Auto merge of #19578 - emilio:parse-keyword, r=Manishearth,canaltinova

Allow deriving Parse on keywords.

This makes patches like #19576 much easier.

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This commit is contained in:
bors-servo 2017-12-15 14:55:49 -06:00 committed by GitHub
commit e631d167bf
7 changed files with 145 additions and 51 deletions

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@ -149,8 +149,10 @@ pub trait Parse : Sized {
/// Parse a value of this type.
///
/// Returns an error on failure.
fn parse<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>)
-> Result<Self, ParseError<'i>>;
fn parse<'i, 't>(
context: &ParserContext,
input: &mut Parser<'i, 't>,
) -> Result<Self, ParseError<'i>>;
}
impl<T> Parse for Vec<T>

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@ -46,11 +46,13 @@ impl BackgroundSize {
}
/// One of the keywords for `background-repeat`.
define_css_keyword_enum! { RepeatKeyword:
"repeat" => Repeat,
"space" => Space,
"round" => Round,
"no-repeat" => NoRepeat
#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, Parse, PartialEq, ToComputedValue, ToCss)]
#[allow(missing_docs)]
pub enum RepeatKeyword {
Repeat,
Space,
Round,
NoRepeat,
}
/// The specified value for the `background-repeat` property.

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@ -42,17 +42,21 @@ pub enum PositionComponent<S> {
Side(S, Option<LengthOrPercentage>),
}
define_css_keyword_enum! { X:
"left" => Left,
"right" => Right,
/// A keyword for the X direction.
#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, Parse, PartialEq, ToComputedValue, ToCss)]
#[allow(missing_docs)]
pub enum X {
Left,
Right,
}
add_impls_for_keyword_enum!(X);
define_css_keyword_enum! { Y:
"top" => Top,
"bottom" => Bottom,
/// A keyword for the Y direction.
#[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, Parse, PartialEq, ToComputedValue, ToCss)]
#[allow(missing_docs)]
pub enum Y {
Top,
Bottom,
}
add_impls_for_keyword_enum!(Y);
impl Parse for Position {
fn parse<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i>> {

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@ -406,3 +406,41 @@ pub fn where_predicate(
)],
})
}
/// Transforms "FooBar" to "foo-bar".
///
/// If the first Camel segment is "Moz", "Webkit", or "Servo", the result string
/// is prepended with "-".
pub fn to_css_identifier(mut camel_case: &str) -> String {
camel_case = camel_case.trim_right_matches('_');
let mut first = true;
let mut result = String::with_capacity(camel_case.len());
while let Some(segment) = split_camel_segment(&mut camel_case) {
if first {
match segment {
"Moz" | "Webkit" | "Servo" => first = false,
_ => {},
}
}
if !first {
result.push_str("-");
}
first = false;
result.push_str(&segment.to_lowercase());
}
result
}
/// Given "FooBar", returns "Foo" and sets `camel_case` to "Bar".
fn split_camel_segment<'input>(camel_case: &mut &'input str) -> Option<&'input str> {
let index = match camel_case.chars().next() {
None => return None,
Some(ch) => ch.len_utf8(),
};
let end_position = camel_case[index..]
.find(char::is_uppercase)
.map_or(camel_case.len(), |pos| index + pos);
let result = &camel_case[..end_position];
*camel_case = &camel_case[end_position..];
Some(result)
}

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@ -2,6 +2,8 @@
* 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/. */
#![recursion_limit = "128"]
#[macro_use] extern crate darling;
extern crate proc_macro;
#[macro_use] extern crate quote;
@ -13,6 +15,7 @@ use proc_macro::TokenStream;
mod animate;
mod cg;
mod compute_squared_distance;
mod parse;
mod to_animated_value;
mod to_animated_zero;
mod to_computed_value;
@ -36,6 +39,12 @@ pub fn derive_to_animated_value(stream: TokenStream) -> TokenStream {
to_animated_value::derive(input).to_string().parse().unwrap()
}
#[proc_macro_derive(Parse)]
pub fn derive_parse(stream: TokenStream) -> TokenStream {
let input = syn::parse_derive_input(&stream.to_string()).unwrap();
parse::derive(input).to_string().parse().unwrap()
}
#[proc_macro_derive(ToAnimatedZero, attributes(animation))]
pub fn derive_to_animated_zero(stream: TokenStream) -> TokenStream {
let input = syn::parse_derive_input(&stream.to_string()).unwrap();

