Conlang: Add range operators

TODO: Limit range operators to at most 2 operands

grammar.ebnf

@@ -17,7 +17,8 @@ Primary     = Item | Identifier | Literal
 (* expression::math *)
 Ignore      = Assign  (IgnoreOp  Assign )* ;
 Assign      = Compare (AssignOp  Compare)* ;
-Compare     = Logic   (CompareOp Logic  )* ;
+Compare     = Range   (CompareOp Range  )* ;
+Range       = Logic   (RangeOp   Logic  )* ;
 Logic       = Bitwise (LogicOp   Bitwise)* ;
 Bitwise     = Shift   (BitwiseOp Shift  )* ;
 Shift       = Term    (ShiftOp   Term   )* ;

libconlang/src/ast.rs

@@ -603,6 +603,12 @@ pub mod expression {
                 /// `^^`: **Non-short-circuiting** logical XOR
                 LogXor,
 
+                // Range operators
+                /// `..`: Exclusive range
+                RangeExc,
+                /// `..=`: Inclusive range
+                RangeInc,
+
                 // Comparison operators
                 /// `<`: Less-than Comparison
                 Less,

libconlang/src/parser.rs

@@ -388,7 +388,8 @@ impl Parser {
         //name    operands operators
         ignore  = assign,  ignore_op;
         assign  = compare, assign_op;
-        compare = logic,   compare_op;
+        compare = range,   compare_op;
+        range   = logic,   range_op;
         logic   = bitwise, logic_op;
         bitwise = shift,   bitwise_op;
         shift   = term,    shift_op;
@@ -443,6 +444,10 @@ impl Parser {
             Type::BarBar => LogOr,
             Type::XorXor => LogXor,
         }
+        range_op: {
+            Type::DotDot => RangeExc,
+            Type::DotDotEq => RangeInc,
+        }
         compare_op: {
             Type::Lt => Less,
             Type::LtEq => LessEq,

libconlang/src/pretty_printer.rs

@@ -98,6 +98,8 @@ impl<W: Write> Visitor<IOResult<()>> for Printer<W> {
             Binary::LogAnd => "&&",
             Binary::LogOr => "||",
             Binary::LogXor => "^^",
+            Binary::RangeExc => "..",
+            Binary::RangeInc => "..=",
             Binary::Less => "<",
             Binary::LessEq => "<=",
             Binary::Equal => "==",