diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 17b2b2d25b99..c5fc149bb7e8 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -12,8 +12,9 @@ use ast::{Block, Crate, Ident, Mac_, PatKind};
use ast::{MacStmtStyle, StmtKind, ItemKind};
use ast;
use ext::hygiene::Mark;
+use ext::placeholders;
use attr::{self, HasAttrs};
-use codemap::{dummy_spanned, ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
+use codemap::{ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
use syntax_pos::{self, Span, ExpnId};
use config::StripUnconfigured;
use ext::base::*;
@@ -35,8 +36,8 @@ macro_rules! expansions {
$(.$fold:ident)* $(lift .$fold_elt:ident)*,
$(.$visit:ident)* $(lift .$visit_elt:ident)*;)*) => {
#[derive(Copy, Clone)]
- enum ExpansionKind { OptExpr, $( $kind, )* }
- enum Expansion { OptExpr(Option
>), $( $kind($ty), )* }
+ pub enum ExpansionKind { OptExpr, $( $kind, )* }
+ pub enum Expansion { OptExpr(Option
>), $( $kind($ty), )* }
impl ExpansionKind {
fn name(self) -> &'static str {
@@ -55,20 +56,20 @@ macro_rules! expansions {
}
impl Expansion {
- fn make_opt_expr(self) -> Option
> {
+ pub fn make_opt_expr(self) -> Option
> {
match self {
Expansion::OptExpr(expr) => expr,
_ => panic!("Expansion::make_* called on the wrong kind of expansion"),
}
}
- $( fn $make(self) -> $ty {
+ $( pub fn $make(self) -> $ty {
match self {
Expansion::$kind(ast) => ast,
_ => panic!("Expansion::make_* called on the wrong kind of expansion"),
}
} )*
- fn fold_with(self, folder: &mut F) -> Self {
+ pub fn fold_with(self, folder: &mut F) -> Self {
use self::Expansion::*;
match self {
OptExpr(expr) => OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
@@ -434,9 +435,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
// If keep_macs is true, expands to a MacEager::items instead.
if self.keep_macs {
- Some(reconstruct_macro_rules(&def, &path))
+ Some(placeholders::reconstructed_macro_rules(&def, &path))
} else {
- Some(macro_scope_placeholder())
+ Some(placeholders::macro_scope_placeholder())
}
}
@@ -650,37 +651,6 @@ impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
}
}
-fn macro_scope_placeholder() -> Expansion {
- Expansion::Items(SmallVector::one(P(ast::Item {
- ident: keywords::Invalid.ident(),
- attrs: Vec::new(),
- id: ast::DUMMY_NODE_ID,
- node: ast::ItemKind::Mac(dummy_spanned(ast::Mac_ {
- path: ast::Path { span: syntax_pos::DUMMY_SP, global: false, segments: Vec::new() },
- tts: Vec::new(),
- })),
- vis: ast::Visibility::Inherited,
- span: syntax_pos::DUMMY_SP,
- })))
-}
-
-fn reconstruct_macro_rules(def: &ast::MacroDef, path: &ast::Path) -> Expansion {
- Expansion::Items(SmallVector::one(P(ast::Item {
- ident: def.ident,
- attrs: def.attrs.clone(),
- id: ast::DUMMY_NODE_ID,
- node: ast::ItemKind::Mac(ast::Mac {
- span: def.span,
- node: ast::Mac_ {
- path: path.clone(),
- tts: def.body.clone(),
- }
- }),
- vis: ast::Visibility::Inherited,
- span: def.span,
- })))
-}
-
pub struct ExpansionConfig<'feat> {
pub crate_name: String,
pub features: Option<&'feat Features>,
diff --git a/src/libsyntax/ext/placeholders.rs b/src/libsyntax/ext/placeholders.rs
new file mode 100644
index 000000000000..f1665bdde751
--- /dev/null
+++ b/src/libsyntax/ext/placeholders.rs
@@ -0,0 +1,172 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 or the MIT license
+// , at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use ast;
+use codemap::{DUMMY_SP, dummy_spanned};
+use ext::expand::{Expansion, ExpansionKind};
+use fold::*;
+use parse::token::keywords;
+use ptr::P;
+use util::small_vector::SmallVector;
+
+use std::collections::HashMap;
+
+pub fn placeholder(kind: ExpansionKind, id: ast::NodeId) -> Expansion {
+ fn mac_placeholder() -> ast::Mac {
+ dummy_spanned(ast::Mac_ {
+ path: ast::Path { span: DUMMY_SP, global: false, segments: Vec::new() },
+ tts: Vec::new(),
+ })
+ }
+
+ let ident = keywords::Invalid.ident();
+ let attrs = Vec::new();
+ let vis = ast::Visibility::Inherited;
+ let span = DUMMY_SP;
+ let expr_placeholder = || P(ast::Expr {
+ id: id, span: span,
+ attrs: ast::ThinVec::new(),
+ node: ast::ExprKind::Mac(mac_placeholder()),
+ });
+
+ match kind {
+ ExpansionKind::Expr => Expansion::Expr(expr_placeholder()),
