src/main/java/org/apache/commons/jexl3/parser/JexlNode.java - commons-jexl - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You 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.apache.commons.jexl3.parser;

 import org.apache.commons.jexl3.JexlInfo;
 import org.apache.commons.jexl3.introspection.JexlMethod;
 import org.apache.commons.jexl3.introspection.JexlPropertyGet;
 import org.apache.commons.jexl3.introspection.JexlPropertySet;

 /**
  * Base class for parser nodes - holds an 'image' of the token for later use.
  *
  * @since 2.0
  */
 public abstract class JexlNode extends SimpleNode {
     // line + column encoded: up to 4096 columns (ie 20 bits for line + 12 bits for column)
     private int lc = -1;

     /**
      * A marker interface for constants.
      * @param <T> the literal type
      */
     public interface Constant<T> {
         T getLiteral();
     }

     public JexlNode(final int id) {
         super(id);
     }

     public JexlNode(final Parser p, final int id) {
         super(p, id);
     }

     public void jjtSetFirstToken(final Token t) {
         // 0xc = 12, 12 bits -> 4096
         // 0xfff, 12 bits mask
         this.lc = (t.beginLine << 0xc) | (0xfff & t.beginColumn);
     }

     public void jjtSetLastToken(final Token t) {
         // nothing
     }

     public int getLine() {
         return this.lc >>> 0xc;
     }

     public int getColumn() {
         return this.lc & 0xfff;
     }

     /**
      * Gets the associated JexlInfo instance.
      *
      * @return the info
      */
     public JexlInfo jexlInfo() {
         JexlInfo info = null;
         JexlNode node = this;
         while (node != null) {
             if (node.jjtGetValue() instanceof JexlInfo) {
                 info = (JexlInfo) node.jjtGetValue();
                 break;
             }
             node = node.jjtGetParent();
         }
         if (lc >= 0) {
             final int c = lc & 0xfff;
             final int l = lc >> 0xc;
             // at least an info with line/column number
             return info != null? info.at(l, c) : new JexlInfo(null, l, c);
         } else {
             // weird though; no jjSetFirstToken(...) ever called?
             return info;
         }
     }

     /**
      * Marker interface for cachable function calls.
      */
     public interface Funcall {}

     /**
      * Clears any cached value of type JexlProperty{G,S}et or JexlMethod.
      * <p>
      * This is called when the engine detects the evaluation of a script occurs with a class loader
      * different that the one that created it.</p>
      */
     public void clearCache() {
         final Object value = jjtGetValue();
         if (value instanceof JexlPropertyGet
             || value instanceof JexlPropertySet
             || value instanceof JexlMethod
             || value instanceof Funcall ) {
             jjtSetValue(null);
         }
         for (int n = 0; n < jjtGetNumChildren(); ++n) {
             jjtGetChild(n).clearCache();
         }
     }

     /**
      * Whether this node is a constant node Its value can not change after the first evaluation and can be cached
      * indefinitely.
      *
      * @return true if constant, false otherwise
      */
     public boolean isConstant() {
         return isConstant(this instanceof JexlNode.Constant<?>);
     }

     protected boolean isConstant(final boolean literal) {
         if (literal) {
             for (int n = 0; n < jjtGetNumChildren(); ++n) {
                 final JexlNode child = jjtGetChild(n);
                 if (child instanceof ASTReference) {
                     final boolean is = child.isConstant(true);
                     if (!is) {
                         return false;
                     }
                 } else if (child instanceof ASTMapEntry) {
                     final boolean is = child.isConstant(true);
                     if (!is) {
                         return false;
                     }
                 } else if (!child.isConstant()) {
                     return false;
                 }
             }
             return true;
         }
         return false;
     }

     /**
      * Whether this node is a left value.
      * @return true if node is assignable, false otherwise
      */
     public boolean isLeftValue() {
         JexlNode walk = this;
         do {
             if (walk instanceof ASTIdentifier
                 || walk instanceof ASTIdentifierAccess
                 || walk instanceof ASTArrayAccess) {
                 return true;
             }
             final int nc = walk.jjtGetNumChildren() - 1;
             if (nc >= 0) {
                 walk = walk.jjtGetChild(nc);
             } else {
                 return walk.jjtGetParent() instanceof ASTReference;
             }
         } while (walk != null);
         return false;
     }

