Add patterns to MacResult

Author: kmcallister

src/libsyntax/ext/base.rs

@@ -114,6 +114,10 @@ pub trait MacResult {
  fn make_items(&self) -> Option<SmallVector<@ast::Item>> {
  None
  }
+ /// Create a pattern.
+ fn make_pat(&self) -> Option<@ast::Pat> {
+ None
+ }
 
  /// Create a statement.
  ///
@@ -139,6 +143,20 @@ impl MacResult for MacExpr {
  Some(self.e)
  }
 }
+/// A convenience type for macros that return a single pattern.
+pub struct MacPat {
+ p: @ast::Pat
+}
+impl MacPat {
+ pub fn new(p: @ast::Pat) -> Box<MacResult> {
+ box MacPat { p: p } as Box<MacResult>
+ }
+}
+impl MacResult for MacPat {
+ fn make_pat(&self) -> Option<@ast::Pat> {
+ Some(self.p)
+ }
+}
 /// A convenience type for macros that return a single item.
 pub struct MacItem {
  i: @ast::Item
@@ -194,12 +212,24 @@ impl DummyResult {
  span: sp,
  }
  }
+
+ /// A plain dummy pattern.
+ pub fn raw_pat(sp: Span) -> @ast::Pat {
+ @ast::Pat {
+ id: ast::DUMMY_NODE_ID,
+ node: ast::PatWild,
+ span: sp,
+ }
+ }
 }
 
 impl MacResult for DummyResult {
  fn make_expr(&self) -> Option<@ast::Expr> {
  Some(DummyResult::raw_expr(self.span))
  }
+ fn make_pat(&self) -> Option<@ast::Pat> {
+ Some(DummyResult::raw_pat(self.span))
+ }
  fn make_items(&self) -> Option<SmallVector<@ast::Item>> {
  if self.expr_only {
  None

src/libsyntax/ext/tt/macro_rules.rs

@@ -63,6 +63,11 @@ impl<'a> MacResult for ParserAnyMacro<'a> {
  self.ensure_complete_parse(true);
  Some(ret)
  }
+ fn make_pat(&self) -> Option<@ast::Pat> {
+ let ret = self.parser.borrow_mut().parse_pat();
+ self.ensure_complete_parse(false);
+ Some(ret)
+ }
  fn make_items(&self) -> Option<SmallVector<@ast::Item>> {
  let mut ret = SmallVector::zero();
  loop {