libsyntax: parse inclusive ranges

7 files changed, 81 insertions, 50 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 23bb6fd141a..0dbfb2c7be6 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -886,6 +886,15 @@ impl fmt::Debug for Expr {
     }
 }
 
+/// Limit types of a range (inclusive or exclusive)
+#[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
+pub enum RangeLimits {
+    /// Inclusive at the beginning, exclusive at the end
+    HalfOpen,
+    /// Inclusive at the beginning and end
+    Closed,
+}
+
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum ExprKind {
     /// A `box x` expression.
@@ -974,8 +983,8 @@ pub enum ExprKind {
     TupField(P<Expr>, Spanned<usize>),
     /// An indexing operation (`foo[2]`)
     Index(P<Expr>, P<Expr>),
-    /// A range (`1..2`, `1..`, or `..2`)
-    Range(Option<P<Expr>>, Option<P<Expr>>),
+    /// A range (`1..2`, `1..`, `..2`, `1...2`, `1...`, `...2`)
+    Range(Option<P<Expr>>, Option<P<Expr>>, RangeLimits),
 
     /// Variable reference, possibly containing `::` and/or type
     /// parameters, e.g. foo::bar::<baz>.
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index d75e8f796ae..591c1295d66 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -1273,9 +1273,10 @@ pub fn noop_fold_expr<T: Folder>(Expr {id, node, span, attrs}: Expr, folder: &mu
             ExprKind::Index(el, er) => {
                 ExprKind::Index(folder.fold_expr(el), folder.fold_expr(er))
             }
-            ExprKind::Range(e1, e2) => {
+            ExprKind::Range(e1, e2, lim) => {
                 ExprKind::Range(e1.map(|x| folder.fold_expr(x)),
-                          e2.map(|x| folder.fold_expr(x)))
+                                e2.map(|x| folder.fold_expr(x)),
+                                lim)
             }
             ExprKind::Path(qself, path) => {
                 let qself = qself.map(|QSelf { ty, position }| {
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b5d29a0d6db..8b563ef00f3 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -20,7 +20,7 @@ use ast::{BlockCheckMode, CaptureBy};
 use ast::{Constness, Crate, CrateConfig};
 use ast::{Decl, DeclKind};
 use ast::{EMPTY_CTXT, EnumDef, ExplicitSelf};
-use ast::{Expr, ExprKind};
+use ast::{Expr, ExprKind, RangeLimits};
 use ast::{Field, FnDecl};
 use ast::{ForeignItem, ForeignItemKind, FunctionRetTy};
 use ast::{Ident, ImplItem, Item, ItemKind};
@@ -2054,9 +2054,10 @@ impl<'a> Parser<'a> {
 
     pub fn mk_range(&mut self,
                     start: Option<P<Expr>>,
-                    end: Option<P<Expr>>)
-                    -> ast::ExprKind {
-        ExprKind::Range(start, end)
+                    end: Option<P<Expr>>,
+                    limits: RangeLimits)
+                    -> ast::Expr_ {
+        ExprKind::Range(start, end, limits)
     }
 
