improvements on AST shape and printing

ast.py

@@ -51,13 +51,29 @@ class Node:
         self.args = args
 
     def __str__(self):
+        """Basic text representation without children."""
+        if self.type == N.CONST:
+            return str(self.value)
         try:
             name = N(self.type).name
             return f"<Node:{name}>"
         except ValueError:
             return f"<Node:{hex(self.type)}>"
 
+    @property
+    def value(self):
+        """Retrive the value of a CONST node."""
+        if self.type != N.CONST:
+            raise Exception("Taking value of non-const node")
+        return self.args[0]
+
+    def constchildren(self):
+        """Checks whether all arguments are constants."""
+        return all(c.type == N.CONST for c in self.args)
+
     def simplify(self):
+        """Simplify arithmetic expressions."""
+
         simpl = lambda n: n.simplify() if isinstance(n, Node) else n
         self.args = [ simpl(arg) for arg in self.args ]
         arity = len(self.args)
@@ -66,9 +82,20 @@ class Node:
             return Node(N.CONST, 1)
         if self.type == N.MUL and arity == 1:
             return self.args[0]
+        if self.type == N.MUL and self.constchildren():
+            prod = 1
+            for c in self.args:
+                prod *= c.value
+            return Node(N.CONST, prod)
+
         if self.type == N.ADD and arity == 0:
             return Node(N.CONST, 0)
         if self.type == N.ADD and arity == 1:
             return self.args[0]
+        if self.type == N.ADD and self.constchildren():
+            return Node(N.CONST, sum(c.value for c in self.args))
+
+        if self.type == N.MINUS and self.constchildren():
+            return Node(N.CONST, -self.args[0].value)
 
         return self

fx92.py

@@ -37,7 +37,7 @@ def main(argv):
     ast = parser.parse_program()
     ast = ast.simplify()
 
-    print_ast(ast, lang="fr")
+    print_ast(ast, lang="ast")
 
 if __name__ == "__main__":
     main(sys.argv)

printer.py

@@ -7,9 +7,21 @@ __all__ = ["print_ast"]
 # Message definitions
 #---
 
+class MessageAST:
+    forward = "FORWARD {}"
+    rotate  = "ROTATE {}"
+    orient  = "ORIENT {}"
+    goto    = "GOTO {}, {}"
+    pendown = "PENDOWN"
+    penup   = "PENUP"
+
 class MessageFrench:
-    multiply = "mul({})"
-    goto = "goto {}, {}"
+    forward = "Avancer de {} pixels"
+    rotate  = "Tourner de {} degrés"
+    orient  = "S'orienter à {} degrés"
+    goto    = "Aller à x={}; y={}"
+    pendown = "Stylo écrit"
+    penup   = "Stylo relevé"
 
 class MessageEnglish:
     pass
@@ -19,8 +31,14 @@ class MessageEnglish:
 #---
 
 def print_ast(n, lang="en", indent=0):
-    if lang == "fr": lang = MessageFrench
-    if lang == "en": lang = MessageEnglish
+    if lang == "fr":  lang = MessageFrench
+    if lang == "en":  lang = MessageEnglish
+    if lang == "ast": lang = MessageAST
+
+    if n.type == N.PROGRAM:
+        for arg in n.args:
+            print_ast(arg, lang=lang, indent=indent)
+        return
 
     print(" " * indent, end="")
 
@@ -30,9 +48,22 @@ def print_ast(n, lang="en", indent=0):
 
     if n.type == N.CONST:
         print(n.args[0])
-    elif n.type == N.VAR:
-        print(f"VAR({n.args[0]})")
+        return
+
+    if n.type == N.VAR:
+        print(f"{n.args[0]}")
+        return
+
+    id = n.type.name.lower()
+
+    if hasattr(lang, id):
+        print(getattr(lang, id).format(*n.args))
     else:
         print(f"{n.type.name}")
-        for arg in n.args:
-            print_ast(arg, lang=lang, indent=indent+2)
+
+    if n.type in [N.FORWARD, N.ROTATE, N.ORIENT, N.GOTO] and \
+        n.constchildren():
+        return
+
+    for arg in n.args:
+        print_ast(arg, lang=lang, indent=indent+2)