From 6e5198cd6dc0572ffaddcdea29d5541085ec5300 Mon Sep 17 00:00:00 2001 From: Aleksey Kladov Date: Tue, 10 Sep 2019 20:09:43 +0300 Subject: add fragmets to expansion --- crates/ra_mbe/src/mbe_expander.rs | 73 +++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 33 deletions(-) (limited to 'crates/ra_mbe/src/mbe_expander.rs') diff --git a/crates/ra_mbe/src/mbe_expander.rs b/crates/ra_mbe/src/mbe_expander.rs index 08b0519d2..db05c6253 100644 --- a/crates/ra_mbe/src/mbe_expander.rs +++ b/crates/ra_mbe/src/mbe_expander.rs @@ -81,21 +81,26 @@ struct Bindings { #[derive(Debug)] enum Binding { - Simple(tt::TokenTree), + Fragment(Fragment), Nested(Vec), Empty, } +#[derive(Debug, Clone)] +enum Fragment { + /// token fragments are just copy-pasted into the output + Tokens(tt::TokenTree), + /// Ast fragments are inserted with fake delimiters, so as to make things + /// like `$i * 2` where `$i = 1 + 1` work as expectd. + Ast(tt::TokenTree), +} + impl Bindings { fn push_optional(&mut self, name: &SmolStr) { // FIXME: Do we have a better way to represent an empty token ? // Insert an empty subtree for empty token - self.inner.insert( - name.clone(), - Binding::Simple( - tt::Subtree { delimiter: tt::Delimiter::None, token_trees: vec![] }.into(), - ), - ); + let tt = tt::Subtree { delimiter: tt::Delimiter::None, token_trees: vec![] }.into(); + self.inner.insert(name.clone(), Binding::Fragment(Fragment::Tokens(tt))); } fn push_empty(&mut self, name: &SmolStr) { @@ -106,13 +111,13 @@ impl Bindings { self.inner.contains_key(name) } - fn get(&self, name: &SmolStr, nesting: &[usize]) -> Result<&tt::TokenTree, ExpandError> { + fn get(&self, name: &SmolStr, nesting: &[usize]) -> Result<&Fragment, ExpandError> { let mut b = self.inner.get(name).ok_or_else(|| { ExpandError::BindingError(format!("could not find binding `{}`", name)) })?; for &idx in nesting.iter() { b = match b { - Binding::Simple(_) => break, + Binding::Fragment(_) => break, Binding::Nested(bs) => bs.get(idx).ok_or_else(|| { ExpandError::BindingError(format!("could not find nested binding `{}`", name)) })?, @@ -125,7 +130,7 @@ impl Bindings { }; } match b { - Binding::Simple(it) => Ok(it), + Binding::Fragment(it) => Ok(it), Binding::Nested(_) => Err(ExpandError::BindingError(format!( "expected simple binding, found nested binding `{}`", name @@ -195,8 +200,8 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result { let kind = kind.as_ref().ok_or(ExpandError::UnexpectedToken)?; match match_meta_var(kind.as_str(), input)? { - Some(tt) => { - res.inner.insert(text.clone(), Binding::Simple(tt)); + Some(fragment) => { + res.inner.insert(text.clone(), Binding::Fragment(fragment)); } None => res.push_optional(text), } @@ -292,7 +297,7 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result Result, ExpandError> { +fn match_meta_var(kind: &str, input: &mut TtCursor) -> Result, ExpandError> { let fragment = match kind { "path" => Path, "expr" => Expr, @@ -303,7 +308,7 @@ fn match_meta_var(kind: &str, input: &mut TtCursor) -> Result MetaItem, "item" => Item, _ => { - let binding = match kind { + let tt = match kind { "ident" => { let ident = input.eat_ident().ok_or(ExpandError::UnexpectedToken)?.clone(); tt::Leaf::from(ident).into() @@ -321,11 +326,12 @@ fn match_meta_var(kind: &str, input: &mut TtCursor) -> Result return Err(ExpandError::UnexpectedToken), }; - return Ok(Some(binding)); + return Ok(Some(Fragment::Tokens(tt))); } }; - let binding = input.eat_fragment(fragment).ok_or(ExpandError::UnexpectedToken)?; - Ok(Some(binding)) + let tt = input.eat_fragment(fragment).ok_or(ExpandError::UnexpectedToken)?; + let fragment = if kind == "expr" { Fragment::Ast(tt) } else { Fragment::Tokens(tt) }; + Ok(Some(fragment)) } #[derive(Debug)] @@ -342,7 +348,7 @@ fn expand_subtree( let mut buf: Vec = Vec::new(); for tt in template.token_trees.iter() { let tt = expand_tt(tt, ctx)?; - push_tt(&mut buf, tt); + push_fragment(&mut buf, tt); } Ok(tt::Subtree { delimiter: template.delimiter, token_trees: buf }) @@ -362,10 +368,7 @@ fn reduce_single_token(mut subtree: tt::Subtree) -> tt::TokenTree { } } -fn expand_tt( - template: &crate::TokenTree, - ctx: &mut ExpandCtx, -) -> Result { +fn expand_tt(template: &crate::TokenTree, ctx: &mut ExpandCtx) -> Result { let res: tt::TokenTree = match template { crate::TokenTree::Subtree(subtree) => expand_subtree(subtree, ctx)?.into(), crate::TokenTree::Repeat(repeat) => { @@ -492,20 +495,24 @@ fn expand_tt( } .into() } else { - let tkn = ctx.bindings.get(&v.text, &ctx.nesting)?.clone(); + let fragment = ctx.bindings.get(&v.text, &ctx.nesting)?.clone(); ctx.var_expanded = true; - - if let tt::TokenTree::Subtree(subtree) = tkn { - reduce_single_token(subtree) - } else { - tkn + match fragment { + Fragment::Tokens(tt) => { + if let tt::TokenTree::Subtree(subtree) = tt { + reduce_single_token(subtree) + } else { + tt + } + } + Fragment::Ast(_) => return Ok(fragment), } } } crate::Leaf::Literal(l) => tt::Leaf::from(tt::Literal { text: l.text.clone() }).into(), }, }; - Ok(res) + Ok(Fragment::Tokens(res)) } #[cfg(test)] @@ -579,10 +586,10 @@ mod tests { } } -fn push_tt(buf: &mut Vec, tt: tt::TokenTree) { - match tt { - tt::TokenTree::Subtree(tt) => push_subtree(buf, tt), - _ => buf.push(tt), +fn push_fragment(buf: &mut Vec, fragment: Fragment) { + match fragment { + Fragment::Tokens(tt::TokenTree::Subtree(tt)) => push_subtree(buf, tt), + Fragment::Tokens(tt) | Fragment::Ast(tt) => buf.push(tt), } } -- cgit v1.2.3