285 lines
10 KiB
Python
285 lines
10 KiB
Python
import ast
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import copy
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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 and float with associated operations
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# not handled now: named expression, type 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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result = parse_constant(ctx, sym_table, body)
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elif isinstance(body, ast.UnaryOp):
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result = parse_unary_ops(ctx, sym_table, body)
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elif isinstance(body, ast.BinOp):
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result = parse_bin_ops(ctx, sym_table, body)
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elif isinstance(body, ast.Name):
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result = parse_name(ctx, sym_table, body)
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elif isinstance(body, ast.List):
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result = parse_list(ctx, sym_table, body)
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elif isinstance(body, ast.Tuple):
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result = parse_tuple(ctx, sym_table, body)
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elif isinstance(body, ast.Attribute):
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result = parse_attribute(ctx, sym_table, body)
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elif isinstance(body, ast.BoolOp):
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result = parse_bool_ops(ctx, sym_table, body)
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elif isinstance(body, ast.Compare):
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result = parse_compare(ctx, sym_table, body)
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elif isinstance(body, ast.Call):
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result = parse_call(ctx, sym_table, body)
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elif isinstance(body, ast.Subscript):
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result = parse_subscript(ctx, sym_table, body)
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elif isinstance(body, ast.IfExp):
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result = parse_if_expr(ctx, sym_table, body)
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elif isinstance(body, ast.ListComp):
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result = parse_list_comprehension(ctx, sym_table, body)
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else:
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raise CustomError(f'{body} is not yet supported', body)
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body.type = result
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return result
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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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elif isinstance(v, float):
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return ctx.types['float']
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else:
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raise CustomError(f'unknown constant {v}', node)
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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}', node)
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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', node)
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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(ctx, sym_table, node.value)
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if isinstance(obj, TypeVariable) and len(obj.constraints) > 0:
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if node.attr not in obj.constraints[0].fields:
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raise CustomError(f'unknown field {node.attr} in {obj}', node)
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ty = obj.constraints[0].fields[node.attr]
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for v in obj.constraints[1:]:
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if node.attr not in v.fields:
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raise CustomError(f'unknown field {node.attr} in {obj}', node)
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if v.fields[node.attr] != ty:
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raise CustomError(
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f'unknown field {node.attr} in {obj} (type mismatch)', node)
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return ty
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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}', node)
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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', node)
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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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try:
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return resolve_call(left, op, [right], {}, ctx)
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except CustomError as e:
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raise e.at(node)
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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(ctx, sym_table, 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', node)
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return b
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try:
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return resolve_call(t, get_unary_op(node.op), [], {}, ctx)
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except CustomError as e:
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raise e.at(node)
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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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try:
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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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except CustomError as e:
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raise e.at(node)
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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', node)
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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(ctx, sym_table, 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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try:
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return resolve_call(obj, f, args, {}, ctx)
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except CustomError as e:
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raise e.at(node)
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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}', node)
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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', node.slice.lower)
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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', node.slice.upper)
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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', node.slice.step)
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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', node)
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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}', node)
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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}', node)
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return ty1
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def parse_simple_binding(name, ty):
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if isinstance(name, ast.Name):
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if name.id == '_':
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return {}
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name.type = ty
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return {name.id: ty}
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elif isinstance(name, ast.Tuple):
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if not isinstance(ty, TupleType):
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raise CustomError(f'cannot pattern match over {ty}')
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if len(name.elts) != len(ty.params):
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raise CustomError(f'pattern matching length mismatch')
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result = {}
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for x, y in zip(name.elts, ty.params):
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binding = parse_simple_binding(x, y)
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expected = len(result) + len(binding)
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result |= parse_simple_binding(x, y)
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if len(result) != expected:
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raise CustomError('variable name clash', x)
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return result
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else:
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raise CustomError(f'binding to {name} is not supported')
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def parse_list_comprehension(ctx: Context,
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sym_table: dict[str, Type],
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node):
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if len(node.generators) != 1:
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raise CustomError(
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'list comprehension with more than 1 for loop is not supported', node)
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if node.generators[0].is_async:
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raise CustomError('async list comprehension is not supported', node)
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ty = parse_expr(ctx, sym_table, node.generators[0].iter)
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if isinstance(ty, TypeVariable) and \
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len(ty.constraints) == 1:
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ty = ty.constraints[0]
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if not isinstance(ty, ListType):
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raise CustomError(f'unable to iterate over {ty}', node)
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try:
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sym_table2 = sym_table | parse_simple_binding(node.generators[0].target, ty.params[0])
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except CustomError as e:
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raise e.at(node)
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b = ctx.types['bool']
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for c in node.generators[0].ifs:
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if parse_expr(ctx, sym_table2, c) != b:
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raise CustomError(f'condition should be of boolean type', c)
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return ListType(parse_expr(ctx, sym_table2, node.elt))
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