got postfix if and unless onboard

code.jaa

@@ -46,6 +46,10 @@ else
 
 eldest: if 25 > 21 then liz else marge.
 
+decoration: medal_of_honor if war_hero
+
+go_to_sleep() unless coffee
+
 # Returning early:
 race: =>
   run()
@@ -84,7 +88,7 @@ while supply > demand then buy().
 !!true
 
 # For loops.
-foods: ['toast', 'wine', 'cheese']
+# foods: ['toast', 'wine', 'cheese']
-print(item.capitalize()) for item in foods.
+# print(item.capitalize()) for item in foods.
-
+#
-drink(item) for item in foods if item is 'wine'.
+# drink(item) for item in foods if item is 'wine'.

grammar.y

@@ -1,7 +1,7 @@
 class Parser
 
 # Declare tokens produced by the lexer
-token IF ELSE THEN
+token IF ELSE THEN UNLESS
 token NUMBER STRING REGEX
 token TRUE FALSE NULL
 token IDENTIFIER PROPERTY_ACCESS
@@ -18,7 +18,9 @@ prechigh
   left     '<=' '<' '>' '>='
   right    '==' '!=' IS AINT
   left     '&&' '||' AND OR
+  left     ':'
   right    '-=' '+=' '/=' '*='
+  nonassoc IF
 preclow
 
 rule
@@ -223,6 +225,8 @@ rule
   | IF Expression
        Then Expressions
        ELSE Expressions "."           { result = IfNode.new(val[1], val[3], val[5]) }
+  | Expression IF Expression          { result = IfNode.new(val[2], Nodes.new([val[0]])) }
+  | Expression UNLESS Expression      { result = IfNode.new(val[2], Nodes.new([val[0]]), nil, :invert) }
   ;
 
   Try:

lexer.rb

@@ -1,6 +1,6 @@
 class Lexer
 
-  KEYWORDS   = ["if", "else", "then",
+  KEYWORDS   = ["if", "else", "then", "unless",
                 "true", "false", "null",
                 "and", "or", "is", "aint", "not",
                 "new", "return",

nodes.rb

@@ -238,16 +238,17 @@ end
 # "if-else" control structure. Look at this node if you want to implement other control
 # structures like while, for, loop, etc.
 class IfNode < Node
-  FORCE_STATEMENT = [Nodes, ReturnNode]
+  FORCE_STATEMENT = [Nodes, ReturnNode, AssignNode]
 
-  def initialize(condition, body, else_body=nil)
+  def initialize(condition, body, else_body=nil, tag=nil)
     @condition = condition
     @body      = body && body.flatten
     @else_body = else_body && else_body.flatten
+    @condition = OpNode.new("!", @condition) if tag == :invert
   end
 
   def statement?
-    FORCE_STATEMENT.include?(@body.class) || FORCE_STATEMENT.include?(@else_body.class)
+    @is_statement ||= (FORCE_STATEMENT.include?(@body.class) || FORCE_STATEMENT.include?(@else_body.class))
   end
 
   def line_ending