     /**
      * @return true if this node looks like a global var
      */
     public boolean isGlobalVar() {
         if (this instanceof ASTVar) {
             return false;
         }
         if (this instanceof ASTIdentifier) {
             return ((ASTIdentifier) this).getSymbol() < 0;
         }
         final int nc = this.jjtGetNumChildren() - 1;
         if (nc >= 0) {
             final JexlNode first = this.jjtGetChild(0);
             return first.isGlobalVar();
         }
         if (jjtGetParent() instanceof ASTReference) {
             return true;
         }
         return false;
     }

     /**
      * Whether this node is a local variable.
      * @return true if local, false otherwise
      */
     public boolean isLocalVar() {
         return this instanceof ASTIdentifier && ((ASTIdentifier) this).getSymbol() >= 0;
     }

     /**
      * Whether this node is the left-hand side of a safe access identifier as in.
      * For instance, in 'x?.y' , 'x' is safe.
      * @param safe whether the engine is in safe-navigation mode
      * @return true if safe lhs, false otherwise
      */
     public boolean isSafeLhs(final boolean safe) {
         if (this instanceof ASTReference) {
             return jjtGetChild(0).isSafeLhs(safe);
         }
         if (this instanceof ASTMethodNode) {
             if (this.jjtGetNumChildren() > 1
                     && this.jjtGetChild(0) instanceof ASTIdentifierAccess
                     && (((ASTIdentifierAccess) this.jjtGetChild(0)).isSafe() || safe)) {
                 return true;
             }
         }
         final JexlNode parent = this.jjtGetParent();
         if (parent == null) {
             return false;
         }
         // find this node in its parent
         final int nsiblings = parent.jjtGetNumChildren();
         int rhs = -1;
         for(int s = 0; s < nsiblings; ++s) {
             final JexlNode sibling = parent.jjtGetChild(s);
             if (sibling == this) {
                 // the next chid offset of this nodes parent
                 rhs = s + 1;
                 break;
             }
         }
         // seek next child in parent
         if (rhs >= 0 && rhs < nsiblings) {
             JexlNode rsibling = parent.jjtGetChild(rhs);
             if (rsibling instanceof ASTMethodNode || rsibling instanceof ASTFunctionNode) {
                 rsibling = rsibling.jjtGetChild(0);
             }
             if (rsibling instanceof ASTIdentifierAccess
                 && (((ASTIdentifierAccess) rsibling).isSafe() || safe)) {
                 return true;
             }
             if (rsibling instanceof ASTArrayAccess) {
                 return safe;
             }
         }
         return false;
     }

     /**
      * Check if a null evaluated expression is protected by a ternary expression.
      * <p>
      * The rationale is that the ternary / elvis expressions are meant for the user to explictly take control
      * over the error generation; ie, ternaries can return null even if the engine in strict mode
      * would normally throw an exception.
      * </p>
      * @return true if nullable variable, false otherwise
      */
     public boolean isTernaryProtected() {
         JexlNode node = this;
         for (JexlNode walk = node.jjtGetParent(); walk != null; walk = walk.jjtGetParent()) {
             // protect only the condition part of the ternary
             if (walk instanceof ASTTernaryNode
                 || walk instanceof ASTNullpNode
                 || walk instanceof ASTEQNode
                 || walk instanceof ASTNENode) {
                 return node == walk.jjtGetChild(0);
             }
             if (!(walk instanceof ASTReference || walk instanceof ASTArrayAccess)) {
                 break;
             }
             node = walk;
         }
         return false;
     }

     /**
      * An info bound to its node.
      * <p>Used to parse expressions for templates.
      */
     public static class Info extends JexlInfo {
         JexlNode node = null;

         /**
          * Default ctor.
          * @param jnode the node
          */
         public Info(final JexlNode jnode) {
             this(jnode, jnode.jexlInfo());
         }

         /**
          * Copy ctor.
          * @param jnode the node
          * @param info the
          */
         public Info(final JexlNode jnode, final JexlInfo info) {
             this(jnode, info.getName(), info.getLine(), info.getColumn());
         }

         /**
          * Full detail ctor.
          * @param jnode the node
          * @param name the file name
          * @param l the line
          * @param c the column
          */
         private Info(final JexlNode jnode, final String name, final int l, final int c) {
             super(name, l, c);
             node = jnode;
         }

         /**
          * @return the node this info is bound to
          */
         public JexlNode getNode() {
             return node;
         }

         @Override
         public JexlInfo at(final int l, final int c) {
             return new Info(node, getName(), l, c);
         }

         @Override
         public JexlInfo detach() {
             node = null;
             return this;
         }
     }

