Hoist ApplicableDeclaration{Block,List} into a separate file.

MozReview-Commit-ID: EXnAzfyoZ1e

12 files changed, 161 insertions, 130 deletions

diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 3d7b0676fb8..957eadb53e4 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -97,6 +97,7 @@ use std::convert::TryFrom;
 use std::default::Default;
 use std::fmt;
 use std::rc::Rc;
+use style::applicable_declarations::ApplicableDeclarationBlock;
 use style::attr::{AttrValue, LengthOrPercentageOrAuto};
 use style::context::{QuirksMode, ReflowGoal};
 use style::element_state::*;
@@ -109,7 +110,6 @@ use style::selector_parser::extended_filtering;
 use style::shared_lock::{SharedRwLock, Locked};
 use style::sink::Push;
 use style::stylearc::Arc;
-use style::stylist::ApplicableDeclarationBlock;
 use style::thread_state;
 use style::values::{CSSFloat, Either};
 use style::values::specified;
diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index 15589619e17..916b9f5a329 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -61,6 +61,7 @@ use std::marker::PhantomData;
 use std::mem::transmute;
 use std::sync::atomic::Ordering;
 use style;
+use style::applicable_declarations::ApplicableDeclarationBlock;
 use style::attr::AttrValue;
 use style::computed_values::display;
 use style::context::{QuirksMode, SharedStyleContext};
@@ -76,7 +77,6 @@ use style::shared_lock::{SharedRwLock as StyleSharedRwLock, Locked as StyleLocke
 use style::sink::Push;
 use style::str::is_whitespace;
 use style::stylearc::Arc;
-use style::stylist::ApplicableDeclarationBlock;
 
