first draft of optional parentheses, with a couple tests ... more to follow

lib/coffee_script/rewriter.rb

@@ -17,6 +17,10 @@ module CoffeeScript
     # Tokens that indicate the close of a clause of an expression.
     EXPRESSION_CLOSE = [:CATCH, :WHEN, :ELSE, :FINALLY] + EXPRESSION_TAIL
 
+    # Tokens that, when immediately following an identifier, activate an
+    # implicit method call.
+    IMPLICIT_CALL = [:IDENTIFIER, :NUMBER, :STRING, :JS, :REGEX]
+
     # The inverse mappings of token pairs we're trying to fix up.
     INVERSES = BALANCED_PAIRS.inject({}) do |memo, pair|
       memo[pair.first] = pair.last
@@ -39,6 +43,7 @@ module CoffeeScript
       remove_mid_expression_newlines
       move_commas_outside_outdents
       add_implicit_indentation
+      add_implicit_parentheses
       ensure_balance(*BALANCED_PAIRS)
       rewrite_closing_parens
       @tokens
@@ -140,6 +145,24 @@ module CoffeeScript
       end
     end
 
+    # Methods may be optionally called without parentheses, for simple cases.
+    # Insert the implicit parentheses here, so that the parser doesn't have to
+    # deal with them.
+    def add_implicit_parentheses
+      open = false
+      scan_tokens do |prev, token, post, i|
+        if open && token[0] == "\n"
+          @tokens.insert(i, [')', Value.new(')', token[1].line)])
+          open = false
+          next 2
+        end
+        next 1 unless prev[0] == :IDENTIFIER && IMPLICIT_CALL.include?(token[0])
+        @tokens.insert(i, ['(', Value.new('(', token[1].line)])
+        open = true
+        next 2
+      end
+    end
+
     # Ensure that all listed pairs of tokens are correctly balanced throughout
     # the course of the token stream.
     def ensure_balance(*pairs)

test/fixtures/execution/test_arguments.coffee

@@ -4,7 +4,7 @@ area: x, y, x1, y1 =>
 x:  y:  10
 x1: y1: 20
 
-print(area(x, y, x1, y1) is 100)
+print area(x, y, x1, y1) is 100
 
 print(area(x, y,
            x1, y1) is 100)
@@ -19,9 +19,9 @@ print(area(
 
 # Arguments are turned into arrays.
 curried: =>
-  print(area.apply(this, arguments.concat(20, 20)) is 100)
+  print area.apply(this, arguments.concat(20, 20)) is 100
 
-curried(10, 10)
+curried 10, 10
 
 
 # Arguments is not a special keyword -- it can be assigned to:
@@ -29,4 +29,4 @@ func: =>
   arguments: 25
   arguments
 
-print(func(100) is 25)
+print func(100) is 25

test/fixtures/execution/test_array_comprehension.coffee

@@ -1,15 +1,15 @@
 nums:    n * n for n in [1, 2, 3] when n % 2 isnt 0
 results: n * 2 for n in nums
 
-print(results.join(',') is '2,18')
+print results.join(',') is '2,18'
 
 
 obj:   {one: 1, two: 2, three: 3}
 names: prop + '!' for prop of obj
 odds:  prop + '!' for prop, value of obj when value % 2 isnt 0
 
-print(names.join(' ') is "one! two! three!")
-print(odds.join(' ')  is "one! three!")
+print names.join(' ') is "one! two! three!"
+print odds.join(' ')  is "one! three!"
 
 
 evens: for num in [1, 2, 3, 4, 5, 6] when num % 2 is 0
@@ -17,12 +17,12 @@ evens: for num in [1, 2, 3, 4, 5, 6] when num % 2 is 0
            num -= 2
            num * -1
 
-print(evens.join(', ') is '4, 6, 8')
+print evens.join(', ') is '4, 6, 8'
 
 
 # Make sure that the "in" operator still works.
 
-print(2 in evens)
+print 2 in evens
 
 
 # When functions are being defined within the body of a comprehension, make
@@ -37,6 +37,6 @@ for method in methods
   obj[name]: =>
     "I'm " + name
 
-print(obj.one()   is "I'm one")
-print(obj.two()   is "I'm two")
-print(obj.three() is "I'm three")
+print obj.one()   is "I'm one"
+print obj.two()   is "I'm two"
+print obj.three() is "I'm three"

test/fixtures/execution/test_assignment.coffee

@@ -7,7 +7,7 @@ catch error
 
 result2: try nonexistent * missing catch error then true
 
-print(result is true and result2 is true)
+print result is true and result2 is true
 
 
 # Assign to conditional.
@@ -16,8 +16,8 @@ get_x: => 10
 
 if x: get_x() then 100
 
-print(x is 10)
+print x is 10
 
 x: if get_x() then 100
 
-print(x is 100)
+print x is 100