Extract mono-cache implementation; lay groundwork for private font matching.

src/servo/gfx.rs

@@ -10,7 +10,11 @@ pub use dl = display_list;
 
 pub use display_list::DisplayList;
 pub use font::Font;
-pub use font_cache::FontCache;
+pub use font::FontDescriptor;
+pub use font::FontGroup;
+pub use font::FontSelector;
+pub use font::FontStyle;
+pub use font::RunMetrics;
 pub use font_context::FontContext;
 pub use font_matcher::FontMatcher;
 pub use geometry::Au;

src/servo/gfx/display_list.rs

@@ -49,7 +49,7 @@ impl DisplayItem {
         match *self {
             SolidColor(_, color) => ctx.draw_solid_color(&self.d().bounds, color),
             Text(_, run, range) => {
-                let new_run = @run.deserialize(ctx.font_cache);
+                let new_run = @run.deserialize(ctx.font_ctx);
                 let font = new_run.font;
                 let origin = self.d().bounds.origin;
                 let baseline_origin = Point2D(origin.x, origin.y + font.metrics.ascent);

src/servo/gfx/font.rs

@@ -38,23 +38,147 @@ enum CSSFontWeight {
     FontWeight800,
     FontWeight900,
 }
+pub impl CSSFontWeight : cmp::Eq;
 
-struct FontStyle {
+// TODO: eventually this will be split into the specified and used
+// font styles.  specified contains uninterpreted CSS font property
+// values, while 'used' is attached to gfx::Font to descript the
+// instance's properties.
+//
+// For now, the cases are differentiated with a typedef
+pub struct FontStyle {
     pt_size: float,
     weight: CSSFontWeight,
     italic: bool,
     oblique: bool,
+    families: ~str,
+    // TODO: font-stretch, text-decoration, font-variant, size-adjust
 }
 
-struct FontFaceProperties {
+// TODO(Issue #181): use deriving for trivial cmp::Eq implementations
+pub impl FontStyle : cmp::Eq {
+    pure fn eq(other: &FontStyle) -> bool {
+        use std::cmp::FuzzyEq;
+
+        self.pt_size.fuzzy_eq(&other.pt_size) &&
+            self.weight == other.weight &&
+            self.italic == other.italic &&
+            self.oblique == other.oblique &&
+            self.families == other.families
+    }
+    pure fn ne(other: &FontStyle) -> bool { !self.eq(other) }
+}
+
+pub type SpecifiedFontStyle = FontStyle;
+pub type UsedFontStyle = FontStyle;
+
+// TODO: move me to layout
+struct ResolvedFont {
+    group: @FontGroup,
+    style: SpecifiedFontStyle,
+}
+
+// FontDescriptor serializes a specific font and used font style
+// options, such as point size.
+
+// It's used to swizzle/unswizzle gfx::Font instances when
+// communicating across tasks, such as the display list between layout
+// and render tasks.
+pub struct FontDescriptor {
+    style: UsedFontStyle,
+    selector: FontSelector,
+}
+
+
+// TODO(Issue #181): use deriving for trivial cmp::Eq implementations
+pub impl FontDescriptor : cmp::Eq {
+    pure fn eq(other: &FontDescriptor) -> bool {
+        self.style == other.style &&
+            self.selector == other.selector
+    }
+    pure fn ne(other: &FontDescriptor) -> bool { !self.eq(other) }
+}
+
+pub impl FontDescriptor {
+    static pure fn new(style: &UsedFontStyle, selector: &FontSelector) -> FontDescriptor {
+        FontDescriptor {
+            style: copy *style,
+            selector: copy *selector,
+        }
+    }
+}
+
+// A FontSelector is a platform-specific strategy for serializing face names.
+pub enum FontSelector {
+    SelectorPlatformName(~str),
+    SelectorStubDummy, // aka, use Josephin Sans
+}
+
+// TODO(Issue #181): use deriving for trivial cmp::Eq implementations
+pub impl FontSelector : cmp::Eq {
+    pure fn eq(other: &FontSelector) -> bool {
+        match (self, *other) {
+            (SelectorStubDummy, SelectorStubDummy) => true,
+            (SelectorPlatformName(a), SelectorPlatformName(b)) => a == b,
+            _ => false
+        }
+    }
+    pure fn ne(other: &FontSelector) -> bool { !self.eq(other) }
+}
+
+// Holds a specific font family, and the various 
+pub struct FontFamily {
     family_name: @str,
-    face_name: ~str,
-    priv weight: u16,
-    priv italic: bool,
+    entries: ~[@FontEntry],
+}
+
+// This struct is the result of mapping a specified FontStyle into the
+// available fonts on the system. It contains an ordered list of font
+// instances to be used in case the prior font cannot be used for
+// rendering the specified language.
+
+// The ordering of font instances is mainly decided by the CSS
+// 'font-family' property. The last font is a system fallback font.
+pub struct FontGroup {
+    families: @str,
+    // style of the first western font in group, which is
+    // used for purposes of calculating text run metrics.
+    style: UsedFontStyle,
+    fonts: ~[@Font],
+}
+
+pub impl FontGroup {
+    static fn new(families: @str, style: &UsedFontStyle, fonts: ~[@Font]) -> FontGroup {
+        FontGroup {
+            families: families,
+            style: copy *style,
+            fonts: move fonts,
+        }
+    }
+}
+
+
+// This struct summarizes an available font's features. In the future,
+// this will include fiddly settings such as special font table handling.
+
+// In the common case, each FontFamily will have a singleton FontEntry, or
+// it will have the standard four faces: Normal, Bold, Italic, BoldItalic.
+struct FontEntry {
+    family: @FontFamily,
+    face_name: ~str,
+    priv weight: CSSFontWeight,
+    priv italic: bool,
+    // TODO: array of OpenType features, etc.
+}
+
+impl FontEntry {
+    pure fn is_bold() -> bool { 
+        match self.weight {
+            FontWeight900 | FontWeight800 | FontWeight700 | FontWeight600 => true,
+            _ => false
+        }
     }
 
