org.eclipse.jdt.core.dom.ASTRequestor.java Source code

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Here is the source code for org.eclipse.jdt.core.dom.ASTRequestor.java

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/*******************************************************************************
 * Copyright (c) 2005, 2010 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 org.eclipse.jdt.core.ICompilationUnit;

/**
 * An AST requestor handles ASTs for compilation units passed to
 * {@link ASTParser#createASTs(ICompilationUnit[], String[], ASTRequestor, org.eclipse.core.runtime.IProgressMonitor) ASTParser.createASTs}.
 * <p>
 * {@link #acceptAST(ICompilationUnit, CompilationUnit) ASTRequestor.acceptAST} is called for each of the
 * compilation units passed to {@link ASTParser#createASTs(ICompilationUnit[], String[], ASTRequestor, org.eclipse.core.runtime.IProgressMonitor) ASTParser.createASTs}.
 * After all the compilation units have been processed,
 * {@link #acceptBinding(String, IBinding) ASTRequestor.acceptBindings} is called for each
 * of the binding keys passed to {@link ASTParser#createASTs(ICompilationUnit[], String[], ASTRequestor, org.eclipse.core.runtime.IProgressMonitor) ASTParser.createASTs}.
 * </p>
 * <p>
 * This class is intended to be subclassed by clients.
 * AST requestors are serially reusable, but neither reentrant nor thread-safe.
 * </p>
 *
 * @see ASTParser#createASTs(ICompilationUnit[], String[], ASTRequestor, org.eclipse.core.runtime.IProgressMonitor)
 * @since 3.1
 */
public abstract class ASTRequestor {

    /**
     * The compilation unit resolver used to resolve bindings, or
     * <code>null</code> if none. Note that this field is non-null
     * only within the dynamic scope of a call to
     * <code>ASTParser.createASTs</code>.
     */
    CompilationUnitResolver compilationUnitResolver = null;

    /**
     * Creates a new instance.
     */
    protected ASTRequestor() {
        // do nothing
    }

    /**
     * Accepts an AST corresponding to the compilation unit.
     * That is, <code>ast</code> is an AST for <code>source</code>.
     * <p>
     * The default implementation of this method does nothing.
     * Clients should override to process the resulting AST.
     * </p>
     *
     * @param source the compilation unit the ast is coming from
     * @param ast the requested abtract syntax tree
     */
    public void acceptAST(ICompilationUnit source, CompilationUnit ast) {
        // do nothing
    }

    /**
     * Accepts a binding corresponding to the binding key.
     * That is, <code>binding</code> is the binding for
     * <code>bindingKey</code>; <code>binding</code> is <code>null</code>
     * if the key cannot be resolved.
     * <p>
     * The default implementation of this method does nothing.
     * Clients should override to process the resulting binding.
     * </p>
     *
     * @param bindingKey the key of the requested binding
     * @param binding the requested binding, or <code>null</code> if none
     */
    public void acceptBinding(String bindingKey, IBinding binding) {
        // do nothing
    }

    /**
     * Resolves bindings for the given binding keys.
     * The given binding keys must have been obtained earlier
     * using {@link IBinding#getKey()}.
     * <p>
     * If a binding key cannot be resolved, <code>null</code> is put in the resulting array.
     * Bindings can only be resolved in the dynamic scope of a <code>ASTParser.createASTs</code>,
     * and only if <code>ASTParser.resolveBindings(true)</code> was specified.
     * </p>
     * <p>
     * Caveat: During an <code>acceptAST</code> callback, there are implementation
     * limitations concerning the look up of binding keys representing local elements.
     * In some cases, the binding is unavailable, and <code>null</code> will be returned.
     * This is only an issue during an <code>acceptAST</code> callback, and only
     * when the binding key represents a local element (e.g., local variable,
     * local class, method declared in anonymous class). There is no such limitation
     * outside of <code>acceptAST</code> callbacks, or for top-level types and their
     * members even within <code>acceptAST</code> callbacks.
     * </p>
     *
     * @param bindingKeys the binding keys to look up
     * @return a list of bindings paralleling the <code>bindingKeys</code> parameter,
     * with <code>null</code> entries for keys that could not be resolved
     */
    public final IBinding[] createBindings(String[] bindingKeys) {
        int length = bindingKeys.length;
        IBinding[] result = new IBinding[length];
        for (int i = 0; i < length; i++) {
            result[i] = null;
            if (this.compilationUnitResolver != null) {
                result[i] = this.compilationUnitResolver.createBinding(bindingKeys[i]);
            }
        }
        return result;
    }
}