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/*
 * Copyright 2000-2012 JetBrains s.r.o.
 *
 * 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 org.intellij.lang.annotations;

import java.lang.annotation.*;

/**
 * 

This annotation intended to help IDEA to detect and auto-complete int and String constants used as an enumeration. * For example, in the {@link java.awt.Label#Label(String, int)} constructor the alignment parameter can be one of the following * int constants: {@link java.awt.Label#LEFT}, {@link java.awt.Label#CENTER} or {@link java.awt.Label#RIGHT} * *

So, if @MagicConstant annotation applied to this constructor, IDEA will check the constructor usages for the allowed values. *

E.g.
*

{@code
 * new Label("text", 0); // 0 is not allowed
 * new Label("text", Label.LEFT); // OK
 * }
* *

* @MagicConstant can be applied to: *

    *
  • Field, local variable, parameter. * *
    E.g.
    *
    {@code @MagicConstant(intValues = {TOP, CENTER, BOTTOM})
     * int textPosition;
     * }
    * IDEA will check expressions assigned to the variable for allowed values: *
    {@code
     *  textPosition = 0; // not allowed
     *  textPosition = TOP; // OK
     * }
    * *
  • Method * *
    E.g.
    *
    {@code @MagicConstant(flagsFromClass = java.lang.reflect.Modifier.class)
     *  public native int getModifiers();
     * }
    * * IDEA will analyse getModifiers() method calls and check if its return value is used with allowed values:
    *
    {@code
     *  if (aClass.getModifiers() == 3) // not allowed
     *  if (aClass.getModifiers() == Modifier.PUBLIC) // OK
     * }
    * *
  • Annotation class
    * Annotation class annotated with @MagicConstant created alias you can use to annotate * everything as if it was annotated with @MagicConstant itself. * *
    E.g.
    *
    {@code @MagicConstant(flags = {Font.PLAIN, Font.BOLD, Font.ITALIC}) }
    *
    {@code @interface FontStyle {} }
    * * IDEA will check constructs annotated with @FontStyle for allowed values:
    * @FontStyle int myStyle = 3; // not allowed
    * @FontStyle int myStyle = Font.BOLD | Font.ITALIC; // OK
    * * *
* * The @MagicConstant annotation has SOURCE retention, i.e. it is removed upon compilation and does not create any runtime overhead. */ @Retention(RetentionPolicy.SOURCE) @Target({ ElementType.FIELD, ElementType.PARAMETER, ElementType.LOCAL_VARIABLE, ElementType.ANNOTATION_TYPE, ElementType.METHOD }) public @interface MagicConstant { /** * @return int values (typically named constants) which are allowed here. * E.g. * * void setConfirmOpenNewProject(@MagicConstant(intValues = {OPEN_PROJECT_ASK, OPEN_PROJECT_NEW_WINDOW, OPEN_PROJECT_SAME_WINDOW}) * int confirmOpenNewProject); * */ long[] intValues() default {}; /** * @return String values (typically named constants) which are allowed here. */ String[] stringValues() default {}; /** * @return allowed int flags (i.e. values (typically named constants) which can be combined with bitwise or operator (|). * Also 0 and -1 are considered allowed. * E.g. * * @MagicConstant(flags = {HierarchyEvent.PARENT_CHANGED,HierarchyEvent.DISPLAYABILITY_CHANGED,HierarchyEvent.SHOWING_CHANGED}) * int hFlags; * * hFlags = 3; // not allowed * if (hFlags & (HierarchyEvent.PARENT_CHANGED | HierarchyEvent.SHOWING_CHANGED) != 0); // OK * */ long[] flags() default {}; /** * @return allowed values which are defined in the specified class public static final constants. * * E.g. * * @MagicConstant(valuesFromClass = Cursor.class) * int cursorType; * * cursorType = 11; // not allowed; * cursorType = Cursor.E_RESIZE_CURSOR; // OK * */ Class valuesFromClass() default void.class; /** * @return allowed int flags which are defined in the specified class public static final constants. * * E.g. * @MagicConstant(flagsFromClass = java.awt.InputEvent.class) * int eventMask; * * eventMask = 10; // not allowed; * eventMask = InputEvent.CTRL_MASK | InputEvent.ALT_MASK; // OK * */ Class flagsFromClass() default void.class; }




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