style: Multiple style nits across parsing code.

components/style/properties/longhand/font.mako.rs

@@ -659,15 +659,17 @@ ${helpers.single_keyword("font-variant-caps",
     /// <length> | <percentage> | <absolute-size> | <relative-size>
     pub fn parse(_: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
         if let Ok(lop) = input.try(specified::LengthOrPercentage::parse_non_negative) {
-            Ok(SpecifiedValue::Length(lop))
-        } else if let Ok(kw) = input.try(KeywordSize::parse) {
-            Ok(SpecifiedValue::Keyword(kw))
-        } else {
-            match_ignore_ascii_case! {&*input.expect_ident()?,
-                "smaller" => Ok(SpecifiedValue::Smaller),
-                "larger" => Ok(SpecifiedValue::Larger),
-                _ => Err(())
-            }
+            return Ok(SpecifiedValue::Length(lop))
+        }
+
+        if let Ok(kw) = input.try(KeywordSize::parse) {
+            return Ok(SpecifiedValue::Keyword(kw))
+        }
+
+        match_ignore_ascii_case! {&*input.expect_ident()?,
+            "smaller" => Ok(SpecifiedValue::Smaller),
+            "larger" => Ok(SpecifiedValue::Larger),
+            _ => Err(())
         }
     }
 </%helpers:longhand>

components/style/properties/longhand/inherited_text.mako.rs

@@ -45,31 +45,33 @@
         }
     }
     /// normal | <number> | <length> | <percentage>
-    pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+    pub fn parse(_: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
         use cssparser::Token;
         use std::ascii::AsciiExt;
-        // We try to parse as a Number first because, for 'line-height', we want "0" to be
-        // parsed as a plain Number rather than a Length (0px); this matches the behaviour
-        // of all major browsers
-        input.try(specified::Number::parse_non_negative)
-            .map(SpecifiedValue::Number)
-            .or_else(|()| {
-                input.try(specified::LengthOrPercentage::parse_non_negative)
-                .map(SpecifiedValue::LengthOrPercentage)
-                .or_else(|()| {
-                    match try!(input.next()) {
-                        Token::Ident(ref value) if value.eq_ignore_ascii_case("normal") => {
-                            Ok(SpecifiedValue::Normal)
-                        }
-                        % if product == "gecko":
-                        Token::Ident(ref value) if value.eq_ignore_ascii_case("-moz-block-height") => {
-                            Ok(SpecifiedValue::MozBlockHeight)
-                        }
-                        % endif
-                        _ => Err(()),
-                    }
-                })
-            })
+
+        // We try to parse as a Number first because, for 'line-height', we want
+        // "0" to be parsed as a plain Number rather than a Length (0px); this
+        // matches the behaviour of all major browsers
+        if let Ok(number) = input.try(specified::Number::parse_non_negative) {
+            return Ok(SpecifiedValue::Number(number))
+        }
+
+        if let Ok(lop) = input.try(specified::LengthOrPercentage::parse_non_negative) {
+            return Ok(SpecifiedValue::LengthOrPercentage(lop))
+        }
+
+
+        match try!(input.next()) {
+            Token::Ident(ref value) if value.eq_ignore_ascii_case("normal") => {
+                Ok(SpecifiedValue::Normal)
+            }
+            % if product == "gecko":
+            Token::Ident(ref value) if value.eq_ignore_ascii_case("-moz-block-height") => {
+                Ok(SpecifiedValue::MozBlockHeight)
+            }
+            % endif
+            _ => Err(()),
+        }
     }
     pub mod computed_value {
         use app_units::Au;

components/style/properties/shorthand/position.mako.rs

@@ -56,8 +56,8 @@
         use values::specified::LengthOrPercentageOrAutoOrContent;
     % endif
 
-    pub fn parse_flexibility(input: &mut Parser)
-                             -> Result<(Number, Option<Number>),()> {
+    fn parse_flexibility(input: &mut Parser)
+                         -> Result<(Number, Option<Number>),()> {
         let grow = try!(Number::parse_non_negative(input));
         let shrink = input.try(Number::parse_non_negative).ok();
         Ok((grow, shrink))

components/style/values/specified/grid.rs

@@ -6,6 +6,7 @@
 
 use cssparser::{Parser, Token};
 use parser::{Parse, ParserContext};
+use std::ascii::AsciiExt;
 use std::fmt;
 use style_traits::ToCss;
 use values::{CSSFloat, HasViewportPercentage};
@@ -130,23 +131,23 @@ pub enum TrackBreadth<L> {
 /// Parse a single flexible length.
 pub fn parse_flex(input: &mut Parser) -> Result<CSSFloat, ()> {
     match try!(input.next()) {
-        Token::Dimension(ref value, ref unit) if unit.to_lowercase() == "fr" && value.value.is_sign_positive()
+        Token::Dimension(ref value, ref unit) if unit.eq_ignore_ascii_case("fr") && value.value.is_sign_positive()
             => Ok(value.value),
         _ => Err(()),
     }
 }
 
