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import ply.yacc as yacc
from chelodina import ast_builder
from chelodina.lexer import Lexer
from chelodina.utils import validator
class Parser:
tokens = Lexer.tokens
module = "turtle"
precedence = (("left", "PLUS", "MINUS"), ("left", "MULT", "DIV"))
def __init__(self):
self.functions = set()
self.calls = []
def parse(self, code):
Lexer().build()
parser = yacc.yacc(module=self, write_tables=False)
parsed_ast = parser.parse(code)
validator.validate_statements(self.calls, self.functions)
parsed_ast = ast_builder.turtle_wrapper(parsed_ast)
parsed_ast = ast_builder.fill_locations(parsed_ast)
return parsed_ast
def p_program(self, p):
"""program : statements"""
p[0] = p[1]
def p_statements(self, p):
"""statements : statements statement
| statement"""
if len(p) == 2:
p[0] = [p[1]]
else:
p[0] = p[1] + [p[2]]
def p_statement(self, p):
"""statement : expression
| funcdef
| repeat"""
p[0] = p[1]
def p_expression(self, p):
"""expression : NAME terms
| NAME """
name = p[1]
module = self.module if validator.is_std_function(name) else ""
self.calls.append(name)
if len(p) == 3:
parameters = p[2]
p[0] = ast_builder.call_expr(name, module, parameters)
else:
p[0] = ast_builder.call_expr(name, module)
def p_terms_number(self, p):
"""terms : terms NUMBER
| NUMBER"""
if len(p) == 2:
number = ast_builder.number(p[1])
p[0] = [number]
else:
numbers = p[1]
number = ast_builder.number(p[2])
p[0] = numbers + [number]
def p_terms_params(self, p):
"""terms : terms PARAM
| PARAM"""
if len(p) == 2:
arg = ast_builder.ast_name(p[1])
p[0] = [arg]
else:
args = p[1]
arg = ast_builder.ast_name(p[2])
p[0] = args + [arg]
def p_terms_binary_operations(self, p):
"""terms : terms PLUS terms
| terms MINUS terms
| terms MULT terms
| terms DIV terms"""
operator = ast_builder.operator(p[2])
# TODO: how can we do this with plain objects outside the array?
operand_a = p[1][0]
operand_b = p[3][0]
p[0] = [ast_builder.binary_operation(operator, operand_a, operand_b)]
def p_funcdef(self, p):
"""funcdef : TO NAME terms statements END
| TO NAME statements END"""
if len(p) == 5: # without params
parameters = []
body = p[3]
elif len(p) == 6: # with params
parameters = p[3]
body = p[4]
name = p[2]
self.functions.add(name)
p[0] = ast_builder.funcdef(name, parameters, body)
def p_repeat(self, p):
"""repeat : REPEAT terms LBRACKET statements RBRACKET"""
# TODO: how can we do this with plain objects outside the array?
times = p[2][0]
body = p[4]
p[0] = ast_builder.repeat(times, body)
def p_error(self, p):
if p:
print("Syntax error at: {0}".format(p))
else:
print("Syntax error at EOF")