    Success(T, &'a str),
+    Failure(String),
+}
+
+pub trait Parse<'a> {
+    type Res;
+
+    fn parse(self, input: &'a str) -> ParseResult<'a, Self::Res>;
+}
+
+pub struct Text(String);
+
+impl<'a> Parse<'a> for Text {
+    type Res = Text;
+
+    fn parse(self, input: &'a str) -> ParseResult<'a, Text> {
+        let mut value = String::new();
+
+        let mut it = input.chars();
+        let mut escape_next = false;
+        while let Some(c) = it.next() {
+            if c == '\\' && !escape_next {
+                escape_next = true;
+                continue;
+            } else if c == ';' {
+                break;
+            }
+            value.push(c);
+
+            escape_next = false;
+        }
+
+        ParseResult::Success(Text(value), it.as_str())
+    }
+}
+
+pub struct Branch<T> {
+    choices: Vec<(&'static str, Option<char>, T)>,
+}
+
+impl<'a, T> Parse<'a> for Branch<T> {
+    type Res = T;
+
+    fn parse(self, input: &'a str) -> ParseResult<'a, T> {
+        let choices: Vec<&'static str> = self.choices.iter().map(|x| x.0).collect();
+
+        for (long, short_op, res) in self.choices {
+            let rest = if input.starts_with(long) {
+                Some(&input[long.len()..])
+            } else if let Some(short) = short_op {
+                if input.starts_with(short) {
+                    Some(&input[1..])
+                } else {
+                    None
+                }
+            } else { None };
+
+            if let Some(rest) = rest {
+                return ParseResult::Success(res, rest);
+            }
+        }
+
+        return ParseResult::Failure(format!("Expected one of [{}]", choices.join(", ")));
+    }
+}
+
+impl<T> Branch<T> {
+    pub fn new() -> Branch<T> {
+        Branch { choices: Vec::new() }
+    }
+
+    pub fn add(&mut self, long: &'static str, short: Option<char>, res: T) {
+        self.choices.push((long, short, res));
+    }
+}