-impl FontFaceProperties {
-    pure fn is_bold() -> bool { self.weight >= (500 as u16) }
     pure fn is_italic() -> bool { self.italic }
 }
 
@@ -69,7 +193,7 @@ struct RunMetrics {
 }
 
 /**
-A font handle. Layout can use this to calculate glyph metrics
+A font instance. Layout can use this to calculate glyph metrics
 and the renderer can use it to render text.
 */
 struct Font {
@@ -77,7 +201,7 @@ struct Font {
     priv handle: FontHandle,
     priv mut azure_font: Option<AzScaledFontRef>,
     priv mut shaper: Option<@Shaper>,
-    style: FontStyle,
+    style: UsedFontStyle,
     metrics: FontMetrics,
 
     drop {
@@ -88,7 +212,7 @@ struct Font {
 
 impl Font {
     // TODO: who should own fontbuf?
-    static fn new(fontbuf: @~[u8], handle: FontHandle, style: FontStyle) -> Font {
+    static fn new(fontbuf: @~[u8], handle: FontHandle, style: UsedFontStyle) -> Font {
         let metrics = handle.get_metrics();
 
         Font {
@@ -214,6 +338,7 @@ pub trait FontMethods {
     fn draw_text_into_context(rctx: &RenderContext, run: &TextRun, range: Range, baseline_origin: Point2D<Au>);
     fn measure_text(&TextRun, Range) -> RunMetrics;
     fn shape_text(@self, &str) -> GlyphStore;
+    fn get_descriptor() -> FontDescriptor;
 
     fn buf(&self) -> @~[u8];
     // these are used to get glyphs and advances in the case that the
@@ -315,6 +440,12 @@ pub impl Font : FontMethods {
         return move store;
     }
 
+    fn get_descriptor() -> FontDescriptor {
+        // TODO(Issue #174): implement by-platform-name FontSelectors,
+        // probably by adding such an API to FontHandle.
+        FontDescriptor::new(&font_context::dummy_style(), &SelectorStubDummy)
+    }
+
     fn buf(&self) -> @~[u8] {
         self.fontbuf
     }

src/servo/gfx/font_cache.rs

@@ -1,14 +1,8 @@
+/*
 use font::{Font, FontStyle, FontWeight300};
 use native::{FontHandle, FontContext};
 
