}
}
-// build a new vector of tts by appling the Folder's fold_ident to
-// all of the identifiers in the token trees.
-pub fn fold_tts<T: Folder>(tts: &[TokenTree], fld: &mut T) -> Vec<TokenTree> {
- tts.iter().map(|tt| {
- match *tt {
- TTTok(span, ref tok) =>
- TTTok(span,maybe_fold_ident(tok,fld)),
- TTDelim(ref tts) => TTDelim(Rc::new(fold_tts(tts.as_slice(), fld))),
- TTSeq(span, ref pattern, ref sep, is_optional) =>
+pub fn fold_tt<T: Folder>(tt: &TokenTree, fld: &mut T) -> TokenTree {
+ match *tt {
+ TTTok(span, ref tok) =>
+ TTTok(span, fold_token(tok,fld)),
+ TTDelim(ref tts) => TTDelim(Rc::new(fold_tts(tts.as_slice(), fld))),
+ TTSeq(span, ref pattern, ref sep, is_optional) =>
TTSeq(span,
Rc::new(fold_tts(pattern.as_slice(), fld)),
- sep.as_ref().map(|tok|maybe_fold_ident(tok,fld)),
+ sep.as_ref().map(|tok| fold_token(tok,fld)),
is_optional),
- TTNonterminal(sp,ref ident) =>
+ TTNonterminal(sp,ref ident) =>
TTNonterminal(sp,fld.fold_ident(*ident))
- }
- }).collect()
+ }
+}
+
+pub fn fold_tts<T: Folder>(tts: &[TokenTree], fld: &mut T) -> Vec<TokenTree> {
+ tts.iter().map(|tt| fold_tt(tt,fld)).collect()
}
-// apply ident folder if it's an ident, otherwise leave it alone
-fn maybe_fold_ident<T: Folder>(t: &token::Token, fld: &mut T) -> token::Token {
+
+// apply ident folder if it's an ident, apply other folds to interpolated nodes
+fn fold_token<T: Folder>(t: &token::Token, fld: &mut T) -> token::Token {
match *t {
token::IDENT(id, followed_by_colons) => {
token::IDENT(fld.fold_ident(id), followed_by_colons)
}
token::LIFETIME(id) => token::LIFETIME(fld.fold_ident(id)),
+ token::INTERPOLATED(ref nt) => token::INTERPOLATED(fold_interpolated(nt,fld)),
_ => (*t).clone()
}
}
+// apply folder to elements of interpolated nodes
+//
+// NB: this can occur only when applying a fold to partially expanded code, where
+// parsed pieces have gotten implanted ito *other* macro invocations. This is relevant
+// for macro hygiene, but possibly not elsewhere.
+//
+// One problem here occurs because the types for fold_item, fold_stmt, etc. allow the
+// folder to return *multiple* items; this is a problem for the nodes here, because
+// they insist on having exactly one piece. One solution would be to mangle the fold
+// trait to include one-to-many and one-to-one versions of these entry points, but that
+// would probably confuse a lot of people and help very few. Instead, I'm just going
+// to put in dynamic checks. I think the performance impact of this will be pretty much
+// nonexistent. The danger is that someone will apply a fold to a partially expanded
+// node, and will be confused by the fact that their "fold_item" or "fold_stmt" isn't
+// getting called on NtItem or NtStmt nodes. Hopefully they'll wind up reading this
+// comment, and doing something appropriate.
+//
+// BTW, design choice: I considered just changing the type of, e.g., NtItem to contain
+// multiple items, but decided against it when I looked at parse_item_or_view_item and
+// tried to figure out what I would do with multiple items there....
+fn fold_interpolated<T: Folder>(nt : &token::Nonterminal, fld: &mut T) -> token::Nonterminal {
+ match *nt {
+ token::NtItem(item) =>
+ token::NtItem(fld.fold_item(item)
+ .expect_one("expected fold to produce exactly one item")),
+ token::NtBlock(block) => token::NtBlock(fld.fold_block(block)),
+ token::NtStmt(stmt) =>
+ token::NtStmt(fld.fold_stmt(stmt)
+ .expect_one("expected fold to produce exactly one statement")),
+ token::NtPat(pat) => token::NtPat(fld.fold_pat(pat)),
+ token::NtExpr(expr) => token::NtExpr(fld.fold_expr(expr)),
+ token::NtTy(ty) => token::NtTy(fld.fold_ty(ty)),
+ token::NtIdent(ref id, is_mod_name) =>
+ token::NtIdent(box fld.fold_ident(**id),is_mod_name),
+ token::NtMeta(meta_item) => token::NtMeta(fold_meta_item_(meta_item,fld)),
+ token::NtPath(ref path) => token::NtPath(box fld.fold_path(*path)),
+ token::NtTT(tt) => token::NtTT(box (GC) fold_tt(tt,fld)),
+ // it looks to me like we can leave out the matchers: token::NtMatchers(matchers)
+ _ => (*nt).clone()
+ }
+}
+
pub fn noop_fold_fn_decl<T: Folder>(decl: &FnDecl, fld: &mut T) -> P<FnDecl> {
P(FnDecl {
inputs: decl.inputs.iter().map(|x| fold_arg_(x, fld)).collect(), // bad copy
}
}
+// fold one item into possibly many items
pub fn noop_fold_item<T: Folder>(i: &Item,
folder: &mut T) -> SmallVector<Gc<Item>> {
+ SmallVector::one(box(GC) noop_fold_item_(i,folder))
+}
+
+
+// fold one item into exactly one item
+pub fn noop_fold_item_<T: Folder>(i: &Item, folder: &mut T) -> Item {
let id = folder.new_id(i.id); // Needs to be first, for ast_map.
let node = folder.fold_item_underscore(&i.node);
let ident = match node {
_ => i.ident
};
- SmallVector::one(box(GC) Item {
+ Item {
id: id,
ident: folder.fold_ident(ident),
attrs: i.attrs.iter().map(|e| folder.fold_attribute(*e)).collect(),
node: node,
vis: i.vis,
span: folder.new_span(i.span)
- })
+ }
}
pub fn noop_fold_foreign_item<T: Folder>(ni: &ForeignItem,