attr.java

来自「是一款用JAVA 编写的编译器 具有很强的编译功能」· Java 代码 · 共 1,568 行 · 第 1/5 页

/*
 * Copyright 1999-2006 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.comp;

import java.util.*;
import java.util.Set;
import javax.lang.model.element.ElementKind;
import javax.tools.JavaFileObject;

import com.sun.tools.javac.code.*;
import com.sun.tools.javac.jvm.*;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.List;

import com.sun.tools.javac.jvm.Target;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.tree.JCTree.*;
import com.sun.tools.javac.code.Type.*;

import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.MemberSelectTree;
import com.sun.source.tree.TreeVisitor;
import com.sun.source.util.SimpleTreeVisitor;

import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.Kinds.*;
import static com.sun.tools.javac.code.TypeTags.*;

/** This is the main context-dependent analysis phase in GJC. It
 *  encompasses name resolution, type checking and constant folding as
 *  subtasks. Some subtasks involve auxiliary classes.
 *  @see Check
 *  @see Resolve
 *  @see ConstFold
 *  @see Infer
 *
 *  <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>
 */
public class Attr extends JCTree.Visitor {
    protected static final Context.Key<Attr> attrKey =
        new Context.Key<Attr>();

    final Name.Table names;
    final Log log;
    final Symtab syms;
    final Resolve rs;
    final Check chk;
    final MemberEnter memberEnter;
    final TreeMaker make;
    final ConstFold cfolder;
    final Enter enter;
    final Target target;
    final Types types;
    final Annotate annotate;

    public static Attr instance(Context context) {
        Attr instance = context.get(attrKey);
        if (instance == null)
            instance = new Attr(context);
        return instance;
    }

    protected Attr(Context context) {
        context.put(attrKey, this);

        names = Name.Table.instance(context);
        log = Log.instance(context);
        syms = Symtab.instance(context);
        rs = Resolve.instance(context);
        chk = Check.instance(context);
        memberEnter = MemberEnter.instance(context);
        make = TreeMaker.instance(context);
        enter = Enter.instance(context);
        cfolder = ConstFold.instance(context);
        target = Target.instance(context);
        types = Types.instance(context);
        annotate = Annotate.instance(context);

        Options options = Options.instance(context);

        Source source = Source.instance(context);
        allowGenerics = source.allowGenerics();
        allowVarargs = source.allowVarargs();
        allowEnums = source.allowEnums();
        allowBoxing = source.allowBoxing();
        allowCovariantReturns = source.allowCovariantReturns();
        allowAnonOuterThis = source.allowAnonOuterThis();
        relax = (options.get("-retrofit") != null ||
                 options.get("-relax") != null);
        useBeforeDeclarationWarning = options.get("useBeforeDeclarationWarning") != null;
    }

    /** Switch: relax some constraints for retrofit mode.
     */
    boolean relax;

    /** Switch: support generics?
     */
    boolean allowGenerics;

    /** Switch: allow variable-arity methods.
     */
    boolean allowVarargs;

    /** Switch: support enums?
     */
    boolean allowEnums;

    /** Switch: support boxing and unboxing?
     */
    boolean allowBoxing;

    /** Switch: support covariant result types?
     */
    boolean allowCovariantReturns;

    /** Switch: allow references to surrounding object from anonymous
     * objects during constructor call?
     */
    boolean allowAnonOuterThis;

    /**
     * Switch: warn about use of variable before declaration?
     * RFE: 6425594
     */
    boolean useBeforeDeclarationWarning;

    /** Check kind and type of given tree against protokind and prototype.
     *  If check succeeds, store type in tree and return it.
     *  If check fails, store errType in tree and return it.
     *  No checks are performed if the prototype is a method type.
     *  Its not necessary in this case since we know that kind and type
     *  are correct.
     *
     *  @param tree     The tree whose kind and type is checked
     *  @param owntype  The computed type of the tree
     *  @param ownkind  The computed kind of the tree
     *  @param pkind    The expected kind (or: protokind) of the tree
     *  @param pt       The expected type (or: prototype) of the tree
     */
    Type check(JCTree tree, Type owntype, int ownkind, int pkind, Type pt) {
        if (owntype.tag != ERROR && pt.tag != METHOD && pt.tag != FORALL) {
            if ((ownkind & ~pkind) == 0) {
                owntype = chk.checkType(tree.pos(), owntype, pt);
            } else {
                log.error(tree.pos(), "unexpected.type",
                          Resolve.kindNames(pkind),
                          Resolve.kindName(ownkind));
                owntype = syms.errType;
            }
        }
        tree.type = owntype;
        return owntype;
    }

