Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2013 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.jdt.core.dom; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * Infix expression AST node type. * <pre> * InfixExpression: * Expression InfixOperator Expression { InfixOperator Expression } * </pre> * * @since 2.0 * @noinstantiate This class is not intended to be instantiated by clients. */ @SuppressWarnings({ "rawtypes", "unchecked" }) public class InfixExpression extends Expression { /** * Infix operators (typesafe enumeration). * <pre> * InfixOperator:<code> * <b>*</b> TIMES * <b>/</b> DIVIDE * <b>%</b> REMAINDER * <b>+</b> PLUS * <b>-</b> MINUS * <b><<</b> LEFT_SHIFT * <b>>></b> RIGHT_SHIFT_SIGNED * <b>>>></b> RIGHT_SHIFT_UNSIGNED * <b><</b> LESS * <b>></b> GREATER * <b><=</b> LESS_EQUALS * <b>>=</b> GREATER_EQUALS * <b>==</b> EQUALS * <b>!=</b> NOT_EQUALS * <b>^</b> XOR * <b>&</b> AND * <b>|</b> OR * <b>&&</b> CONDITIONAL_AND * <b>||</b> CONDITIONAL_OR</code> * </pre> */ public static class Operator { /** * The token for the operator. */ private String token; /** * Creates a new infix operator with the given token. * <p> * Note: this constructor is private. The only instances * ever created are the ones for the standard operators. * </p> * * @param token the character sequence for the operator */ private Operator(String token) { this.token = token; } /** * Returns the character sequence for the operator. * * @return the character sequence for the operator */ @Override public String toString() { return this.token; } /** Multiplication "*" operator. */ public static final Operator TIMES = new Operator("*");//$NON-NLS-1$ /** Division "/" operator. */ public static final Operator DIVIDE = new Operator("/");//$NON-NLS-1$ /** Remainder "%" operator. */ public static final Operator REMAINDER = new Operator("%");//$NON-NLS-1$ /** Addition (or string concatenation) "+" operator. */ public static final Operator PLUS = new Operator("+");//$NON-NLS-1$ /** Subtraction "-" operator. */ public static final Operator MINUS = new Operator("-");//$NON-NLS-1$ /** Left shift "<<" operator. */ public static final Operator LEFT_SHIFT = new Operator("<<");//$NON-NLS-1$ /** Signed right shift ">>" operator. */ public static final Operator RIGHT_SHIFT_SIGNED = new Operator(">>");//$NON-NLS-1$ /** Unsigned right shift ">>>" operator. */ public static final Operator RIGHT_SHIFT_UNSIGNED = new Operator(">>>");//$NON-NLS-1$ /** Less than "<" operator. */ public static final Operator LESS = new Operator("<");//$NON-NLS-1$ /** Greater than ">" operator. */ public static final Operator GREATER = new Operator(">");//$NON-NLS-1$ /** Less than or equals "<=" operator. */ public static final Operator LESS_EQUALS = new Operator("<=");//$NON-NLS-1$ /** Greater than or equals ">=;" operator. */ public static final Operator GREATER_EQUALS = new Operator(">=");//$NON-NLS-1$ /** Equals "==" operator. */ public static final Operator EQUALS = new Operator("==");//$NON-NLS-1$ /** Not equals "!=" operator. */ public static final Operator NOT_EQUALS = new Operator("!=");//$NON-NLS-1$ /** Exclusive OR "^" operator. */ public static final Operator XOR = new Operator("^");//$NON-NLS-1$ /** Inclusive OR "|" operator. */ public static final Operator OR = new Operator("|");//$NON-NLS-1$ /** AND "&" operator. */ public static final Operator AND = new Operator("&");//$NON-NLS-1$ /** Conditional OR "||" operator. */ public static final Operator CONDITIONAL_OR = new Operator("||");//$NON-NLS-1$ /** Conditional AND "&&" operator. */ public static final Operator CONDITIONAL_AND = new Operator("&&");//$NON-NLS-1$ /** * Map from token to operator (key type: <code>String</code>; * value type: <code>Operator</code>). */ private static final Map CODES; static { CODES = new HashMap(20); Operator[] ops = { TIMES, DIVIDE, REMAINDER, PLUS, MINUS, LEFT_SHIFT, RIGHT_SHIFT_SIGNED, RIGHT_SHIFT_UNSIGNED, LESS, GREATER, LESS_EQUALS, GREATER_EQUALS, EQUALS, NOT_EQUALS, XOR, OR, AND, CONDITIONAL_OR, CONDITIONAL_AND, }; for (int i = 0; i < ops.length; i++) { CODES.put(ops[i].toString(), ops[i]); } } /** * Returns the infix operator corresponding to the given string, * or <code>null</code> if none. * <p> * <code>toOperator</code> is the converse of <code>toString</code>: * that is, <code>Operator.toOperator(op.toString()) == op</code> for * all operators <code>op</code>. * </p> * * @param token the character sequence for the operator * @return the infix operator, or <code>null</code> if none */ public static Operator toOperator(String token) { return (Operator) CODES.get(token); } } /** * The "leftOperand" structural property of this node type (child type: {@link Expression}). * @since 3.0 */ public static final ChildPropertyDescriptor LEFT_OPERAND_PROPERTY = new ChildPropertyDescriptor( InfixExpression.class, "leftOperand", Expression.