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use std::fmt::{self, Debug, Formatter};
use ecow::{eco_format, EcoVec};
use super::{Array, Cast, Dict, Str, Value};
use crate::diag::{bail, At, SourceResult};
use crate::syntax::{Span, Spanned};
use crate::util::pretty_array_like;
/// Evaluated arguments to a function.
#[derive(Clone, PartialEq, Hash)]
pub struct Args {
/// The span of the whole argument list.
pub span: Span,
/// The positional and named arguments.
pub items: EcoVec<Arg>,
}
/// An argument to a function call: `12` or `draw: false`.
#[derive(Clone, PartialEq, Hash)]
pub struct Arg {
/// The span of the whole argument.
pub span: Span,
/// The name of the argument (`None` for positional arguments).
pub name: Option<Str>,
/// The value of the argument.
pub value: Spanned<Value>,
}
impl Args {
/// Create positional arguments from a span and values.
pub fn new(span: Span, values: impl IntoIterator<Item = Value>) -> Self {
let items = values
.into_iter()
.map(|value| Arg { span, name: None, value: Spanned::new(value, span) })
.collect();
Self { span, items }
}
/// Push a positional argument.
pub fn push(&mut self, span: Span, value: Value) {
self.items.push(Arg {
span: self.span,
name: None,
value: Spanned::new(value, span),
})
}
/// Consume and cast the first positional argument if there is one.
pub fn eat<T>(&mut self) -> SourceResult<Option<T>>
where
T: Cast<Spanned<Value>>,
{
for (i, slot) in self.items.iter().enumerate() {
if slot.name.is_none() {
let value = self.items.remove(i).value;
let span = value.span;
return T::cast(value).at(span).map(Some);
}
}
Ok(None)
}
/// Consume n positional arguments if possible.
pub fn consume(&mut self, n: usize) -> SourceResult<EcoVec<Arg>> {
if n > self.items.len() {
bail!(self.span, "not enough arguments");
}
let vec = self.items.to_vec();
let (left, right) = vec.split_at(n);
self.items = right.into();
Ok(left.into())
}
/// Consume and cast the first positional argument.
///
/// Returns a `missing argument: {what}` error if no positional argument is
/// left.
pub fn expect<T>(&mut self, what: &str) -> SourceResult<T>
where
T: Cast<Spanned<Value>>,
{
match self.eat()? {
Some(v) => Ok(v),
None => bail!(self.span, "missing argument: {}", what),
}
}
/// Find and consume the first castable positional argument.
pub fn find<T>(&mut self) -> SourceResult<Option<T>>
where
T: Cast<Spanned<Value>>,
{
for (i, slot) in self.items.iter().enumerate() {
if slot.name.is_none() && T::is(&slot.value) {
let value = self.items.remove(i).value;
let span = value.span;
return T::cast(value).at(span).map(Some);
}
}
Ok(None)
}
/// Find and consume all castable positional arguments.
pub fn all<T>(&mut self) -> SourceResult<Vec<T>>
where
T: Cast<Spanned<Value>>,
{
let mut list = vec![];
while let Some(value) = self.find()? {
list.push(value);
}
Ok(list)
}
/// Cast and remove the value for the given named argument, returning an
/// error if the conversion fails.
pub fn named<T>(&mut self, name: &str) -> SourceResult<Option<T>>
where
T: Cast<Spanned<Value>>,
{
// We don't quit once we have a match because when multiple matches
// exist, we want to remove all of them and use the last one.
let mut i = 0;
let mut found = None;
while i < self.items.len() {
if self.items[i].name.as_deref() == Some(name) {
let value = self.items.remove(i).value;
let span = value.span;
found = Some(T::cast(value).at(span)?);
} else {
i += 1;
}
}
Ok(found)
}
/// Same as named, but with fallback to find.
pub fn named_or_find<T>(&mut self, name: &str) -> SourceResult<Option<T>>
where
T: Cast<Spanned<Value>>,
{
match self.named(name)? {
Some(value) => Ok(Some(value)),
None => self.find(),
}
}
/// Take out all arguments into a new instance.
pub fn take(&mut self) -> Self {
Self {
span: self.span,
items: std::mem::take(&mut self.items),
}
}
/// Return an "unexpected argument" error if there is any remaining
/// argument.
pub fn finish(self) -> SourceResult<()> {
if let Some(arg) = self.items.first() {
bail!(
arg.span,
match &arg.name {
Some(name) => eco_format!("unexpected argument: {}", name),
_ => eco_format!("unexpected argument"),
}
)
}
Ok(())
}
/// Extract the positional arguments as an array.
pub fn to_pos(&self) -> Array {
self.items
.iter()
.filter(|item| item.name.is_none())
.map(|item| item.value.v.clone())
.collect()
}
/// Extract the named arguments as a dictionary.
pub fn to_named(&self) -> Dict {
self.items
.iter()
.filter_map(|item| item.name.clone().map(|name| (name, item.value.v.clone())))
.collect()
}
}
impl Debug for Args {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
let pieces: Vec<_> =
self.items.iter().map(|arg| eco_format!("{arg:?}")).collect();
f.write_str(&pretty_array_like(&pieces, false))
}
}
impl Debug for Arg {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
if let Some(name) = &self.name {
f.write_str(name)?;
f.write_str(": ")?;
}
Debug::fmt(&self.value.v, f)
}
}
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