     pub fn mk_field(&mut self, expr: P<Expr>, ident: ast::SpannedIdent) -> ast::ExprKind {
@@ -2894,7 +2895,7 @@ impl<'a> Parser<'a> {
                 LhsExpr::AttributesParsed(attrs) => Some(attrs),
                 _ => None,
             };
-            if self.token == token::DotDot {
+            if self.token == token::DotDot || self.token == token::DotDotDot {
                 return self.parse_prefix_range_expr(attrs);
             } else {
                 try!(self.parse_prefix_expr(attrs))
@@ -2940,32 +2941,32 @@ impl<'a> Parser<'a> {
                                    ExprKind::Type(lhs, rhs), None);
                 continue
             } else if op == AssocOp::DotDot {
-                    // If we didn’t have to handle `x..`, it would be pretty easy to generalise
-                    // it to the Fixity::None code.
-                    //
-                    // We have 2 alternatives here: `x..y` and `x..` The other two variants are
-                    // handled with `parse_prefix_range_expr` call above.
-                    let rhs = if self.is_at_start_of_range_notation_rhs() {
-                        let rhs = self.parse_assoc_expr_with(op.precedence() + 1,
-                                                             LhsExpr::NotYetParsed);
-                        match rhs {
-                            Ok(e) => Some(e),
-                            Err(mut e) => {
-                                e.cancel();
-                                None
-                            }
+                // If we didn’t have to handle `x..`, it would be pretty easy to generalise
+                // it to the Fixity::None code.
+                //
+                // We have 2 alternatives here: `x..y` and `x..` The other two variants are
+                // handled with `parse_prefix_range_expr` call above.
+                let rhs = if self.is_at_start_of_range_notation_rhs() {
+                    let rhs = self.parse_assoc_expr_with(op.precedence() + 1,
+                                                         LhsExpr::NotYetParsed);
+                    match rhs {
+                        Ok(e) => Some(e),
+                        Err(mut e) => {
+                            e.cancel();
+                            None
                         }
-                    } else {
-                        None
-                    };
-                    let (lhs_span, rhs_span) = (lhs_span, if let Some(ref x) = rhs {
-                        x.span
-                    } else {
-                        cur_op_span
-                    });
-                    let r = self.mk_range(Some(lhs), rhs);
-                    lhs = self.mk_expr(lhs_span.lo, rhs_span.hi, r, None);
-                    break
+                    }
+                } else {
+                    None
+                };
+                let (lhs_span, rhs_span) = (lhs.span, if let Some(ref x) = rhs {
+                    x.span
+                } else {
+                    cur_op_span
+                });
+                let r = self.mk_range(Some(lhs), rhs, RangeLimits::HalfOpen);
+                lhs = self.mk_expr(lhs_span.lo, rhs_span.hi, r, None);
+                break
             }
 
             let rhs = try!(match op.fixity() {
@@ -2981,8 +2982,8 @@ impl<'a> Parser<'a> {
                         this.parse_assoc_expr_with(op.precedence() + 1,
                             LhsExpr::NotYetParsed)
                 }),
-                // We currently have no non-associative operators that are not handled above by
-                // the special cases. The code is here only for future convenience.
+                // the only operator handled here is `...` (the other non-associative operators are
+                // special-cased above)
                 Fixity::None => self.with_res(
                     restrictions - Restrictions::RESTRICTION_STMT_EXPR,
                     |this| {
@@ -3023,6 +3024,11 @@ impl<'a> Parser<'a> {
                     let aopexpr = self.mk_assign_op(codemap::respan(cur_op_span, aop), lhs, rhs);
                     self.mk_expr(lhs_span.lo, rhs_span.hi, aopexpr, None)
                 }
+                AssocOp::DotDotDot => {
+                    let (lhs_span, rhs_span) = (lhs.span, rhs.span);
+                    let r = self.mk_range(Some(lhs), Some(rhs), RangeLimits::Closed);
+                    self.mk_expr(lhs_span.lo, rhs_span.hi, r, None)
+                }
                 AssocOp::As | AssocOp::Colon | AssocOp::DotDot => {
                     self.bug("As, Colon or DotDot branch reached")
                 }
@@ -3054,18 +3060,19 @@ impl<'a> Parser<'a> {
         }
     }
 
-    /// Parse prefix-forms of range notation: `..expr` and `..`
+    /// Parse prefix-forms of range notation: `..expr`, `..`, `...expr`
     fn parse_prefix_range_expr(&mut self,
                                already_parsed_attrs: Option<ThinAttributes>)
                                -> PResult<'a, P<Expr>> {
-        debug_assert!(self.token == token::DotDot);
+        debug_assert!(self.token == token::DotDot || self.token == token::DotDotDot);
+        let tok = self.token.clone();
         let attrs = try!(self.parse_or_use_outer_attributes(already_parsed_attrs));
         let lo = self.span.lo;
         let mut hi = self.span.hi;
         self.bump();
         let opt_end = if self.is_at_start_of_range_notation_rhs() {
-            // RHS must be parsed with more associativity than DotDot.
-            let next_prec = AssocOp::from_token(&token::DotDot).unwrap().precedence() + 1;
+            // RHS must be parsed with more associativity than the dots.
+            let next_prec = AssocOp::from_token(&tok).unwrap().precedence() + 1;
             Some(try!(self.parse_assoc_expr_with(next_prec,
                                                  LhsExpr::NotYetParsed)
             .map(|x|{
@@ -3075,7 +3082,13 @@ impl<'a> Parser<'a> {
          } else {
             None
         };
-        let r = self.mk_range(None, opt_end);
+        let r = self.mk_range(None,
+                              opt_end,
+                              if tok == token::DotDot {
+                                  RangeLimits::HalfOpen
+                              } else {
+                                  RangeLimits::Closed
+                              });
         Ok(self.mk_expr(lo, hi, r, attrs))
     }
 
