Added tree iterator, cloning
parent
a991c3bb91
commit
0dae1afb61
GPG Key ID:
AD62BB059C2AAEE4
315
lamb/__main__.py
315
lamb/__main__.py
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@ -48,6 +48,40 @@ r = runner.Runner(
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macro_table = {}
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class TreeWalker:
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def __init__(self, expr):
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self.expr = expr
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self.ptr = expr
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self.from_side = Direction.UP
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def __next__(self):
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if self.ptr is self.expr.parent:
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raise StopIteration
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out = self.ptr
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out_side = self.from_side
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if isinstance(self.ptr, EndNode):
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self.from_side, self.ptr = self.ptr.go_up()
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elif isinstance(self.ptr, Func):
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if self.from_side == Direction.UP:
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self.from_side, self.ptr = self.ptr.go_left()
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elif self.from_side == Direction.LEFT:
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self.from_side, self.ptr = self.ptr.go_up()
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elif isinstance(self.ptr, Call):
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if self.from_side == Direction.UP:
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self.from_side, self.ptr = self.ptr.go_left()
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elif self.from_side == Direction.LEFT:
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self.from_side, self.ptr = self.ptr.go_right()
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elif self.from_side == Direction.RIGHT:
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self.from_side, self.ptr = self.ptr.go_up()
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else:
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raise TypeError(f"I don't know how to iterate a {type(self.ptr)}")
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return out_side, out
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class Direction(enum.Enum):
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UP = enum.auto()
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LEFT = enum.auto()
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@ -73,8 +107,33 @@ class Node:
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self.parent_side: Direction | None = None
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# Left and right nodes, None if empty
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self.left: Node | None = None
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self.right: Node | None = None
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self._left: Node | None = None
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self._right: Node | None = None
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def __iter__(self):
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return TreeWalker(self)
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@property
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def left(self):
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return self._left
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@left.setter
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def left(self, node):
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if node is not None:
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node.set_parent(self, Direction.LEFT)
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self._left = node
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@property
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def right(self):
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return self._right
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@right.setter
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def right(self, node):
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if node is not None:
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node.set_parent(self, Direction.RIGHT)
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self._right = node
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def set_parent(self, parent, side):
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if (parent is not None) and (side is None):
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@ -83,16 +142,17 @@ class Node:
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raise Exception("If a node has no parent, it cannot have a direction.")
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self.parent = parent
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self.parent_side = side
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return self
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def go_left(self):
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if self.left is None:
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if self._left is None:
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raise Exception("Can't go left when left is None")
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return Direction.UP, self.left
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return Direction.UP, self._left
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def go_right(self):
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if self.right is None:
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if self._right is None:
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raise Exception("Can't go right when right is None")
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return Direction.UP, self.right
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return Direction.UP, self._right
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def go_up(self):
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return self.parent_side, self.parent
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@ -172,7 +232,7 @@ class Church(ExpandableEndNode):
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chain = a
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for i in range(self.value):
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chain = Call(f, chain)
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chain = Call(clone(f), clone(chain))
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return Func(
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f,
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@ -316,19 +376,13 @@ p = lamb.parser.LambdaParser(
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def clone_one(ptr, out):
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if ptr.parent_side == Direction.LEFT:
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out.left = ptr.clone()
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out.left.set_parent(out, Direction.LEFT)
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else:
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out.right = ptr.clone()
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out.right.set_parent(out, Direction.RIGHT)
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def clone(expr: Node):
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if not isinstance(expr, Node):
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raise TypeError(f"I don't know what to do with a {type(expr)}")
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# Disconnect parent while cloning
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old_parent = expr.parent
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expr.parent = None
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out = expr.clone()
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out_ptr = out # Stays one step behind ptr, in the new tree.