 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You 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.apache.commons.jexl3.parser;

	import org.apache.commons.jexl3.JexlInfo;
	import org.apache.commons.jexl3.introspection.JexlMethod;
	import org.apache.commons.jexl3.introspection.JexlPropertyGet;
	import org.apache.commons.jexl3.introspection.JexlPropertySet;

	/**
	* Base class for parser nodes - holds an 'image' of the token for later use.
	*
	* @since 2.0
	*/
	public abstract class JexlNode extends SimpleNode {
	// line + column encoded: up to 4096 columns (ie 20 bits for line + 12 bits for column)
	private int lc = -1;

	/**
	* A marker interface for constants.
	* @param <T> the literal type
	*/
	public interface Constant<T> {
	T getLiteral();
	}

	public JexlNode(final int id) {
	super(id);
	}

	public JexlNode(final Parser p, final int id) {
	super(p, id);
	}

	public void jjtSetFirstToken(final Token t) {
	// 0xc = 12, 12 bits -> 4096
	// 0xfff, 12 bits mask
	this.lc = (t.beginLine << 0xc) \| (0xfff & t.beginColumn);
	}

	public void jjtSetLastToken(final Token t) {
	// nothing
	}

	public int getLine() {
	return this.lc >>> 0xc;
	}

	public int getColumn() {
	return this.lc & 0xfff;
	}

	/**
	* Gets the associated JexlInfo instance.
	*
	* @return the info
	*/
	public JexlInfo jexlInfo() {
	JexlInfo info = null;
	JexlNode node = this;
	while (node != null) {
	if (node.jjtGetValue() instanceof JexlInfo) {
	info = (JexlInfo) node.jjtGetValue();
	break;
	}
	node = node.jjtGetParent();
	}
	if (lc >= 0) {
	final int c = lc & 0xfff;
	final int l = lc >> 0xc;
	// at least an info with line/column number
	return info != null? info.at(l, c) : new JexlInfo(null, l, c);
	} else {
	// weird though; no jjSetFirstToken(...) ever called?
	return info;
	}
	}

	/**
	* Marker interface for cachable function calls.
	*/
	public interface Funcall {}

	/**
	* Clears any cached value of type JexlProperty{G,S}et or JexlMethod.
	* <p>
	* This is called when the engine detects the evaluation of a script occurs with a class loader
	* different that the one that created it.</p>
	*/
	public void clearCache() {
	final Object value = jjtGetValue();
	if (value instanceof JexlPropertyGet
	\|\| value instanceof JexlPropertySet
	\|\| value instanceof JexlMethod
	\|\| value instanceof Funcall ) {
	jjtSetValue(null);
	}
	for (int n = 0; n < jjtGetNumChildren(); ++n) {
	jjtGetChild(n).clearCache();
	}
	}

	/**
	* Whether this node is a constant node Its value can not change after the first evaluation and can be cached
	* indefinitely.
	*
	* @return true if constant, false otherwise
	*/
	public boolean isConstant() {
	return isConstant(this instanceof JexlNode.Constant<?>);
	}

	protected boolean isConstant(final boolean literal) {
	if (literal) {
	for (int n = 0; n < jjtGetNumChildren(); ++n) {
	final JexlNode child = jjtGetChild(n);
	if (child instanceof ASTReference) {
	final boolean is = child.isConstant(true);
	if (!is) {
	return false;
	}
	} else if (child instanceof ASTMapEntry) {
	final boolean is = child.isConstant(true);
	if (!is) {
	return false;
	}
	} else if (!child.isConstant()) {
	return false;
	}
	}
	return true;
	}
	return false;
	}

	/**
	* Whether this node is a left value.
	* @return true if node is assignable, false otherwise
	*/
	public boolean isLeftValue() {
	JexlNode walk = this;
	do {
	if (walk instanceof ASTIdentifier
	\|\| walk instanceof ASTIdentifierAccess
	\|\| walk instanceof ASTArrayAccess) {
	return true;
	}
	final int nc = walk.jjtGetNumChildren() - 1;
	if (nc >= 0) {
	walk = walk.jjtGetChild(nc);
	} else {
	return walk.jjtGetParent() instanceof ASTReference;
	}
	} while (walk != null);
	return false;
	}

