/*

 * Copyright 1999-2009 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 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.tree.JCTree.*;

import com.sun.tools.javac.code.Lint;

import com.sun.tools.javac.code.Lint.LintCategory;

import com.sun.tools.javac.code.Type.*;

import com.sun.tools.javac.code.Symbol.*;

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

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

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

/** Type checking helper class for the attribution phase.

 *

 *  <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 Check {

    protected static final Context.Key<Check> checkKey =

        new Context.Key<Check>();

    private final Names names;

    private final Log log;

    private final Symtab syms;

    private final Infer infer;

    private final Types types;

    private final JCDiagnostic.Factory diags;

    private final boolean skipAnnotations;

    private boolean warnOnSyntheticConflicts;

    private final TreeInfo treeinfo;

    // The set of lint options currently in effect. It is initialized

    // from the context, and then is set/reset as needed by Attr as it

    // visits all the various parts of the trees during attribution.

    private Lint lint;

    public static Check instance(Context context) {

        Check instance = context.get(checkKey);

        if (instance == null)

            instance = new Check(context);

        return instance;

    }

    protected Check(Context context) {

        context.put(checkKey, this);

        names = Names.instance(context);

        log = Log.instance(context);

        syms = Symtab.instance(context);

        infer = Infer.instance(context);

        this.types = Types.instance(context);

        diags = JCDiagnostic.Factory.instance(context);

        Options options = Options.instance(context);

        lint = Lint.instance(context);

        treeinfo = TreeInfo.instance(context);

        Source source = Source.instance(context);

        allowGenerics = source.allowGenerics();

        allowAnnotations = source.allowAnnotations();

        allowCovariantReturns = source.allowCovariantReturns();

        complexInference = options.get("-complexinference") != null;

        skipAnnotations = options.get("skipAnnotations") != null;

        warnOnSyntheticConflicts = options.get("warnOnSyntheticConflicts") != null;

        Target target = Target.instance(context);

        syntheticNameChar = target.syntheticNameChar();

        boolean verboseDeprecated = lint.isEnabled(LintCategory.DEPRECATION);

        boolean verboseUnchecked = lint.isEnabled(LintCategory.UNCHECKED);

        boolean verboseSunApi = lint.isEnabled(LintCategory.SUNAPI);

        boolean enforceMandatoryWarnings = source.enforceMandatoryWarnings();

        deprecationHandler = new MandatoryWarningHandler(log, verboseDeprecated,

                enforceMandatoryWarnings, "deprecated");

        uncheckedHandler = new MandatoryWarningHandler(log, verboseUnchecked,

                enforceMandatoryWarnings, "unchecked");

        sunApiHandler = new MandatoryWarningHandler(log, verboseSunApi,

                enforceMandatoryWarnings, "sunapi");

    }

    /** Switch: generics enabled?

     */

    boolean allowGenerics;

    /** Switch: annotations enabled?

     */

    boolean allowAnnotations;

    /** Switch: covariant returns enabled?

     */

    boolean allowCovariantReturns;

    /** Switch: -complexinference option set?

     */

    boolean complexInference;

    /** Character for synthetic names

     */

    char syntheticNameChar;

    /** A table mapping flat names of all compiled classes in this run to their

     *  symbols; maintained from outside.

     */

    public Map<Name,ClassSymbol> compiled = new HashMap<Name, ClassSymbol>();

    /** A handler for messages about deprecated usage.

     */

    private MandatoryWarningHandler deprecationHandler;

    /** A handler for messages about unchecked or unsafe usage.

     */

    private MandatoryWarningHandler uncheckedHandler;

    /** A handler for messages about using Sun proprietary API.

     */

    private MandatoryWarningHandler sunApiHandler;

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

 * Errors and Warnings

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

    Lint setLint(Lint newLint) {

        Lint prev = lint;

        lint = newLint;

        return prev;

    }

    /** Warn about deprecated symbol.

     *  @param pos        Position to be used for error reporting.

     *  @param sym        The deprecated symbol.

     */

    void warnDeprecated(DiagnosticPosition pos, Symbol sym) {

        if (!lint.isSuppressed(LintCategory.DEPRECATION))

            deprecationHandler.report(pos, "has.been.deprecated", sym, sym.location());

    }

    /** Warn about unchecked operation.

     *  @param pos        Position to be used for error reporting.

     *  @param msg        A string describing the problem.

