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Add support for stringify! builtin macro #2348

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Merged
merged 1 commit into from
Nov 22, 2019
Merged

Add support for stringify! builtin macro #2348

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27 changes: 27 additions & 0 deletions crates/ra_hir_expand/src/builtin_macro.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ use crate::quote;
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum BuiltinExpander {
Line,
Stringify,
}

impl BuiltinExpander {
Expand All @@ -22,6 +23,7 @@ impl BuiltinExpander {
) -> Result<tt::Subtree, mbe::ExpandError> {
match self {
BuiltinExpander::Line => line_expand(db, id, tt),
BuiltinExpander::Stringify => stringify_expand(db, id, tt),
}
}
}
Expand All @@ -34,6 +36,8 @@ pub fn find_builtin_macro(
// FIXME: Better registering method
if ident == &name::LINE_MACRO {
Some(MacroDefId { krate, ast_id, kind: MacroDefKind::BuiltIn(BuiltinExpander::Line) })
} else if ident == &name::STRINGIFY_MACRO {
Some(MacroDefId { krate, ast_id, kind: MacroDefKind::BuiltIn(BuiltinExpander::Stringify) })
} else {
None
}
Expand Down Expand Up @@ -78,3 +82,26 @@ fn line_expand(

Ok(expanded)
}

fn stringify_expand(
db: &dyn AstDatabase,
id: MacroCallId,
_tt: &tt::Subtree,
) -> Result<tt::Subtree, mbe::ExpandError> {
let loc = db.lookup_intern_macro(id);
let macro_call = loc.ast_id.to_node(db);

let macro_content = {
let arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
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Might be a stupid question, but is this the same as _tt?

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There is no spacing information in _tt but I agree it is more accurate to use _tt directly here :

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The builtin stringify! macro do not preserve space too.

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Might be worth adding a test.

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I think either solution is fine. It's also a shame that we can't easily add a test here, because there's no testing infra in hir_expand, but I think it makes sense to merge this without blocking on the said infra

let macro_args = arg.syntax().clone();
let text = macro_args.text();
let without_parens = TextUnit::of_char('(')..text.len() - TextUnit::of_char(')');
text.slice(without_parens).to_string()
};

let expanded = quote! {
#macro_content
};

Ok(expanded)
}
1 change: 1 addition & 0 deletions crates/ra_hir_expand/src/name.rs
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Expand Up @@ -143,3 +143,4 @@ pub const BOX_TYPE: Name = Name::new_inline_ascii(3, b"Box");

// Builtin Macros
pub const LINE_MACRO: Name = Name::new_inline_ascii(4, b"line");
pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(9, b"stringify");