-// TODO(Issue #164): delete, and get default font from font list
-const TEST_FONT: [u8 * 33004] = #include_bin("JosefinSans-SemiBold.ttf");
-
-fn test_font_bin() -> ~[u8] {
-    return vec::from_fn(33004, |i| TEST_FONT[i]);
-}
-
-// Dummy font cache.
+// Font cache that reuses gfx::Font instances.
 
 struct FontCache {
     fctx: @FontContext,
@@ -24,36 +18,19 @@ impl FontCache {
     }
     
     pub fn get_test_font(@self) -> @Font {
-        let dummy_style = FontStyle {
-            pt_size: 40f,
-            weight: FontWeight300,
-            italic: false,
-            oblique: false
-        };
+
 
         return match self.cached_font {
             Some(font) => font,
             None => match self.get_font(&dummy_style) {
                 Ok(font) => { self.cached_font = Some(font); font }
-                Err(*) => /* FIXME */ fail
+                Err(*) => fail
             }
         }
     }
 
-    // TODO: maybe FontStyle should be canonicalized when used in FontCache?
-    priv fn create_font(style: &FontStyle) -> Result<@Font, ()> {
-        let font_bin = @test_font_bin();
-        let native_font = FontHandle::new(self.fctx, font_bin, style.pt_size);
-        let native_font = if native_font.is_ok() {
-            result::unwrap(move native_font)
-        } else {
-            return Err(native_font.get_err());
-        };
-
-        return Ok(@Font::new(font_bin, move native_font, copy *style));
-    }
-
     pub fn get_font(@self, style: &FontStyle) -> Result<@Font, ()> {
         self.create_font(style)
     }
 }
+*/

src/servo/gfx/font_context.rs

@@ -1,3 +1,34 @@
+use dvec::DVec;
+
+use util::cache;
+use gfx::{
+    FontDescriptor,
+    FontSelector,
+    FontStyle,
+};
+use gfx::font::{SelectorPlatformName, SelectorStubDummy, SpecifiedFontStyle};
+use gfx::native::FontHandle;
+
+// TODO(Issue #164): delete, and get default font from font list
+const TEST_FONT: [u8 * 33004] = #include_bin("JosefinSans-SemiBold.ttf");
+
+fn test_font_bin() -> ~[u8] {
+    return vec::from_fn(33004, |i| TEST_FONT[i]);
+}
+
+// TODO(Rust #3934): creating lots of new dummy styles is a workaround
+// for not being able to store symbolic enums in top-level constants.
+pub fn dummy_style() -> FontStyle {
+    use gfx::font::FontWeight300;
+    return FontStyle {
+        pt_size: 20f,
+        weight: FontWeight300,
+        italic: false,
+        oblique: false,
+        families: ~"Helvetica, serif",
+    }
+}
+
 // TODO(Issue #163): this is a workaround for static methods and
 // typedefs not working well together. It should be removed.
 
@@ -5,21 +36,91 @@
 // to conditionally define the entire impl.
 
 #[cfg(target_os = "macos")]
-type FontContext/& = quartz::font_context::QuartzFontContext;
+type FontContextHandle/& = quartz::font_context::QuartzFontContext;
 
 #[cfg(target_os = "linux")]
-type FontContext/& = freetype::font_context::FreeTypeFontContext;
+type FontContextHandle/& = freetype::font_context::FreeTypeFontContext;
 
 #[cfg(target_os = "macos")]
-pub impl FontContext {
-    static pub fn new() -> FontContext {
+pub impl FontContextHandle {
+    static pub fn new() -> FontContextHandle {
         quartz::font_context::QuartzFontContext::new()
     }
 }
 