+ ExpansionKind::OptExpr => Expansion::OptExpr(Some(expr_placeholder())),
+ ExpansionKind::Items => Expansion::Items(SmallVector::one(P(ast::Item {
+ id: id, span: span, ident: ident, vis: vis, attrs: attrs,
+ node: ast::ItemKind::Mac(mac_placeholder()),
+ }))),
+ ExpansionKind::TraitItems => Expansion::TraitItems(SmallVector::one(ast::TraitItem {
+ id: id, span: span, ident: ident, attrs: attrs,
+ node: ast::TraitItemKind::Macro(mac_placeholder()),
+ })),
+ ExpansionKind::ImplItems => Expansion::ImplItems(SmallVector::one(ast::ImplItem {
+ id: id, span: span, ident: ident, vis: vis, attrs: attrs,
+ node: ast::ImplItemKind::Macro(mac_placeholder()),
+ defaultness: ast::Defaultness::Final,
+ })),
+ ExpansionKind::Pat => Expansion::Pat(P(ast::Pat {
+ id: id, span: span, node: ast::PatKind::Mac(mac_placeholder()),
+ })),
+ ExpansionKind::Ty => Expansion::Ty(P(ast::Ty {
+ id: id, span: span, node: ast::TyKind::Mac(mac_placeholder()),
+ })),
+ ExpansionKind::Stmts => Expansion::Stmts(SmallVector::one({
+ let mac = P((mac_placeholder(), ast::MacStmtStyle::Braces, ast::ThinVec::new()));
+ ast::Stmt { id: id, span: span, node: ast::StmtKind::Mac(mac) }
+ })),
+ }
+}
+
+pub fn macro_scope_placeholder() -> Expansion {
+ placeholder(ExpansionKind::Items, ast::DUMMY_NODE_ID)
+}
+
+pub struct PlaceholderExpander {
+ expansions: HashMap,
+}
+
+impl PlaceholderExpander {
+ pub fn new(expansions: HashMap) -> Self {
+ PlaceholderExpander {
+ expansions: expansions,
+ }
+ }
+
+ pub fn remove(&mut self, id: ast::NodeId) -> Expansion {
+ let expansion = self.expansions.remove(&id).unwrap();
+ expansion.fold_with(self)
+ }
+}
+
+impl Folder for PlaceholderExpander {
+ fn fold_item(&mut self, item: P) -> SmallVector> {
+ match item.node {
+ // Scope placeholder
+ ast::ItemKind::Mac(_) if item.id == ast::DUMMY_NODE_ID => SmallVector::one(item),
+ ast::ItemKind::Mac(_) => self.remove(item.id).make_items(),
+ _ => noop_fold_item(item, self),
+ }
+ }
+
+ fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector {
+ match item.node {
+ ast::TraitItemKind::Macro(_) => self.remove(item.id).make_trait_items(),
+ _ => noop_fold_trait_item(item, self),
+ }
+ }
+
+ fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector {
+ match item.node {
+ ast::ImplItemKind::Macro(_) => self.remove(item.id).make_impl_items(),
+ _ => noop_fold_impl_item(item, self),
+ }
+ }
+
+ fn fold_expr(&mut self, expr: P) -> P {
+ match expr.node {
+ ast::ExprKind::Mac(_) => self.remove(expr.id).make_expr(),
+ _ => expr.map(|expr| noop_fold_expr(expr, self)),
+ }
+ }
+
+ fn fold_opt_expr(&mut self, expr: P) -> Option> {
+ match expr.node {
+ ast::ExprKind::Mac(_) => self.remove(expr.id).make_opt_expr(),
+ _ => noop_fold_opt_expr(expr, self),
+ }
+ }
+
+ fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector {
+ let (style, mut expansion) = match stmt.node {
+ ast::StmtKind::Mac(mac) => (mac.1, self.remove(stmt.id).make_stmts()),
+ _ => return noop_fold_stmt(stmt, self),
+ };
+
+ if style == ast::MacStmtStyle::Semicolon {
+ if let Some(stmt) = expansion.pop() {
+ expansion.push(stmt.add_trailing_semicolon());
+ }
+ }
+
+ expansion
+ }
+
+ fn fold_pat(&mut self, pat: P) -> P {
+ match pat.node {
+ ast::PatKind::Mac(_) => self.remove(pat.id).make_pat(),
+ _ => noop_fold_pat(pat, self),
+ }
+ }
+
+ fn fold_ty(&mut self, ty: P) -> P {
+ match ty.node {
+ ast::TyKind::Mac(_) => self.remove(ty.id).make_ty(),
+ _ => noop_fold_ty(ty, self),
+ }
+ }
+}
+
+pub fn reconstructed_macro_rules(def: &ast::MacroDef, path: &ast::Path) -> Expansion {
+ Expansion::Items(SmallVector::one(P(ast::Item {
+ ident: def.ident,
+ attrs: def.attrs.clone(),
+ id: ast::DUMMY_NODE_ID,
+ node: ast::ItemKind::Mac(ast::Mac {
+ span: def.span,
+ node: ast::Mac_ {
+ path: path.clone(),
+ tts: def.body.clone(),
+ }
+ }),
+ vis: ast::Visibility::Inherited,
+ span: def.span,
+ })))
+}
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 65bc9f34c906..42201231247a 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -126,6 +126,7 @@ pub mod ext {
pub mod base;
pub mod build;
pub mod expand;
+ pub mod placeholders;
pub mod hygiene;
pub mod proc_macro_shim;
pub mod quote;