| // Copyright 2018 The Bazel Authors. All rights reserved. |
| // |
| // 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. |
| |
| package net.starlark.java.eval; |
| |
| /** {@link GuardedValue} that controls access based on an experimental or incompatible flag. */ |
| public final class FlagGuardedValue { |
| /** |
| * Creates a flag guard which only permits access of the given object when the given boolean flag |
| * is true. If the given flag is false and the object would be accessed, an error is thrown |
| * describing the feature as experimental, and describing that the flag must be set to true. |
| * |
| * <p>The flag identifier must have a + or - prefix; see StarlarkSemantics. |
| */ |
| public static GuardedValue onlyWhenExperimentalFlagIsTrue(String flag, Object obj) { |
| if (flag.charAt(0) != '-' && flag.charAt(0) != '+') { |
| throw new IllegalArgumentException(String.format("flag needs [+-] prefix: %s", flag)); |
| } |
| return new GuardedValue() { |
| @Override |
| public Object getObject() { |
| return obj; |
| } |
| |
| @Override |
| public String getErrorFromAttemptingAccess(String name) { |
| return name |
| + " is experimental and thus unavailable with the current flags. It may be enabled by" |
| + " setting --" |
| + flag.substring(1); |
| } |
| |
| @Override |
| public boolean isObjectAccessibleUsingSemantics( |
| StarlarkSemantics semantics, Object clientData) { |
| return semantics.isFeatureEnabledBasedOnTogglingFlags(flag, ""); |
| } |
| }; |
| } |
| |
| /** |
| * Creates a flag guard which only permits access of the given object when the given boolean flag |
| * is false. If the given flag is true and the object would be accessed, an error is thrown |
| * describing the feature as deprecated, and describing that the flag must be set to false. |
| * |
| * <p>The flag identifier must have a + or - prefix; see StarlarkSemantics. |
| */ |
| public static GuardedValue onlyWhenIncompatibleFlagIsFalse(String flag, Object obj) { |
| if (flag.charAt(0) != '-' && flag.charAt(0) != '+') { |
| throw new IllegalArgumentException(String.format("flag needs [+-] prefix: %s", flag)); |
| } |
| return new GuardedValue() { |
| @Override |
| public Object getObject() { |
| return obj; |
| } |
| |
| @Override |
| public String getErrorFromAttemptingAccess(String name) { |
| return name |
| + " is deprecated and will be removed soon. It may be temporarily re-enabled by" |
| + " setting --" |
| + flag.substring(1) |
| + "=false"; |
| } |
| |
| @Override |
| public boolean isObjectAccessibleUsingSemantics( |
| StarlarkSemantics semantics, Object clientData) { |
| return semantics.isFeatureEnabledBasedOnTogglingFlags("", flag); |
| } |
| }; |
| } |
| |
| private FlagGuardedValue() {} |
| } |