api/src/main/java/jakarta/el/MapELResolver.java - third_party/jakartaee/expression-language - Git at Google

 /*
  * Copyright (c) 1997, 2022 Oracle and/or its affiliates and others.
  * All rights reserved.
  * Copyright 2004 The Apache Software 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.
  */

 package jakarta.el;

 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;

 /**
  * Defines property resolution behavior on instances of {@link java.util.Map}.
  *
  * <p>
  * This resolver handles base objects of type <code>java.util.Map</code>. It accepts any object as a property and uses
  * that object as a key in the map. The resulting value is the value in the map that is associated with that key.
  * </p>
  *
  * <p>
  * This resolver can be constructed in read-only mode, which means that {@link #isReadOnly} will always return
  * <code>true</code> and {@link #setValue} will always throw <code>PropertyNotWritableException</code>.
  * </p>
  *
  * <p>
  * <code>ELResolver</code>s are combined together using {@link CompositeELResolver}s, to define rich semantics for
  * evaluating an expression. See the javadocs for {@link ELResolver} for details.
  * </p>
  *
  * @see CompositeELResolver
  * @see ELResolver
  * @see java.util.Map
  * @since Jakarta Server Pages 2.1
  */
 public class MapELResolver extends ELResolver {

     static private Class<?> theUnmodifiableMapClass = Collections.unmodifiableMap(new HashMap<>()).getClass();
     private boolean isReadOnly;

     /**
      * Creates a new read/write <code>MapELResolver</code>.
      */
     public MapELResolver() {
         isReadOnly = false;
     }

     /**
      * Creates a new <code>MapELResolver</code> whose read-only status is determined by the given parameter.
      *
      * @param isReadOnly <code>true</code> if this resolver cannot modify maps; <code>false</code> otherwise.
      */
     public MapELResolver(boolean isReadOnly) {
         this.isReadOnly = isReadOnly;
     }

     /**
      * If the base object is a map, returns the most general acceptable type for a value in this map.
      *
      * <p>
      * If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
      * must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
      * this method is called, the caller should ignore the return value.
      * </p>
      *
      * <p>
      * Assuming the base is a <code>Map</code>, this method will always return <code>Object.class</code> unless the
      * resolver is constructed in read-only mode in which case {@code null} will be returned. This is because
      * <code>Map</code>s accept any object as the value for a given key.
      * </p>
      *
      * @param context The context of this evaluation.
      * @param base The map to analyze. Only bases of type <code>Map</code> are handled by this resolver.
      * @param property The key to return the acceptable type for. Ignored by this resolver.
      * @return If the <code>propertyResolved</code> property of <code>ELContext</code> was set to <code>true</code>, then
      * the most general acceptable type which must be {@code null} if the either the property or the resolver is
      * read-only; otherwise undefined
      * @throws NullPointerException if context is <code>null</code>
      * @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
      * exception must be included as the cause property of this exception, if available.
      */
     @Override
     public Class<?> getType(ELContext context, Object base, Object property) {
         if (context == null) {
             throw new NullPointerException();
         }

         if (base != null && base instanceof Map) {
             context.setPropertyResolved(true);

             Map<?, ?> map = (Map<?, ?>) base;
             if (isReadOnly || map.getClass() == theUnmodifiableMapClass) {
                 return null;
             }

             return Object.class;
         }

         return null;
     }

     /**
      * If the base object is a map, returns the value associated with the given key, as specified by the
      * <code>property</code> argument. If the key was not found, <code>null</code> is returned.
      *
      * <p>
      * If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
      * must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
      * this method is called, the caller should ignore the return value.
      * </p>
      *
      * <p>
      * Just as in {@link java.util.Map#get}, just because <code>null</code> is returned doesn't mean there is no mapping for
      * the key; it's also possible that the <code>Map</code> explicitly maps the key to <code>null</code>.
      * </p>
      *
      * @param context The context of this evaluation.
      * @param base The map to be analyzed. Only bases of type <code>Map</code> are handled by this resolver.
      * @param property The key whose associated value is to be returned.
      * @return If the <code>propertyResolved</code> property of <code>ELContext</code> was set to <code>true</code>, then
      * the value associated with the given key or <code>null</code> if the key was not found. Otherwise, undefined.
      * @throws ClassCastException if the key is of an inappropriate type for this map (optionally thrown by the underlying
      * <code>Map</code>).
      * @throws NullPointerException if context is <code>null</code>, or if the key is null and this map does not permit null
      * keys (the latter is optionally thrown by the underlying <code>Map</code>).
      * @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
      * exception must be included as the cause property of this exception, if available.
      */
     @Override
     public Object getValue(ELContext context, Object base, Object property) {
         if (context == null) {
             throw new NullPointerException();
         }

