Add @media and media type parsing (no Media Queries yet.)

media_queries.rs

@@ -0,0 +1,125 @@
+/* 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 std::ascii::to_ascii_lower;
+use cssparser::*;
+use errors::{ErrorLoggerIterator, log_css_error};
+use stylesheets::{CSSRule, CSSMediaRule, parse_style_rule, parse_nested_at_rule};
+use namespaces::NamespaceMap;
+
+
+pub struct MediaRule {
+    media_queries: MediaQueryList,
+    rules: ~[CSSRule],
+}
+
+
+pub struct MediaQueryList {
+    // "not all" is omitted from the list.
+    // An empty list never matches.
+    media_queries: ~[MediaQuery]
+}
+
+// For now, this is a "Level 2 MQ", ie. a media type.
+struct MediaQuery {
+    media_type: MediaQueryType,
+    // TODO: Level 3 MQ expressions
+}
+
+
+enum MediaQueryType {
+    All,  // Always true
+    MediaType(MediaType),
+}
+
+#[deriving(Eq)]
+pub enum MediaType {
+    Screen,
+    Print,
+}
+
+pub struct Device {
+    media_type: MediaType,
+    // TODO: Level 3 MQ data: viewport size, etc.
+}
+
+
+pub fn parse_media_rule(rule: AtRule, parent_rules: &mut ~[CSSRule],
+                        namespaces: &NamespaceMap) {
+    let media_queries = parse_media_query_list(rule.prelude);
+    let block = match rule.block {
+        Some(block) => block,
+        None => {
+            log_css_error(rule.location, "Invalid @media rule");
+            return
+        }
+    };
+    let mut rules = ~[];
+    for rule in ErrorLoggerIterator(parse_rule_list(block.consume_iter())) {
+        match rule {
+            QualifiedRule(rule) => parse_style_rule(rule, &mut rules, namespaces),
+            AtRule(rule) => parse_nested_at_rule(
+                to_ascii_lower(rule.name), rule, &mut rules, namespaces),
+        }
+    }
+    parent_rules.push(CSSMediaRule(MediaRule {
+        media_queries: media_queries,
+        rules: rules,
+    }))
+}
+
+
+pub fn parse_media_query_list(input: &[ComponentValue]) -> MediaQueryList {
+    let iter = &mut input.skip_whitespace();
+    let mut next = iter.next();
+    if next.is_none() {
+        return MediaQueryList{ media_queries: ~[MediaQuery{media_type: All}] }
+    }
+    let mut queries = ~[];
+    loop {
+        let mq = match next {
+            Some(&Ident(ref value)) => {
+                let media_type: &str = to_ascii_lower(value.as_slice());
+                match media_type {
+                    "screen" => Some(MediaQuery{ media_type: MediaType(Screen) }),
+                    "print" => Some(MediaQuery{ media_type: MediaType(Print) }),
+                    "all" => Some(MediaQuery{ media_type: All }),
+                    _ => None
+                }
+            },
+            _ => None
+        };
+        match iter.next() {
+            None => {
+                mq.map_move(|mq| queries.push(mq));
+                return MediaQueryList{ media_queries: queries }
+            },
+            Some(&Comma) => {
+                mq.map_move(|mq| queries.push(mq));
+            },
+            // Ingnore this comma-separated part
+            _ => loop {
+                match iter.next() {
+                    Some(&Comma) => break,
+                    None => return MediaQueryList{ media_queries: queries },
+                    _ => (),
+                }
+            },
+        }
+        next = iter.next();
+    }
+}
+
+
+impl MediaQueryList {
+    pub fn evaluate(&self, device: &Device) -> bool {
+        do self.media_queries.iter().any |mq| {
+            match mq.media_type {
+                MediaType(media_type) => media_type == device.media_type,
+                All => true,
+            }
+            // TODO: match Level 3 expressions
+        }
+    }
+}

servo-style.rc

@@ -13,3 +13,4 @@ pub mod errors;
 pub mod selectors;
 pub mod properties;
 pub mod namespaces;
+pub mod media_queries;

stylesheets.rs

@@ -9,6 +9,7 @@ use selectors;
 use properties;
 use errors::{ErrorLoggerIterator, log_css_error};
 use namespaces::{NamespaceMap, parse_namespace_rule};
+use media_queries::{MediaRule, parse_media_rule};
 
 
 pub struct Stylesheet {
@@ -19,7 +20,7 @@ pub struct Stylesheet {
 
 pub enum CSSRule {
     CSSStyleRule(StyleRule),
-//    CSSMediaRule(MediaRule),
+    CSSMediaRule(MediaRule),
 }
 
 
@@ -42,9 +43,13 @@ fn parse_stylesheet(css: &str) -> Stylesheet {
     for rule in ErrorLoggerIterator(parse_stylesheet_rules(tokenize(css))) {
         let next_state;  // Unitialized to force each branch to set it.
         match rule {
+            QualifiedRule(rule) => {
+                next_state = STATE_BODY;
+                parse_style_rule(rule, &mut rules, &namespaces)
+            },
             AtRule(rule) => {
-                let name: &str = to_ascii_lower(rule.name);
-                match name {
+                let lower_name: &str = to_ascii_lower(rule.name);
+                match lower_name {
                     "charset" => {
                         if state > STATE_CHARSET {
                             log_css_error(rule.location, "@charset must be the first rule")
@@ -76,14 +81,10 @@ fn parse_stylesheet(css: &str) -> Stylesheet {
                     },
                     _ => {
                         next_state = STATE_BODY;
-                        log_css_error(rule.location, fmt!("Unsupported at-rule: @%s", name))
+                        parse_nested_at_rule(lower_name, rule, &mut rules, &namespaces)
                     },
                 }
             },
-            QualifiedRule(rule) => {
-                next_state = STATE_BODY;
-                parse_style_rule(rule, &mut rules, &namespaces)
-            },
         }
         state = next_state;
     }
@@ -91,14 +92,24 @@ fn parse_stylesheet(css: &str) -> Stylesheet {
 }
 
 
-fn parse_style_rule(rule: QualifiedRule, rule_list: &mut ~[CSSRule],
-                    namespaces: &NamespaceMap) {
+pub fn parse_style_rule(rule: QualifiedRule, parent_rules: &mut ~[CSSRule],
+                        namespaces: &NamespaceMap) {
     let QualifiedRule{location: location, prelude: prelude, block: block} = rule;
     match selectors::parse_selector_list(prelude, namespaces) {
-        Some(selectors) => rule_list.push(CSSStyleRule(StyleRule{
+        Some(selectors) => parent_rules.push(CSSStyleRule(StyleRule{
             selectors: selectors,
             declarations: properties::parse_property_declaration_list(block)
         })),
         None => log_css_error(location, "Unsupported CSS selector."),
     }
 }
+
+
+// lower_name is passed explicitly to avoid computing it twice.
+pub fn parse_nested_at_rule(lower_name: &str, rule: AtRule,
+                            parent_rules: &mut ~[CSSRule], namespaces: &NamespaceMap) {
+    match lower_name {
+        "media" => parse_media_rule(rule, parent_rules, namespaces),
+        _ => log_css_error(rule.location, fmt!("Unsupported at-rule: @%s", lower_name))
+    }
+}