 #[cfg(target_os = "linux")]
-pub impl FontContext {
-    static pub fn new() -> FontContext {
+pub impl FontContextHandle {
+    static pub fn new() -> FontContextHandle {
         freetype::font_context::FreeTypeFontContext::new()
     }
 }
+
+pub struct FontContext {
+    instance_cache: cache::MonoCache<FontDescriptor, @Font>,
+    handle: FontContextHandle,
+}
+
+pub impl FontContext {
+    static fn new() -> FontContext {
+        FontContext { 
+            // TODO(Rust #3902): remove extraneous type parameters once they are inferred correctly.
+            instance_cache: cache::new::<FontDescriptor, @Font, cache::MonoCache<FontDescriptor, @Font>>(10),
+            handle: FontContextHandle::new()
+        }
+    }
+
+    fn get_resolved_font_for_style(style: &SpecifiedFontStyle) -> @FontGroup {
+        // TODO(Issue #178, E): implement a cache of FontGroup instances.
+        self.create_font_group(style)
+    }
+
+    fn get_font_by_descriptor(desc: &FontDescriptor) -> Result<@Font, ()> {
+        match self.instance_cache.find(desc) {
+            Some(f) => Ok(f),
+            None => { 
+                let result = self.create_font_instance(desc);
+                match result {
+                    Ok(font) => {
+                        self.instance_cache.insert(desc, font);
+                    }, _ => {}
+                };
+                result
+            }
+        }
+    }
+
+    priv fn create_font_group(style: &SpecifiedFontStyle) -> @FontGroup {
+        // TODO(Issue #178, D): implement private font matching 
+        // TODO(Issue #174): implement by-platform-name FontSelectors
+        let desc = FontDescriptor::new(&font_context::dummy_style(), &SelectorStubDummy);
+        let fonts = DVec();
+        match self.get_font_by_descriptor(&desc) {
+            Ok(instance) => fonts.push(instance),
+            Err(()) => {}
+        }
+
+        assert fonts.len() > 0;
+        // TODO(Issue #179): Split FontStyle into specified and used styles
+        let used_style = copy *style;
+
+        @FontGroup::new(style.families.to_managed(), &used_style, dvec::unwrap(move fonts))
+    }
+
+    priv fn create_font_instance(desc: &FontDescriptor) -> Result<@Font, ()> {
+        match desc.selector {
+            SelectorStubDummy => {
+                let font_bin = @test_font_bin();
+                let handle = FontHandle::new(&self.handle, font_bin, desc.style.pt_size);
+                let handle = if handle.is_ok() {
+                    result::unwrap(move handle)
+                } else {
+                    return Err(handle.get_err());
+                };
+                
+                return Ok(@Font::new(font_bin, move handle, copy desc.style));
+            },
+            // TODO(Issue #174): implement by-platform-name font selectors.
+            SelectorPlatformName(_) => { fail ~"FontContext::create_font_instance() can't yet handle SelectorPlatformName." }
+        }
+    }
+}

src/servo/gfx/font_handle.rs

@@ -20,14 +20,14 @@ pub type FontHandle/& = freetype::font_handle::FreeTypeFontHandle;
 // to conditionally define the entire impl.
 #[cfg(target_os = "macos")]
 impl FontHandle {
-    static pub fn new(fctx: &native::FontContext, buf: @~[u8], pt_size: float) -> Result<FontHandle, ()> {
+    static pub fn new(fctx: &native::FontContextHandle, buf: @~[u8], pt_size: float) -> Result<FontHandle, ()> {
         quartz::font_handle::QuartzFontHandle::new(fctx, buf, pt_size)
     }
 }
 
 #[cfg(target_os = "linux")]
 impl FontHandle {
-    static pub fn new(fctx: &native::FontContext, buf: @~[u8], pt_size: float) -> Result<FontHandle, ()> {
+    static pub fn new(fctx: &native::FontContextHandle, buf: @~[u8], pt_size: float) -> Result<FontHandle, ()> {
         freetype::font_handle::FreeTypeFontHandle::new(fctx, buf, pt_size)
     }
 }

src/servo/gfx/harfbuzz/shaper.rs

@@ -1,11 +1,9 @@
 extern mod harfbuzz;
 