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ptr = expr
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@ -337,7 +391,12 @@ def clone(expr: Node):
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if isinstance(expr, EndNode):
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return out
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print("cloning", expr)
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while True:
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print("p", ptr)
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print("o", out_ptr)
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print("r", out)
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if isinstance(ptr, EndNode):
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from_side, ptr = ptr.go_up()
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_, out_ptr = out_ptr.go_up()
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@ -361,57 +420,53 @@ def clone(expr: Node):
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elif from_side == Direction.RIGHT:
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from_side, ptr = ptr.go_up()
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_, out_ptr = out_ptr.go_up()
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if ptr is None:
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if ptr is expr.parent:
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break
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expr.parent = old_parent
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if out_ptr is None:
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print("fail")
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print(out_ptr)
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print(out)
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print(ptr, expr.parent)
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print("<fail")
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#return False
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return out
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def print_expr(expr) -> str:
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out = ""
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# Type check
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if isinstance(expr, MacroDef):
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out = expr.label + " = "
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expr = expr.expr
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elif not isinstance(expr, Node):
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raise TypeError(f"I don't know what to do with a {type(expr)}")
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ptr = expr
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from_side = Direction.UP
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while True:
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print(ptr)
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if isinstance(ptr, EndNode):
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out += ptr.print_value()
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, Func):
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if from_side == Direction.UP:
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if isinstance(ptr.parent, Func):
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out += ptr.input.name
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else:
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out += "λ" + ptr.input.name
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if not isinstance(ptr.left, Func):
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out = ""
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for s, n in expr:
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print(out)
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if isinstance(n, EndNode):
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out += n.print_value()
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elif isinstance(n, Func):
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if s == Direction.UP:
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if isinstance(n.parent, Func):
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out += n.input.name
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else:
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out += "λ" + n.input.name
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if not isinstance(n.left, Func):
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out += "."
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from_side, ptr = ptr.go_left()
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elif from_side == Direction.LEFT:
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, Call):
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if from_side == Direction.UP:
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elif isinstance(n, Call):
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if s == Direction.UP:
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out += "("
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from_side, ptr = ptr.go_left()
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elif from_side == Direction.LEFT:
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elif s == Direction.LEFT:
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out += " "
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from_side, ptr = ptr.go_right()
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elif from_side == Direction.RIGHT:
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elif s == Direction.RIGHT:
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out += ")"
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from_side, ptr = ptr.go_up()
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if ptr is None:
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break
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return out
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def bind_variables(expr) -> None:
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@ -422,118 +477,51 @@ def bind_variables(expr) -> None:
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elif not isinstance(expr, Node):
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raise TypeError(f"I don't know what to do with a {type(expr)}")
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ptr = expr
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from_side = Direction.UP
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bound_variables = {}
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while True:
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if isinstance(ptr, Func):
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if from_side == Direction.UP:
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for s, n in expr:
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if isinstance(n, Func):
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if s == Direction.UP:
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# Add this function's input to the table of bound variables.
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# If it is already there, raise an error.
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if (ptr.input.name in bound_variables):
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raise ReductionError(f"Bound variable name conflict: \"{ptr.input.name}\"")
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if (n.input.name in bound_variables):
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raise ReductionError(f"Bound variable name conflict: \"{n.input.name}\"")
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else:
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bound_variables[ptr.input.name] = Bound(ptr.input.name)
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ptr.input = bound_variables[ptr.input.name]
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bound_variables[n.input.name] = Bound(n.input.name)
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n.input = bound_variables[n.input.name]
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# If output is a macro, swap it with a bound variable.
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if isinstance(ptr.left, Macro):
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if ptr.left.name in bound_variables:
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ptr.left = bound_variables[ptr.left.name].clone()
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ptr.left.set_parent(ptr, Direction.LEFT)
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if isinstance(n.left, Macro):
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if n.left.name in bound_variables:
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n.left = clone(bound_variables[n.left.name])
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# If we can't move down the tree, move up.
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if isinstance(ptr.left, EndNode):
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del bound_variables[ptr.input.name]
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from_side, ptr = ptr.go_up()
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else:
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from_side, ptr = ptr.go_left()
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elif s == Direction.LEFT:
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del bound_variables[n.input.name]
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elif from_side == Direction.LEFT:
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del bound_variables[ptr.input.name]
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, Call):
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if from_side == Direction.UP:
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elif isinstance(n, Call):
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if s == Direction.UP:
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# Bind macros
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if isinstance(ptr.left, Macro):
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if ptr.left.name in bound_variables:
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ptr.left = bound_variables[ptr.left.name].clone()
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ptr.left.set_parent(ptr, Direction.LEFT)
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if isinstance(ptr.right, Macro):
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if ptr.right.name in bound_variables:
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ptr.right = bound_variables[ptr.right.name].clone()
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ptr.right.set_parent(ptr, Direction.RIGHT)
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if not isinstance(ptr.left, EndNode):
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from_side, ptr = ptr.go_left()
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elif not isinstance(ptr.right, EndNode):
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from_side, ptr = ptr.go_right()
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else:
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from_side, ptr = ptr.go_up()
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elif from_side == Direction.LEFT:
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if not isinstance(ptr.right, EndNode):
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from_side, ptr = ptr.go_right()
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else:
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from_side, ptr = ptr.go_up()
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elif from_side == Direction.RIGHT:
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from_side, ptr = ptr.go_up()
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if ptr is None:
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break
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if isinstance(n.left, Macro):
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if n.left.name in bound_variables:
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n.left = clone(bound_variables[n.left.name])
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if isinstance(n.right, Macro):
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if n.right.name in bound_variables:
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n.right = clone(bound_variables[n.right.name])
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# Apply a function.
