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Simplifications to statement macro handling.

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SmallVector::pop no longer worries about converting a Many repr downward
to One or Zero.

expand_stmt makes use of `if let` for style purposes.
This commit is contained in:
Christopher Chambers 2015-04-10 23:06:34 -05:00
parent fae29e497c
commit 22eb3193a6
2 changed files with 12 additions and 37 deletions
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25
src/libsyntax/ext/expand.rs
View File

@ -772,20 +772,17 @@ fn expand_stmt(stmt: P<Stmt>, fld: &mut MacroExpander) -> SmallVector<P<Stmt>> {
// If this is a macro invocation with a semicolon, then apply that
// semicolon to the final statement produced by expansion.
if style == MacStmtWithSemicolon {
match fully_expanded.pop() {
Some(stmt) => {
let new_stmt = stmt.map(|Spanned {node, span}| {
Spanned {
node: match node {
StmtExpr(e, stmt_id) => StmtSemi(e, stmt_id),
_ => node /* might already have a semi */
},
span: span
}
});
fully_expanded.push(new_stmt);
}
None => (),
if let Some(stmt) = fully_expanded.pop() {
let new_stmt = stmt.map(|Spanned {node, span}| {
Spanned {
node: match node {
StmtExpr(e, stmt_id) => StmtSemi(e, stmt_id),
_ => node /* might already have a semi */
},
span: span
}
});
fully_expanded.push(new_stmt);
}
}

24
src/libsyntax/util/small_vector.rs
View File

@ -79,29 +79,7 @@ impl<T> SmallVector<T> {
_ => unreachable!()
}
}
Many(..) => {
let mut many = mem::replace(&mut self.repr, Zero);
let item =
match many {
Many(ref mut vs) if vs.len() == 1 => {
// self.repr is already Zero
vs.pop()
},
Many(ref mut vs) if vs.len() == 2 => {
let item = vs.pop();
mem::replace(&mut self.repr, One(vs.pop().unwrap()));
item
},
Many(ref mut vs) if vs.len() > 2 => {
let item = vs.pop();
let rest = mem::replace(vs, vec!());
mem::replace(&mut self.repr, Many(rest));
item
},
_ => unreachable!()
};
item
}
Many(ref mut vs) => vs.pop(),
}
}