 #[derive(Copy, Clone)]
 pub struct ServoLayoutNode<'a> {
diff --git a/components/style/applicable_declarations.rs b/components/style/applicable_declarations.rs
new file mode 100644
index 00000000000..17cf13f7f4d
--- /dev/null
+++ b/components/style/applicable_declarations.rs
@@ -0,0 +1,137 @@
+/* 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/. */
+
+//! Applicable declarations management.
+
+use properties::PropertyDeclarationBlock;
+use rule_tree::{CascadeLevel, StyleSource};
+use shared_lock::Locked;
+use smallvec::SmallVec;
+use std::fmt::{Debug, self};
+use std::mem;
+use stylearc::Arc;
+
+/// List of applicable declarations. This is a transient structure that shuttles
+/// declarations between selector matching and inserting into the rule tree, and
+/// therefore we want to avoid heap-allocation where possible.
+///
+/// In measurements on wikipedia, we pretty much never have more than 8 applicable
+/// declarations, so we could consider making this 8 entries instead of 16.
+/// However, it may depend a lot on workload, and stack space is cheap.
+pub type ApplicableDeclarationList = SmallVec<[ApplicableDeclarationBlock; 16]>;
+
+/// Blink uses 18 bits to store source order, and does not check overflow [1].
+/// That's a limit that could be reached in realistic webpages, so we use
+/// 24 bits and enforce defined behavior in the overflow case.
+///
+/// Note that the value of 24 is also hard-coded into the level() accessor,
+/// which does a byte-aligned load of the 4th byte. If you change this value
+/// you'll need to change that as well.
+///
+/// [1] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/
+///     RuleSet.h?l=128&rcl=90140ab80b84d0f889abc253410f44ed54ae04f3
+const SOURCE_ORDER_BITS: usize = 24;
+const SOURCE_ORDER_MASK: u32 = (1 << SOURCE_ORDER_BITS) - 1;
+const SOURCE_ORDER_MAX: u32 = SOURCE_ORDER_MASK;
+
+/// Stores the source order of a block and the cascade level it belongs to.
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Copy, Clone, Eq, PartialEq)]
+struct SourceOrderAndCascadeLevel(u32);
+
+impl SourceOrderAndCascadeLevel {
+    fn new(source_order: u32, cascade_level: CascadeLevel) -> SourceOrderAndCascadeLevel {
+        let mut bits = ::std::cmp::min(source_order, SOURCE_ORDER_MAX);
+        bits |= (cascade_level as u8 as u32) << SOURCE_ORDER_BITS;
+        SourceOrderAndCascadeLevel(bits)
+    }
+
+    fn order(&self) -> u32 {
+        self.0 & SOURCE_ORDER_MASK
+    }
+
+    fn level(&self) -> CascadeLevel {
+        unsafe {
+            // Transmute rather than shifting so that we're sure the compiler
+            // emits a simple byte-aligned load.
+            let as_bytes: [u8; 4] = mem::transmute(self.0);
+            CascadeLevel::from_byte(as_bytes[3])
+        }
+    }
+}
+
+impl Debug for SourceOrderAndCascadeLevel {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("SourceOrderAndCascadeLevel")
+            .field("order", &self.order())
+            .field("level", &self.level())
+            .finish()
+    }
+}
+
+/// A property declaration together with its precedence among rules of equal
+/// specificity so that we can sort them.
+///
+/// This represents the declarations in a given declaration block for a given
+/// importance.
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+#[derive(Debug, Clone, PartialEq)]
+pub struct ApplicableDeclarationBlock {
+    /// The style source, either a style rule, or a property declaration block.
+    #[cfg_attr(feature = "servo", ignore_heap_size_of = "Arc")]
+    pub source: StyleSource,
+    /// The source order of the block, and the cascade level it belongs to.
+    order_and_level: SourceOrderAndCascadeLevel,
+    /// The specificity of the selector this block is represented by.
+    pub specificity: u32,
+}
+
+impl ApplicableDeclarationBlock {
+    /// Constructs an applicable declaration block from a given property
+    /// declaration block and importance.
+    #[inline]
+    pub fn from_declarations(declarations: Arc<Locked<PropertyDeclarationBlock>>,
+                             level: CascadeLevel)
+                             -> Self {
+        ApplicableDeclarationBlock {
+            source: StyleSource::Declarations(declarations),
+            order_and_level: SourceOrderAndCascadeLevel::new(0, level),
+            specificity: 0,
+        }
+    }
+
+    /// Constructs an applicable declaration block from the given components
+    #[inline]
+    pub fn new(source: StyleSource,
+               order: u32,
+               level: CascadeLevel,
+               specificity: u32) -> Self {
+        ApplicableDeclarationBlock {
+            source: source,
+            order_and_level: SourceOrderAndCascadeLevel::new(order, level),
+            specificity: specificity,
+        }
+
+    }
+
+    /// Returns the source order of the block.
+    #[inline]
+    pub fn source_order(&self) -> u32 {
+        self.order_and_level.order()
+    }
+
+    /// Returns the cascade level of the block.
+    #[inline]
+    pub fn level(&self) -> CascadeLevel {
+        self.order_and_level.level()
+    }
+
+    /// Convenience method to consume self and return the source alongside the
+    /// level.
+    #[inline]
+    pub fn order_and_level(self) -> (StyleSource, CascadeLevel) {
+        let level = self.level();
+        (self.source, level)
+    }
+}
diff --git a/components/style/dom.rs b/components/style/dom.rs
index aef401dc43e..bbb4b279bf3 100644
--- a/components/style/dom.rs
+++ b/components/style/dom.rs
@@ -8,6 +8,7 @@
 #![deny(missing_docs)]
 
 use {Atom, Namespace, LocalName};
+use applicable_declarations::ApplicableDeclarationBlock;
 use atomic_refcell::{AtomicRef, AtomicRefCell, AtomicRefMut};
 #[cfg(feature = "gecko")] use context::UpdateAnimationsTasks;
 use data::ElementData;
@@ -29,7 +30,6 @@ use std::fmt::Debug;
 use std::hash::Hash;
 use std::ops::Deref;
 use stylearc::Arc;
-use stylist::ApplicableDeclarationBlock;
 use thread_state;
 
 pub use style_traits::UnsafeNode;
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 0ceb2c82a1b..64068a875f6 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -15,6 +15,7 @@
 //! the separation between the style system implementation and everything else.
 
 use app_units::Au;
+use applicable_declarations::ApplicableDeclarationBlock;
 use atomic_refcell::AtomicRefCell;
 use context::{QuirksMode, SharedStyleContext, UpdateAnimationsTasks};
 use data::ElementData;
@@ -87,7 +88,6 @@ use std::ptr;
 use string_cache::{Atom, Namespace, WeakAtom, WeakNamespace};
 use stylearc::Arc;
 use stylesheets::UrlExtraData;
-use stylist::ApplicableDeclarationBlock;
 