         if (base != null && base instanceof Map) {
             context.setPropertyResolved(base, property);
             Map<?, ?> map = (Map<?, ?>) base;
             return map.get(property);
         }

         return null;
     }

     /**
      * If the base object is a map, attempts to set the value associated with the given key, as specified by the
      * <code>property</code> argument.
      *
      * <p>
      * If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
      * must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
      * this method is called, the caller can safely assume no value was set.
      * </p>
      *
      * <p>
      * If this resolver was constructed in read-only mode, this method will always throw
      * <code>PropertyNotWritableException</code>.
      * </p>
      *
      * <p>
      * If a <code>Map</code> was created using {@link java.util.Collections#unmodifiableMap}, this method must throw
      * <code>PropertyNotWritableException</code>. Unfortunately, there is no Collections API method to detect this. However,
      * an implementation can create a prototype unmodifiable <code>Map</code> and query its runtime type to see if it
      * matches the runtime type of the base object as a workaround.
      * </p>
      *
      * @param context The context of this evaluation.
      * @param base The map to be modified. Only bases of type <code>Map</code> are handled by this resolver.
      * @param property The key with which the specified value is to be associated.
      * @param val The value to be associated with the specified key.
      * @throws ClassCastException if the class of the specified key or value prevents it from being stored in this map.
      * @throws NullPointerException if context is <code>null</code>, or if this map does not permit <code>null</code> keys
      * or values, and the specified key or value is <code>null</code>.
      * @throws IllegalArgumentException if some aspect of this key or value prevents it from being stored in this map.
      * @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
      * exception must be included as the cause property of this exception, if available.
      * @throws PropertyNotWritableException if this resolver was constructed in read-only mode, or if the put operation is
      * not supported by the underlying map.
      */
     @Override
     public void setValue(ELContext context, Object base, Object property, Object val) {
         if (context == null) {
             throw new NullPointerException();
         }

         if (base != null && base instanceof Map) {
             context.setPropertyResolved(base, property);

             // The cast is safe
             @SuppressWarnings("unchecked")
             Map<Object, Object> map = (Map<Object, Object>) base;
             if (isReadOnly || map.getClass() == theUnmodifiableMapClass) {
                 throw new PropertyNotWritableException();
             }

             try {
                 map.put(property, val);
             } catch (UnsupportedOperationException ex) {
                 throw new PropertyNotWritableException();
             }
         }
     }

     /**
      * If the base object is a map, returns whether a call to {@link #setValue} will always fail.
      *
      * <p>
      * If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
      * must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
      * this method is called, the caller should ignore the return value.
      * </p>
      *
      * <p>
      * If this resolver was constructed in read-only mode, this method will always return <code>true</code>.
      * </p>
      *
      * <p>
      * If a <code>Map</code> was created using {@link java.util.Collections#unmodifiableMap}, this method must return
      * <code>true</code>. Unfortunately, there is no Collections API method to detect this. However, an implementation can
      * create a prototype unmodifiable <code>Map</code> and query its runtime type to see if it matches the runtime type of
      * the base object as a workaround.
      * </p>
      *
      * @param context The context of this evaluation.
      * @param base The map to analyze. Only bases of type <code>Map</code> are handled by this resolver.
      * @param property The key to return the read-only status for. Ignored by this resolver.
      * @return If the <code>propertyResolved</code> property of <code>ELContext</code> was set to <code>true</code>, then
      * <code>true</code> if calling the <code>setValue</code> method will always fail or <code>false</code> if it is
      * possible that such a call may succeed; otherwise undefined.
      * @throws NullPointerException if context is <code>null</code>
      * @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
      * exception must be included as the cause property of this exception, if available.
      */
     @Override
     public boolean isReadOnly(ELContext context, Object base, Object property) {
         if (context == null) {
             throw new NullPointerException();
         }

         if (base != null && base instanceof Map) {
             context.setPropertyResolved(true);
             Map<?, ?> map = (Map<?, ?>) base;
             return isReadOnly || map.getClass() == theUnmodifiableMapClass;
         }

         return false;
     }

     /**
      * If the base object is a map, returns the most general type that this resolver accepts for the <code>property</code>
      * argument. Otherwise, returns <code>null</code>.
      *
      * <p>
      * Assuming the base is a <code>Map</code>, this method will always return <code>Object.class</code>. This is because
      * <code>Map</code>s accept any object as a key.
      * </p>
      *
      * @param context The context of this evaluation.
      * @param base The map to analyze. Only bases of type <code>Map</code> are handled by this resolver.
      * @return <code>null</code> if base is not a <code>Map</code>; otherwise <code>Object.class</code>.
      */
     @Override
     public Class<?> getCommonPropertyType(ELContext context, Object base) {
         if (base != null && base instanceof Map) {
             return Object.class;
         }

         return null;
     }

 }
	/*
	* Copyright (c) 1997, 2022 Oracle and/or its affiliates and others.
	* All rights reserved.
	* Copyright 2004 The Apache Software 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.
	*/

	package jakarta.el;

	import java.util.Collections;
	import java.util.HashMap;
	import java.util.Map;