    /** Is given blank final variable assignable, i.e. in a scope where it
     *  may be assigned to even though it is final?
     *  @param v      The blank final variable.
     *  @param env    The current environment.
     */
    boolean isAssignableAsBlankFinal(VarSymbol v, Env<AttrContext> env) {
        Symbol owner = env.info.scope.owner;
           // owner refers to the innermost variable, method or
           // initializer block declaration at this point.
        return
            v.owner == owner
            ||
            ((owner.name == names.init ||    // i.e. we are in a constructor
              owner.kind == VAR ||           // i.e. we are in a variable initializer
              (owner.flags() & BLOCK) != 0)  // i.e. we are in an initializer block
             &&
             v.owner == owner.owner
             &&
             ((v.flags() & STATIC) != 0) == Resolve.isStatic(env));
    }

    /** Check that variable can be assigned to.
     *  @param pos    The current source code position.
     *  @param v      The assigned varaible
     *  @param base   If the variable is referred to in a Select, the part
     *                to the left of the `.', null otherwise.
     *  @param env    The current environment.
     */
    void checkAssignable(DiagnosticPosition pos, VarSymbol v, JCTree base, Env<AttrContext> env) {
        if ((v.flags() & FINAL) != 0 &&
            ((v.flags() & HASINIT) != 0
             ||
             !((base == null ||
               (base.getTag() == JCTree.IDENT && TreeInfo.name(base) == names._this)) &&
               isAssignableAsBlankFinal(v, env)))) {
            log.error(pos, "cant.assign.val.to.final.var", v);
        }
    }

    /** Does tree represent a static reference to an identifier?
     *  It is assumed that tree is either a SELECT or an IDENT.
     *  We have to weed out selects from non-type names here.
     *  @param tree    The candidate tree.
     */
    boolean isStaticReference(JCTree tree) {
        if (tree.getTag() == JCTree.SELECT) {
            Symbol lsym = TreeInfo.symbol(((JCFieldAccess) tree).selected);
            if (lsym == null || lsym.kind != TYP) {
                return false;
            }
        }
        return true;
    }

    /** Is this symbol a type?
     */
    static boolean isType(Symbol sym) {
        return sym != null && sym.kind == TYP;
    }

    /** The current `this' symbol.
     *  @param env    The current environment.
     */
    Symbol thisSym(DiagnosticPosition pos, Env<AttrContext> env) {
        return rs.resolveSelf(pos, env, env.enclClass.sym, names._this);
    }

    /** Attribute a parsed identifier.
     * @param tree Parsed identifier name
     * @param topLevel The toplevel to use
     */
    public Symbol attribIdent(JCTree tree, JCCompilationUnit topLevel) {
        Env<AttrContext> localEnv = enter.topLevelEnv(topLevel);
        localEnv.enclClass = make.ClassDef(make.Modifiers(0),
                                           syms.errSymbol.name,
                                           null, null, null, null);
        localEnv.enclClass.sym = syms.errSymbol;
        return tree.accept(identAttributer, localEnv);
    }
    // where
        private TreeVisitor<Symbol,Env<AttrContext>> identAttributer = new IdentAttributer();
        private class IdentAttributer extends SimpleTreeVisitor<Symbol,Env<AttrContext>> {
            @Override
            public Symbol visitMemberSelect(MemberSelectTree node, Env<AttrContext> env) {
                Symbol site = visit(node.getExpression(), env);
                if (site.kind == ERR)
                    return site;
                Name name = (Name)node.getIdentifier();
                if (site.kind == PCK) {
                    env.toplevel.packge = (PackageSymbol)site;
                    return rs.findIdentInPackage(env, (TypeSymbol)site, name, TYP | PCK);
                } else {
                    env.enclClass.sym = (ClassSymbol)site;
                    return rs.findMemberType(env, site.asType(), name, (TypeSymbol)site);
                }
            }
    
            @Override
            public Symbol visitIdentifier(IdentifierTree node, Env<AttrContext> env) {
                return rs.findIdent(env, (Name)node.getName(), TYP | PCK);
            }
        }

    public Type coerce(Type etype, Type ttype) {
        return cfolder.coerce(etype, ttype);
    }

    public Type attribType(JCTree node, TypeSymbol sym) {
        Env<AttrContext> env = enter.typeEnvs.get(sym);
        Env<AttrContext> localEnv = env.dup(node, env.info.dup());
        return attribTree(node, localEnv, Kinds.TYP, Type.noType);
    }  

    public Env<AttrContext> attribExprToTree(JCTree expr, Env<AttrContext> env, JCTree tree) {
        breakTree = tree;
        JavaFileObject prev = log.useSource(null);
        try {
            attribExpr(expr, env);
        } catch (BreakAttr b) {
            return b.env;
        } finally {
            breakTree = null;
            log.useSource(prev);
        }
        return env;
    }    

    public Env<AttrContext> attribStatToTree(JCTree stmt, Env<AttrContext> env, JCTree tree) {
        breakTree = tree;
        JavaFileObject prev = log.useSource(null);
        try {