Skip to content

Commit

Permalink
Re-impl, vol.2
Browse files Browse the repository at this point in the history
  • Loading branch information
@tyranron
tyranron committed Jul 24, 2024
1 parent dc223cf commit 4a506c4
Show file tree
Hide file tree
Showing 2 changed files with 71 additions and 62 deletions.
21 changes: 15 additions & 6 deletions impl/src/fmt/display.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,11 +113,20 @@ fn expand_enum(
e: &syn::DataEnum,
(container_attrs, _, trait_ident, attr_name): ExpansionCtx<'_>,
) -> syn::Result<(Vec<syn::WherePredicate>, TokenStream)> {
/*if let Some(shared_attr) = &container_attrs.fmt {
if shared_attr.placeholders_by_name("_variant").any(|p| false) {
todo!()
if let Some(shared_fmt) = &container_attrs.fmt {
if shared_fmt
.placeholders_by_arg("_variant")
.any(|p| p.has_modifiers || p.trait_name != "Display")
{
// TODO: This limitation can be lifted, by analyzing the `shared_fmt` deeper and using
// `&dyn fmt::TraitName` for transparency instead of just `format_args!()` in the
// expansion.
return Err(syn::Error::new(
shared_fmt.span(),
"shared format `_variant` placeholder cannot contain format specifiers",
));
}
}*/
}

let (bounds, match_arms) = e.variants.iter().try_fold(
(Vec::new(), TokenStream::new()),
Expand Down Expand Up @@ -303,7 +312,7 @@ impl<'a> Expansion<'a> {
quote! { derive_more::core::write!(__derive_more_f, #shared_fmt) }
};

body = if shared_fmt.contains_parameter("_variant") {
body = if shared_fmt.contains_arg("_variant") {
quote! { match #body { _variant => #shared_body } }
} else {
shared_body
Expand All @@ -319,7 +328,7 @@ impl<'a> Expansion<'a> {

if self
.shared_attr
.map_or(true, |a| a.contains_parameter("_variant"))
.map_or(true, |a| a.contains_arg("_variant"))
{
if let Some(fmt) = &self.attrs.fmt {
bounds.extend(
Expand Down
112 changes: 56 additions & 56 deletions impl/src/fmt/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -235,31 +235,42 @@ impl FmtAttribute {
})
}

/// Checks whether this [`FmtAttribute`] contains an argument with the provided `name`, either
/// in its direct [`FmtArgument`]s or inside [`Placeholder`]s.
fn contains_parameter(&self, name: &str) -> bool {
#[cfg(feature = "display")]
/// Checks whether this [`FmtAttribute`] contains an argument with the provided `name` (either
/// in its direct [`FmtArgument`]s or inside [`Placeholder`]s).
fn contains_arg(&self, name: &str) -> bool {
self.placeholders_by_arg(name).next().is_some()
}

#[cfg(feature = "display")]
/// Returns an [`Iterator`] over [`Placeholder`]s using an argument with the provided `name`
/// (either in its direct [`FmtArgument`]s of this [`FmtAttribute`] or inside the
/// [`Placeholder`] itself).
fn placeholders_by_arg<'a>(
&'a self,
name: &'a str,
) -> impl Iterator<Item = Placeholder> + 'a {
let placeholders = Placeholder::parse_fmt_string(&self.lit.value());

placeholders
.into_iter()
.filter_map(move |placeholder| {
match placeholder.arg {
Parameter::Named(name) => self
.args
.iter()
.find_map(|a| (a.alias()? == &name).then_some(&a.expr))
.map_or(Some(name), |expr| {
expr.ident().map(ToString::to_string)
}),
Parameter::Positional(i) => self
.args
.iter()
.nth(i)
.and_then(|a| a.expr.ident().filter(|_| a.alias.is_none()))
.map(ToString::to_string),
}
})
.any(|arg_name| arg_name == name)
placeholders.into_iter().filter(move |placeholder| {
match &placeholder.arg {
Parameter::Named(name) => self
.args
.iter()
.find_map(|a| (a.alias()? == name).then_some(&a.expr))
.map_or(Some(name.clone()), |expr| {
expr.ident().map(ToString::to_string)
}),
Parameter::Positional(i) => self
.args
.iter()
.nth(*i)
.and_then(|a| a.expr.ident().filter(|_| a.alias.is_none()))
.map(ToString::to_string),
}
.as_deref()
== Some(name)
})
}

/// Errors in case legacy syntax is encountered: `fmt = "...", (arg),*`.
Expand Down Expand Up @@ -377,20 +388,13 @@ impl<'a> From<parsing::Argument<'a>> for Parameter {
/// Representation of a formatting placeholder.
#[derive(Debug, Eq, PartialEq)]
struct Placeholder {
/// Formatting argument (either named or positional) to be used by this placeholder.
/// Formatting argument (either named or positional) to be used by this [`Placeholder`].
arg: Parameter,

/// [Width parameter][1], if present.
///
/// [1]: https://doc.rust-lang.org/stable/std/fmt/index.html#width
width: Option<Parameter>,
/// Indicator whether this [`Placeholder`] has any formatting modifiers.
has_modifiers: bool,

/// [Precision parameter][1], if present.
///
/// [1]: https://doc.rust-lang.org/stable/std/fmt/index.html#precision
precision: Option<Parameter>,

/// Name of [`std::fmt`] trait to be used for rendering this placeholder.
/// Name of [`std::fmt`] trait to be used for rendering this [`Placeholder`].
trait_name: &'static str,
}

Expand All @@ -415,16 +419,18 @@ impl Placeholder {

Self {
arg: position,
width: format.spec.and_then(|s| match s.width {
Some(parsing::Count::Parameter(arg)) => Some(arg.into()),
_ => None,
}),
precision: format.spec.and_then(|s| match s.precision {
Some(parsing::Precision::Count(parsing::Count::Parameter(
arg,
))) => Some(arg.into()),
_ => None,
}),
has_modifiers: format
.spec
.map(|s| {
s.align.is_some()
|| s.sign.is_some()
|| s.alternate.is_some()
|| s.zero_padding.is_some()
|| s.width.is_some()
|| s.precision.is_some()
|| !s.ty.is_trivial()
})
.unwrap_or_default(),
trait_name: ty.trait_name(),
}
})
Expand Down Expand Up @@ -603,38 +609,32 @@ mod placeholder_parse_fmt_string_spec {
vec![
Placeholder {
arg: Parameter::Positional(0),
width: None,
precision: None,
has_modifiers: false,
trait_name: "Display",
},
Placeholder {
arg: Parameter::Positional(1),
width: None,
precision: None,
has_modifiers: false,
trait_name: "Debug",
},
Placeholder {
arg: Parameter::Positional(1),
width: Some(Parameter::Positional(0)),
precision: None,
has_modifiers: true,
trait_name: "Display",
},
Placeholder {
arg: Parameter::Positional(2),
width: None,
precision: Some(Parameter::Positional(1)),
has_modifiers: true,
trait_name: "LowerHex",
},
Placeholder {
arg: Parameter::Named("par".to_owned()),
width: None,
precision: None,
has_modifiers: true,
trait_name: "Debug",
},
Placeholder {
arg: Parameter::Positional(2),
width: Some(Parameter::Named("width".to_owned())),
precision: None,
has_modifiers: true,
trait_name: "Display",
},
],
Expand Down

0 comments on commit 4a506c4

Please sign in to comment.