Forgot to add the form file. Whoops.

lib/src/form.rs

@@ -0,0 +1,126 @@
+use std::str::FromStr;
+use error::Error;
+
+pub trait FromForm<'f>: Sized {
+    fn from_form_string(s: &'f str) -> Result<Self, Error>;
+}
+
+pub trait FromFormValue<'v>: Sized {
+    type Error;
+
+    fn parse(v: &'v str) -> Result<Self, Self::Error>;
+}
+
+impl<'v> FromFormValue<'v> for &'v str {
+    type Error = Error;
+
+    fn parse(v: &'v str) -> Result<Self, Self::Error> {
+        Ok(v)
+    }
+}
+
+impl<'v> FromFormValue<'v> for isize {
+    type Error = &'v str;
+
+    fn parse(v: &'v str) -> Result<Self, Self::Error> {
+        isize::from_str(v).map_err(|_| v)
+    }
+}
+
+impl<'v, T: FromFormValue<'v>> FromFormValue<'v> for Option<T> {
+    type Error = Error;
+
+    fn parse(v: &'v str) -> Result<Self, Self::Error> {
+        match T::parse(v) {
+            Ok(v) => Ok(Some(v)),
+            Err(_) => Ok(None)
+        }
+    }
+}
+
+// TODO: Add more useful implementations (range, regex, etc.).
+impl<'v, T: FromFormValue<'v>> FromFormValue<'v> for Result<T, T::Error> {
+    type Error = Error;
+
+    fn parse(v: &'v str) -> Result<Self, Self::Error> {
+        match T::parse(v) {
+            ok@Ok(_) => Ok(ok),
+            e@Err(_) => Ok(e)
+        }
+    }
+}
+
+pub fn form_items<'f>(string: &'f str, items: &mut [(&'f str, &'f str)]) -> usize {
+    let mut param_num = 0;
+    let mut rest = string;
+    while rest.len() > 0 && param_num < items.len() {
+        let (key, remainder) = match rest.find('=') {
+            Some(index) => (&rest[..index], &rest[(index + 1)..]),
+            None => return param_num
+        };
+
+        rest = remainder;
+        let (value, remainder) = match rest.find('&') {
+            Some(index) => (&rest[..index], &rest[(index + 1)..]),
+            None => (rest, "")
+        };
+
+        rest = remainder;
+        items[param_num] = (key, value);
+        param_num += 1;
+    }
+
+    param_num
+}
+
+#[cfg(test)]
+mod test {
+    use super::form_items;
+
+    macro_rules! check_form {
+        ($string:expr, $expected: expr) => ({
+            let mut output = Vec::with_capacity($expected.len());
+            unsafe { output.set_len($expected.len()); }
+
+            let results = output.as_mut_slice();
+            assert_eq!($expected.len(), form_items($string, results));
+
+            for i in 0..results.len() {
+                let (expected_key, actual_key) = ($expected[i].0, results[i].0);
+                let (expected_val, actual_val) = ($expected[i].1, results[i].1);
+
+                assert!(expected_key == actual_key,
+                    "key [{}] mismatch: expected {}, got {}",
+                        i, expected_key, actual_key);
+
+                assert!(expected_val == actual_val,
+                    "val [{}] mismatch: expected {}, got {}",
+                        i, expected_val, actual_val);
+            }
+        })
+    }
+
+    #[test]
+    fn test_form_string() {
+        let results = &[("username", "user"), ("password", "pass")];
+        check_form!("username=user&password=pass", results);
+
+        let results = &[("user", "user"), ("user", "pass")];
+        check_form!("user=user&user=pass", results);
+
+        let results = &[("user", ""), ("password", "pass")];
+        check_form!("user=&password=pass", results);
+
+        let results = &[("", ""), ("", "")];
+        check_form!("=&=", results);
+
+        let results = &[("a", "b")];
+        check_form!("a=b", results);
+
+        let results = &[("a", "b")];
+        check_form!("a=b&a", results);
+
+        let results = &[("a", "b"), ("a", "")];
+        check_form!("a=b&a=", results);
+    }
+}