Implement parsing of tree pseudo-elements.

components/style/gecko/pseudo_element.rs

@@ -8,7 +8,7 @@
 //! `pseudo_element_definition.mako.rs`. If you touch that file, you probably
 //! need to update the checked-in files for Servo.
 
-use cssparser::ToCss;
+use cssparser::{ToCss, serialize_identifier};
 use gecko_bindings::structs::{self, CSSPseudoElementType};
 use selector_parser::{NonTSPseudoClass, PseudoElementCascadeType, SelectorImpl};
 use std::fmt;
@@ -114,10 +114,3 @@ impl PseudoElement {
         }
     }
 }
-
-impl ToCss for PseudoElement {
-    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        dest.write_char(':')?;
-        dest.write_str(self.as_str())
-    }
-}

components/style/gecko/pseudo_element_definition.mako.rs

@@ -7,7 +7,11 @@
 pub enum PseudoElement {
     % for pseudo in PSEUDOS:
         /// ${pseudo.value}
+        % if pseudo.is_tree_pseudo_element():
+        ${pseudo.capitalized()}(Box<[String]>),
+        % else:
         ${pseudo.capitalized()},
+        % endif
     % endfor
 }
 
@@ -23,8 +27,11 @@ pub const EAGER_PSEUDOS: [PseudoElement; EAGER_PSEUDO_COUNT] = [
     % endfor
 ];
 
-<%def name="pseudo_element_variant(pseudo)">
+<% TREE_PSEUDOS = [pseudo for pseudo in PSEUDOS if pseudo.is_tree_pseudo_element()] %>
-    PseudoElement::${pseudo.capitalized()}
+<% SIMPLE_PSEUDOS = [pseudo for pseudo in PSEUDOS if not pseudo.is_tree_pseudo_element()] %>
+
+<%def name="pseudo_element_variant(pseudo, tree_arg='..')">\
+PseudoElement::${pseudo.capitalized()}${"({})".format(tree_arg) if pseudo.is_tree_pseudo_element() else ""}\
 </%def>
 
 impl PseudoElement {
@@ -33,7 +40,7 @@ impl PseudoElement {
     pub fn each_simple<F>(mut fun: F)
         where F: FnMut(Self),
     {
-        % for pseudo in PSEUDOS:
+        % for pseudo in SIMPLE_PSEUDOS:
             fun(${pseudo_element_variant(pseudo)});
         % endfor
     }
@@ -74,7 +81,9 @@ impl PseudoElement {
         match *self {
             % for pseudo in PSEUDOS:
                 ${pseudo_element_variant(pseudo)} =>
-                % if pseudo.is_anon_box():
+                % if pseudo.is_tree_pseudo_element():
+                    0,
+                % elif pseudo.is_anon_box():
                     structs::CSS_PSEUDO_ELEMENT_UA_SHEET_ONLY,
                 % else:
                     structs::SERVO_CSS_PSEUDO_ELEMENT_FLAGS_${pseudo.original_ident},
@@ -102,7 +111,9 @@ impl PseudoElement {
     #[inline]
     pub fn from_anon_box_atom(atom: &Atom) -> Option<Self> {
         % for pseudo in PSEUDOS:
-            % if pseudo.is_anon_box():
+            % if pseudo.is_tree_pseudo_element():
+                // We cannot generate ${pseudo_element_variant(pseudo)} from just an atom.
+            % elif pseudo.is_anon_box():
                 if atom == &atom!("${pseudo.value}") {
                     return Some(${pseudo_element_variant(pseudo)});
                 }
@@ -122,7 +133,10 @@ impl PseudoElement {
     pub fn from_slice(s: &str, in_ua_stylesheet: bool) -> Option<Self> {
         use std::ascii::AsciiExt;
 
-        % for pseudo in PSEUDOS:
+        // We don't need to support tree pseudos because functional
+        // pseudo-elements needs arguments, and thus should be created
+        // via other methods.
+        % for pseudo in SIMPLE_PSEUDOS:
             if in_ua_stylesheet || ${pseudo_element_variant(pseudo)}.exposed_in_non_ua_sheets() {
                 if s.eq_ignore_ascii_case("${pseudo.value[1:]}") {
                     return Some(${pseudo_element_variant(pseudo)});
@@ -133,13 +147,47 @@ impl PseudoElement {
         None
     }
 
