207 lines
7.0 KiB
Python
207 lines
7.0 KiB
Python
import ast
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from helper import *
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from type_def import *
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from inference import *
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# we assume having the following types:
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# bool, int32 with associated operations
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# not handled now: slice, comprehensions, named expression, if expression, type
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# guard
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def parse_expr(ctx: Context,
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sym_table: dict[str, Type],
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expr: ast.expr):
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if isinstance(expr, ast.Expression):
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body = expr.body
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else:
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body = expr
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if isinstance(body, ast.Constant):
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return parse_constant(ctx, sym_table, body)
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if isinstance(body, ast.UnaryOp):
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return parse_unary_op(ctx, sym_table, body)
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if isinstance(body, ast.BinOp):
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return parse_bin_ops(ctx, sym_table, body)
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if isinstance(body, ast.Name):
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return parse_name(ctx, sym_table, body)
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if isinstance(body, ast.List):
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return parse_list(ctx, sym_table, body)
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if isinstance(body, ast.Tuple):
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return parse_tuple(ctx, sym_table, body)
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if isinstance(body, ast.Attribute):
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return parse_attribute(ctx, sym_table, body)
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if isinstance(body, ast.BoolOp):
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return parse_bool_ops(ctx, sym_table, body)
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if isinstance(body, ast.Compare):
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return parse_compare(ctx, sym_table, body)
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if isinstance(body, ast.Call):
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return parse_call(ctx, sym_table, body)
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if isinstance(body, ast.Subscript):
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return parse_subscript(ctx, sym_table, body)
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if isinstance(body, ast.IfExp):
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return parse_if_expr(ctx, sym_table, body)
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raise CustomError(f'{body} is not yet supported')
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def get_unary_op(op):
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if isinstance(op, ast.UAdd):
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return '__pos__'
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if isinstance(op, ast.USub):
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return '__neg__'
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if isinstance(op, ast.Invert):
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return '__invert__'
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raise Exception(f'Unknown {expr}')
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def get_bin_ops(op):
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if isinstance(op, ast.Div):
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return '__truediv__'
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if isinstance(op, ast.BitAnd):
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return '__and__'
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if isinstance(op, ast.BitOr):
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return '__or__'
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if isinstance(op, ast.BitXor):
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return '__xor__'
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return f'__{type(op).__name__.lower()}__'
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def parse_constant(ctx: Context,
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sym_table: dict[str, Type],
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node):
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v = node.value
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if isinstance(v, bool):
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return ctx.types['bool']
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elif isinstance(v, int):
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return ctx.types['int32']
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else:
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raise CustomError(f'unknown constant {v}')
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def parse_name(ctx: Context,
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sym_table: dict[str, Type],
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node):
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if node.id in sym_table:
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return sym_table[node.id]
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else:
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raise CustomError(f'unbounded variable {node.id}')
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def parse_list(ctx: Context,
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sym_table: dict[str, Type],
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node):
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types = [parse_expr(ctx, sym_table, e) for e in node.elts]
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if len(types) == 0:
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return ListType(BotType())
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for t in types[1:]:
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if t != types[0]:
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raise CustomError(f'inhomogeneous list is not allowed')
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return ListType(types[0])
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def parse_tuple(ctx: Context,
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sym_table: dict[str, Type],
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node):
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types = [parse_expr(ctx, sym_table, e) for e in node.elts]
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return TupleType(types)
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def parse_attribute(ctx: Context,
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sym_table: dict[str, Type],
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node):
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obj = parse_expr(node.value)
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if node.attr in obj.fields:
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return obj.fields[node.attr]
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raise CustomError(f'unknown field {node.attr} in {obj}')
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def parse_bool_ops(ctx: Context,
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sym_table: dict[str, Type],
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node):
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assert len(node.values) == 2
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left = parse_expr(ctx, sym_table, node.values[0])
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right = parse_expr(ctx, sym_table, node.values[1])
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b = ctx.types['bool']
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if left != b or right != b:
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raise CustomError('operands of bool ops must be booleans')
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return b
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def parse_bin_ops(ctx: Context,
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sym_table: dict[str, Type],
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node):
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left = parse_expr(ctx, sym_table, node.left)
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right = parse_expr(ctx, sym_table, node.right)
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op = get_bin_ops(node.op)
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return resolve_call(left, op, [right], {}, ctx)
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def parse_unary_ops(ctx: Context,
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sym_table: dict[str, Type],
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node):
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t = parse_expr(node.operand)
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if isinstance(node.op, ast.Not):
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b = ctx.types['bool']
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if t != b:
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raise CustomError('operands of bool ops must be booleans')
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return b
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return resolve_call(t, get_unary_op(node.op), [], {}, ctx)
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def parse_compare(ctx: Context,
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sym_table: dict[str, Type],
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node):
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items = [parse_expr(ctx, sym_table, v) for v in node.comparators]
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items.insert(0, parse_expr(ctx, sym_table, node.left))
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boolean = ctx.types['bool']
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ops = [get_bin_ops(v) for v in node.ops]
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for a, b, op in zip(items[:-1], items[1:], ops):
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result = resolve_call(a, op, [b], {}, ctx)
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if result != boolean:
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raise CustomError(
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f'result of comparison must be bool instead of {result}')
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return boolean
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def parse_call(ctx: Context,
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sym_table: dict[str, Type],
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node):
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if len(node.keywords) > 0:
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raise CustomError('keyword arguments are not supported')
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args = [parse_expr(ctx, sym_table, v) for v in node.args]
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obj = None
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f = None
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if isinstance(node.func, ast.Attribute):
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obj = parse_expr(node.func.value)
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f = node.func.attr
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elif isinstance(node.func, ast.Name):
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f = node.func.id
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return resolve_call(obj, f, args, {}, ctx)
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def parse_subscript(ctx: Context,
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sym_table: dict[str, Type],
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node):
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value = parse_expr(ctx, sym_table, node.value)
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if not isinstance(value, ListType):
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raise CustomError(f'cannot take index of {value}')
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i32 = ctx.types['int32']
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if isinstance(node.slice, ast.Slice):
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if node.slice.lower is not None:
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if parse_expr(ctx, sym_table, node.slice.lower) != i32:
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raise CustomError(f'slice index must be int32')
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if node.slice.upper is not None:
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if parse_expr(ctx, sym_table, node.slice.upper) != i32:
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raise CustomError(f'slice index must be int32')
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if node.slice.step is not None:
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if parse_expr(ctx, sym_table, node.slice.step) != i32:
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raise CustomError(f'slice index must be int32')
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return value
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else:
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s = parse_expr(ctx, sym_table, node.slice)
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if s == i32:
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return value.params[0]
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else:
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raise CustomError(f'index of type {s} is not supported')
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def parse_if_expr(ctx: Context,
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sym_table: dict[str, Type],
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node):
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b = ctx.types['bool']
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t = parse_expr(ctx, sym_table, node.test)
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if t != b:
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raise CustomError(f'type of conditional must be bool instead of {t}')
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ty1 = parse_expr(ctx, sym_table, node.body)
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ty2 = parse_expr(ctx, sym_table, node.orelse)
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if ty1 != ty2:
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raise CustomError(f'divergent type for if expression: {ty1} != {ty2}')
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return ty1
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