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use super::*;
pub(super) const THIN: Em = Em::new(1.0 / 6.0);
pub(super) const MEDIUM: Em = Em::new(2.0 / 9.0);
pub(super) const THICK: Em = Em::new(5.0 / 18.0);
pub(super) const QUAD: Em = Em::new(1.0);
pub(super) const WIDE: Em = Em::new(2.0);
/// Hook up all spacings.
pub(super) fn define(math: &mut Scope) {
math.define("thin", HElem::new(THIN.into()).pack());
math.define("med", HElem::new(MEDIUM.into()).pack());
math.define("thick", HElem::new(THICK.into()).pack());
math.define("quad", HElem::new(QUAD.into()).pack());
math.define("wide", HElem::new(WIDE.into()).pack());
}
/// Create the spacing between two fragments in a given style.
pub(super) fn spacing(
l: &MathFragment,
space: Option<MathFragment>,
r: &MathFragment,
) -> Option<MathFragment> {
use MathClass::*;
let class = |f: &MathFragment| f.class().unwrap_or(Special);
let resolve = |v: Em, f: &MathFragment| {
Some(MathFragment::Spacing(f.font_size().map_or(Abs::zero(), |size| v.at(size))))
};
let script =
|f: &MathFragment| f.style().map_or(false, |s| s.size <= MathSize::Script);
match (class(l), class(r)) {
// No spacing before punctuation; thin spacing after punctuation, unless
// in script size.
(_, Punctuation) => None,
(Punctuation, _) if !script(l) => resolve(THIN, l),
// No spacing after opening delimiters and before closing delimiters.
(Opening, _) | (_, Closing) => None,
// Thick spacing around relations, unless followed by a another relation
// or in script size.
(Relation, Relation) => None,
(Relation, _) if !script(l) => resolve(THICK, l),
(_, Relation) if !script(r) => resolve(THICK, r),
// Medium spacing around binary operators, unless in script size.
(Binary, _) if !script(l) => resolve(MEDIUM, l),
(_, Binary) if !script(r) => resolve(MEDIUM, r),
// Thin spacing around large operators, unless to the left of
// an opening delimiter. TeXBook, p170
(Large, Opening | Fence) => None,
(Large, _) => resolve(THIN, l),
(_, Large) => resolve(THIN, r),
// Spacing around spaced frames.
_ if (l.is_spaced() || r.is_spaced()) => space,
_ => None,
}
}
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