 impl Parse for TrackBreadth<LengthOrPercentage> {
-    fn parse(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+    fn parse(_: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
         if let Ok(lop) = input.try(LengthOrPercentage::parse_non_negative) {
-            Ok(TrackBreadth::Breadth(lop))
-        } else {
-            if let Ok(f) = input.try(parse_flex) {
-                Ok(TrackBreadth::Flex(f))
-            } else {
-                TrackKeyword::parse(input).map(TrackBreadth::Keyword)
-            }
+            return Ok(TrackBreadth::Breadth(lop))
         }
+
+        if let Ok(f) = input.try(parse_flex) {
+            return Ok(TrackBreadth::Flex(f))
+        }
+
+        TrackKeyword::parse(input).map(TrackBreadth::Keyword)
     }
 }
 
@@ -223,24 +224,28 @@ impl<L> Default for TrackSize<L> {
 impl Parse for TrackSize<LengthOrPercentage> {
     fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
         if let Ok(b) = input.try(|i| TrackBreadth::parse(context, i)) {
-            Ok(TrackSize::Breadth(b))
-        } else {
-            if input.try(|i| i.expect_function_matching("minmax")).is_ok() {
-                Ok(try!(input.parse_nested_block(|input| {
-                    let inflexible_breadth = if let Ok(lop) = input.try(LengthOrPercentage::parse_non_negative) {
-                        Ok(TrackBreadth::Breadth(lop))
-                    } else {
-                        TrackKeyword::parse(input).map(TrackBreadth::Keyword)
+            return Ok(TrackSize::Breadth(b))
+        }
+
+        if input.try(|i| i.expect_function_matching("minmax")).is_ok() {
+            return input.parse_nested_block(|input| {
+                let inflexible_breadth =
+                    match input.try(LengthOrPercentage::parse_non_negative) {
+                        Ok(lop) => TrackBreadth::Breadth(lop),
+                        Err(..) => {
+                            let keyword = try!(TrackKeyword::parse(input));
+                            TrackBreadth::Keyword(keyword)
+                        }
                     };
 
-                    try!(input.expect_comma());
-                    Ok(TrackSize::MinMax(try!(inflexible_breadth), try!(TrackBreadth::parse(context, input))))
-                })))
-            } else {
-                try!(input.expect_function_matching("fit-content"));
-                Ok(try!(LengthOrPercentage::parse(context, input).map(TrackSize::FitContent)))
-            }
+                try!(input.expect_comma());
+                Ok(TrackSize::MinMax(inflexible_breadth, try!(TrackBreadth::parse(context, input))))
+            });
         }
+
+        try!(input.expect_function_matching("fit-content"));
+        // FIXME(emilio): This needs a parse_nested_block, doesn't it?
+        Ok(try!(LengthOrPercentage::parse(context, input).map(TrackSize::FitContent)))
     }
 }
 

components/style/values/specified/length.rs

@@ -442,7 +442,7 @@ impl Length {
     /// Parse a non-negative length
     #[inline]
     pub fn parse_non_negative(input: &mut Parser) -> Result<Length, ()> {
-        Length::parse_internal(input, AllowedNumericType::NonNegative)
+        Self::parse_internal(input, AllowedNumericType::NonNegative)
     }
 
     /// Get an absolute length from a px value.
@@ -462,7 +462,7 @@ impl Length {
 
 impl Parse for Length {
     fn parse(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
-        Length::parse_internal(input, AllowedNumericType::All)
+        Self::parse_internal(input, AllowedNumericType::All)
     }
 }
 
@@ -1049,7 +1049,7 @@ impl LengthOrPercentage {
     /// Parse a non-negative length.
     #[inline]
     pub fn parse_non_negative(input: &mut Parser) -> Result<LengthOrPercentage, ()> {
-        LengthOrPercentage::parse_internal(input, AllowedNumericType::NonNegative)
+        Self::parse_internal(input, AllowedNumericType::NonNegative)
     }
 