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# Returns the function's output.
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def call_func(fn: Func, arg: Node):
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ptr = fn
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# Temporarily disconnect this function's
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# parent to keep our pointer inside this
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# subtree.
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old_parent = fn.parent
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fn.parent = None
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from_side = Direction.UP
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while True:
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if isinstance(ptr, Bound):
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if ptr == fn.input:
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if ptr.parent is None:
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for s, n in fn:
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if isinstance(n, Bound):
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if n == fn.input:
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if n.parent is None:
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raise Exception("Tried to substitute a None bound variable.")
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if ptr.parent_side == Direction.LEFT:
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ptr.parent.left = clone(arg)
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ptr.parent.left.set_parent(ptr, Direction.LEFT)
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if n.parent_side == Direction.LEFT:
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n.parent.left = clone(arg)
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else:
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ptr.parent.right = clone(arg)
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ptr.parent.right.set_parent(ptr, Direction.RIGHT)
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, Func):
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if from_side == Direction.UP:
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from_side, ptr = ptr.go_left()
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elif from_side == Direction.LEFT:
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, Call):
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if from_side == Direction.UP:
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from_side, ptr = ptr.go_left()
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elif from_side == Direction.LEFT:
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from_side, ptr = ptr.go_right()
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elif from_side == Direction.RIGHT:
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from_side, ptr = ptr.go_up()
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else:
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from_side, ptr = ptr.go_up()
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if ptr is None:
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break
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fn.parent = old_parent
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n.parent.right = clone(arg)
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return fn.left
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@ -543,48 +531,26 @@ def reduce(expr) -> tuple[bool, Node]:
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if not isinstance(expr, Node):
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raise TypeError(f"I can't reduce a {type(expr)}")
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ptr = expr
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from_side = Direction.UP
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reduced = False
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while True:
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print("redu", ptr)
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if isinstance(ptr, Call):
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if from_side == Direction.UP:
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if isinstance(ptr.left, Func):
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if ptr.parent is None:
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expr = call_func(ptr.left, ptr.right)
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for s, n in expr:
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if isinstance(n, Call):
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if s == Direction.UP:
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if isinstance(n.left, Func):
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if n.parent is None:
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expr = call_func(n.left, n.right)
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expr.set_parent(None, None)
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else:
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ptr.parent.left = call_func(ptr.left, ptr.right)
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ptr.parent.left.set_parent(ptr.parent, Direction.LEFT)
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n.parent.left = call_func(n.left, n.right)
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reduced = True
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break
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elif isinstance(ptr.left, ExpandableEndNode):
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ptr.left = ptr.left.expand()
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elif isinstance(n.left, ExpandableEndNode):
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n.left = n.left.expand()
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reduced = True
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break
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elif isinstance(ptr.left, Call):
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from_side, ptr = ptr.go_left()
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else:
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from_side, ptr = ptr.go_right()
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else:
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, Func):
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if from_side == Direction.UP:
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from_side, ptr = ptr.go_left()
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else:
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from_side, ptr = ptr.go_up()
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elif isinstance(ptr, EndNode):
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from_side, ptr = ptr.go_up()
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if ptr is None:
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break
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print("r")
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return reduced, expr
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@ -605,18 +571,19 @@ for l in [
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"H = λp.((PAIR (p F)) (S (p F)))",
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"D = λn.n H (PAIR 0 0) T",
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"FAC = λyn.(Z n)(1)(MULT n (y (D n)))",
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"S (λfa.f a)"
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"3 NOT T"
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]:
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n = p.parse_line(l)
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bind_variables(n)
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if isinstance(n, MacroDef):
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macro_table[n.label] = n.expr
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print(print_expr(n))
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else:
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for i in range(10):
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r, n = reduce(n)
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print(print_expr(n))
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if not r:
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break
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print(print_expr(n))
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#print(print_expr(clone(n)))
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