	/**
	* @return true if this node looks like a global var
	*/
	public boolean isGlobalVar() {
	if (this instanceof ASTVar) {
	return false;
	}
	if (this instanceof ASTIdentifier) {
	return ((ASTIdentifier) this).getSymbol() < 0;
	}
	final int nc = this.jjtGetNumChildren() - 1;
	if (nc >= 0) {
	final JexlNode first = this.jjtGetChild(0);
	return first.isGlobalVar();
	}
	if (jjtGetParent() instanceof ASTReference) {
	return true;
	}
	return false;
	}

	/**
	* Whether this node is a local variable.
	* @return true if local, false otherwise
	*/
	public boolean isLocalVar() {
	return this instanceof ASTIdentifier && ((ASTIdentifier) this).getSymbol() >= 0;
	}

	/**
	* Whether this node is the left-hand side of a safe access identifier as in.
	* For instance, in 'x?.y' , 'x' is safe.
	* @param safe whether the engine is in safe-navigation mode
	* @return true if safe lhs, false otherwise
	*/
	public boolean isSafeLhs(final boolean safe) {
	if (this instanceof ASTReference) {
	return jjtGetChild(0).isSafeLhs(safe);
	}
	if (this instanceof ASTMethodNode) {
	if (this.jjtGetNumChildren() > 1
	&& this.jjtGetChild(0) instanceof ASTIdentifierAccess
	&& (((ASTIdentifierAccess) this.jjtGetChild(0)).isSafe() \|\| safe)) {
	return true;
	}
	}
	final JexlNode parent = this.jjtGetParent();
	if (parent == null) {
	return false;
	}
	// find this node in its parent
	final int nsiblings = parent.jjtGetNumChildren();
	int rhs = -1;
	for(int s = 0; s < nsiblings; ++s) {
	final JexlNode sibling = parent.jjtGetChild(s);
	if (sibling == this) {
	// the next chid offset of this nodes parent
	rhs = s + 1;
	break;
	}
	}
	// seek next child in parent
	if (rhs >= 0 && rhs < nsiblings) {
	JexlNode rsibling = parent.jjtGetChild(rhs);
	if (rsibling instanceof ASTMethodNode \|\| rsibling instanceof ASTFunctionNode) {
	rsibling = rsibling.jjtGetChild(0);
	}
	if (rsibling instanceof ASTIdentifierAccess
	&& (((ASTIdentifierAccess) rsibling).isSafe() \|\| safe)) {
	return true;
	}
	if (rsibling instanceof ASTArrayAccess) {
	return safe;
	}
	}
	return false;
	}

	/**
	* Check if a null evaluated expression is protected by a ternary expression.
	* <p>
	* The rationale is that the ternary / elvis expressions are meant for the user to explictly take control
	* over the error generation; ie, ternaries can return null even if the engine in strict mode
	* would normally throw an exception.
	* </p>
	* @return true if nullable variable, false otherwise
	*/
	public boolean isTernaryProtected() {
	JexlNode node = this;
	for (JexlNode walk = node.jjtGetParent(); walk != null; walk = walk.jjtGetParent()) {
	// protect only the condition part of the ternary
	if (walk instanceof ASTTernaryNode
	\|\| walk instanceof ASTNullpNode
	\|\| walk instanceof ASTEQNode
	\|\| walk instanceof ASTNENode) {
	return node == walk.jjtGetChild(0);
	}
	if (!(walk instanceof ASTReference \|\| walk instanceof ASTArrayAccess)) {
	break;
	}
	node = walk;
	}
	return false;
	}

	/**
	* An info bound to its node.
	* <p>Used to parse expressions for templates.
	*/
	public static class Info extends JexlInfo {
	JexlNode node = null;

	/**
	* Default ctor.
	* @param jnode the node
	*/
	public Info(final JexlNode jnode) {
	this(jnode, jnode.jexlInfo());
	}

	/**
	* Copy ctor.
	* @param jnode the node
	* @param info the
	*/
	public Info(final JexlNode jnode, final JexlInfo info) {
	this(jnode, info.getName(), info.getLine(), info.getColumn());
	}

	/**
	* Full detail ctor.
	* @param jnode the node
	* @param name the file name
	* @param l the line
	* @param c the column
	*/
	private Info(final JexlNode jnode, final String name, final int l, final int c) {
	super(name, l, c);
	node = jnode;
	}

	/**
	* @return the node this info is bound to
	*/
	public JexlNode getNode() {
	return node;
	}

	@Override
	public JexlInfo at(final int l, final int c) {
	return new Info(node, getName(), l, c);
	}

	@Override
	public JexlInfo detach() {
	node = null;
	return this;
	}
	}

	}