better error message
This commit is contained in:
parent
56215cbac1
commit
00ed5e867d
@ -1,9 +1,21 @@
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import ast
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class CustomError(Exception):
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def __init__(self, msg):
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def __init__(self, msg, node = None):
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self.msg = msg
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if node is not None:
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self.at(node)
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def at(self, node):
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self.msg = f'Error at {node.lineno}:{node.col_offset+1}-' \
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f'{node.end_lineno}:{node.end_col_offset+1} ' \
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f'"{ast.unparse(node)}"\n{self.msg}'
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return self
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def stringify_subst(subst):
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if isinstance(subst, str):
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return subst
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elements = [f"{key}: {str(value)}" for key, value in subst.items()]
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return "{" + ', '.join(elements) + "}"
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@ -5,7 +5,7 @@ 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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# bool, int32 and float with associated operations
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# not handled now: named expression, type guard
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@ -42,7 +42,7 @@ def parse_expr(ctx: Context,
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return parse_if_expr(ctx, sym_table, body)
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if isinstance(body, ast.ListComp):
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return parse_list_comprehension(ctx, sym_table, body)
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raise CustomError(f'{body} is not yet supported')
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raise CustomError(f'{body} is not yet supported', body)
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def get_unary_op(op):
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@ -73,8 +73,10 @@ def parse_constant(ctx: Context,
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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}')
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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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@ -82,7 +84,7 @@ def parse_name(ctx: Context,
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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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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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@ -92,7 +94,7 @@ def parse_list(ctx: Context,
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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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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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@ -107,7 +109,7 @@ def parse_attribute(ctx: Context,
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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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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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@ -117,7 +119,7 @@ def parse_bool_ops(ctx: Context,
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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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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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@ -126,7 +128,10 @@ def parse_bin_ops(ctx: Context,
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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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@ -135,9 +140,12 @@ def parse_unary_ops(ctx: Context,
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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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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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@ -147,17 +155,21 @@ def parse_compare(ctx: Context,
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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')
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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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@ -166,32 +178,35 @@ def parse_call(ctx: Context,
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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}')
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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')
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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')
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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')
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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')
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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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@ -199,11 +214,11 @@ def parse_if_expr(ctx: Context,
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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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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}')
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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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@ -222,7 +237,7 @@ def parse_simple_binding(name, ty):
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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')
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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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@ -231,16 +246,20 @@ 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('list comprehension with more than 1 for loop is not supported')
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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')
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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 not isinstance(ty, ListType):
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raise CustomError(f'unable to iterate over {ty}')
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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')
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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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@ -26,7 +26,7 @@ def parse_stmts(ctx: Context,
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elif isinstance(node, ast.Break) or isinstance(node, ast.Continue):
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continue
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else:
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raise CustomError(f'{node} is not supported yet')
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raise CustomError(f'{node} is not supported yet', node)
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sym_table2 |= a
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used_sym_table2 |= b
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if returned:
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@ -40,24 +40,24 @@ def get_target_type(ctx: Context,
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if isinstance(target, ast.Subscript):
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t = get_target_type(ctx, sym_table, used_sym_table, target.value)
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if not isinstance(t, ListType):
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raise CustomError(f'cannot index through type {t}')
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raise CustomError(f'cannot index through type {t}', target)
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if isinstance(target.slice, ast.Slice):
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raise CustomError(f'assignment to slice is not supported')
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raise CustomError(f'assignment to slice is not supported', target)
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i = parse_expr(ctx, sym_table, target.slice)
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if i != ctx.types['int32']:
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raise CustomError(f'index must be int32')