 /// A simple wrapper over a non-null Gecko node (`nsINode`) pointer.
 ///
diff --git a/components/style/lib.rs b/components/style/lib.rs
index 0cde26b37f0..66cde1211d3 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -91,6 +91,7 @@ extern crate unicode_segmentation;
 mod macros;
 
 pub mod animation;
+pub mod applicable_declarations;
 #[allow(missing_docs)] // TODO.
 #[cfg(feature = "servo")] pub mod attr;
 pub mod bezier;
diff --git a/components/style/matching.rs b/components/style/matching.rs
index 00eaba9b63e..d93eec27026 100644
--- a/components/style/matching.rs
+++ b/components/style/matching.rs
@@ -7,6 +7,7 @@
 #![allow(unsafe_code)]
 #![deny(missing_docs)]
 
+use applicable_declarations::ApplicableDeclarationList;
 use cascade_info::CascadeInfo;
 use context::{SelectorFlagsMap, SharedStyleContext, StyleContext};
 use data::{ComputedStyle, ElementData, RestyleData};
@@ -25,7 +26,7 @@ use selectors::matching::{ElementSelectorFlags, MatchingContext, MatchingMode, S
 use selectors::matching::{VisitedHandlingMode, AFFECTED_BY_PSEUDO_ELEMENTS};
 use sharing::StyleSharingBehavior;
 use stylearc::Arc;
-use stylist::{ApplicableDeclarationList, RuleInclusion};
+use stylist::RuleInclusion;
 
 /// The way a style should be inherited.
 enum InheritMode {
diff --git a/components/style/rule_tree/mod.rs b/components/style/rule_tree/mod.rs
index 66e5bd214f0..c1a3b2b69d5 100644
--- a/components/style/rule_tree/mod.rs
+++ b/components/style/rule_tree/mod.rs
@@ -6,6 +6,7 @@
 
 //! The rule tree.
 
+use applicable_declarations::ApplicableDeclarationList;
 #[cfg(feature = "servo")]
 use heapsize::HeapSizeOf;
 use properties::{AnimationRules, Importance, LonghandIdSet, PropertyDeclarationBlock};
@@ -17,7 +18,6 @@ use std::ptr;
 use std::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
 use stylearc::{Arc, NonZeroPtrMut};
 use stylesheets::StyleRule;
-use stylist::ApplicableDeclarationList;
 use thread_state;
 
 /// The rule tree, the structure servo uses to preserve the results of selector
@@ -230,7 +230,7 @@ impl RuleTree {
                              guards: &StylesheetGuards)
                              -> StrongRuleNode
     {
-        let rules = applicable_declarations.drain().map(|d| d.source_and_level());
+        let rules = applicable_declarations.drain().map(|d| d.order_and_level());
         let rule_node = self.insert_ordered_rules_with_important(rules, guards);
         rule_node
     }
diff --git a/components/style/selector_map.rs b/components/style/selector_map.rs
index 8bb9eeb8e31..6a5733877a2 100644
--- a/components/style/selector_map.rs
+++ b/components/style/selector_map.rs
@@ -6,6 +6,7 @@
 //! name, ids and hash.
 
 use {Atom, LocalName};
+use applicable_declarations::ApplicableDeclarationBlock;
 use dom::TElement;
 use fnv::FnvHashMap;
 use pdqsort::sort_by;
@@ -18,7 +19,7 @@ use smallvec::VecLike;
 use std::borrow::Borrow;
 use std::collections::HashMap;
 use std::hash::Hash;
-use stylist::{ApplicableDeclarationBlock, Rule};
+use stylist::Rule;
 
 /// A trait to abstract over a given selector map entry.
 pub trait SelectorMapEntry : Sized + Clone {
diff --git a/components/style/sharing/mod.rs b/components/style/sharing/mod.rs
index 3c17f576156..5971eb34367 100644
--- a/components/style/sharing/mod.rs
+++ b/components/style/sharing/mod.rs
@@ -65,6 +65,7 @@
 //! elements makes sense.
 
