# Copyright 2018 The Cirq Developers
#
# 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
#
# https://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 json
import re
from cirq.value.value_equality import value_equality
_identifier_pattern = '[a-zA-Z_][a-zA-Z0-9_]*$'
def _is_valid_identifier(text):
return re.match(_identifier_pattern, text)
def _encode(text):
return json.JSONEncoder().encode(text)
[docs]@value_equality
class Symbol:
"""A constant plus the runtime value of a parameter with a given key.
Attributes:
name: The non-empty name of a parameter to lookup at runtime and add
to the constant offset.
"""
[docs] def __init__(self, name: str) -> None:
"""Initializes a Symbol with the given name.
Args:
name: The name of a parameter.
"""
self.name = name
def __str__(self):
return (self.name
if _is_valid_identifier(self.name)
else 'Symbol({})'.format(_encode(self.name)))
def __repr__(self):
return 'cirq.Symbol({!r})'.format(self.name)
def _value_equality_values_(self):
return self.name
def __mul__(self, other):
return self if other == 1 else NotImplemented
def __rmul__(self, other):
return self if other == 1 else NotImplemented
def __add__(self, other):
return self if other == 0 else NotImplemented
def __radd__(self, other):
return self if other == 0 else NotImplemented