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raise CustomError(f'index must be int32', target.slice)
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return t.params[0]
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elif isinstance(target, ast.Attribute):
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t = get_target_type(ctx, sym_table, used_sym_table, target.value)
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if target.attr not in t.fields:
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raise CustomError(f'{t} has no field {target.attr}')
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raise CustomError(f'{t} has no field {target.attr}', target)
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return t.fields[target.attr]
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elif isinstance(target, ast.Name):
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if target.id not in sym_table:
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raise CustomError(f'unbounded {target.id}')
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raise CustomError(f'unbounded {target.id}', target)
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return sym_table[target.id]
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else:
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raise CustomError(f'assignment to {target} is not supported')
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raise CustomError(f'assignment to {target} is not supported', target)
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def parse_stmt_binding(ctx: Context,
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sym_table: dict[str, Type],
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@ -67,15 +67,17 @@ def parse_stmt_binding(ctx: Context,
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if isinstance(target, ast.Name):
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if target.id in used_sym_table:
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if used_sym_table[target.id] != ty:
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raise CustomError('inconsistent type')
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raise CustomError(f'inconsistent type, {target.id} was ' \
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f'defined to be {used_sym_table[target.id]}, ' \
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f'but is now {ty}', target)
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if target.id == '_':
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return {}
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return {target.id: ty}
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elif isinstance(target, 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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raise CustomError(f'cannot pattern match over {ty}', target)
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if len(target.elts) != len(ty.params):
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raise CustomError(f'pattern matching length mismatch')
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raise CustomError(f'pattern matching length mismatch', target)
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result = {}
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for x, y in zip(target.elts, ty.params):
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new = parse_stmt_binding(ctx, sym_table, used_sym_table, x, y)
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@ -83,12 +85,12 @@ def parse_stmt_binding(ctx: Context,
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result |= new
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used_sym_table |= new
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if len(result) != old_len + len(new):
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raise CustomError(f'variable name clash')
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raise CustomError(f'variable name clash', target)
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return result
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else:
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t = get_target_type(ctx, sym_table, used_sym_table, target)
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if ty != t:
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raise CustomError(f'inconsistent type')
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raise CustomError(f'type mismatch', target)
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return {}
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def parse_assign(ctx: Context,
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@ -113,7 +115,7 @@ def parse_if_stmt(ctx: Context,
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node):
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test = parse_expr(ctx, sym_table, node.test)
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if test != ctx.types['bool']:
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raise CustomError(f'condition must be bool instead of {test}')
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raise CustomError(f'condition must be bool instead of {test}', node.test)
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a, b, r = parse_stmts(ctx, sym_table, used_sym_table, return_ty, node.body)
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used_sym_table |= b
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a1, b1, r1 = parse_stmts(ctx, sym_table, used_sym_table, return_ty, node.orelse)
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@ -127,12 +129,12 @@ def parse_for_stmt(ctx: Context,
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node):
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ty = parse_expr(ctx, sym_table, node.iter)
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if not isinstance(ty, ListType):
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raise CustomError('only iteration over list is supported')
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raise CustomError('only iteration over list is supported', node.iter)
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binding = parse_simple_binding(node.target, ty.params[0])
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for key, value in binding.items():
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if key in used_sym_table:
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if value != used_sym_table[key]:
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raise CustomError('inconsistent type')
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raise CustomError('inconsistent type', node)
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# more sophisticated return analysis is needed...
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a, b, _ = parse_stmts(ctx, sym_table | binding, used_sym_table | binding,
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return_ty, node.body)
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@ -148,7 +150,7 @@ def parse_while_stmt(ctx: Context,
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node):
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ty = parse_expr(ctx, sym_table, node.test)
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if ty != ctx.types['bool']:
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raise CustomError('condition must be bool')
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raise CustomError('condition must be bool', node.test)
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# more sophisticated return analysis is needed...
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a, b, _ = parse_stmts(ctx, sym_table, used_sym_table, return_ty, node.body)
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a1, b1, _ = parse_stmts(ctx, sym_table, used_sym_table | b,
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@ -163,10 +165,10 @@ def parse_return_stmt(ctx: Context,
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node):
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if return_ty is None:
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if node.value is not None:
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raise CustomError('no return value is allowed')
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raise CustomError('no return value is allowed', node)
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return {}, {}, True
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ty = parse_expr(ctx, sym_table, node.value)
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if ty != return_ty:
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raise CustomError(f'expected returning {return_ty} but got {ty}')
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raise CustomError(f'expected returning {return_ty} but got {ty}', node)
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return {}, {}, True
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