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@ -0,0 +1,74 @@
/* 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/. */
use cg;
use quote::Tokens;
use syn::DeriveInput;
use synstructure;
pub fn derive(input: DeriveInput) -> Tokens {
let name = &input.ident;
let mut match_body = quote! {};
let style = synstructure::BindStyle::Ref.into();
synstructure::each_variant(&input, &style, |bindings, variant| {
assert!(
bindings.is_empty(),
"Parse is only supported for single-variant enums for now"
);
let identifier = cg::to_css_identifier(variant.ident.as_ref());
match_body = quote! {
#match_body
#identifier => Ok(#name::#variant),
}
});
let parse_trait_impl = quote! {
impl ::parser::Parse for #name {
#[inline]
fn parse<'i, 't>(
_: &::parser::ParserContext,
input: &mut ::cssparser::Parser<'i, 't>,
) -> Result<Self, ::style_traits::ParseError<'i>> {
Self::parse(input)
}
}
};
// TODO(emilio): It'd be nice to get rid of these, but that makes the
// conversion harder...
let methods_impl = quote! {
impl #name {
/// Parse this keyword.
#[inline]
pub fn parse<'i, 't>(
input: &mut ::cssparser::Parser<'i, 't>,
) -> Result<Self, ::style_traits::ParseError<'i>> {
let location = input.current_source_location();
let ident = input.expect_ident()?;
Self::from_ident(ident.as_ref()).map_err(|()| {
location.new_unexpected_token_error(
::cssparser::Token::Ident(ident.clone())
)
})
}
/// Parse this keyword from a string slice.
#[inline]
pub fn from_ident(ident: &str) -> Result<Self, ()> {
match_ignore_ascii_case! { ident,
#match_body
_ => Err(()),
}
}
}
};
quote! {
#parse_trait_impl
#methods_impl
}
}

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@ -16,7 +16,7 @@ pub fn derive(input: DeriveInput) -> Tokens {
let input_attrs = cg::parse_input_attrs::<CssInputAttrs>(&input);
let style = synstructure::BindStyle::Ref.into();
let match_body = synstructure::each_variant(&input, &style, |bindings, variant| {
let mut identifier = to_css_identifier(variant.ident.as_ref());
let mut identifier = cg::to_css_identifier(variant.ident.as_ref());
let variant_attrs = cg::parse_variant_attrs::<CssVariantAttrs>(variant);
let separator = if variant_attrs.comma { ", " } else { " " };
@ -118,38 +118,3 @@ struct CssVariantAttrs {
comma: bool,
dimension: bool,
}
/// Transforms "FooBar" to "foo-bar".
///
/// If the first Camel segment is "Moz" or "Webkit", the result string
/// is prepended with "-".
fn to_css_identifier(mut camel_case: &str) -> String {
camel_case = camel_case.trim_right_matches('_');
let mut first = true;
let mut result = String::with_capacity(camel_case.len());
while let Some(segment) = split_camel_segment(&mut camel_case) {
if first {
match segment {
"Moz" | "Webkit" => first = false,
_ => {},
}
}
if !first {
result.push_str("-");
}
first = false;
result.push_str(&segment.to_lowercase());
}
result
}
/// Given "FooBar", returns "Foo" and sets `camel_case` to "Bar".
fn split_camel_segment<'input>(camel_case: &mut &'input str) -> Option<&'input str> {
let index = camel_case.chars().next()?.len_utf8();
let end_position = camel_case[index..]
.find(char::is_uppercase)
.map_or(camel_case.len(), |pos| index + pos);
let result = &camel_case[..end_position];
*camel_case = &camel_case[end_position..];
Some(result)
}