226 lines
9.6 KiB
Python
226 lines
9.6 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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from top_level import parse_type
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from parse_expr import parse_expr, parse_simple_binding
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def parse_stmts(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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return_ty: Type,
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nodes):
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sym_table2 = copy.copy(sym_table)
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used_sym_table2 = copy.copy(used_sym_table)
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for node in nodes:
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if isinstance(node, ast.Assign):
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a, b, returned = parse_assign(ctx, sym_table2, used_sym_table2, return_ty, node)
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elif isinstance(node, ast.If):
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a, b, returned = parse_if_stmt(ctx, sym_table2, used_sym_table2, return_ty, node)
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elif isinstance(node, ast.While):
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a, b, returned = parse_while_stmt(ctx, sym_table2, used_sym_table2, return_ty, node)
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elif isinstance(node, ast.For):
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a, b, returned = parse_for_stmt(ctx, sym_table2, used_sym_table2, return_ty, node)
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elif isinstance(node, ast.Return):
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a, b, returned = parse_return_stmt(ctx, sym_table2, used_sym_table2, return_ty, node)
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elif isinstance(node, ast.Expr):
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parse_expr(ctx, sym_table2, node.value)
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continue
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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', 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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return sym_table2, used_sym_table2, True
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return sym_table2, used_sym_table2, False
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def get_target_type(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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target):
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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}', target)
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if isinstance(target.slice, ast.Slice):
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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', target.slice)
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target.type = t.params[0]
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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}', target)
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target.type = t.fields[target.attr]
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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}', target)
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target.type = sym_table[target.id]
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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', target)
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def parse_stmt_binding(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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target,
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ty):
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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(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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target.type = ty
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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}', target)
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if len(target.elts) != len(ty.params):
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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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old_len = len(result)
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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', 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'type mismatch', target)
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return {}
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def parse_assign(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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return_ty: Type,
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node):
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# permitted assignment targets:
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# variables, class fields, list elements
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# function evaluation is only allowed within list index
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# may relax later after when we settle on lifetime handling
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ty = parse_expr(ctx, sym_table, node.value)
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results = {}
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for target in node.targets:
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results |= parse_stmt_binding(ctx, sym_table, used_sym_table, target, ty)
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return results, results, False
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def parse_if_stmt(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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return_ty: Type,
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node):
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if isinstance(node.test, ast.Compare) and \
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isinstance(node.test.left, ast.Call) and \
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isinstance(node.test.left.func, ast.Name) and \
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node.test.left.func.id == 'type' and \
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len(node.test.left.args) == 1 and \
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len(node.test.ops) == 1 and \
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(isinstance(node.test.ops[0], ast.Eq) or\
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isinstance(node.test.ops[0], ast.NotEq)):
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t = parse_expr(ctx, sym_table, node.test.left.args[0])
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if not isinstance(t, TypeVariable):
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raise CustomError(
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'type guard only support type variables',
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node.test)
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t1, _ = parse_type(ctx, node.test.comparators[0])
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if len(t.constraints) > 0 and t1 not in t.constraints:
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raise CustomError(
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f'{t1} is not a possible instance of {t}',
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node.test)
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t2 = [v for v in t.constraints if v != t1]
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try:
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t.constraints = [t1]
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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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t.constraints = t2
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a1, b1, r1 = parse_stmts(ctx, sym_table, used_sym_table, return_ty, node.orelse)
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defined = {k: a[k] for k in a if k in a1}
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return defined, b | b1, r and r1
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finally:
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t.constraints = t
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else:
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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}', 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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defined = {k: a[k] for k in a if k in a1}
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return defined, b | b1, r and r1
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def parse_for_stmt(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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return_ty: Type,
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node):
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ty = parse_expr(ctx, sym_table, node.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('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', 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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a1, b1, _ = parse_stmts(ctx, sym_table, used_sym_table | b,
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return_ty, node.orelse)
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defined = {k: a[k] for k in a if k in a1}
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return defined, b | b1, False
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def parse_while_stmt(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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return_ty: Type,
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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', 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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return_ty, node.orelse)
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defined = {k: a[k] for k in a if k in a1}
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return defined, b | b1, False
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def parse_return_stmt(ctx: Context,
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sym_table: dict[str, Type],
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used_sym_table: dict[str, Type],
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return_ty: Type,
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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', node)
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return {}, {}, True
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ty = parse_expr(ctx, sym_table, node.value)
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if isinstance(node.value, ast.Name) and \
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node.value.id == 'self' and \
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'self' in sym_table and \
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isinstance(return_ty, SelfType):
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return {}, {}, True
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if ty != return_ty:
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if isinstance(return_ty, TypeVariable):
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if len(return_ty.constraints) == 1 and \
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return_ty.constraints[0] == ty:
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return {}, {}, True
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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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