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Copy pathevaluation.py
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156 lines (132 loc) · 5.55 KB
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# Copyright 2008-2015 Nokia Networks
# Copyright 2016- Robot Framework Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import builtins
import token
from collections.abc import MutableMapping
from io import StringIO
from tokenize import generate_tokens, untokenize
from robot.errors import DataError
from robot.utils import get_error_message, type_name
from .search import search_variable
from .notfound import variable_not_found
PYTHON_BUILTINS = set(builtins.__dict__)
def evaluate_expression(expression, variables, modules=None, namespace=None,
resolve_variables=False):
original = expression
try:
if not isinstance(expression, str):
raise TypeError(f'Expression must be string, got {type_name(expression)}.')
if resolve_variables:
expression = variables.replace_scalar(expression)
if not isinstance(expression, str):
return expression
if not expression:
raise ValueError('Expression cannot be empty.')
return _evaluate(expression, variables.store, modules, namespace)
except DataError as err:
error = str(err)
recommendation = ''
except Exception:
error = get_error_message()
recommendation = _recommend_special_variables(original)
raise DataError(f"Evaluating expression '{expression}' failed: {error}\n\n"
f"{recommendation}".strip())
def _evaluate(expression, variable_store, modules=None, namespace=None):
if '$' in expression:
expression = _decorate_variables(expression, variable_store)
# Given namespace must be included in our custom local namespace to make
# it possible to detect which names are not found and should be imported
# automatically as modules. It must be also be used as the global namespace
# with `eval()` because lambdas and possibly other special constructs don't
# see the local namespace at all.
namespace = dict(namespace or ())
if modules:
namespace.update(_import_modules(modules))
local_ns = EvaluationNamespace(variable_store, namespace)
return eval(expression, namespace, local_ns)
def _decorate_variables(expression, variable_store):
variable_started = False
variable_found = False
tokens = []
for toknum, tokval, _, _, _ in generate_tokens(StringIO(expression).readline):
if variable_started:
if toknum == token.NAME:
if tokval not in variable_store:
variable_not_found('$%s' % tokval,
variable_store.as_dict(decoration=False),
deco_braces=False)
tokval = 'RF_VAR_' + tokval
variable_found = True
else:
tokens.append((token.ERRORTOKEN, '$'))
variable_started = False
if toknum == token.ERRORTOKEN and tokval == '$':
variable_started = True
else:
tokens.append((toknum, tokval))
return untokenize(tokens).strip() if variable_found else expression
def _import_modules(module_names):
modules = {}
for name in module_names.replace(' ', '').split(','):
if not name:
continue
modules[name] = __import__(name)
# If we just import module 'root.sub', module 'root' is not found.
while '.' in name:
name, _ = name.rsplit('.', 1)
modules[name] = __import__(name)
return modules
def _recommend_special_variables(expression):
example = []
remaining = expression
while True:
match = search_variable(remaining)
if not match:
break
example[-1:] = [match.before, match.identifier, match.base, match.after]
remaining = example[-1]
if not example:
return ''
example = ''.join(example)
return (f"Variables in the original expression '{expression}' were resolved "
f"before the expression was evaluated. Try using '{example}' "
f"syntax to avoid that. See Evaluating Expressions appendix in "
f"Robot Framework User Guide for more details.")
class EvaluationNamespace(MutableMapping):
def __init__(self, variable_store, namespace):
self.namespace = namespace
self.variables = variable_store
def __getitem__(self, key):
if key.startswith('RF_VAR_'):
return self.variables[key[7:]]
if key in self.namespace:
return self.namespace[key]
return self._import_module(key)
def __setitem__(self, key, value):
self.namespace[key] = value
def __delitem__(self, key):
self.namespace.pop(key)
def _import_module(self, name):
if name in PYTHON_BUILTINS:
raise KeyError
try:
return __import__(name)
except ImportError:
raise NameError(f"name '{name}' is not defined nor importable as module")
def __iter__(self):
yield from self.variables
yield from self.namespace
def __len__(self):
return len(self.variables) + len(self.namespace)