javacelements.java

是一款用JAVA 编写的编译器 具有很强的编译功能

/*
 * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package com.sun.tools.javac.model;

import java.lang.annotation.Annotation;
import java.lang.annotation.Inherited;
import java.util.Map;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.util.Elements;
import javax.tools.JavaFileObject;
import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.TypeTags;
import com.sun.tools.javac.comp.AttrContext;
import com.sun.tools.javac.comp.Enter;
import com.sun.tools.javac.comp.Env;
import com.sun.tools.javac.jvm.ClassReader;
import com.sun.tools.javac.main.JavaCompiler;
import com.sun.tools.javac.processing.PrintingProcessor;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.*;
import com.sun.tools.javac.tree.TreeInfo;
import com.sun.tools.javac.tree.TreeScanner;
import com.sun.tools.javac.util.Name;
import com.sun.tools.javac.util.*;

import static javax.lang.model.util.ElementFilter.methodsIn;

/**
 * Utility methods for operating on program elements.
 *
 * <p><b>This is NOT part of any API supported by Sun Microsystems.
 * If you write code that depends on this, you do so at your own
 * risk.  This code and its internal interfaces are subject to change
 * or deletion without notice.</b></p>
 */
public class JavacElements implements Elements {

    private JavaCompiler javaCompiler;
    private Symtab syms;
    private Name.Table names;
    private Types types;
    private Enter enter;
    private ClassReader reader;

    private static final Context.Key<JavacElements> KEY =
	    new Context.Key<JavacElements>();

    public static JavacElements instance(Context context) {
	JavacElements instance = context.get(KEY);
	if (instance == null) {
	    instance = new JavacElements(context);
	    context.put(KEY, instance);
	}
	return instance;
    }

    /**
     * Public for use only by JavacProcessingEnvironment
     */
    // TODO JavacElements constructor should be protected
    public JavacElements(Context context) {
	setContext(context);
    }

    /**
     * Use a new context.  May be called from outside to update
     * internal state for a new annotation-processing round.
     * This instance is *not* then registered with the new context.
     */
    public void setContext(Context context) {
	javaCompiler = JavaCompiler.instance(context);
        syms = Symtab.instance(context);
        names = Name.Table.instance(context);
	types = Types.instance(context);
	enter = Enter.instance(context);
        reader = ClassReader.instance(context);
    }


    /**
     * An internal-use utility that creates a reified annotation.
     */
    public static <A extends Annotation> A getAnnotation(Symbol annotated,
							 Class<A> annoType) {
        if (!annoType.isAnnotation())
            throw new IllegalArgumentException("Not an annotation type: "
                                               + annoType);
        String name = annoType.getName();
        for (Attribute.Compound anno : annotated.getAnnotationMirrors())
            if (name.equals(anno.type.tsym.flatName().toString()))
                return AnnotationProxyMaker.generateAnnotation(anno, annoType);
        return null;
    }
    
    /**
     * An internal-use utility that creates a reified annotation.
     * This overloaded version take annotation inheritance into account.
     */
    public static <A extends Annotation> A getAnnotation(ClassSymbol annotated,
                                                         Class<A> annoType) {
        boolean inherited = annoType.isAnnotationPresent(Inherited.class);
        A result = null;
        while (annotated.name != annotated.name.table.java_lang_Object) {
            result = getAnnotation((Symbol)annotated, annoType);
            if (result != null || !inherited)
                break;
            Type sup = annotated.getSuperclass();
            if (sup.tag != TypeTags.CLASS || sup.isErroneous())
                break;
            annotated = (ClassSymbol) sup.tsym;
        }
        return result;
    }


    public PackageSymbol getPackageElement(CharSequence name) {
	String strName = name.toString();
	if (strName.equals(""))
	    return syms.unnamedPackage;
	return SourceVersion.isName(strName)
	    ? nameToSymbol(strName, PackageSymbol.class)
	    : null;
    }

    public ClassSymbol getTypeElement(CharSequence name) {
	String strName = name.toString();
	return SourceVersion.isName(strName)
	    ? nameToSymbol(strName, ClassSymbol.class)
	    : null;
    }

