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//! Alignment function.
use super::prelude::*;
use crate::layout::Alignment;
/// Allows to align content in different ways.
#[derive(Debug, PartialEq)]
pub struct AlignFunc {
alignment: Alignment,
body: Option<SyntaxTree>,
}
impl Function for AlignFunc {
fn parse(header: &FuncHeader, body: Option<&str>, ctx: ParseContext)
-> ParseResult<Self> where Self: Sized {
if header.args.len() != 1 || !header.kwargs.is_empty() {
return err("expected exactly one positional argument specifying the alignment");
}
let alignment = if let Expression::Ident(ident) = &header.args[0] {
match ident.as_str() {
"left" => Alignment::Left,
"right" => Alignment::Right,
s => return err(format!("invalid alignment specifier: '{}'", s)),
}
} else {
return err(format!("expected alignment specifier, found: '{}'", header.args[0]));
};
let body = if let Some(body) = body {
Some(parse(body, ctx)?)
} else {
None
};
Ok(AlignFunc { alignment, body })
}
fn layout(&self, mut ctx: LayoutContext) -> LayoutResult<Option<Layout>> {
if let Some(body) = &self.body {
// Override the previous alignment and do the layouting.
ctx.space.alignment = self.alignment;
layout(body, ctx)
.map(|l| Some(Layout::Boxed(l)))
} else {
unimplemented!("context-modifying align func")
}
}
}
|
