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//! Simplifies argument parsing.
use std::mem;
use super::{Conv, EvalContext, RefKey, TryFromValue, Value, ValueDict};
use crate::diag::Diag;
use crate::syntax::{Span, SpanVec, SpanWith, Spanned};
/// A wrapper around a dictionary value that simplifies argument parsing in
/// functions.
pub struct Args(pub Spanned<ValueDict>);
impl Args {
/// Retrieve and remove the argument associated with the given key if there
/// is any.
///
/// Generates an error if the key exists, but the value can't be converted
/// into the type `T`.
pub fn get<'a, K, T>(&mut self, ctx: &mut EvalContext, key: K) -> Option<T>
where
K: Into<RefKey<'a>>,
T: TryFromValue,
{
self.0.v.remove(key).and_then(|entry| {
let span = entry.value.span;
conv_diag(T::try_from_value(entry.value), &mut ctx.f.diags, span)
})
}
/// This is the same as [`get`](Self::get), except that it generates an error about a
/// missing argument with the given `name` if the key does not exist.
pub fn need<'a, K, T>(
&mut self,
ctx: &mut EvalContext,
key: K,
name: &str,
) -> Option<T>
where
K: Into<RefKey<'a>>,
T: TryFromValue,
{
if let Some(entry) = self.0.v.remove(key) {
let span = entry.value.span;
conv_diag(T::try_from_value(entry.value), &mut ctx.f.diags, span)
} else {
ctx.f.diags.push(error!(self.0.span, "missing argument: {}", name));
None
}
}
/// Retrieve and remove the first matching positional argument.
pub fn find<T>(&mut self) -> Option<T>
where
T: TryFromValue,
{
for (&key, entry) in self.0.v.nums_mut() {
let span = entry.value.span;
let slot = &mut entry.value;
let conv = conv_put_back(T::try_from_value(mem::take(slot)), slot, span);
if let Some(t) = conv {
self.0.v.remove(key);
return Some(t);
}
}
None
}
/// Retrieve and remove all matching positional arguments.
pub fn find_all<T>(&mut self) -> impl Iterator<Item = T> + '_
where
T: TryFromValue,
{
let mut skip = 0;
std::iter::from_fn(move || {
for (&key, entry) in self.0.v.nums_mut().skip(skip) {
let span = entry.value.span;
let slot = &mut entry.value;
let conv = conv_put_back(T::try_from_value(mem::take(slot)), slot, span);
if let Some(t) = conv {
self.0.v.remove(key);
return Some(t);
}
skip += 1;
}
None
})
}
/// Retrieve and remove all matching named arguments.
pub fn find_all_str<T>(&mut self) -> impl Iterator<Item = (String, T)> + '_
where
T: TryFromValue,
{
let mut skip = 0;
std::iter::from_fn(move || {
for (key, entry) in self.0.v.strs_mut().skip(skip) {
let span = entry.value.span;
let slot = &mut entry.value;
let conv = conv_put_back(T::try_from_value(mem::take(slot)), slot, span);
if let Some(t) = conv {
let key = key.clone();
self.0.v.remove(&key);
return Some((key, t));
}
skip += 1;
}
None
})
}
/// Generated _unexpected argument_ errors for all remaining entries.
pub fn done(&self, ctx: &mut EvalContext) {
for entry in self.0.v.values() {
let span = entry.key_span.join(entry.value.span);
ctx.diag(error!(span, "unexpected argument"));
}
}
}
fn conv_diag<T>(conv: Conv<T>, diags: &mut SpanVec<Diag>, span: Span) -> Option<T> {
match conv {
Conv::Ok(t) => Some(t),
Conv::Warn(t, warn) => {
diags.push(warn.span_with(span));
Some(t)
}
Conv::Err(_, err) => {
diags.push(err.span_with(span));
None
}
}
}
fn conv_put_back<T>(conv: Conv<T>, slot: &mut Spanned<Value>, span: Span) -> Option<T> {
match conv {
Conv::Ok(t) => Some(t),
Conv::Warn(t, _) => Some(t),
Conv::Err(v, _) => {
*slot = v.span_with(span);
None
}
}
}
#[cfg(test)]
mod tests {
use super::super::{Dict, SpannedEntry, Value};
use super::*;
fn entry(value: Value) -> SpannedEntry<Value> {
SpannedEntry::value(Spanned::zero(value))
}
#[test]
fn test_args_find() {
let mut args = Args(Spanned::zero(Dict::new()));
args.0.v.insert(1, entry(Value::Bool(false)));
args.0.v.insert(2, entry(Value::Str("hi".to_string())));
assert_eq!(args.find::<String>(), Some("hi".to_string()));
assert_eq!(args.0.v.len(), 1);
assert_eq!(args.find::<bool>(), Some(false));
assert!(args.0.v.is_empty());
}
#[test]
fn test_args_find_all() {
let mut args = Args(Spanned::zero(Dict::new()));
args.0.v.insert(1, entry(Value::Bool(false)));
args.0.v.insert(3, entry(Value::Float(0.0)));
args.0.v.insert(7, entry(Value::Bool(true)));
assert_eq!(args.find_all::<bool>().collect::<Vec<_>>(), [false, true]);
assert_eq!(args.0.v.len(), 1);
assert_eq!(args.0.v[3].value.v, Value::Float(0.0));
}
}
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