/*

 * Copyright 1999-2008 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 Names 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 JCDiagnostic.Factory diags;

    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 = Names.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);

        diags = JCDiagnostic.Factory.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.

     *  It is 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",

                          kindNames(pkind),

                          kindName(ownkind));

                owntype = types.createErrorType(owntype);

            }

        }

        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 {

            attribStat(stmt, env);

        } catch (BreakAttr b) {

            return b.env;

        } finally {

            breakTree = null;

            log.useSource(prev);

        }

        return env;

    }

    private JCTree breakTree = null;

    private static class BreakAttr extends RuntimeException {

        static final long serialVersionUID = -6924771130405446405L;

        private Env<AttrContext> env;

        private BreakAttr(Env<AttrContext> env) {

            this.env = env;

        }

    }

/* ************************************************************************

 * Visitor methods

 *************************************************************************/

    /** Visitor argument: the current environment.

     */

    Env<AttrContext> env;

    /** Visitor argument: the currently expected proto-kind.

     */

    int pkind;

    /** Visitor argument: the currently expected proto-type.

     */

    Type pt;

    /** Visitor result: the computed type.

     */

    Type result;

    /** Visitor method: attribute a tree, catching any completion failure

     *  exceptions. Return the tree's type.

     *

     *  @param tree    The tree to be visited.

     *  @param env     The environment visitor argument.

     *  @param pkind   The protokind visitor argument.

     *  @param pt      The prototype visitor argument.

     */

    Type attribTree(JCTree tree, Env<AttrContext> env, int pkind, Type pt) {

        Env<AttrContext> prevEnv = this.env;

        int prevPkind = this.pkind;

        Type prevPt = this.pt;

        try {

            this.env = env;

            this.pkind = pkind;

            this.pt = pt;

            tree.accept(this);

            if (tree == breakTree)

                throw new BreakAttr(env);

            return result;

        } catch (CompletionFailure ex) {

            tree.type = syms.errType;

            return chk.completionError(tree.pos(), ex);

        } finally {

            this.env = prevEnv;

            this.pkind = prevPkind;

            this.pt = prevPt;

        }

    }

    /** Derived visitor method: attribute an expression tree.

     */

    public Type attribExpr(JCTree tree, Env<AttrContext> env, Type pt) {

        return attribTree(tree, env, VAL, pt.tag != ERROR ? pt : Type.noType);

    }

    /** Derived visitor method: attribute an expression tree with

     *  no constraints on the computed type.

     */

    Type attribExpr(JCTree tree, Env<AttrContext> env) {

        return attribTree(tree, env, VAL, Type.noType);

    }

    /** Derived visitor method: attribute a type tree.

     */

    Type attribType(JCTree tree, Env<AttrContext> env) {

        Type result = attribTree(tree, env, TYP, Type.noType);

        return result;

    }

    /** Derived visitor method: attribute a statement or definition tree.

     */

    public Type attribStat(JCTree tree, Env<AttrContext> env) {

        return attribTree(tree, env, NIL, Type.noType);

    }

    /** Attribute a list of expressions, returning a list of types.

     */

    List<Type> attribExprs(List<JCExpression> trees, Env<AttrContext> env, Type pt) {

        ListBuffer<Type> ts = new ListBuffer<Type>();

        for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)

            ts.append(attribExpr(l.head, env, pt));

        return ts.toList();

    }

    /** Attribute a list of statements, returning nothing.

     */

    <T extends JCTree> void attribStats(List<T> trees, Env<AttrContext> env) {

        for (List<T> l = trees; l.nonEmpty(); l = l.tail)

            attribStat(l.head, env);

    }

    /** Attribute the arguments in a method call, returning a list of types.

     */

    List<Type> attribArgs(List<JCExpression> trees, Env<AttrContext> env) {

        ListBuffer<Type> argtypes = new ListBuffer<Type>();

        for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)

            argtypes.append(chk.checkNonVoid(

                l.head.pos(), types.upperBound(attribTree(l.head, env, VAL, Infer.anyPoly))));

        return argtypes.toList();

    }

    /** Attribute a type argument list, returning a list of types.

     */

    List<Type> attribTypes(List<JCExpression> trees, Env<AttrContext> env) {

        ListBuffer<Type> argtypes = new ListBuffer<Type>();

        for (List<JCExpression> l = trees; l.nonEmpty(); l = l.tail)

            argtypes.append(chk.checkRefType(l.head.pos(), attribType(l.head, env)));

        return argtypes.toList();

    }

    /**

     * Attribute type variables (of generic classes or methods).

     * Compound types are attributed later in attribBounds.

     * @param typarams the type variables to enter

     * @param env      the current environment

     */

    void attribTypeVariables(List<JCTypeParameter> typarams, Env<AttrContext> env) {

        for (JCTypeParameter tvar : typarams) {

            TypeVar a = (TypeVar)tvar.type;

            a.tsym.flags_field |= UNATTRIBUTED;

            a.bound = Type.noType;

            if (!tvar.bounds.isEmpty()) {

                List<Type> bounds = List.of(attribType(tvar.bounds.head, env));

                for (JCExpression bound : tvar.bounds.tail)

                    bounds = bounds.prepend(attribType(bound, env));

                types.setBounds(a, bounds.reverse());

            } else {

                // if no bounds are given, assume a single bound of

                // java.lang.Object.

                types.setBounds(a, List.of(syms.objectType));

            }

            a.tsym.flags_field &= ~UNATTRIBUTED;

        }

        for (JCTypeParameter tvar : typarams)

            chk.checkNonCyclic(tvar.pos(), (TypeVar)tvar.type);

        attribStats(typarams, env);

    }

    void attribBounds(List<JCTypeParameter> typarams) {

        for (JCTypeParameter typaram : typarams) {

            Type bound = typaram.type.getUpperBound();

            if (bound != null && bound.tsym instanceof ClassSymbol) {

                ClassSymbol c = (ClassSymbol)bound.tsym;

                if ((c.flags_field & COMPOUND) != 0) {

                    assert (c.flags_field & UNATTRIBUTED) != 0 : c;

                    attribClass(typaram.pos(), c);

                }

            }

        }

    }

    /**

     * Attribute the type references in a list of annotations.

     */

    void attribAnnotationTypes(List<JCAnnotation> annotations,

                               Env<AttrContext> env) {

        for (List<JCAnnotation> al = annotations; al.nonEmpty(); al = al.tail) {

            JCAnnotation a = al.head;

            attribType(a.annotationType, env);

        }

    }

    /** Attribute type reference in an `extends' or `implements' clause.

     *

     *  @param tree              The tree making up the type reference.

     *  @param env               The environment current at the reference.

     *  @param classExpected     true if only a class is expected here.

     *  @param interfaceExpected true if only an interface is expected here.

     */

    Type attribBase(JCTree tree,

                    Env<AttrContext> env,

                    boolean classExpected,

                    boolean interfaceExpected,

                    boolean checkExtensible) {

        Type t = attribType(tree, env);

        return checkBase(t, tree, env, classExpected, interfaceExpected, checkExtensible);

    }

    Type checkBase(Type t,

                   JCTree tree,

                   Env<AttrContext> env,

                   boolean classExpected,

                   boolean interfaceExpected,

                   boolean checkExtensible) {

        if (t.tag == TYPEVAR && !classExpected && !interfaceExpected) {

            // check that type variable is already visible

            if (t.getUpperBound() == null) {

                log.error(tree.pos(), "illegal.forward.ref");