 use Atom;
+use applicable_declarations::ApplicableDeclarationBlock;
 use bit_vec::BitVec;
 use bloom::StyleBloom;
 use cache::{LRUCache, LRUCacheMutIterator};
@@ -78,7 +79,7 @@ use selectors::matching::{ElementSelectorFlags, VisitedHandlingMode, StyleRelati
 use smallvec::SmallVec;
 use std::mem;
 use std::ops::Deref;
-use stylist::{ApplicableDeclarationBlock, Stylist};
+use stylist::Stylist;
 
 mod checks;
 
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index ecda82f269e..321e417a428 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -5,6 +5,7 @@
 //! Selector matching.
 
 use {Atom, LocalName, Namespace};
+use applicable_declarations::{ApplicableDeclarationBlock, ApplicableDeclarationList};
 use bit_vec::BitVec;
 use context::{QuirksMode, SharedStyleContext};
 use data::ComputedStyle;
@@ -33,11 +34,10 @@ use selectors::parser::{SelectorIter, SelectorMethods};
 use selectors::visitor::SelectorVisitor;
 use shared_lock::{Locked, SharedRwLockReadGuard, StylesheetGuards};
 use sink::Push;
-use smallvec::{SmallVec, VecLike};
-use std::fmt::{Debug, self};
+use smallvec::VecLike;
+use std::fmt::Debug;
 #[cfg(feature = "servo")]
 use std::marker::PhantomData;
-use std::mem;
 use style_traits::viewport::ViewportConstraints;
 use stylearc::Arc;
 #[cfg(feature = "gecko")]
@@ -50,15 +50,6 @@ use thread_state;
 
 pub use ::fnv::FnvHashMap;
 
-/// List of applicable declaration. This is a transient structure that shuttles
-/// declarations between selector matching and inserting into the rule tree, and
-/// therefore we want to avoid heap-allocation where possible.
-///
-/// In measurements on wikipedia, we pretty much never have more than 8 applicable
-/// declarations, so we could consider making this 8 entries instead of 16.
-/// However, it may depend a lot on workload, and stack space is cheap.
-pub type ApplicableDeclarationList = SmallVec<[ApplicableDeclarationBlock; 16]>;
-
 /// This structure holds all the selectors and device characteristics
 /// for a given document. The selectors are converted into `Rule`s
 /// (defined in rust-selectors), and introduced in a `SelectorMap`
@@ -756,7 +747,7 @@ impl Stylist {
 
         let rule_node =
             self.rule_tree.insert_ordered_rules_with_important(
-                declarations.into_iter().map(|a| a.source_and_level()),
+                declarations.into_iter().map(|a| a.order_and_level()),
                 guards);
         if rule_node == self.rule_tree.root() {
             None
@@ -1208,7 +1199,7 @@ impl Stylist {
                                                           CascadeLevel::StyleAttributeNormal)
         ];
         let rule_node =
-            self.rule_tree.insert_ordered_rules(v.into_iter().map(|a| a.source_and_level()));
+            self.rule_tree.insert_ordered_rules(v.into_iter().map(|a| a.order_and_level()));
 
         // This currently ignores visited styles.  It appears to be used for
         // font styles in <canvas> via Servo_StyleSet_ResolveForDeclarations.
@@ -1529,11 +1520,11 @@ impl Rule {
     pub fn to_applicable_declaration_block(&self,
                                            level: CascadeLevel)
                                            -> ApplicableDeclarationBlock {
-        ApplicableDeclarationBlock {
-            source: StyleSource::Style(self.style_rule.clone()),
-            source_and_level: SourceOrderAndCascadeLevel::new(self.source_order, level),
-            specificity: self.specificity(),
-        }
+        let source = StyleSource::Style(self.style_rule.clone());
+        ApplicableDeclarationBlock::new(source,
+                                        self.source_order,
+                                        level,
+                                        self.specificity())
     }
 