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$ /** * The "operator" structural property of this node type (type: {@link InfixExpression.Operator}). * @since 3.0 */ public static final SimplePropertyDescriptor OPERATOR_PROPERTY = new SimplePropertyDescriptor( InfixExpression.class, "operator", InfixExpression.Operator.class, MANDATORY); //$NON-NLS-1$ /** * The "rightOperand" structural property of this node type (child type: {@link Expression}). * @since 3.0 */ public static final ChildPropertyDescriptor RIGHT_OPERAND_PROPERTY = new ChildPropertyDescriptor( InfixExpression.class, "rightOperand", Expression.class, MANDATORY, CYCLE_RISK); //$NON-NLS-1$ /** * The "extendedOperands" structural property of this node type (element type: {@link Expression}). * @since 3.0 */ public static final ChildListPropertyDescriptor EXTENDED_OPERANDS_PROPERTY = new ChildListPropertyDescriptor( InfixExpression.class, "extendedOperands", Expression.class, CYCLE_RISK); //$NON-NLS-1$ /** * A list of property descriptors (element type: * {@link StructuralPropertyDescriptor}), * or null if uninitialized. */ private static final List PROPERTY_DESCRIPTORS; static { List properyList = new ArrayList(5); createPropertyList(InfixExpression.class, properyList); addProperty(LEFT_OPERAND_PROPERTY, properyList); addProperty(OPERATOR_PROPERTY, properyList); addProperty(RIGHT_OPERAND_PROPERTY, properyList); addProperty(EXTENDED_OPERANDS_PROPERTY, properyList); PROPERTY_DESCRIPTORS = reapPropertyList(properyList); } /** * Returns a list of structural property descriptors for this node type. * Clients must not modify the result. * * @param apiLevel the API level; one of the * <code>AST.JLS*</code> constants * @return a list of property descriptors (element type: * {@link StructuralPropertyDescriptor}) * @since 3.0 */ public static List propertyDescriptors(int apiLevel) { return PROPERTY_DESCRIPTORS; } /** * The infix operator; defaults to InfixExpression.Operator.PLUS. */ private InfixExpression.Operator operator = InfixExpression.Operator.PLUS; /** * The left operand; lazily initialized; defaults to an unspecified, * but legal, simple name. */ private Expression leftOperand = null; /** * The right operand; lazily initialized; defaults to an unspecified, * but legal, simple name. */ private Expression rightOperand = null; /** * The list of extended operand expressions (element type: * {@link Expression}). Lazily initialized; defaults to an empty list. */ private ASTNode.NodeList extendedOperands = null; /** * Creates a new AST node for an infix expression owned by the given * AST. By default, the node has unspecified (but legal) operator, * left and right operands, and an empty list of additional operands. * * @param ast the AST that is to own this node */ InfixExpression(AST ast) { super(ast); } @Override final List internalStructuralPropertiesForType(int apiLevel) { return propertyDescriptors(apiLevel); } @Override final Object internalGetSetObjectProperty(SimplePropertyDescriptor property, boolean get, Object value) { if (property == OPERATOR_PROPERTY) { if (get) { return getOperator(); } else { setOperator((Operator) value); return null; } } // allow default implementation to flag the error return super.internalGetSetObjectProperty(property, get, value); } @Override final ASTNode internalGetSetChildProperty(ChildPropertyDescriptor property, boolean get, ASTNode child) { if (property == LEFT_OPERAND_PROPERTY) { if (get) { return getLeftOperand(); } else { setLeftOperand((Expression) child); return null; } } if (property == RIGHT_OPERAND_PROPERTY) { if (get) { return getRightOperand(); } else { setRightOperand((Expression) child); return null; } } // allow default implementation to flag the error return super.internalGetSetChildProperty(property, get, child); } @Override final List internalGetChildListProperty(ChildListPropertyDescriptor property) { if (property == EXTENDED_OPERANDS_PROPERTY) { return extendedOperands(); } // allow default implementation to flag the error return super.internalGetChildListProperty(property); } @Override final int getNodeType0() { return INFIX_EXPRESSION; } @Override ASTNode clone0(AST target) { InfixExpression result = new InfixExpression(target); result.setSourceRange(getStartPosition(), getLength()); result.setOperator(getOperator()); result.setLeftOperand((Expression) getLeftOperand().clone(target)); result.setRightOperand((Expression) getRightOperand().clone(target)); if (this.extendedOperands != null) { // be careful not to trigger lazy creation of list result.extendedOperands().addAll(ASTNode.copySubtrees(target, extendedOperands())); } return