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Make 'and' and 'or' short-circuit (ref. #233, closes #766)

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This commit is contained in:
Ryan Gonzalez 2015-02-18 15:40:07 -06:00
parent d95bfbaa8e
commit 95cef09c6a
2 changed files with 70 additions and 8 deletions
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66
hy/compiler.py
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@ -1672,14 +1672,68 @@ class HyASTCompiler(object):
@checkargs(min=2)
def compile_logical_or_and_and_operator(self, expression):
ops = {"and": ast.And,
"or": ast.Or}
"or" : ast.Or}
operator = expression.pop(0)
values, ret, _ = self._compile_collect(expression)
ret = Result()
values = list(map(self.compile, expression))
has_stmt = any(value.stmts for value in values)
root_line, root_column = operator.start_line, operator.start_column
if has_stmt:
# Compile it to an if...else sequence
var = self.get_anon_var()
name = ast.Name(id=var,
ctx=ast.Store(),
lineno=root_line,
col_offset=root_column)
expr_name = ast.Name(id=var,
ctx=ast.Load(),
lineno=root_line,
col_offset=root_column)
ret += ast.BoolOp(op=ops[operator](),
lineno=operator.start_line,
col_offset=operator.start_column,
values=values)
def make_assign(value, node=None):
if node is None:
line, column = root_line, root_column
else:
line, column = node.lineno, node.col_offset
return ast.Assign(targets=[ast.Name(id=var,
ctx=ast.Store(),
lineno=line,
col_offset=column)],
value=value,
lineno=line,
col_offset=column)
root = []
current = root
for i, value in enumerate(values):
if value.stmts:
node = value.stmts[0]
current.extend(value.stmts)
else:
node = value.expr
current.append(make_assign(value.force_expr, value.force_expr))
if i == len(values)-1:
# Skip a redundant 'if'.
break
if operator == "and":
cond = expr_name
elif operator == "or":
cond = ast.UnaryOp(op=ast.Not(),
operand=expr_name,
lineno=node.lineno,
col_offset=node.col_offset)
current.append(ast.If(test=cond,
body=[],
lineno=node.lineno,
col_offset=node.col_offset,
orelse=[]))
current = current[-1].body
ret = sum(root, ret)
ret += Result(expr=expr_name, temp_variables=[expr_name, name])
else:
ret += ast.BoolOp(op=ops[operator](),
lineno=root_line,
col_offset=root_column,
values=[value.force_expr for value in values])
return ret
@builds("=")

12
tests/native_tests/language.hy
View File

@ -767,7 +767,11 @@
(let [[and123 (and 1 2 3)]
[and-false (and 1 False 3)]]
(assert (= and123 3))
(assert (= and-false False))))
(assert (= and-false False)))
; short circuiting
(setv a 1)
(and 0 (setv a 2))
(assert (= a 1)))
(defn test-or []
@ -777,7 +781,11 @@
[or-none-true (or False False)]]
(assert (= or-all-true 1))
(assert (= or-some-true "hello"))
(assert (= or-none-true False))))
(assert (= or-none-true False)))
; short circuiting
(setv a 1)
(or 1 (setv a 2))
(assert (= a 1)))
(defn test-if-return-branching []