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Refactor lower_stmts

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This commit is contained in:
Cameron Steffen 2021-08-04 12:47:58 -05:00
parent 581abbfc6d
commit 120d46e255
1 changed files with 56 additions and 55 deletions
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111
compiler/rustc_ast_lowering/src/block.rs
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@ -2,7 +2,7 @@ use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext};
use rustc_ast::{Block, BlockCheckMode, Local, Stmt, StmtKind};
use rustc_hir as hir;
use smallvec::{smallvec, SmallVec};
use smallvec::SmallVec;
impl<'a, 'hir> LoweringContext<'a, 'hir> {
pub(super) fn lower_block(
@ -18,66 +18,67 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
b: &Block,
targeted_by_break: bool,
) -> hir::Block<'hir> {
let (stmts, expr) = match &*b.stmts {
[stmts @ .., Stmt { kind: StmtKind::Expr(e), .. }] => (stmts, Some(&*e)),
stmts => (stmts, None),
};
let stmts = self.arena.alloc_from_iter(stmts.iter().flat_map(|stmt| self.lower_stmt(stmt)));
let expr = expr.map(|e| self.lower_expr(e));
let (stmts, expr) = self.lower_stmts(&b.stmts);
let rules = self.lower_block_check_mode(&b.rules);
let hir_id = self.lower_node_id(b.id);
hir::Block { hir_id, stmts, expr, rules, span: self.lower_span(b.span), targeted_by_break }
}
fn lower_stmt(&mut self, s: &Stmt) -> SmallVec<[hir::Stmt<'hir>; 1]> {
let (hir_id, kind) = match s.kind {
StmtKind::Local(ref l) => {
let l = self.lower_local(l);
let hir_id = self.lower_node_id(s.id);
self.alias_attrs(hir_id, l.hir_id);
return smallvec![hir::Stmt {
hir_id,
kind: hir::StmtKind::Local(self.arena.alloc(l)),
span: self.lower_span(s.span),
}];
fn lower_stmts(
&mut self,
mut ast_stmts: &[Stmt],
) -> (&'hir [hir::Stmt<'hir>], Option<&'hir hir::Expr<'hir>>) {
let mut stmts = SmallVec::<[hir::Stmt<'hir>; 8]>::new();
let mut expr = None;
while let [s, tail @ ..] = ast_stmts {
match s.kind {
StmtKind::Local(ref l) => {
let l = self.lower_local(l);
let hir_id = self.lower_node_id(s.id);
self.alias_attrs(hir_id, l.hir_id);
let kind = hir::StmtKind::Local(self.arena.alloc(l));
let span = self.lower_span(s.span);
stmts.push(hir::Stmt { hir_id, kind, span });
}
StmtKind::Item(ref it) => {
stmts.extend(self.lower_item_id(it).into_iter().enumerate().map(
|(i, item_id)| {
let hir_id = match i {
0 => self.lower_node_id(s.id),
_ => self.next_id(),
};
let kind = hir::StmtKind::Item(item_id);
let span = self.lower_span(s.span);
hir::Stmt { hir_id, kind, span }
},
));
}
StmtKind::Expr(ref e) => {
let e = self.lower_expr(e);
if tail.is_empty() {
expr = Some(e);
} else {
let hir_id = self.lower_node_id(s.id);
self.alias_attrs(hir_id, e.hir_id);
let kind = hir::StmtKind::Expr(e);
let span = self.lower_span(s.span);
stmts.push(hir::Stmt { hir_id, kind, span });
}
}
StmtKind::Semi(ref e) => {
let e = self.lower_expr(e);
let hir_id = self.lower_node_id(s.id);
self.alias_attrs(hir_id, e.hir_id);
let kind = hir::StmtKind::Semi(e);
let span = self.lower_span(s.span);
stmts.push(hir::Stmt { hir_id, kind, span });
}
StmtKind::Empty => {}
StmtKind::MacCall(..) => panic!("shouldn't exist here"),
}
StmtKind::Item(ref it) => {
// Can only use the ID once.
let mut id = Some(s.id);
return self
.lower_item_id(it)
.into_iter()
.map(|item_id| {
let hir_id = id
.take()
.map(|id| self.lower_node_id(id))
.unwrap_or_else(|| self.next_id());
hir::Stmt {
hir_id,
kind: hir::StmtKind::Item(item_id),
span: self.lower_span(s.span),
}
})
.collect();
}
StmtKind::Expr(ref e) => {
let e = self.lower_expr(e);
let hir_id = self.lower_node_id(s.id);
self.alias_attrs(hir_id, e.hir_id);
(hir_id, hir::StmtKind::Expr(e))
}
StmtKind::Semi(ref e) => {
let e = self.lower_expr(e);
let hir_id = self.lower_node_id(s.id);
self.alias_attrs(hir_id, e.hir_id);
(hir_id, hir::StmtKind::Semi(e))
}
StmtKind::Empty => return smallvec![],
StmtKind::MacCall(..) => panic!("shouldn't exist here"),
};
smallvec![hir::Stmt { hir_id, kind, span: self.lower_span(s.span) }]
ast_stmts = &ast_stmts[1..];
}
(self.arena.alloc_from_iter(stmts), expr)
}
fn lower_local(&mut self, l: &Local) -> hir::Local<'hir> {