// CSS Values and Units Level 4 — numeric primitives and dimension types.
// Spec: https://drafts.csswg.org/css-values-4/
// This is the canonical base grammar; other CSS grammars import from here.
//
// Usage: @import "css-value-unit.bbnf" ;
// All dimension types (length, angle, time, etc.) produce [number, unit] tuples.
// Override `number` and `integer` at runtime for proper numeric parsing.
// --- Numeric primitives (§3.1) ---
number = /[-+]?(\d+)?(\.\d+)?([eE][-+]?\d+)?/ ;
integer = /[-+]?\d+/ ;
// --- Length units (§6) ---
// §6.2 — Absolute lengths
absoluteLengthUnit = "cm" | "mm" | "Q" | "in" | "pc" | "pt" | "px" ;
// §6.3 — Viewport-percentage lengths (added in L4: vi/vb, s/l/d prefixed)
viewportLengthUnit = "vw" | "vh" | "vmin" | "vmax" | "vb" | "vi"
| "svw" | "svh" | "svmin" | "svmax" | "svb" | "svi"
| "lvw" | "lvh" | "lvmin" | "lvmax" | "lvb" | "lvi"
| "dvw" | "dvh" | "dvmin" | "dvmax" | "dvb" | "dvi" ;
// Container query units (CSS Containment Level 3)
containerLengthUnit = "cqw" | "cqh" | "cqi" | "cqb" | "cqmin" | "cqmax" ;
// §6.1 — Font-relative lengths
fontLengthUnit = "em" | "ex" | "ch" | "rem" | "lh" | "rlh" | "cap" | "ic" | "rcap" | "rex" | "rch" | "ric" | "rlh" ;
relativeLengthUnit = fontLengthUnit | viewportLengthUnit | containerLengthUnit ;
lengthUnit = absoluteLengthUnit | relativeLengthUnit ;
// --- Other dimension units ---
// §6.4 — Angle units
angleUnit = "deg" | "rad" | "grad" | "turn" ;
// §6.5 — Duration units
timeUnit = "ms" | "s" ;
// §6.6 — Frequency units
frequencyUnit = "Hz" | "kHz" ;
// §6.7 — Resolution units
resolutionUnit = "dpi" | "dpcm" | "dppx" | "x" ;
// CSS Grid Layout Level 1 — Flexible lengths
flexUnit = "fr" ;
// §5.1.1 — Percentage
percentageUnit = "%" ;
// --- Dimension types ---
// Each produces a [number, unit] tuple for runtime mapping.
length = number , lengthUnit ;
angle = number , angleUnit ;
time = number , timeUnit ;
frequency = number , frequencyUnit ;
resolution = number , resolutionUnit ;
flex = number , flexUnit ;
percentage = number , percentageUnit ;
unitless = number ;
valueUnit = length | angle | time | frequency | resolution | flex | percentage | unitless ;