     /// Parse a length, treating dimensionless numbers as pixels
@@ -1057,11 +1057,13 @@ impl LengthOrPercentage {
     /// https://www.w3.org/TR/SVG2/types.html#presentation-attribute-css-value
     pub fn parse_numbers_are_pixels(input: &mut Parser) -> Result<LengthOrPercentage, ()> {
         if let Ok(lop) = input.try(|i| Self::parse_internal(i, AllowedNumericType::All)) {
-            Ok(lop)
-        } else {
-            let num = input.expect_number()?;
-            Ok(LengthOrPercentage::Length(NoCalcLength::Absolute(Au((AU_PER_PX * num) as i32))))
+            return Ok(lop)
         }
+
+        // TODO(emilio): Probably should use Number::parse_non_negative to
+        // handle calc()?
+        let num = input.expect_number()?;
+        Ok(LengthOrPercentage::Length(NoCalcLength::Absolute(Au((AU_PER_PX * num) as i32))))
     }
 
     /// Parse a non-negative length, treating dimensionless numbers as pixels
@@ -1069,14 +1071,16 @@ impl LengthOrPercentage {
     /// This is nonstandard behavior used by Firefox for SVG
     pub fn parse_numbers_are_pixels_non_negative(input: &mut Parser) -> Result<LengthOrPercentage, ()> {
         if let Ok(lop) = input.try(|i| Self::parse_internal(i, AllowedNumericType::NonNegative)) {
-            Ok(lop)
+            return Ok(lop)
+        }
+
+        // TODO(emilio): Probably should use Number::parse_non_negative to
+        // handle calc()?
+        let num = input.expect_number()?;
+        if num >= 0. {
+            Ok(LengthOrPercentage::Length(NoCalcLength::Absolute(Au((AU_PER_PX * num) as i32))))
         } else {
-            let num = input.expect_number()?;
-            if num >= 0. {
-                Ok(LengthOrPercentage::Length(NoCalcLength::Absolute(Au((AU_PER_PX * num) as i32))))
-            } else {
-                Err(())
-            }
+            Err(())
         }
     }
 
@@ -1092,7 +1096,7 @@ impl LengthOrPercentage {
 impl Parse for LengthOrPercentage {
     #[inline]
     fn parse(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
-        LengthOrPercentage::parse_internal(input, AllowedNumericType::All)
+        Self::parse_internal(input, AllowedNumericType::All)
     }
 }
 
@@ -1168,7 +1172,7 @@ impl LengthOrPercentageOrAuto {
     /// Parse a non-negative length, percentage, or auto.
     #[inline]
     pub fn parse_non_negative(input: &mut Parser) -> Result<LengthOrPercentageOrAuto, ()> {
-        LengthOrPercentageOrAuto::parse_internal(input, AllowedNumericType::NonNegative)
+        Self::parse_internal(input, AllowedNumericType::NonNegative)
     }
 
     /// Parse a non-negative length, percentage, or auto.
@@ -1183,7 +1187,7 @@ impl LengthOrPercentageOrAuto {
 impl Parse for LengthOrPercentageOrAuto {
     #[inline]
     fn parse(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
-        LengthOrPercentageOrAuto::parse_internal(input, AllowedNumericType::All)
+        Self::parse_internal(input, AllowedNumericType::All)
     }
 }
 
@@ -1241,15 +1245,15 @@ impl LengthOrPercentageOrNone {
     }
     /// Parse a non-negative LengthOrPercentageOrNone.
     #[inline]
-    pub fn parse_non_negative(input: &mut Parser) -> Result<LengthOrPercentageOrNone, ()> {
-        LengthOrPercentageOrNone::parse_internal(input, AllowedNumericType::NonNegative)
+    pub fn parse_non_negative(input: &mut Parser) -> Result<Self, ()> {
+        Self::parse_internal(input, AllowedNumericType::NonNegative)
     }
 }
 
 impl Parse for LengthOrPercentageOrNone {
     #[inline]
     fn parse(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
-        LengthOrPercentageOrNone::parse_internal(input, AllowedNumericType::All)
+        Self::parse_internal(input, AllowedNumericType::All)
     }
 }
 
@@ -1341,15 +1345,15 @@ pub type LengthOrNumber = Either<Length, Number>;
 
 impl LengthOrNumber {
     /// Parse a non-negative LengthOrNumber.
-    pub fn parse_non_negative(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
-        // We try to parse as a Number first because, for cases like LengthOrNumber,
-        // we want "0" to be parsed as a plain Number rather than a Length (0px); this
-        // matches the behaviour of all major browsers
+    pub fn parse_non_negative(_: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+        // We try to parse as a Number first because, for cases like
+        // LengthOrNumber, we want "0" to be parsed as a plain Number rather
+        // than a Length (0px); this matches the behaviour of all major browsers
         if let Ok(v) = input.try(Number::parse_non_negative) {
-            Ok(Either::Second(v))
-        } else {
-            Length::parse_non_negative(input).map(Either::First)
+            return Ok(Either::Second(v))
         }
+
+        Length::parse_non_negative(input).map(Either::First)
     }
 }