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|
use crate::prelude::*;
use std::fmt::{self, Display, Formatter};
/// `align`: Align content along the layouting axes.
///
/// # Positional arguments
/// - At most two of `left`, `right`, `top`, `bottom`, `center`.
///
/// When `center` is used as a positional argument, it is automatically inferred
/// which axis it should apply to depending on further arguments, defaulting
/// to the axis, text is set along.
///
/// # Keyword arguments
/// - `horizontal`: Any of `left`, `right` or `center`.
/// - `vertical`: Any of `top`, `bottom` or `center`.
///
/// There may not be two alignment specifications for the same axis.
pub fn align(mut args: Args, ctx: &mut EvalContext) -> Value {
let snapshot = ctx.state.clone();
let body = args.find::<SynTree>();
let first = args.get::<_, Spanned<AlignArg>>(ctx, 0);
let second = args.get::<_, Spanned<AlignArg>>(ctx, 1);
let hor = args.get::<_, Spanned<AlignArg>>(ctx, "horizontal");
let ver = args.get::<_, Spanned<AlignArg>>(ctx, "vertical");
args.done(ctx);
let iter = first
.into_iter()
.chain(second.into_iter())
.map(|align| (align.v.axis(), align))
.chain(hor.into_iter().map(|align| (Some(SpecAxis::Horizontal), align)))
.chain(ver.into_iter().map(|align| (Some(SpecAxis::Vertical), align)));
let prev_main = ctx.state.aligns.main;
ctx.state.aligns = dedup_aligns(ctx, iter);
if prev_main != ctx.state.aligns.main {
ctx.end_par_group();
ctx.start_par_group();
}
if let Some(body) = body {
body.eval(ctx);
ctx.state = snapshot;
}
Value::None
}
/// Deduplicate alignments and deduce to which axes they apply.
fn dedup_aligns(
ctx: &mut EvalContext,
iter: impl Iterator<Item = (Option<SpecAxis>, Spanned<AlignArg>)>,
) -> Gen<Align> {
let mut aligns = ctx.state.aligns;
let mut had = Gen::new(false, false);
let mut had_center = false;
for (axis, Spanned { v: align, span }) in iter {
// Check whether we know which axis this alignment belongs to.
if let Some(axis) = axis {
// We know the axis.
let gen_axis = axis.switch(ctx.state.dirs);
let gen_align = align.switch(ctx.state.dirs);
if align.axis().map_or(false, |a| a != axis) {
ctx.diag(error!(
span,
"invalid alignment `{}` for {} axis", align, axis,
));
} else if had.get(gen_axis) {
ctx.diag(error!(span, "duplicate alignment for {} axis", axis));
} else {
*aligns.get_mut(gen_axis) = gen_align;
*had.get_mut(gen_axis) = true;
}
} else {
// We don't know the axis: This has to be a `center` alignment for a
// positional argument.
debug_assert_eq!(align, AlignArg::Center);
if had.main && had.cross {
ctx.diag(error!(span, "duplicate alignment"));
} else if had_center {
// Both this and the previous one are unspecified `center`
// alignments. Both axes should be centered.
aligns = Gen::new(Align::Center, Align::Center);
had = Gen::new(true, true);
} else {
had_center = true;
}
}
// If we we know one alignment, we can handle the unspecified `center`
// alignment.
if had_center && (had.main || had.cross) {
if had.main {
aligns.cross = Align::Center;
had.cross = true;
} else {
aligns.main = Align::Center;
had.main = true;
}
had_center = false;
}
}
// If center has not been flushed by now, it is the only argument and then
// we default to applying it to the cross axis.
if had_center {
aligns.cross = Align::Center;
}
aligns
}
/// An alignment argument.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
enum AlignArg {
Left,
Right,
Top,
Bottom,
Center,
}
impl AlignArg {
/// The specific axis this alignment refers to.
///
/// Returns `None` if this is `Center` since the axis is unknown.
pub fn axis(self) -> Option<SpecAxis> {
match self {
Self::Left => Some(SpecAxis::Horizontal),
Self::Right => Some(SpecAxis::Horizontal),
Self::Top => Some(SpecAxis::Vertical),
Self::Bottom => Some(SpecAxis::Vertical),
Self::Center => None,
}
}
}
impl Switch for AlignArg {
type Other = Align;
fn switch(self, dirs: Gen<Dir>) -> Self::Other {
let get = |dir: Dir, at_positive_start| {
if dir.is_positive() == at_positive_start {
Align::Start
} else {
Align::End
}
};
let dirs = dirs.switch(dirs);
match self {
Self::Left => get(dirs.horizontal, true),
Self::Right => get(dirs.horizontal, false),
Self::Top => get(dirs.vertical, true),
Self::Bottom => get(dirs.vertical, false),
Self::Center => Align::Center,
}
}
}
convert_ident!(AlignArg, "alignment", |v| match v {
"left" => Some(Self::Left),
"right" => Some(Self::Right),
"top" => Some(Self::Top),
"bottom" => Some(Self::Bottom),
"center" => Some(Self::Center),
_ => None,
});
impl Display for AlignArg {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.pad(match self {
Self::Left => "left",
Self::Right => "right",
Self::Top => "top",
Self::Bottom => "bottom",
Self::Center => "center",
})
}
}
|
