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//! Primitives for argument parsing in library functions.
use crate::error::{Error, Errors};
use super::expr::{Expr, Ident, Tuple, Object, Pair};
use super::span::{Span, Spanned};
pub_use_mod!(maps);
pub_use_mod!(keys);
pub_use_mod!(values);
/// The parsed header of a function.
#[derive(Debug, Clone, PartialEq)]
pub struct FuncHeader {
/// The function name, that is:
/// ```typst
/// [box: w=5cm]
/// ^^^
/// ```
pub name: Spanned<Ident>,
/// The arguments passed to the function.
pub args: FuncArgs,
}
/// The positional and keyword arguments passed to a function.
#[derive(Debug, Clone, PartialEq)]
pub struct FuncArgs {
/// The positional arguments.
pub pos: Tuple,
/// They keyword arguments.
pub key: Object,
}
impl FuncArgs {
/// Create new empty function arguments.
pub fn new() -> FuncArgs {
FuncArgs {
pos: Tuple::new(),
key: Object::new(),
}
}
/// Add an argument.
pub fn add(&mut self, arg: FuncArg) {
match arg {
FuncArg::Pos(item) => self.pos.add(item),
FuncArg::Key(pair) => self.key.add(pair),
}
}
/// Iterate over all arguments.
pub fn into_iter(self) -> impl Iterator<Item=FuncArg> {
self.pos.items.into_iter().map(|item| FuncArg::Pos(item))
.chain(self.key.pairs.into_iter().map(|pair| FuncArg::Key(pair)))
}
}
/// Either a positional or keyword argument.
#[derive(Debug, Clone, PartialEq)]
pub enum FuncArg {
/// A positional argument.
Pos(Spanned<Expr>),
/// A keyword argument.
Key(Pair),
}
impl FuncArg {
/// The full span of this argument.
///
/// In case of a positional argument this is just the span of the expression
/// and in case of a keyword argument the combined span of key and value.
pub fn span(&self) -> Span {
match self {
FuncArg::Pos(item) => item.span,
FuncArg::Key(Pair { key, value }) => Span::merge(key.span, value.span),
}
}
}
/// Extra methods on [`Options`](Option) used for argument parsing.
pub trait OptionExt: Sized {
/// Add an error about a missing argument `arg` with the given span if the
/// option is `None`.
fn or_missing(self, errors: &mut Errors, span: Span, arg: &str) -> Self;
}
impl<T> OptionExt for Option<T> {
fn or_missing(self, errors: &mut Errors, span: Span, arg: &str) -> Self {
if self.is_none() {
errors.push(err!(span; "missing argument: {}", arg));
}
self
}
}
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