+use gfx::au;
 use gfx::{
-    au,
-
     Au,
     Font,
-    FontCache,
 };
 
 use geom::point::Point2D;

src/servo/gfx/native.rs

@@ -5,4 +5,4 @@ Note that you still must define each of the files as a module in
 servo.rc. This is not ideal and may be changed in the future. */
 
 pub use font_handle::FontHandle;
-pub use font_context::FontContext;
+pub use font_context::FontContextHandle;

src/servo/gfx/render_context.rs

@@ -1,12 +1,12 @@
-use au = geometry;
 use compositor::LayerBuffer;
+use gfx::au;
 use gfx::{
+    Au,
     Font,
-    FontCache,
+    FontContext,
     TextRun,
 };
 use image::base::Image;
-use au::Au;
 use util::range::Range;
 
 use cairo::cairo_hl::ImageSurface;
@@ -23,7 +23,7 @@ use azure::azure_hl::{DrawTarget, Linear};
 
 struct RenderContext {
     canvas: &LayerBuffer,
-    font_cache: @FontCache,
+    font_ctx: @FontContext,
 }
 
 impl RenderContext  {

src/servo/gfx/render_task.rs

@@ -9,7 +9,6 @@ use geom::matrix2d::Matrix2D;
 
 use dl = display_list;
 use gfx::{
-    FontCache,
     FontContext,
     RenderContext,
     RenderLayer,
@@ -42,7 +41,7 @@ pub fn RenderTask<C: Compositor Send>(compositor: C) -> RenderTask {
             port: po,
             compositor: move compositor,
             mut layer_buffer_set_port: Cell(move layer_buffer_set_port),
-            font_cache: @FontCache::new(@FontContext::new()),
+            font_ctx: @FontContext::new(),
         }.start();
     }
 }
@@ -51,7 +50,7 @@ priv struct Renderer<C: Compositor Send> {
     port: comm::Port<Msg>,
     compositor: C,
     layer_buffer_set_port: Cell<pipes::Port<LayerBufferSet>>,
-    font_cache: @FontCache
+    font_ctx: @FontContext
 }
 
 impl<C: Compositor Send> Renderer<C> {
@@ -97,7 +96,7 @@ impl<C: Compositor Send> Renderer<C> {
                     |render_layer, layer_buffer| {
                 let ctx = RenderContext {
                     canvas: layer_buffer,
-                    font_cache: self.font_cache
+                    font_ctx: self.font_ctx
                 };
 
                 // Apply the translation to render the tile we want.

src/servo/gfx/text_run.rs

@@ -1,11 +1,15 @@
 use arc = std::arc;
 use arc::ARC;
-use au = gfx::geometry;
-use font::{RunMetrics, Font};
-use font_cache::FontCache;
 use geom::point::Point2D;
 use geom::size::Size2D;
-use gfx::geometry::Au;
+use gfx::au;
+use gfx::{
+    Au,
+    Font,
+    FontContext,
+    FontDescriptor,
+    RunMetrics,
+};
 use glyph::GlyphStore;
 use layout::context::LayoutContext;
 use libc::{c_void};
@@ -23,16 +27,20 @@ pub struct TextRun {
 // we instead use ARC<TextRun> everywhere.
 pub struct SendableTextRun {
     text: ~str,
-    font_descriptor: (),
+    font: FontDescriptor,
     priv glyphs: GlyphStore,
 }
 
 impl SendableTextRun {
-    pub fn deserialize(&self, cache: @FontCache) -> TextRun {
+    pub fn deserialize(&self, fctx: @FontContext) -> TextRun {
+        let font = match fctx.get_font_by_descriptor(&self.font) {
+            Ok(f) => f,
+            Err(_) => fail fmt!("Font descriptor deserialization failed! desc=%?", self.font)
+        };
+
         TextRun {
             text: copy self.text,
-            // TODO: actually deserialize a font descriptor thingy
-            font: cache.get_test_font(),
+            font: font,
             glyphs: copy self.glyphs
         }
     }
@@ -49,11 +57,10 @@ impl TextRun {
         return move run;
     }
 
-    pub pure fn serialize(&self, _cache: @FontCache) -> SendableTextRun {
+    pub fn serialize(&self) -> SendableTextRun {
         SendableTextRun {
             text: copy self.text,
-            // TODO: actually serialize a font descriptor thingy
-            font_descriptor: (),
+            font: self.font.get_descriptor(),
             glyphs: copy self.glyphs,
         }
     }

