Module compact_cache 

Three-tier numeric property cache for fast style resolution. Compact layout property cache — three-tier numeric encoding

Replaces BTreeMap-based CSS property lookups with cache-friendly arrays.

• Tier 1: Vec<u64> — ALL 21 enum properties bitpacked (8 B/node)
• Tier 2 hot: Vec<CompactNodeProps> — layout-critical numeric dimensions (68 B/node)
• Tier 2 cold: Vec<CompactNodePropsCold> — paint-only properties (28 B/node)
• Tier 2b: Vec<CompactTextProps> — text/IFC properties (24 B/node)

Non-compact properties (background, box-shadow, transform, etc.) are resolved via the slow cascade path in CssPropertyCache::get_property_slow().

Structs

CompactLayoutCache

Overflow properties that couldn’t fit in Tier 1/2 encoding. Contains the original CssProperty values for properties that:

CompactNodeProps

Layout-hot compact numeric properties for a single node (68 bytes). Only fields accessed during the constraint-solving loop. All dimensions use MSB-sentinel encoding.

CompactNodePropsCold

Paint-cold compact properties for a single node. Only accessed during display list generation, table layout, or text shaping.

CompactTextProps

Compact text/IFC properties for a single node (24 bytes).

Constants

ALIGN_CONTENT_SHIFT

ALIGN_ITEMS_SHIFT

ALIGN_MASK

ALIGN_SELF_MASK

ALIGN_SELF_SHIFT

BORDER_COLLAPSE_MASK

BORDER_COLLAPSE_SHIFT

BOX_SIZING_MASK

BOX_SIZING_SHIFT

CLEAR_MASK

CLEAR_SHIFT

DIRECTION_MASK

DIRECTION_SHIFT

DISPLAY_MASK

DISPLAY_SHIFT

DOM_HAS_COLUMN_COUNT

DOM_HAS_COLUMN_GAP

DOM_HAS_COLUMN_WIDTH

DOM_HAS_EXCLUSION_MARGIN

DOM_HAS_HANGING_PUNCTUATION

DOM_HAS_HYPHENATION_LANGUAGE

DOM_HAS_HYPHENS

DOM_HAS_INITIAL_LETTER

DOM_HAS_INITIAL_LETTER_ALIGN

DOM_HAS_LINE_BREAK

DOM_HAS_LINE_CLAMP

DOM_HAS_LINE_HEIGHT

DOM_HAS_OVERFLOW_WRAP

DOM_HAS_SHAPE_INSIDE

DOM_HAS_SHAPE_MARGIN

DOM_HAS_SHAPE_OUTSIDE

DOM_HAS_TEXT_ALIGN_LAST

DOM_HAS_TEXT_BOX_TRIM

DOM_HAS_TEXT_COMBINE_UPRIGHT

DOM_HAS_TEXT_INDENT

DOM_HAS_TEXT_JUSTIFY

DOM_HAS_UNICODE_BIDI

DOM_HAS_WORD_BREAK

EXTRA_FLAG_HAS_BACKDROP_FILTER

EXTRA_FLAG_HAS_BREAK

EXTRA_FLAG_HAS_COUNTER

EXTRA_FLAG_HAS_FILTER

EXTRA_FLAG_HAS_MIX_BLEND_MODE

EXTRA_FLAG_HAS_SCROLLBAR_CSS

EXTRA_FLAG_HAS_TEXT_ORIENTATION

EXTRA_FLAG_HAS_TEXT_SHADOW

FLEX_DIRECTION_SHIFT

FLEX_DIR_MASK

FLEX_WRAP_MASK

FLEX_WRAP_SHIFT

FLOAT_MASK

FLOAT_SHIFT

FONT_STYLE_MASK

FONT_STYLE_SHIFT

FONT_WEIGHT_MASK

FONT_WEIGHT_SHIFT

GRID_AUTO_FLOW_MASK

GRID_AUTO_FLOW_SHIFT

HOT_FLAG_HAS_BACKGROUND

HOT_FLAG_HAS_BOX_SHADOW

HOT_FLAG_HAS_CLIP_PATH

HOT_FLAG_HAS_TEXT_DECORATION

HOT_FLAG_HAS_TRANSFORM

HOT_FLAG_HAS_TRANSFORM_ORIGIN

HOT_FLAG_SCROLLBAR_GUTTER_MASK

HOT_FLAG_SCROLLBAR_GUTTER_SHIFT

I16_AUTO

I16_INHERIT

I16_INITIAL

I16_SENTINEL

i16 sentinel values (for signed resolved-px ×10)

I16_SENTINEL_THRESHOLD

Any i16 value >= this threshold is a sentinel

JUSTIFY_CONTENT_SHIFT

JUSTIFY_ITEMS_MASK

JUSTIFY_ITEMS_SHIFT

JUSTIFY_MASK

JUSTIFY_SELF_MASK

JUSTIFY_SELF_SHIFT

OPACITY_SENTINEL

OVERFLOW_MASK

OVERFLOW_X_SHIFT

OVERFLOW_Y_SHIFT

POSITION_MASK

POSITION_SHIFT

SCROLLBAR_GUTTER_AUTO

SCROLLBAR_GUTTER_BOTH_EDGES

SCROLLBAR_GUTTER_MIRROR

SCROLLBAR_GUTTER_STABLE

TEXT_ALIGN_MASK

TEXT_ALIGN_SHIFT

TIER1_POPULATED_BIT

Special value stored in the spare bits [63:51] to indicate this node has NO tier-1 data (i.e., all defaults). 0 is a valid all-defaults encoding, so we use bit 63 as a “tier1 populated” flag. If bit 63 is 0 and all other bits are 0, it means “all defaults” (Display::Block, Position::Static, etc.). We set bit 63 = 1 to mark that the node HAS been populated.

