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from consts import *
from tokenizer import Token
class ParserError(Exception):
pass
class Node:
def __init__(self, node_type, value=None, subtype=None):
self.type = node_type
self.value = value
self.subtype = subtype
self.parent = None
self.right = None
self.left = None
def __eq__(self, other):
return self.type == other.type and self.value == other.value
def __repr__(self):
# NUMBER, OPERATOR, SYMBOL, FUNCALL, UNARY, ASSIGNMENT, *_
if self.type == NodeType.NUMBER:
return f"Node({self.value})"
if self.type == NodeType.OPERATOR:
return f"Node({self.subtype})"
if self.type == NodeType.SYMBOL:
return f"Node(SYMBOL {self.value})"
if self.type == NodeType.FUNCALL:
return f"Node(FUNCALL {self.value})"
if self.type == NodeType.UNARY:
return f"Node(UNARY {self.subtype})"
if self.type == NodeType.ASSIGNMENT:
return f"Node(ASSIGNMENT)"
return "Node(repr not defined)"
__str__ = __repr__
def parse_parenthesis(tokens, start):
end = start
depth = 0
while True:
token = tokens[end]
if token.type == TokenType.RIGHT_PARENTHESIS:
depth -= 1
if token.type == TokenType.LEFT_PARENTHESIS:
depth += 1
if depth == 0 and token.type == TokenType.RIGHT_PARENTHESIS:
break
end += 1
node = parse_expr(tokens[start + 1: end])
return node, end
def parse_args(tokens, start):
end = start
depth = 0
while True:
token = tokens[end]
if token.type == TokenType.RIGHT_PARENTHESIS:
depth -= 1
if token.type == TokenType.LEFT_PARENTHESIS:
depth += 1
if depth == 0 and token.type == TokenType.RIGHT_PARENTHESIS:
break
end += 1
args = []
arg = []
for token in tokens[start + 1: end]:
if token.type != TokenType.COMMA:
arg.append(token)
else:
args.append(arg.copy())
arg.clear()
if len(arg) != 0:
args.append(arg)
return list(map(parse_expr, args))
def parse_expr(tokens, start):
state = State.NAME
i = start
current_node = None
while i < len(tokens):
token = tokens[i]
if state == State.OPERATOR and token.type == TokenType.LEFT_PARENTHESIS:
args = parse_args(tokens, i)
current_node.type = NodeType.FUNCALL
current_node.value = (current_node.value, args)
elif token.type in [TokenType.LEFT_PARENTHESIS, TokenType.NUMBER, TokenType.SYMBOL] or token.subtype == TokenType.UNARY:
if token.type == TokenType.LEFT_PARENTHESIS:
node, i = parse_parenthesis(tokens, i)
state = State.NAME
elif token.type == TokenType.NUMBER:
node = Node(NodeType.NUMBER, value=token.value)
state = State.OPERATOR
elif token.type == TokenType.SYMBOL:
node = Node(NodeType.SYMBOL, value=token.value)
state = State.OPERATOR
elif token.subtype == TokenType.UNARY:
node = Node(NodeType.OPERATOR, subtype=NodeType.UNARY)
node.left = Node(NodeType.OPERATOR, subtype=token.value)
state = State.NAME
if current_node is None:
current_node = node
elif current_node.type == NodeType.NUMBER:
raise ValueError("Not a valid expression")
elif current_node.type == NodeType.OPERATOR:
if current_node.left is None:
current_node.left = node
node.parent = current_node
elif current_node.right is None:
current_node.right = node
node.parent = current_node
current_node = node
else:
raise ValueError("Not a valid expression")
elif token.type == TokenType.OPERATOR:
node = Node(NodeType.OPERATOR, subtype=token.subtype, value=token.value)
if current_node is None:
raise ValueError("Not a valid expression")
elif current_node.type in [NodeType.NUMBER, NodeType.OPERATOR, NodeType.FUNCALL]:
while current_node.parent is not None:
if PRECEDENCE[current_node.parent.subtype] < PRECEDENCE[node.subtype]:
node.parent = current_node.parent
if node.parent is not None:
node.parent.right = node
break
current_node = current_node.parent
current_node.parent = node
node.left = current_node
current_node = node
else:
raise ValueError("Not a valid expression")
state = State.NAME
elif token.type == TokenType.SEMICOLON:
break
i += 1
while current_node.parent is not None:
current_node = current_node.parent
return current_node, i - 1
def parse_let_statement(tokens: list[Token], start: int):
class LetStates:
(WAIT_LET, WAIT_SYMBOL, WAIT_EQUALS, WAIT_EXPR, WAIT_SEMICOLON, PARSE_END, *_) = range(100)
root_node = Node(NodeType.ASSIGNMENT)
state = LetStates.WAIT_LET
i = start
while i < len(tokens):
token = tokens[i]
if state == LetStates.WAIT_LET:
if token.type == TokenType.KEYWORD and token.subtype == Keyword.LET:
state = LetStates.WAIT_SYMBOL
else:
raise ParserError(f"Waited for let, got {token}")
elif state == LetStates.WAIT_SYMBOL:
if token.type == TokenType.SYMBOL:
node = Node(NodeType.SYMBOL, value=token.value)
root_node.left = node
state = LetStates.WAIT_EQUALS
else:
raise ParserError(f"Waited for symbol, got {token}")
elif state == LetStates.WAIT_EQUALS:
if token.type == TokenType.EQUALS:
state = LetStates.WAIT_EXPR
else:
raise ParserError(f"Waited for equals, got {token}")
elif state == LetStates.WAIT_EXPR:
node, i = parse_expr(tokens, i)
root_node.right = node
state = LetStates.WAIT_SEMICOLON
elif state == LetStates.WAIT_SEMICOLON:
if token.type == TokenType.SEMICOLON:
state = LetStates.PARSE_END
break
else:
raise ParserError(f"Waited for semicolon, got {token}")
i += 1
if state != LetStates.PARSE_END:
raise ParserError("Statement ended unexpectedly")
return root_node, i
def parse(tokens: list[Token]):
_statements = [
[Keyword.LET, TokenType.SYMBOL, TokenType.EQUALS, "EXPR", TokenType.SEMICOLON],
[Keyword.FN, TokenType.SYMBOL, TokenType.LEFT_PARENTHESIS, "ARGS", TokenType.RIGHT_PARENTHESIS, TokenType.LEFT_BRACE, ["STATEMENTS"], TokenType.RIGHT_BRACE],
]
statements = []
i = 0
while i < len(tokens):
if tokens[i].type == TokenType.KEYWORD and tokens[i].subtype == Keyword.LET:
node, i = parse_let_statement(tokens, i)
statements.append(node)
i += 1
return statements
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