/*
 * @(#)JavaCompiler.java	1.15 06/09/25
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.tools;

import java.io.File;
import java.io.InputStream;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.Callable;
import javax.annotation.processing.Processor;

/**
 * Interface to invoke Java™ programming language compilers from
 * programs.
 *
 * <p>The compiler might generate diagnostics during compilation (for
 * example, error messages).  If a diagnostic listener is provided,
 * the diagnostics will be supplied to the listener.  If no listener
 * is provided, the diagnostics will be formatted in an unspecified
 * format and written to the default output, which is {@code
 * System.err} unless otherwise specified.  Even if a diagnostic
 * listener is supplied, some diagnostics might not fit in a {@code
 * Diagnostic} and will be written to the default output.
 *
 * <p>A compiler tool has an associated standard file manager, which
 * is the file manager that is native to the tool (or built-in).  The
 * standard file manager can be obtained by calling {@linkplain
 * #getStandardFileManager getStandardFileManager}.
 *
 * <p>A compiler tool must function with any file manager as long as
 * any additional requirements as detailed in the methods below are
 * met.  If no file manager is provided, the compiler tool will use a
 * standard file manager such as the one returned by {@linkplain
 * #getStandardFileManager getStandardFileManager}.
 *
 * <p>An instance implementing this interface must conform to the Java
 * Language Specification and generate class files conforming to the
 * Java Virtual Machine specification.  The versions of these
 * specifications are defined in the {@linkplain Tool} interface.  
 *
 * Additionally, an instance of this interface supporting {@link
 * javax.lang.model.SourceVersion#RELEASE_6 SourceVersion.RELEASE_6}
 * or higher must also support {@linkplain javax.annotation.processing
 * annotation processing}.
 *
 * <p>The compiler relies on two services: {@linkplain
 * DiagnosticListener diagnostic listener} and {@linkplain
 * JavaFileManager file manager}.  Although most classes and
 * interfaces in this package defines an API for compilers (and
 * tools in general) the interfaces {@linkplain DiagnosticListener},
 * {@linkplain JavaFileManager}, {@linkplain FileObject}, and
 * {@linkplain JavaFileObject} are not intended to be used in
 * applications.  Instead these interfaces are intended to be
 * implemented and used to provide customized services for a
 * compiler and thus defines an SPI for compilers.
 *
 * <p>There are a number of classes and interfaces in this package
 * which are designed to ease the implementation of the SPI to
 * customize the behavior of a compiler:
 *
 * <dl>
 *   <dt>{@link StandardJavaFileManager}</dt>
 *   <dd>
 *
 *     Every compiler which implements this interface provides a
 *     standard file manager for operating on regular {@linkplain
 *     java.io.File files}.  The StandardJavaFileManager interface
 *     defines additional methods for creating file objects from
 *     regular files.
 *
 *     <p>The standard file manager serves two purposes:
 *
 *     <ul>
 *       <li>basic building block for customizing how a compiler reads
 *       and writes files</li>
 *       <li>sharing between multiple compilation tasks</li>
 *     </ul>
 *
 *     <p>Reusing a file manager can potentially reduce overhead of
 *     scanning the file system and reading jar files.  Although there
 *     might be no reduction in overhead, a standard file manager must
 *     work with multiple sequential compilations making the following
 *     example a recommended coding pattern:
 *
 *     <pre>
 *       Files[] files1 = ... ; // input for first compilation task
 *       Files[] files2 = ... ; // input for second compilation task
 *
 *       JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
 *       StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);
 *
 *       {@code Iterable<? extends JavaFileObject>} compilationUnits1 =
 *           fileManager.getJavaFileObjectsFromFiles({@linkplain java.util.Arrays#asList Arrays.asList}(files1));