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index accbb54c629..0c59c240bcd 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -196,7 +196,7 @@ impl Token {
             BinOp(Or)                   => true, // in lambda syntax
             OrOr                        => true, // in lambda syntax
             AndAnd                      => true, // double borrow
-            DotDot                      => true, // range notation
+            DotDot | DotDotDot          => true, // range notation
             ModSep                      => true,
             Interpolated(NtExpr(..))    => true,
             Interpolated(NtIdent(..))   => true,
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index b4e08d65a0a..8d81787d922 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -2163,11 +2163,15 @@ impl<'a> State<'a> {
                 try!(self.print_expr(&index));
                 try!(word(&mut self.s, "]"));
             }
-            ast::ExprKind::Range(ref start, ref end) => {
+            ast::ExprKing::Range(ref start, ref end, limits) => {
                 if let &Some(ref e) = start {
                     try!(self.print_expr(&e));
                 }
-                try!(word(&mut self.s, ".."));
+                if limits == ast::RangeLimits::HalfOpen {
+                    try!(word(&mut self.s, ".."));
+                } else {
+                    try!(word(&mut self.s, "..."));
+                }
                 if let &Some(ref e) = end {
                     try!(self.print_expr(&e));
                 }
diff --git a/src/libsyntax/util/parser.rs b/src/libsyntax/util/parser.rs
index 6fb81bb6a76..df4eb1c9ed7 100644
--- a/src/libsyntax/util/parser.rs
+++ b/src/libsyntax/util/parser.rs
@@ -61,6 +61,8 @@ pub enum AssocOp {
     As,
     /// `..` range
     DotDot,
+    /// `...` range
+    DotDotDot,
     /// `:`
     Colon,
 }
@@ -102,6 +104,7 @@ impl AssocOp {
             Token::AndAnd => Some(LAnd),
             Token::OrOr => Some(LOr),
             Token::DotDot => Some(DotDot),
+            Token::DotDotDot => Some(DotDotDot),
             Token::Colon => Some(Colon),
             _ if t.is_keyword(keywords::As) => Some(As),
             _ => None
@@ -147,7 +150,7 @@ impl AssocOp {
             Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual => 7,
             LAnd => 6,
             LOr => 5,
-            DotDot => 4,
+            DotDot | DotDotDot => 4,
             Inplace => 3,
             Assign | AssignOp(_) => 2,
         }
@@ -162,7 +165,7 @@ impl AssocOp {
             As | Multiply | Divide | Modulus | Add | Subtract | ShiftLeft | ShiftRight | BitAnd |
             BitXor | BitOr | Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual |
             LAnd | LOr | Colon => Fixity::Left,
-            DotDot => Fixity::None
+            DotDot | DotDotDot => Fixity::None
         }
     }
 
@@ -171,7 +174,8 @@ impl AssocOp {
         match *self {
             Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual => true,
             Inplace | Assign | AssignOp(_) | As | Multiply | Divide | Modulus | Add | Subtract |
-            ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd | LOr | DotDot | Colon => false
+            ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd | LOr |
+            DotDot | DotDotDot | Colon => false
         }
     }
 
@@ -181,7 +185,7 @@ impl AssocOp {
             Assign | AssignOp(_) | Inplace => true,
             Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual | As | Multiply | Divide |
             Modulus | Add | Subtract | ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd |
-            LOr | DotDot | Colon => false
+            LOr | DotDot | DotDotDot | Colon => false
         }
     }
 
@@ -206,7 +210,7 @@ impl AssocOp {
             BitOr => Some(BinOpKind::BitOr),
             LAnd => Some(BinOpKind::And),
             LOr => Some(BinOpKind::Or),
-            Inplace | Assign | AssignOp(_) | As | DotDot | Colon => None
+            Inplace | Assign | AssignOp(_) | As | DotDot | DotDotDot | Colon => None
         }
     }
 }
diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs
index f26610b8b8d..73ad488e55c 100644
--- a/src/libsyntax/visit.rs
+++ b/src/libsyntax/visit.rs
@@ -763,7 +763,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
             visitor.visit_expr(main_expression);
             visitor.visit_expr(index_expression)
         }
-        ExprKind::Range(ref start, ref end) => {
+        ExprKind::Range(ref start, ref end, _) => {
             walk_list!(visitor, visit_expr, start);
             walk_list!(visitor, visit_expr, end);
         }