1 files changed, 145 insertions, 0 deletions
diff --git a/src/values/length.rs b/src/values/length.rs
new file mode 100644
index 0000000..28a7156
--- /dev/null
+++ b/src/values/length.rs
@@ -0,0 +1,145 @@
+use std::num::{ParseFloatError, ParseIntError};
+use std::str::FromStr;
+
+use iced::Length;
+
+use super::Value;
+
+#[derive(Debug, thiserror::Error, Clone, PartialEq)]
+pub enum ParseLengthError {
+    #[error("float parsing error: {0}")]
+    ParseFloatError(ParseFloatError),
+    #[error("int parsing error: {0}")]
+    ParseIntError(ParseIntError),
+    #[error("invalid type")]
+    InvalidType,
+    #[error("invalid prefix")]
+    InvalidPrefix,
+    #[error("missing prefix")]
+    MissingPrefix,
+    #[error("cannot parse length from empty string")]
+    Empty,
+}
+
+impl From<ParseFloatError> for ParseLengthError {
+    fn from(value: ParseFloatError) -> Self {
+        Self::ParseFloatError(value)
+    }
+}
+
+impl From<ParseIntError> for ParseLengthError {
+    fn from(value: ParseIntError) -> Self {
+        Self::ParseIntError(value)
+    }
+}
+
+impl Value for Length {
+    type Err = ParseLengthError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let s = s.trim();
+
+        if s.is_empty() {
+            return Err(ParseLengthError::Empty);
+        }
+
+        if !s.contains(|c: char| c.is_ascii_digit()) {
+            match s {
+                "fill" => Ok(Self::Fill),
+                "shrink" => Ok(Self::Shrink),
+                _ => Err(ParseLengthError::InvalidType),
+            }
+        } else {
+            if s.starts_with(|c: char| !c.is_alphabetic()) {
+                return Err(ParseLengthError::MissingPrefix);
+            }
+
+            let (prefix, value) = s.split_at(2);
+            match prefix.to_lowercase().as_str() {
+                "fx" => Ok(Self::Fixed(f32::from_str(value)?)),
+                "fp" => Ok(Self::FillPortion(u16::from_str(value)?)),
+                _ => Err(ParseLengthError::InvalidPrefix),
+            }
+        }
+    }
+
+    fn to_string(&self) -> String {
+        match self {
+            Self::Fill => String::from("fill"),
+            Self::Shrink => String::from("shrink"),
+            Self::Fixed(value) => format!("fx{}", value),
+            Self::FillPortion(value) => format!("fp{}", value),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn can_parse_fill() {
+        assert_eq!(Length::from_str("fill"), Ok(Length::Fill))
+    }
+
+    #[test]
+    fn can_parse_shrink_with_space() {
+        assert_eq!(Length::from_str("shrink "), Ok(Length::Shrink))
+    }
+
+    #[test]
+    fn can_parse_fill_portion() {
+        assert_eq!(Length::from_str("fp15"), Ok(Length::FillPortion(15)))
+    }
+
+    #[test]
+    fn can_parse_fixed_with_spaces() {
+        assert_eq!(Length::from_str(" fx3.1 "), Ok(Length::Fixed(3.1)))
+    }
+
+    #[test]
+    fn cant_parse_invalid_type() {
+        assert_eq!(
+            Length::from_str("fillportion"),
+            Err(ParseLengthError::InvalidType)
+        )
+    }
+
+    #[test]
+    fn cant_parse_invalid_prefix() {
+        assert_eq!(
+            Length::from_str("f2.0"),
+            Err(ParseLengthError::InvalidPrefix),
+        )
+    }
+
+    #[test]
+    fn cant_parse_invalid_float() {
+        assert_eq!(
+            Length::from_str(" fx2.a"),
+            Err(ParseLengthError::ParseFloatError(
+                f32::from_str("2.a").expect_err("float parse should fail")
+            ))
+        )
+    }
+
+    #[test]
+    fn cant_parse_invalid_integer() {
+        assert_eq!(
+            Length::from_str("fp1a "),
+            Err(ParseLengthError::ParseIntError(
+                u16::from_str("1a").expect_err("integer parse should fail")
+            ))
+        )
+    }
+
+    #[test]
+    fn cant_parse_with_missing_prefix() {
+        assert_eq!(Length::from_str("24"), Err(ParseLengthError::MissingPrefix))
+    }
+
+    #[test]
+    fn cant_parse_empty_string() {
+        assert_eq!(Length::from_str(" "), Err(ParseLengthError::Empty))
+    }
+}