Use generics for the line-height property

components/style/values/specified/text.rs

@@ -0,0 +1,97 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Specified types for text properties.
+
+use cssparser::Parser;
+use parser::{Parse, ParserContext};
+use std::ascii::AsciiExt;
+use values::computed::{Context, ToComputedValue};
+use values::computed::text::LineHeight as ComputedLineHeight;
+use values::generics::text::LineHeight as GenericLineHeight;
+use values::specified::Number;
+use values::specified::length::{FontRelativeLength, Length, LengthOrPercentage, NoCalcLength};
+
+/// A specified value for the `line-height` property.
+pub type LineHeight = GenericLineHeight<Number, LengthOrPercentage>;
+
+impl Parse for LineHeight {
+    fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+        if let Ok(number) = input.try(|i| Number::parse_non_negative(context, i)) {
+            return Ok(GenericLineHeight::Number(number))
+        }
+        if let Ok(lop) = input.try(|i| LengthOrPercentage::parse_non_negative(context, i)) {
+            return Ok(GenericLineHeight::Length(lop))
+        }
+        match &input.expect_ident()? {
+            ident if ident.eq_ignore_ascii_case("normal") => {
+                Ok(GenericLineHeight::Normal)
+            },
+            #[cfg(feature = "gecko")]
+            ident if ident.eq_ignore_ascii_case("-moz-block-height") => {
+                Ok(GenericLineHeight::MozBlockHeight)
+            },
+            _ => Err(()),
+        }
+    }
+}
+
+impl ToComputedValue for LineHeight {
+    type ComputedValue = ComputedLineHeight;
+
+    #[inline]
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        match *self {
+            GenericLineHeight::Normal => {
+                GenericLineHeight::Normal
+            },
+            #[cfg(feature = "gecko")]
+            GenericLineHeight::MozBlockHeight => {
+                GenericLineHeight::MozBlockHeight
+            },
+            GenericLineHeight::Number(number) => {
+                GenericLineHeight::Number(number.to_computed_value(context))
+            },
+            GenericLineHeight::Length(LengthOrPercentage::Length(ref length)) => {
+                GenericLineHeight::Length(length.to_computed_value(context))
+            },
+            GenericLineHeight::Length(LengthOrPercentage::Percentage(p)) => {
+                let font_relative_length =
+                    Length::NoCalc(NoCalcLength::FontRelative(FontRelativeLength::Em(p.0)));
+                GenericLineHeight::Length(font_relative_length.to_computed_value(context))
+            },
+            GenericLineHeight::Length(LengthOrPercentage::Calc(ref calc)) => {
+                let computed_calc = calc.to_computed_value(context);
+                let font_relative_length =
+                    Length::NoCalc(NoCalcLength::FontRelative(FontRelativeLength::Em(computed_calc.percentage())));
+                let absolute_length = computed_calc.unclamped_length();
+                let computed_length = computed_calc.clamping_mode.clamp(
+                    absolute_length + font_relative_length.to_computed_value(context)
+                );
+                GenericLineHeight::Length(computed_length)
+            },
+        }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        match *computed {
+            GenericLineHeight::Normal => {
+                GenericLineHeight::Normal
+            },
+            #[cfg(feature = "gecko")]
+            GenericLineHeight::MozBlockHeight => {
+                GenericLineHeight::MozBlockHeight
+            },
+            GenericLineHeight::Number(ref number) => {
+                GenericLineHeight::Number(Number::from_computed_value(number))
+            },
+            GenericLineHeight::Length(ref length) => {
+                GenericLineHeight::Length(LengthOrPercentage::Length(
+                    NoCalcLength::from_computed_value(length)
+                ))
+            }
+        }
+    }
+}