    /**
     * Returns a symbol given the type's or packages's canonical name,
     * or null if the name isn't found.
     */
    private <S extends Symbol> S nameToSymbol(String nameStr, Class<S> clazz) {
	Name name = names.fromString(nameStr);
	// First check cache.
	Symbol sym = (clazz == ClassSymbol.class)
		    ? syms.classes.get(name)
		    : syms.packages.get(name);

	try {
	    if (sym == null)
		sym = javaCompiler.resolveIdent(nameStr);

	    sym.complete();

	    return (sym.kind != Kinds.ERR &&
		    sym.exists() &&
		    clazz.isInstance(sym) &&
		    name.equals(sym.getQualifiedName()))
		? clazz.cast(sym)
		: null;
	} catch (CompletionFailure e) {
	    return null;
	}
    }

    public JavacSourcePosition getSourcePosition(Element e) {
	Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);
	if (treeTop == null)
	    return null;
	JCTree tree = treeTop.fst;
	JCCompilationUnit toplevel = treeTop.snd;
	JavaFileObject sourcefile = toplevel.sourcefile;
	if (sourcefile == null)
	    return null;
	return new JavacSourcePosition(sourcefile, tree.pos, toplevel.lineMap);
    }

    public JavacSourcePosition getSourcePosition(Element e, AnnotationMirror a) {
	Pair<JCTree, JCCompilationUnit> treeTop = getTreeAndTopLevel(e);
	if (treeTop == null)
	    return null;
	JCTree tree = treeTop.fst;
	JCCompilationUnit toplevel = treeTop.snd;
	JavaFileObject sourcefile = toplevel.sourcefile;
	if (sourcefile == null)
	    return null;

	JCTree annoTree = matchAnnoToTree(a, e, tree);
	if (annoTree == null)
	    return null;
	return new JavacSourcePosition(sourcefile, annoTree.pos,
				       toplevel.lineMap);
    }

    public JavacSourcePosition getSourcePosition(Element e, AnnotationMirror a,
					    AnnotationValue v) {
	// TODO: better accuracy in getSourcePosition(... AnnotationValue)
	return getSourcePosition(e, a);
    }

    /**
     * Returns the tree for an annotation given the annotated element
     * and the element's own tree.  Returns null if the tree cannot be found.
     */
    private JCTree matchAnnoToTree(AnnotationMirror findme,
				   Element e, JCTree tree) {
	Symbol sym = cast(Symbol.class, e);
	class Vis extends JCTree.Visitor {
	    List<JCAnnotation> result = null;
	    public void visitTopLevel(JCCompilationUnit tree) {
		result = tree.packageAnnotations;
	    }
	    public void visitClassDef(JCClassDecl tree) {
		result = tree.mods.annotations;
	    }
	    public void visitMethodDef(JCMethodDecl tree) {
		result = tree.mods.annotations;
	    }
	    public void visitVarDef(JCVariableDecl tree) {
		result = tree.mods.annotations;
	    }
	}
	Vis vis = new Vis();
	tree.accept(vis);
	if (vis.result == null)
	    return null;
	return matchAnnoToTree(cast(Attribute.Compound.class, findme),
			       sym.getAnnotationMirrors(),
			       vis.result);
    }

    /**
     * Returns the tree for an annotation given a list of annotations
     * in which to search (recursively) and their corresponding trees.
     * Returns null if the tree cannot be found.
     */
    private JCTree matchAnnoToTree(Attribute.Compound findme,
				   List<Attribute.Compound> annos,
				   List<JCAnnotation> trees) {
	for (Attribute.Compound anno : annos) {
	    for (JCAnnotation tree : trees) {
		JCTree match = matchAnnoToTree(findme, anno, tree);
		if (match != null)
		    return match;
	    }
	}
	return null;
    }

    /**
     * Returns the tree for an annotation given an Attribute to
     * search (recursively) and its corresponding tree.
     * Returns null if the tree cannot be found.
     */
    private JCTree matchAnnoToTree(final Attribute.Compound findme,
				   final Attribute attr,
				   final JCTree tree) {
	if (attr == findme)
	    return (tree.type.tsym == findme.type.tsym) ? tree : null;

	class Vis implements Attribute.Visitor {
	    JCTree result = null;
	    public void visitConstant(Attribute.Constant value) {
	    }
	    public void visitClass(Attribute.Class clazz) {
	    }
	    public void visitCompound(Attribute.Compound anno) {
		for (Pair<MethodSymbol, Attribute> pair : anno.values) {
		    JCExpression expr = scanForAssign(pair.fst, tree);
		    if (expr != null) {
			JCTree match = matchAnnoToTree(findme, pair.snd, expr);
			if (match != null) {
			    result = match;
			    return;
			}
		    }
		}
	    }
	    public void visitArray(Attribute.Array array) {
		if (tree.getTag() == JCTree.NEWARRAY &&
			types.elemtype(array.type).tsym == findme.type.tsym) {
		    List<JCExpression> elems = ((JCNewArray) tree).elems;
		    for (Attribute value : array.values) {
			if (value == findme) {
			    result = elems.head;
			    return;
			}
			elems = elems.tail;
		    }
		}
	    }
	    public void visitEnum(Attribute.Enum e) {
	    }
	    public void visitError(Attribute.Error e) {
	    }
	}
	Vis vis = new Vis();
	attr.accept(vis);
	return vis.result;
    }

    /**
     * Scans for a JCAssign node with a LHS matching a given