src/servo/layout/box.rs

@@ -409,9 +409,7 @@ impl RenderBox : RenderBoxMethods {
         match *self {
             UnscannedTextBox(*) => fail ~"Shouldn't see unscanned boxes here.",
             TextBox(_,d) => {
-                list.append_item(~DisplayItem::new_Text(&abs_box_bounds, 
-                                                        ~d.run.serialize(builder.ctx.font_cache),
-                                                        d.range));
+                list.append_item(~DisplayItem::new_Text(&abs_box_bounds, ~d.run.serialize(), d.range));
                 // debug frames for text box bounds
                 debug!("%?", { 
                     list.append_item(~DisplayItem::new_Border(&abs_box_bounds, au::from_px(1),

src/servo/layout/context.rs

@@ -1,7 +1,7 @@
 use geom::rect::Rect;
 use gfx::{
     Au,
-    FontCache,
+    FontContext,
 };
 use resource::local_image_cache::LocalImageCache;
 use std::net::url::Url;
@@ -9,7 +9,7 @@ use std::net::url::Url;
 /* Represents layout task context. */
 
 struct LayoutContext {
-    font_cache: @FontCache,
+    font_ctx: @FontContext,
     image_cache: @LocalImageCache,
     doc_url: Url,
     screen_size: Rect<Au>

src/servo/layout/inline.rs

@@ -7,6 +7,7 @@ use geom::point::Point2D;
 use geom::rect::Rect;
 use geom::size::Size2D;
 use gfx::display_list::{DisplayList, DisplayListBuilder};
+use gfx::font::FontStyle;
 use gfx::geometry::Au;
 use layout::box::*;
 use layout::context::LayoutContext;
@@ -235,8 +236,13 @@ impl TextRunScanner {
                 // TODO(Issue #115): use actual CSS 'white-space' property of relevant style.
                 let compression = CompressWhitespaceNewline;
                 let transformed_text = transform_text(text, compression);
-                // TODO(Issue #116): use actual font for corresponding DOM node to create text run.
-                let run = @TextRun::new(ctx.font_cache.get_test_font(), move transformed_text);
+                // TODO(Issue #116): use actual font and style for corresponding 
+                // DOM node to create text run.
+                // TODO(Issue #177): text run creation must account for text-renderability by fontgroup fonts.
+                // this is probably achieved by creating fontgroup above, and then letting FontGroup decide
+                // which Font to stick into the TextRun.
+                let fontgroup = ctx.font_ctx.get_resolved_font_for_style(&gfx::font_context::dummy_style());
+                let run = @TextRun::new(fontgroup.fonts[0], move transformed_text);
                 debug!("TextRunScanner: pushing single text box in range: %?", self.clump);
                 let new_box = layout::text::adapt_textbox_with_range(in_boxes[self.clump.begin()].d(), run,
                                                                      Range(0, run.text.len()));
@@ -269,7 +275,11 @@ impl TextRunScanner {
                 // create the run, then make new boxes with the run and adjusted text indices
 
                 // TODO(Issue #116): use actual font for corresponding DOM node to create text run.
-                let run = @gfx::TextRun::new(ctx.font_cache.get_test_font(), move run_str);
+                // TODO(Issue #177): text run creation must account for text-renderability by fontgroup fonts.
+                // this is probably achieved by creating fontgroup above, and then letting FontGroup decide
+                // which Font to stick into the TextRun.
+                let fontgroup = ctx.font_ctx.get_resolved_font_for_style(&gfx::font_context::dummy_style());
+                let run = @TextRun::new(fontgroup.fonts[0], move run_str);
                 debug!("TextRunScanner: pushing box(es) in range: %?", self.clump);
                 for self.clump.eachi |i| {
                     let range = new_ranges[i - self.clump.begin()];

src/servo/layout/layout_task.rs

@@ -11,11 +11,10 @@ use dom::node::{Node, LayoutData};
 use geom::point::Point2D;
 use geom::rect::Rect;
 use geom::size::Size2D;
+use gfx::{au, dl};
 use gfx::{
-    au, dl,
     Au,
     DisplayList,
-    FontCache,
     FontContext,
     FontMatcher,
     RenderLayer,
@@ -81,7 +80,7 @@ struct Layout {
     local_image_cache: @LocalImageCache,
     from_content: comm::Port<Msg>,
 