-    /// Returns the pseudo-element's definition as a string, with only one colon
+    /// Constructs a tree pseudo-element from the given name and arguments.
-    /// before it.
+    /// "name" must start with "-moz-tree-".
-    pub fn as_str(&self) -> &'static str {
+    ///
-        match *self {
+    /// Returns `None` if the pseudo-element is not recognized.
-        % for pseudo in PSEUDOS:
+    #[inline]
-            PseudoElement::${pseudo.capitalized()} => "${pseudo.value}",
+    pub fn tree_pseudo_element(name: &str, args: Box<[String]>) -> Option<Self> {
+        use std::ascii::AsciiExt;
+        debug_assert!(name.starts_with("-moz-tree-"));
+        let tree_part = &name[10..];
+        % for pseudo in TREE_PSEUDOS:
+            if tree_part.eq_ignore_ascii_case("${pseudo.value[11:]}") {
+                return Some(${pseudo_element_variant(pseudo, "args")});
+            }
         % endfor
+        None
+    }
+}
+
+impl ToCss for PseudoElement {
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+        dest.write_char(':')?;
+        match *self {
+            % for pseudo in PSEUDOS:
+                ${pseudo_element_variant(pseudo)} => dest.write_str("${pseudo.value}")?,
+            % endfor
+        }
+        match *self {
+            ${" |\n            ".join("PseudoElement::{}(ref args)".format(pseudo.capitalized())
+                                      for pseudo in TREE_PSEUDOS)} => {
+                dest.write_char('(')?;
+                let mut iter = args.iter();
+                if let Some(first) = iter.next() {
+                    serialize_identifier(first, dest)?;
+                    for item in iter {
+                        dest.write_str(", ")?;
+                        serialize_identifier(item, dest)?;
+                    }
+                }
+                dest.write_char(')')
+            }
+            _ => Ok(()),
         }
     }
 }

components/style/gecko/regen_atoms.py

@@ -103,6 +103,9 @@ class Atom:
     def is_anon_box(self):
         return self.type() == "nsICSSAnonBoxPseudo"
 
+    def is_tree_pseudo_element(self):
+        return self.value.startswith(":-moz-tree-")
+
 
 def collect_atoms(objdir):
     atoms = []

components/style/gecko/selector_parser.rs

@@ -4,7 +4,7 @@
 
 //! Gecko-specific bits for selector-parsing.
 
-use cssparser::{Parser, ToCss, CompactCowStr};
+use cssparser::{BasicParseError, Parser, ToCss, Token, CompactCowStr};
 use element_state::ElementState;
 use gecko_bindings::structs::CSSPseudoClassType;
 use selector_parser::{SelectorParser, PseudoElementCascadeType};
@@ -267,6 +267,11 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
     type Impl = SelectorImpl;
     type Error = StyleParseError<'i>;
 
+    fn is_pseudo_element_allows_single_colon(name: &CompactCowStr<'i>) -> bool {
+        ::selectors::parser::is_css2_pseudo_element(name) ||
+            name.starts_with("-moz-tree-") // tree pseudo-elements
+    }
+
     fn parse_non_ts_pseudo_class(&self, name: CompactCowStr<'i>)
                                  -> Result<NonTSPseudoClass, ParseError<'i>> {
         macro_rules! pseudo_class_parse {
@@ -338,6 +343,30 @@ impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
             .ok_or(SelectorParseError::UnexpectedIdent(name.clone()).into())
     }
 
+    fn parse_functional_pseudo_element<'t>(&self, name: CompactCowStr<'i>,
+                                           parser: &mut Parser<'i, 't>)
+                                           -> Result<PseudoElement, ParseError<'i>> {
+        if name.starts_with("-moz-tree-") {
+            // Tree pseudo-elements can have zero or more arguments,
+            // separated by either comma or space.
+            let mut args = Vec::new();
+            loop {
+                match parser.next() {
+                    Ok(Token::Ident(ident)) => args.push(ident.into_owned()),
+                    Ok(Token::Comma) => {},
+                    Ok(t) => return Err(BasicParseError::UnexpectedToken(t).into()),
+                    Err(BasicParseError::EndOfInput) => break,
+                    _ => unreachable!("Parser::next() shouldn't return any other error"),
+                }
+            }
+            let args = args.into_boxed_slice();
+            if let Some(pseudo) = PseudoElement::tree_pseudo_element(&name, args) {
+                return Ok(pseudo);
+            }
+        }
+        Err(SelectorParseError::UnexpectedIdent(name.clone()).into())
+    }
+
     fn default_namespace(&self) -> Option<Namespace> {
         self.namespaces.default.clone().as_ref().map(|&(ref ns, _)| ns.clone())
     }