basic statements and if statement

This commit is contained in:
pca006132 2020-12-21 16:58:40 +08:00 committed by pca006132
parent 594fbf1061
commit eb2ddfc617
2 changed files with 209 additions and 0 deletions

111
toy-impl/parse_stmt.py Normal file
View File

@ -0,0 +1,111 @@
import ast
import copy
from helper import *
from type_def import *
from inference import *
from parse_expr import parse_expr
def parse_stmts(ctx: Context,
sym_table: dict[str, Type],
used_sym_table: dict[str, Type],
nodes):
sym_table2 = copy.copy(sym_table)
used_sym_table2 = copy.copy(used_sym_table)
for node in nodes:
if isinstance(node, ast.Assign):
a, b, returned = parse_assign(ctx, sym_table2, used_sym_table2, node)
elif isinstance(node, ast.If):
a, b, returned = parse_if_stmt(ctx, sym_table2, used_sym_table2, node)
else:
raise CustomError(f'{node} is not supported yet')
sym_table2 |= a
used_sym_table2 |= b
if returned:
return sym_table2, used_sym_table2, True
return sym_table2, used_sym_table2, False
def get_target_type(ctx: Context,
sym_table: dict[str, Type],
used_sym_table: dict[str, Type],
target):
if isinstance(target, ast.Subscript):
t = get_target_type(ctx, sym_table, used_sym_table, target.value)
if not isinstance(t, ListType):
raise CustomError(f'cannot index through type {t}')
if isinstance(target.slice, ast.Slice):
raise CustomError(f'assignment to slice is not supported')
i = parse_expr(ctx, sym_table, target.slice)
if i != ctx.types['int32']:
raise CustomError(f'index must be int32')
return t.params[0]
elif isinstance(target, ast.Attribute):
t = get_target_type(ctx, sym_table, used_sym_table, target.value)
if target.attr not in t.fields:
raise CustomError(f'{t} has no field {target.attr}')
return t.fields[target.attr]
elif isinstance(target, ast.Name):
if target.id not in sym_table:
raise CustomError(f'unbounded {target.id}')
return sym_table[target.id]
else:
raise CustomError(f'assignment to {target} is not supported')
def parse_binding(ctx: Context,
sym_table: dict[str, Type],
used_sym_table: dict[str, Type],
target,
ty):
if isinstance(target, ast.Name):
if target.id in used_sym_table:
if used_sym_table[target.id] != ty:
raise CustomError('inconsistent type')
if target.id == '_':
return {}
return {target.id: ty}
elif isinstance(target, ast.Tuple):
if not isinstance(ty, TupleType):
raise CustomError(f'cannot pattern match over {ty}')
if len(target.elts) != len(ty.params):
raise CustomError(f'pattern matching length mismatch')
result = {}
for x, y in zip(target.elts, ty.params):
new = parse_binding(ctx, sym_table, used_sym_table, x, y)
old_len = len(result)
result |= new
used_sym_table |= new
if len(result) != old_len + len(new):
raise CustomError(f'variable name clash')
return result
else:
t = get_target_type(ctx, sym_table, used_sym_table, target)
if ty != t:
raise CustomError(f'inconsistent type')
return {}
def parse_assign(ctx: Context,
sym_table: dict[str, Type],
used_sym_table: dict[str, Type],
node):
# permitted assignment targets:
# variables, class fields, list elements
# function evaluation is only allowed within list index
# may relax later after when we settle on lifetime handling
ty = parse_expr(ctx, sym_table, node.value)
results = {}
for target in node.targets:
results |= parse_binding(ctx, sym_table, used_sym_table, target, ty)
return results, results, False
def parse_if_stmt(ctx: Context,
sym_table: dict[str, Type],
used_sym_table: dict[str, Type],
node):
test = parse_expr(ctx, sym_table, node.test)
if test != ctx.types['bool']:
raise CustomError(f'condition must be bool instead of {test}')
a, b, r = parse_stmts(ctx, sym_table, used_sym_table, node.body)
used_sym_table |= b
a1, b1, r1 = parse_stmts(ctx, sym_table, used_sym_table, node.orelse)
defined = {k: a[k] for k in a if k in a1}
return defined, b | b1, r and r1

98
toy-impl/test_stmt.py Normal file
View File

@ -0,0 +1,98 @@
import ast
from type_def import *
from inference import *
from helper import *
from parse_stmt import *
types = {
'int32': PrimitiveType('int32'),
'int64': PrimitiveType('int64'),
'str': PrimitiveType('str'),
'bool': PrimitiveType('bool')
}
i32 = types['int32']
i64 = types['int64']
s = types['str']
b = types['bool']
variables = {
'X': TypeVariable('X', []),
'Y': TypeVariable('Y', []),
'I': TypeVariable('I', [i32, i64]),
'A': TypeVariable('A', [i32, i64, s]),
}
X = variables['X']
Y = variables['Y']
I = variables['I']
A = variables['A']
i32.methods['__init__'] = ([SelfType(), I], None, set())
i32.methods['__add__'] = ([SelfType(), i32], i32, set())
i32.methods['__sub__'] = ([SelfType(), i32], i32, set())
i32.methods['__lt__'] = ([SelfType(), i32], b, set())
i32.methods['__gt__'] = ([SelfType(), i32], b, set())
i32.methods['__eq__'] = ([SelfType(), i32], b, set())
i32.methods['__ne__'] = ([SelfType(), i32], b, set())
i32.methods['__le__'] = ([SelfType(), i32], b, set())
i32.methods['__ge__'] = ([SelfType(), i32], b, set())
i64.methods['__init__'] = ([SelfType(), I], None, set())
i64.methods['__add__'] = ([SelfType(), i64], i64, set())
i64.methods['__sub__'] = ([SelfType(), i64], i64, set())
i64.methods['__lt__'] = ([SelfType(), i64], b, set())
i64.methods['__gt__'] = ([SelfType(), i64], b, set())
i64.methods['__eq__'] = ([SelfType(), i64], b, set())
i64.methods['__ne__'] = ([SelfType(), i64], b, set())
i64.methods['__le__'] = ([SelfType(), i64], b, set())
i64.methods['__ge__'] = ([SelfType(), i64], b, set())
ctx = Context(variables, types)
def test_stmt(stmt, sym_table = {}):
print(f'Testing {stmt} w.r.t. {stringify_subst(sym_table)}')
try:
tree = ast.parse(stmt)
a, b, _ = parse_stmts(ctx, sym_table, sym_table, tree.body)
print(stringify_subst(a))
except CustomError as err:
print(f'error: {err.msg}')
test_stmt('a, b = 1, 2', {})
test_stmt('a, b = 1, [1, 2, 3]', {})
test_stmt('a, b[c] = 1, 2', {'b': ListType(i32), 'c': i32})
test_stmt('a, b[c] = 1, [1, 2]', {'b': ListType(i32), 'c': i32})
test_stmt('b = [1, 2, 3]\nc = 1\na, b[c] = 1, 2\na = 2')
test_stmt("""
if True:
a = 1
else:
a = 2
b = 1
c = a
""")
test_stmt("""
if True:
a = 1
else:
a = 2
b = 1
c = a
d = b
""")
test_stmt("""
if True:
a = 1
else:
a = 2
b = 1
c = a
b = [1, 2, 3]
""")