	/**
	* Defines property resolution behavior on instances of {@link java.util.Map}.
	*
	* <p>
	* This resolver handles base objects of type <code>java.util.Map</code>. It accepts any object as a property and uses
	* that object as a key in the map. The resulting value is the value in the map that is associated with that key.
	* </p>
	*
	* <p>
	* This resolver can be constructed in read-only mode, which means that {@link #isReadOnly} will always return
	* <code>true</code> and {@link #setValue} will always throw <code>PropertyNotWritableException</code>.
	* </p>
	*
	* <p>
	* <code>ELResolver</code>s are combined together using {@link CompositeELResolver}s, to define rich semantics for
	* evaluating an expression. See the javadocs for {@link ELResolver} for details.
	* </p>
	*
	* @see CompositeELResolver
	* @see ELResolver
	* @see java.util.Map
	* @since Jakarta Server Pages 2.1
	*/
	public class MapELResolver extends ELResolver {

	static private Class<?> theUnmodifiableMapClass = Collections.unmodifiableMap(new HashMap<>()).getClass();
	private boolean isReadOnly;

	/**
	* Creates a new read/write <code>MapELResolver</code>.
	*/
	public MapELResolver() {
	isReadOnly = false;
	}

	/**
	* Creates a new <code>MapELResolver</code> whose read-only status is determined by the given parameter.
	*
	* @param isReadOnly <code>true</code> if this resolver cannot modify maps; <code>false</code> otherwise.
	*/
	public MapELResolver(boolean isReadOnly) {
	this.isReadOnly = isReadOnly;
	}

	/**
	* If the base object is a map, returns the most general acceptable type for a value in this map.
	*
	* <p>
	* If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
	* must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
	* this method is called, the caller should ignore the return value.
	* </p>
	*
	* <p>
	* Assuming the base is a <code>Map</code>, this method will always return <code>Object.class</code> unless the
	* resolver is constructed in read-only mode in which case {@code null} will be returned. This is because
	* <code>Map</code>s accept any object as the value for a given key.
	* </p>
	*
	* @param context The context of this evaluation.
	* @param base The map to analyze. Only bases of type <code>Map</code> are handled by this resolver.
	* @param property The key to return the acceptable type for. Ignored by this resolver.
	* @return If the <code>propertyResolved</code> property of <code>ELContext</code> was set to <code>true</code>, then
	* the most general acceptable type which must be {@code null} if the either the property or the resolver is
	* read-only; otherwise undefined
	* @throws NullPointerException if context is <code>null</code>
	* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
	* exception must be included as the cause property of this exception, if available.
	*/
	@Override
	public Class<?> getType(ELContext context, Object base, Object property) {
	if (context == null) {
	throw new NullPointerException();
	}

	if (base != null && base instanceof Map) {
	context.setPropertyResolved(true);

	Map<?, ?> map = (Map<?, ?>) base;
	if (isReadOnly \|\| map.getClass() == theUnmodifiableMapClass) {
	return null;
	}

	return Object.class;
	}

	return null;
	}

	/**
	* If the base object is a map, returns the value associated with the given key, as specified by the
	* <code>property</code> argument. If the key was not found, <code>null</code> is returned.
	*
	* <p>
	* If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
	* must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
	* this method is called, the caller should ignore the return value.
	* </p>
	*
	* <p>
	* Just as in {@link java.util.Map#get}, just because <code>null</code> is returned doesn't mean there is no mapping for
	* the key; it's also possible that the <code>Map</code> explicitly maps the key to <code>null</code>.
	* </p>
	*
	* @param context The context of this evaluation.
	* @param base The map to be analyzed. Only bases of type <code>Map</code> are handled by this resolver.
	* @param property The key whose associated value is to be returned.
	* @return If the <code>propertyResolved</code> property of <code>ELContext</code> was set to <code>true</code>, then
	* the value associated with the given key or <code>null</code> if the key was not found. Otherwise, undefined.
	* @throws ClassCastException if the key is of an inappropriate type for this map (optionally thrown by the underlying
	* <code>Map</code>).
	* @throws NullPointerException if context is <code>null</code>, or if the key is null and this map does not permit null
	* keys (the latter is optionally thrown by the underlying <code>Map</code>).
	* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
	* exception must be included as the cause property of this exception, if available.
	*/
	@Override
	public Object getValue(ELContext context, Object base, Object property) {
	if (context == null) {
	throw new NullPointerException();
	}

	if (base != null && base instanceof Map) {
	context.setPropertyResolved(base, property);
	Map<?, ?> map = (Map<?, ?>) base;
	return map.get(property);
	}