     /// Creates a new Rule.
@@ -1551,104 +1542,3 @@ impl Rule {
         }
     }
 }
-
-/// Blink uses 18 bits to store source order, and does not check overflow [1].
-/// That's a limit that could be reached in realistic webpages, so we use
-/// 24 bits and enforce defined behavior in the overflow case.
-///
-/// Note that the value of 24 is also hard-coded into the level() accessor,
-/// which does a byte-aligned load of the 4th byte. If you change this value
-/// you'll need to change that as well.
-///
-/// [1] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/
-///     RuleSet.h?l=128&rcl=90140ab80b84d0f889abc253410f44ed54ae04f3
-const SOURCE_ORDER_BITS: usize = 24;
-const SOURCE_ORDER_MASK: u32 = (1 << SOURCE_ORDER_BITS) - 1;
-const SOURCE_ORDER_MAX: u32 = SOURCE_ORDER_MASK;
-
-/// Stores the source order of a block and the cascade level it belongs to.
-#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Copy, Clone, Eq, PartialEq)]
-struct SourceOrderAndCascadeLevel(u32);
-
-impl SourceOrderAndCascadeLevel {
-    fn new(source_order: u32, cascade_level: CascadeLevel) -> SourceOrderAndCascadeLevel {
-        let mut bits = ::std::cmp::min(source_order, SOURCE_ORDER_MAX);
-        bits |= (cascade_level as u8 as u32) << SOURCE_ORDER_BITS;
-        SourceOrderAndCascadeLevel(bits)
-    }
-
-    fn order(&self) -> u32 {
-        self.0 & SOURCE_ORDER_MASK
-    }
-
-    fn level(&self) -> CascadeLevel {
-        unsafe {
-            // Transmute rather than shifting so that we're sure the compiler
-            // emits a simple byte-aligned load.
-            let as_bytes: [u8; 4] = mem::transmute(self.0);
-            CascadeLevel::from_byte(as_bytes[3])
-        }
-    }
-}
-
-impl Debug for SourceOrderAndCascadeLevel {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("SourceOrderAndCascadeLevel")
-            .field("order", &self.order())
-            .field("level", &self.level())
-            .finish()
-    }
-}
-
-/// A property declaration together with its precedence among rules of equal
-/// specificity so that we can sort them.
-///
-/// This represents the declarations in a given declaration block for a given
-/// importance.
-#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-#[derive(Debug, Clone, PartialEq)]
-pub struct ApplicableDeclarationBlock {
-    /// The style source, either a style rule, or a property declaration block.
-    #[cfg_attr(feature = "servo", ignore_heap_size_of = "Arc")]
-    pub source: StyleSource,
-    /// The source order of the block, and the cascade level it belongs to.
-    source_and_level: SourceOrderAndCascadeLevel,
-    /// The specificity of the selector this block is represented by.
-    pub specificity: u32,
-}
-
-impl ApplicableDeclarationBlock {
-    /// Constructs an applicable declaration block from a given property
-    /// declaration block and importance.
-    #[inline]
-    pub fn from_declarations(declarations: Arc<Locked<PropertyDeclarationBlock>>,
-                             level: CascadeLevel)
-                             -> Self {
-        ApplicableDeclarationBlock {
-            source: StyleSource::Declarations(declarations),
-            source_and_level: SourceOrderAndCascadeLevel::new(0, level),
-            specificity: 0,
-        }
-    }
-
-    /// Returns the source order of the block.
-    #[inline]
-    pub fn source_order(&self) -> u32 {
-        self.source_and_level.order()
-    }
-
-    /// Returns the cascade level of the block.
-    #[inline]
-    pub fn level(&self) -> CascadeLevel {
-        self.source_and_level.level()
-    }
-
-    /// Convenience method to consume self and return the source alongside the
-    /// level.
-    #[inline]
-    pub fn source_and_level(self) -> (StyleSource, CascadeLevel) {
-        let level = self.level();
-        (self.source, level)
-    }
-}
diff --git a/tests/unit/stylo/size_of.rs b/tests/unit/stylo/size_of.rs
index 6c90f53ffe6..72acb2c2d5f 100644
--- a/tests/unit/stylo/size_of.rs
+++ b/tests/unit/stylo/size_of.rs
@@ -6,11 +6,11 @@ use selectors::gecko_like_types as dummies;
 use servo_arc::Arc;
 use std::mem::{size_of, align_of};
 use style;
+use style::applicable_declarations::ApplicableDeclarationBlock;
 use style::data::{ComputedStyle, ElementData, ElementStyles};
 use style::gecko::selector_parser as real;
 use style::properties::ComputedValues;
 use style::rule_tree::StrongRuleNode;
-use style::stylist::ApplicableDeclarationBlock;
 
 #[test]
 fn size_of_selectors_dummy_types() {