-    font_cache: @FontCache,
+    font_ctx: @FontContext,
     font_matcher: @FontMatcher,
     // This is used to root auxilliary RCU reader data
     layout_refs: DVec<@LayoutData>,
@@ -100,7 +99,7 @@ fn Layout(render_task: RenderTask,
         local_image_cache: @LocalImageCache(move image_cache_task),
         from_content: from_content,
         font_matcher: @FontMatcher::new(fctx),
-        font_cache: @FontCache::new(fctx),
+        font_ctx: fctx,
         layout_refs: DVec(),
         css_select_ctx: Mut(new_css_select_ctx())
     }
@@ -169,7 +168,7 @@ impl Layout {
 
         let layout_ctx = LayoutContext {
             image_cache: self.local_image_cache,
-            font_cache: self.font_cache,
+            font_ctx: self.font_ctx,
             doc_url: move doc_url,
             screen_size: Rect(Point2D(Au(0), Au(0)), screen_size)
         };

src/servo/servo.rc

@@ -142,6 +142,7 @@ pub mod resource {
 
 pub mod util {
     pub mod actor;
+    pub mod cache;
     pub mod range;
     pub mod text;
     pub mod time;

src/servo/util/cache.rs

@@ -0,0 +1,59 @@
+use core::cmp::*;
+
+trait Cache<K: Copy Eq, V: Copy> {
+    static fn new(size: uint) -> self;
+    fn insert(key: &K, value: V);
+    fn find(key: &K) -> Option<V>;
+    fn find_or_create(key: &K, blk: pure fn&(&K) -> V) -> V;
+    fn evict_all();
+}
+
+pub struct MonoCache<K: Copy Eq, V: Copy> {
+    mut entry: Option<(K,V)>,
+}
+
+pub impl<K: Copy Eq, V: Copy> MonoCache<K,V> : Cache<K,V> {
+    static fn new(_size: uint) -> MonoCache<K,V> {
+        MonoCache { entry: None }
+    }
+
+    fn insert(key: &K, value: V) {
+        self.entry = Some((copy *key, value));
+    }
+
+    fn find(key: &K) -> Option<V> {
+        match self.entry {
+            None => None,
+            Some((ref k,v)) => if *k == *key { Some(v) } else { None }
+        }
+    }
+
+    fn find_or_create(key: &K, blk: pure fn&(&K) -> V) -> V {
+        return match self.find(key) {
+            None => { 
+                let value = blk(key);
+                self.entry = Some((copy *key, copy value));
+                move value
+            },
+            Some(v) => v
+        };
+    }
+    fn evict_all() {
+        self.entry = None;
+    }
+}
+
+#[test]
+fn test_monocache() {
+    // TODO: this is hideous because of Rust Issue #3902
+    let cache = cache::new::<uint, @str, MonoCache<uint, @str>>(10);
+    let one = @"one";
+    let two = @"two";
+    cache.insert(1, one);
+
+    assert cache.find(1).is_some();
+    assert cache.find(2).is_none();
+    cache.find_or_create(2, |_v| { two });
+    assert cache.find(2).is_some();
+    assert cache.find(1).is_none();
+}

src/servo/util/text.rs

@@ -162,7 +162,7 @@ fn test_transform_discard_newline() {
                                    ~"foo bar baz",
                                    ~"foobarbaz"];
 
-    assert core::vec::same_length(test_strs, oracle_strs);
+    assert test_strs.len() == oracle_strs.len();
     let mode = DiscardNewline;
 
     for uint::range(0, test_strs.len()) |i| {
@@ -188,7 +188,7 @@ fn test_transform_compress_whitespace() {
                                  ~"foo bar baz",
                                  ~"foobarbaz\n\n"];
 
-    assert core::vec::same_length(test_strs, oracle_strs);
+    assert test_strs.len() == oracle_strs.len();
     let mode = CompressWhitespace;
 
     for uint::range(0, test_strs.len()) |i| {
@@ -214,7 +214,7 @@ fn test_transform_compress_whitespace_newline() {
                                  ~"foo bar baz",
                                  ~"foobarbaz "];
 
-    assert core::vec::same_length(test_strs, oracle_strs);
+    assert test_strs.len() == oracle_strs.len();
     let mode = CompressWhitespaceNewline;
 
     for uint::range(0, test_strs.len()) |i| {