	return null;
	}

	/**
	* If the base object is a map, attempts to set the value associated with the given key, as specified by the
	* <code>property</code> argument.
	*
	* <p>
	* If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
	* must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
	* this method is called, the caller can safely assume no value was set.
	* </p>
	*
	* <p>
	* If this resolver was constructed in read-only mode, this method will always throw
	* <code>PropertyNotWritableException</code>.
	* </p>
	*
	* <p>
	* If a <code>Map</code> was created using {@link java.util.Collections#unmodifiableMap}, this method must throw
	* <code>PropertyNotWritableException</code>. Unfortunately, there is no Collections API method to detect this. However,
	* an implementation can create a prototype unmodifiable <code>Map</code> and query its runtime type to see if it
	* matches the runtime type of the base object as a workaround.
	* </p>
	*
	* @param context The context of this evaluation.
	* @param base The map to be modified. Only bases of type <code>Map</code> are handled by this resolver.
	* @param property The key with which the specified value is to be associated.
	* @param val The value to be associated with the specified key.
	* @throws ClassCastException if the class of the specified key or value prevents it from being stored in this map.
	* @throws NullPointerException if context is <code>null</code>, or if this map does not permit <code>null</code> keys
	* or values, and the specified key or value is <code>null</code>.
	* @throws IllegalArgumentException if some aspect of this key or value prevents it from being stored in this map.
	* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
	* exception must be included as the cause property of this exception, if available.
	* @throws PropertyNotWritableException if this resolver was constructed in read-only mode, or if the put operation is
	* not supported by the underlying map.
	*/
	@Override
	public void setValue(ELContext context, Object base, Object property, Object val) {
	if (context == null) {
	throw new NullPointerException();
	}

	if (base != null && base instanceof Map) {
	context.setPropertyResolved(base, property);

	// The cast is safe
	@SuppressWarnings("unchecked")
	Map<Object, Object> map = (Map<Object, Object>) base;
	if (isReadOnly \|\| map.getClass() == theUnmodifiableMapClass) {
	throw new PropertyNotWritableException();
	}

	try {
	map.put(property, val);
	} catch (UnsupportedOperationException ex) {
	throw new PropertyNotWritableException();
	}
	}
	}

	/**
	* If the base object is a map, returns whether a call to {@link #setValue} will always fail.
	*
	* <p>
	* If the base is a <code>Map</code>, the <code>propertyResolved</code> property of the <code>ELContext</code> object
	* must be set to <code>true</code> by this resolver, before returning. If this property is not <code>true</code> after
	* this method is called, the caller should ignore the return value.
	* </p>
	*
	* <p>
	* If this resolver was constructed in read-only mode, this method will always return <code>true</code>.
	* </p>
	*
	* <p>
	* If a <code>Map</code> was created using {@link java.util.Collections#unmodifiableMap}, this method must return
	* <code>true</code>. Unfortunately, there is no Collections API method to detect this. However, an implementation can
	* create a prototype unmodifiable <code>Map</code> and query its runtime type to see if it matches the runtime type of
	* the base object as a workaround.
	* </p>
	*
	* @param context The context of this evaluation.
	* @param base The map to analyze. Only bases of type <code>Map</code> are handled by this resolver.
	* @param property The key to return the read-only status for. Ignored by this resolver.
	* @return If the <code>propertyResolved</code> property of <code>ELContext</code> was set to <code>true</code>, then
	* <code>true</code> if calling the <code>setValue</code> method will always fail or <code>false</code> if it is
	* possible that such a call may succeed; otherwise undefined.
	* @throws NullPointerException if context is <code>null</code>
	* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
	* exception must be included as the cause property of this exception, if available.
	*/
	@Override
	public boolean isReadOnly(ELContext context, Object base, Object property) {
	if (context == null) {
	throw new NullPointerException();
	}

	if (base != null && base instanceof Map) {
	context.setPropertyResolved(true);
	Map<?, ?> map = (Map<?, ?>) base;
	return isReadOnly \|\| map.getClass() == theUnmodifiableMapClass;
	}

	return false;
	}

	/**
	* If the base object is a map, returns the most general type that this resolver accepts for the <code>property</code>
	* argument. Otherwise, returns <code>null</code>.
	*
	* <p>
	* Assuming the base is a <code>Map</code>, this method will always return <code>Object.class</code>. This is because
	* <code>Map</code>s accept any object as a key.
	* </p>
	*
	* @param context The context of this evaluation.
	* @param base The map to analyze. Only bases of type <code>Map</code> are handled by this resolver.
	* @return <code>null</code> if base is not a <code>Map</code>; otherwise <code>Object.class</code>.
	*/
	@Override
	public Class<?> getCommonPropertyType(ELContext context, Object base) {
	if (base != null && base instanceof Map) {
	return Object.class;
	}

	return null;
	}

	}