style: Implement basic column spans.

This patch provides some of the groundwork for column spans greater than
1. It implements the column-span CSS property (prefixed so as not to be
exposed to content) as well as the corresponding colspan attribute;
although the former is not well-specified outside of CSS multi-column
layout, INTRINSIC refers to it. Although width is distributed to
spanning columns, they do not yet contribute minimum and preferred
widths; this will be implemented in a follow-up.

Additionally, this patch cleans up some miscellaneous formatting issues
and improves the handling of table rowgroups.

3 files changed, 25 insertions, 2 deletions

diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 0cdf78b697d..6795511a3d0 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -44,8 +44,9 @@ use dom::node::{window_from_node};
 use dom::nodelist::NodeList;
 use dom::virtualmethods::{VirtualMethods, vtable_for};
 use devtools_traits::AttrInfo;
-use style::{mod, BgColorSimpleColorAttribute, BorderUnsignedIntegerAttribute, IntegerAttribute};
-use style::{LengthAttribute, SimpleColorAttribute, SizeIntegerAttribute, UnsignedIntegerAttribute};
+use style::{mod, BgColorSimpleColorAttribute, BorderUnsignedIntegerAttribute};
+use style::{ColSpanUnsignedIntegerAttribute, IntegerAttribute, LengthAttribute};
+use style::{SimpleColorAttribute, SizeIntegerAttribute, UnsignedIntegerAttribute};
 use style::{WidthLengthAttribute, matches, parse_selector_list_from_str};
 use servo_util::namespace;
 use servo_util::str::{DOMString, LengthOrPercentageOrAuto, SimpleColor};
@@ -349,6 +350,14 @@ impl RawLayoutElementHelpers for Element {
                     None
                 }
             }
+            ColSpanUnsignedIntegerAttribute => {
+                if self.is_htmltablecellelement() {
+                    let this: &HTMLTableCellElement = mem::transmute(self);
+                    this.get_colspan()
+                } else {
+                    panic!("I'm not a table cell!")
+                }
+            }
         }
     }
 
diff --git a/components/script/dom/htmltablecellelement.rs b/components/script/dom/htmltablecellelement.rs
index 25a5e9e78b0..81a6ba3f9f0 100644
--- a/components/script/dom/htmltablecellelement.rs
+++ b/components/script/dom/htmltablecellelement.rs
@@ -22,6 +22,7 @@ pub struct HTMLTableCellElement {
     htmlelement: HTMLElement,
     background_color: Cell<Option<SimpleColor>>,
     border: Cell<Option<u32>>,
+    colspan: Cell<Option<u32>>,
     width: Cell<LengthOrPercentageOrAuto>,
 }
 
@@ -45,6 +46,7 @@ impl HTMLTableCellElement {
             htmlelement: HTMLElement::new_inherited(type_id, tag_name, prefix, document),
             background_color: Cell::new(None),
             border: Cell::new(None),
+            colspan: Cell::new(None),
             width: Cell::new(AutoLpa),
         }
     }
@@ -58,6 +60,7 @@ impl HTMLTableCellElement {
 pub trait HTMLTableCellElementHelpers {
     fn get_background_color(&self) -> Option<SimpleColor>;
     fn get_border(&self) -> Option<u32>;
+    fn get_colspan(&self) -> Option<u32>;
     fn get_width(&self) -> LengthOrPercentageOrAuto;
 }
 
@@ -70,6 +73,10 @@ impl HTMLTableCellElementHelpers for HTMLTableCellElement {
         self.border.get()
     }
 
+    fn get_colspan(&self) -> Option<u32> {
+        self.colspan.get()
+    }
+
     fn get_width(&self) -> LengthOrPercentageOrAuto {
         self.width.get()
     }
@@ -97,6 +104,9 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLTableCellElement> {
                                                                      .as_slice()
                                                                      .chars()).unwrap_or(1)))
             }
+            &atom!("colspan") => {
+                self.colspan.set(str::parse_unsigned_integer(attr.value().as_slice().chars()));
+            }
             &atom!("width") => self.width.set(str::parse_length(attr.value().as_slice())),
             _ => ()
         }
@@ -111,6 +121,7 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLTableCellElement> {
         match attr.local_name() {
             &atom!("bgcolor") => self.background_color.set(None),
             &atom!("border") => self.border.set(None),
+            &atom!("colspan") => self.colspan.set(None),
             &atom!("width") => self.width.set(AutoLpa),
             _ => ()
         }
diff --git a/components/script/dom/htmltableelement.rs b/components/script/dom/htmltableelement.rs
index 4ece4c8b9f9..d88017fe151 100644
--- a/components/script/dom/htmltableelement.rs
+++ b/components/script/dom/htmltableelement.rs
@@ -108,6 +108,7 @@ impl HTMLTableElementHelpers for HTMLTableElement {
     fn get_border(&self) -> Option<u32> {
         self.border.get()
     }
+
     fn get_width(&self) -> LengthOrPercentageOrAuto {
         self.width.get()
     }
@@ -135,6 +136,7 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLTableElement> {
                                                                      .as_slice()
                                                                      .chars()).unwrap_or(1)))
             }
+            &atom!("width") => self.width.set(str::parse_length(attr.value().as_slice())),
             _ => ()
         }
     }
@@ -148,6 +150,7 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLTableElement> {
         match attr.local_name() {
             &atom!("bgcolor") => self.background_color.set(None),
             &atom!("border") => self.border.set(None),
+            &atom!("width") => self.width.set(AutoLpa),
             _ => ()
         }
     }