1 files changed, 117 insertions, 0 deletions
diff --git a/src/values/line_height.rs b/src/values/line_height.rs
new file mode 100644
index 0000000..0ea1524
--- /dev/null
+++ b/src/values/line_height.rs
@@ -0,0 +1,117 @@
+use std::num::ParseFloatError;
+use std::str::FromStr;
+
+use iced::Pixels;
+use iced::advanced::text::LineHeight;
+
+use super::Value;
+
+#[derive(Debug, thiserror::Error, Clone, PartialEq)]
+pub enum ParseLineHeightError {
+    #[error("float parsing error: {0}")]
+    ParseFloatError(ParseFloatError),
+    #[error("missing prefix")]
+    MissingPrefix,
+    #[error("invalid prefix")]
+    InvalidPrefix,
+    #[error("cannot parse line height from empty string")]
+    Empty,
+}
+
+impl From<ParseFloatError> for ParseLineHeightError {
+    fn from(value: ParseFloatError) -> Self {
+        Self::ParseFloatError(value)
+    }
+}
+
+impl Value for LineHeight {
+    type Err = ParseLineHeightError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let s = s.trim();
+
+        if s.is_empty() {
+            return Err(ParseLineHeightError::Empty);
+        }
+
+        if s.starts_with(|c: char| !c.is_ascii_digit()) {
+            let (prefix, value) = s.split_at(1);
+            match prefix.to_lowercase().as_str() {
+                "r" => Ok(Self::Relative(f32::from_str(value)?)),
+                "a" => Ok(Self::Absolute(Pixels::from_str(value)?)),
+                _ => Err(ParseLineHeightError::InvalidPrefix),
+            }
+        } else {
+            Err(ParseLineHeightError::MissingPrefix)
+        }
+    }
+
+    fn to_string(&self) -> String {
+        match self {
+            Self::Relative(value) => format!("r{}", value),
+            Self::Absolute(value) => format!("a{}", value.0),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn can_parse_with_r_prefix() {
+        assert_eq!(
+            LineHeight::from_str("  r3.2"),
+            Ok(LineHeight::Relative(3.2))
+        );
+
+        assert_eq!(
+            LineHeight::from_str(" R6.5 "),
+            Ok(LineHeight::Relative(6.5))
+        )
+    }
+
+    #[test]
+    fn can_parse_with_a_prefix() {
+        assert_eq!(
+            LineHeight::from_str("a9.4 "),
+            Ok(LineHeight::Absolute(Pixels(9.4)))
+        );
+
+        assert_eq!(
+            LineHeight::from_str("A1.3"),
+            Ok(LineHeight::Absolute(Pixels(1.3)))
+        )
+    }
+
+    #[test]
+    fn cant_parse_with_missing_prefix() {
+        assert_eq!(
+            LineHeight::from_str("5.1"),
+            Err(ParseLineHeightError::MissingPrefix)
+        )
+    }
+
+    #[test]
+    fn cant_parse_invalid_prefix() {
+        assert_eq!(
+            LineHeight::from_str("g21"),
+            Err(ParseLineHeightError::InvalidPrefix)
+        )
+    }
+
+    #[test]
+    fn cant_parse_invalid_float() {
+        assert_eq!(
+            LineHeight::from_str("a2f"),
+            Err(ParseLineHeightError::ParseFloatError(
+                f32::from_str("2f").expect_err("float parse should fail")
+            ))
+        )
+    }
+
+    #[test]
+    fn cant_parse_empty_string() {
+        assert_eq!(LineHeight::from_str(" "), Err(ParseLineHeightError::Empty))
+    }
+}