1 files changed, 131 insertions, 0 deletions
diff --git a/components/style/media_queries.rs b/components/style/media_queries.rs
new file mode 100644
index 00000000000..2c7b6b4b08f
--- /dev/null
+++ b/components/style/media_queries.rs
@@ -0,0 +1,131 @@
+/* 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::StrAsciiExt;
+use cssparser::parse_rule_list;
+use cssparser::ast::*;
+
+use errors::{ErrorLoggerIterator, log_css_error};
+use stylesheets::{CSSRule, CSSMediaRule, parse_style_rule, parse_nested_at_rule};
+use namespaces::NamespaceMap;
+use url::Url;
+
+
+pub struct MediaRule {
+    pub media_queries: MediaQueryList,
+    pub rules: Vec<CSSRule>,
+}
+
+
+pub struct MediaQueryList {
+    // "not all" is omitted from the list.
+    // An empty list never matches.
+    media_queries: Vec<MediaQuery>
+}
+
+// For now, this is a "Level 2 MQ", ie. a media type.
+pub struct MediaQuery {
+    media_type: MediaQueryType,
+    // TODO: Level 3 MQ expressions
+}
+
+
+pub enum MediaQueryType {
+    All,  // Always true
+    MediaType(MediaType),
+}
+
+#[deriving(PartialEq)]
+pub enum MediaType {
+    Screen,
+    Print,
+}
+
+pub struct Device {
+    pub media_type: MediaType,
+    // TODO: Level 3 MQ data: viewport size, etc.
+}
+
+
+pub fn parse_media_rule(rule: AtRule, parent_rules: &mut Vec<CSSRule>,
+                        namespaces: &NamespaceMap, base_url: &Url) {
+    let media_queries = parse_media_query_list(rule.prelude.as_slice());
+    let block = match rule.block {
+        Some(block) => block,
+        None => {
+            log_css_error(rule.location, "Invalid @media rule");
+            return
+        }
+    };
+    let mut rules = vec!();
+    for rule in ErrorLoggerIterator(parse_rule_list(block.move_iter())) {
+        match rule {
+            QualifiedRule(rule) => parse_style_rule(rule, &mut rules, namespaces, base_url),
+            AtRule(rule) => parse_nested_at_rule(
+                rule.name.as_slice().to_ascii_lower().as_slice(), rule, &mut rules, namespaces, base_url),
+        }
+    }
+    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: vec!(MediaQuery{media_type: All}) }
+    }
+    let mut queries = vec!();
+    loop {
+        let mq = match next {
+            Some(&Ident(ref value)) => {
+                match value.as_slice().to_ascii_lower().as_slice() {
+                    "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 => {
+                for mq in mq.move_iter() {
+                    queries.push(mq);
+                }
+                return MediaQueryList{ media_queries: queries }
+            },
+            Some(&Comma) => {
+                for mq in mq.move_iter() {
+                    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 {
+        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
+        })
+    }
+}