U16_SENTINEL

u16 sentinel values (for resolved-px ×10 and flex ×100)

U16_SENTINEL_THRESHOLD

Any u16 value >= this threshold is a sentinel, not a real value

U32_AUTO

U32_INHERIT

U32_INITIAL

U32_MAX_CONTENT

U32_MIN_CONTENT

U32_NONE

U32_SENTINEL

u32 sentinel values (for dimension properties with unit info)

U32_SENTINEL_THRESHOLD

Any u32 value >= this threshold is a sentinel

VERTICAL_ALIGN_MASK

VERTICAL_ALIGN_SHIFT

VISIBILITY_MASK

VISIBILITY_SHIFT

WHITE_SPACE_MASK

WHITE_SPACE_SHIFT

WRITING_MODE_MASK

WRITING_MODE_SHIFT

Functions

border_collapse_from_u8

border_collapse_to_u8

border_style_from_u8

border_style_to_u8

decode_align_content

decode_align_items

decode_border_bottom_style

Decode border-bottom-style from packed u16

decode_border_collapse

decode_border_left_style

Decode border-left-style from packed u16

decode_border_right_style

Decode border-right-style from packed u16

decode_border_top_style

Decode border-top-style from packed u16

decode_box_sizing

decode_clear

decode_color_u32

Decode a u32 back to ColorU. Returns None if sentinel (0x00000000).

decode_direction

decode_display

Decode individual enum properties from a Tier 1 u64. Each function is #[inline(always)] for zero-cost extraction.

decode_flex_direction

decode_flex_u16

Decode a u16 flex value back to f32. Returns None for sentinel values.

decode_flex_wrap

decode_float

decode_font_style

decode_font_weight

decode_justify_content

decode_overflow_x

decode_overflow_y

decode_pixel_value_u32

Decode a u32 back to PixelValue. Returns None for sentinel values.

decode_position

decode_resolved_px_i16

Decode an i16 back to resolved px. Returns None for sentinel values.

decode_text_align

decode_vertical_align

decode_visibility

decode_white_space

decode_writing_mode

encode_border_styles_packed

Encode 4 border styles into a u16: [3:0]=top, [7:4]=right, [11:8]=bottom, [15:12]=left

encode_color_u32

Encode a ColorU as u32 (0xRRGGBBAA). Returns 0 for sentinel/unset.

encode_css_pixel_as_i16

Resolve a CssPropertyValue to an i16 ×10 encoding. Only handles Exact(px(...)) values. Everything else → sentinel. For the compact cache builder, we only pre-resolve absolute pixel values. Relative units (em, %, etc.) get sentinel and fall back to the slow path.

encode_flex_u16

Encode a u16 flex value (×100). Returns U16_SENTINEL if out of range. Range: 0.00 ..= 655.27 at 0.01 precision.

encode_pixel_value_u32

u32 encoding for dimension properties (width, height, min-, max-, flex-basis, font-size).

encode_resolved_px_i16

Encode an i16 resolved px value (×10). Returns I16_SENTINEL if out of range. Range: -3276.8 ..= +3276.3 px at 0.1px precision.

encode_tier1

Pack all 21 enum properties into a single u64.

layout_align_content_from_u8

layout_align_content_to_u8

layout_align_items_from_u8

layout_align_items_to_u8

layout_align_self_from_u8

layout_align_self_to_u8

layout_box_sizing_from_u8

layout_box_sizing_to_u8

layout_clear_from_u8

layout_clear_to_u8

layout_display_from_u8

Decode display from u8. 0 = Block (most common HTML default). Value 31 (0x1F) = sentinel: look up in slow path for uncommon values. Returns default (Block) on invalid input.

layout_display_to_u8

Encode display to u8. 0 = Block (most common HTML default).

layout_flex_direction_from_u8

layout_flex_direction_to_u8

layout_flex_wrap_from_u8

0 = NoWrap (CSS initial value for flex-wrap)

layout_flex_wrap_to_u8

layout_float_from_u8

Decode float from u8. 0 = None (CSS initial value).

layout_float_to_u8

Encode float to u8. 0 = None (CSS initial value).

layout_grid_auto_flow_from_u8

layout_grid_auto_flow_to_u8

layout_justify_content_from_u8

layout_justify_content_to_u8

layout_justify_items_from_u8

layout_justify_items_to_u8

layout_justify_self_from_u8

layout_justify_self_to_u8

layout_overflow_from_u8

Decode overflow from u8. 0 = Visible (CSS initial value).

layout_overflow_to_u8

Encode overflow to u8. 0 = Visible (CSS initial value).

layout_position_from_u8

layout_position_to_u8

layout_writing_mode_from_u8

layout_writing_mode_to_u8

size_metric_from_u8

u8 → SizeMetric

size_metric_to_u8

SizeMetric → u8 (4 bits, 12 variants)

style_direction_from_u8

style_direction_to_u8

style_font_style_from_u8

style_font_style_to_u8

style_font_weight_from_u8

0 = Normal/400 (CSS initial value for font-weight)

style_font_weight_to_u8

0 = Normal/400 (CSS initial value for font-weight)

style_text_align_from_u8

style_text_align_to_u8

style_vertical_align_from_u8

style_vertical_align_to_u8

style_visibility_from_u8

style_visibility_to_u8

style_white_space_from_u8

style_white_space_to_u8