result; } @Override final boolean subtreeMatch0(ASTMatcher matcher, Object other) { // dispatch to correct overloaded match method return matcher.match(this, other); } @Override void accept0(ASTVisitor visitor) { boolean visitChildren = visitor.visit(this); if (visitChildren) { // visit children in normal left to right reading order acceptChild(visitor, getLeftOperand()); acceptChild(visitor, getRightOperand()); if (this.extendedOperands != null) { // be careful not to trigger lazy creation of list acceptChildren(visitor, this.extendedOperands); } } visitor.endVisit(this); } /** * Returns the operator of this infix expression. * * @return the infix operator */ public InfixExpression.Operator getOperator() { return this.operator; } /** * Sets the operator of this infix expression. * * @param operator the infix operator * @exception IllegalArgumentException if the argument is incorrect */ public void setOperator(InfixExpression.Operator operator) { if (operator == null) { throw new IllegalArgumentException(); } preValueChange(OPERATOR_PROPERTY); this.operator = operator; postValueChange(OPERATOR_PROPERTY); } /** * Returns the left operand of this infix expression. * * @return the left operand node */ public Expression getLeftOperand() { if (this.leftOperand == null) { // lazy init must be thread-safe for readers synchronized (this) { if (this.leftOperand == null) { preLazyInit(); this.leftOperand = new SimpleName(this.ast); postLazyInit(this.leftOperand, LEFT_OPERAND_PROPERTY); } } } return this.leftOperand; } /** * Sets the left operand of this infix expression. * * @param expression the left operand node * @exception IllegalArgumentException if: * <ul> * <li>the node belongs to a different AST</li> * <li>the node already has a parent</li> * <li>a cycle in would be created</li> * </ul> */ public void setLeftOperand(Expression expression) { if (expression == null) { throw new IllegalArgumentException(); } ASTNode oldChild = this.leftOperand; preReplaceChild(oldChild, expression, LEFT_OPERAND_PROPERTY); this.leftOperand = expression; postReplaceChild(oldChild, expression, LEFT_OPERAND_PROPERTY); } /** * Returns the right operand of this infix expression. * * @return the right operand node */ public Expression getRightOperand() { if (this.rightOperand == null) { // lazy init must be thread-safe for readers synchronized (this) { if (this.rightOperand == null) { preLazyInit(); this.rightOperand = new SimpleName(this.ast); postLazyInit(this.rightOperand, RIGHT_OPERAND_PROPERTY); } } } return this.rightOperand; } /** * Sets the right operand of this infix expression. * * @param expression the right operand node * @exception IllegalArgumentException if: * <ul> * <li>the node belongs to a different AST</li> * <li>the node already has a parent</li> * <li>a cycle in would be created</li> * </ul> */ public void setRightOperand(Expression expression) { if (expression == null) { throw new IllegalArgumentException(); } ASTNode oldChild = this.rightOperand; preReplaceChild(oldChild, expression, RIGHT_OPERAND_PROPERTY); this.rightOperand = expression; postReplaceChild(oldChild, expression, RIGHT_OPERAND_PROPERTY); } /** * Returns where there are any extended operands. * * @return <code>true</code> if there are one or more extended operands, * and <code>false</code> if there are no extended operands */ public boolean hasExtendedOperands() { return (this.extendedOperands != null) && this.extendedOperands.size() > 0; } /** * Returns the live list of extended operands. * <p> * The extended operands is the preferred way of representing deeply nested * expressions of the form <code>L op R op R2 op R3...</code> where * the same operator appears between all the operands (the most * common case being lengthy string concatenation expressions). Using * the extended operands keeps the trees from getting too deep; this * decreases the risk is running out of thread stack space at runtime * when traversing such trees. * ((a + b) + c) + d would be translated to: * leftOperand: a * rightOperand: b * extendedOperands: {c, d} * operator: + * </p> * * @return the live list of extended operands * (element type: {@link Expression}) */ public List extendedOperands() { if (this.extendedOperands == null) { // lazily initialize this.extendedOperands = new ASTNode.NodeList(EXTENDED_OPERANDS_PROPERTY); } return this.extendedOperands; } @Override int memSize() { // treat Operator as free return BASE_NODE_SIZE + 4 * 4; } @Override int treeSize() { return memSize() + (this.leftOperand == null ? 0 : getLeftOperand().treeSize()) + (this.rightOperand == null ? 0 : getRightOperand().treeSize()) + (this.extendedOperands == null ? 0 : this.extendedOperands.listSize()); } }