     */

    public void warnUnchecked(DiagnosticPosition pos, String msg, Object... args) {

        if (!lint.isSuppressed(LintCategory.UNCHECKED))

            uncheckedHandler.report(pos, msg, args);

    }

    /** Warn about using Sun proprietary API.

     *  @param pos        Position to be used for error reporting.

     *  @param msg        A string describing the problem.

     */

    public void warnSunApi(DiagnosticPosition pos, String msg, Object... args) {

        if (!lint.isSuppressed(LintCategory.SUNAPI))

            sunApiHandler.report(pos, msg, args);

    }

    /**

     * Report any deferred diagnostics.

     */

    public void reportDeferredDiagnostics() {

        deprecationHandler.reportDeferredDiagnostic();

        uncheckedHandler.reportDeferredDiagnostic();

        sunApiHandler.reportDeferredDiagnostic();

    }

    /** Report a failure to complete a class.

     *  @param pos        Position to be used for error reporting.

     *  @param ex         The failure to report.

     */

    public Type completionError(DiagnosticPosition pos, CompletionFailure ex) {

        log.error(pos, "cant.access", ex.sym, ex.getDetailValue());

        if (ex instanceof ClassReader.BadClassFile) throw new Abort();

        else return syms.errType;

    }

    /** Report a type error.

     *  @param pos        Position to be used for error reporting.

     *  @param problem    A string describing the error.

     *  @param found      The type that was found.

     *  @param req        The type that was required.

     */

    Type typeError(DiagnosticPosition pos, Object problem, Type found, Type req) {

        log.error(pos, "prob.found.req",

                  problem, found, req);

        return types.createErrorType(found);

    }

    Type typeError(DiagnosticPosition pos, String problem, Type found, Type req, Object explanation) {

        log.error(pos, "prob.found.req.1", problem, found, req, explanation);

        return types.createErrorType(found);

    }

    /** Report an error that wrong type tag was found.

     *  @param pos        Position to be used for error reporting.

     *  @param required   An internationalized string describing the type tag

     *                    required.

     *  @param found      The type that was found.

     */

    Type typeTagError(DiagnosticPosition pos, Object required, Object found) {

        // this error used to be raised by the parser,

        // but has been delayed to this point:

        if (found instanceof Type && ((Type)found).tag == VOID) {

            log.error(pos, "illegal.start.of.type");

            return syms.errType;

        }

        log.error(pos, "type.found.req", found, required);

        return types.createErrorType(found instanceof Type ? (Type)found : syms.errType);

    }

    /** Report an error that symbol cannot be referenced before super

     *  has been called.

     *  @param pos        Position to be used for error reporting.

     *  @param sym        The referenced symbol.

     */

    void earlyRefError(DiagnosticPosition pos, Symbol sym) {

        log.error(pos, "cant.ref.before.ctor.called", sym);

    }

    /** Report duplicate declaration error.

     */

    void duplicateError(DiagnosticPosition pos, Symbol sym) {

        if (!sym.type.isErroneous()) {

            log.error(pos, "already.defined", sym, sym.location());

        }

    }

    /** Report array/varargs duplicate declaration

     */

    void varargsDuplicateError(DiagnosticPosition pos, Symbol sym1, Symbol sym2) {

        if (!sym1.type.isErroneous() && !sym2.type.isErroneous()) {

            log.error(pos, "array.and.varargs", sym1, sym2, sym2.location());

        }

    }

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

 * duplicate declaration checking

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

    /** Check that variable does not hide variable with same name in

     *  immediately enclosing local scope.

     *  @param pos           Position for error reporting.

     *  @param v             The symbol.

     *  @param s             The scope.

     */

    void checkTransparentVar(DiagnosticPosition pos, VarSymbol v, Scope s) {

        if (s.next != null) {

            for (Scope.Entry e = s.next.lookup(v.name);

                 e.scope != null && e.sym.owner == v.owner;

                 e = e.next()) {

                if (e.sym.kind == VAR &&

                    (e.sym.owner.kind & (VAR | MTH)) != 0 &&

                    v.name != names.error) {

                    duplicateError(pos, e.sym);

                    return;

                }

            }

        }

    }

    /** Check that a class or interface does not hide a class or

     *  interface with same name in immediately enclosing local scope.

     *  @param pos           Position for error reporting.

     *  @param c             The symbol.

     *  @param s             The scope.

     */

    void checkTransparentClass(DiagnosticPosition pos, ClassSymbol c, Scope s) {

        if (s.next != null) {

            for (Scope.Entry e = s.next.lookup(c.name);

                 e.scope != null && e.sym.owner == c.owner;

                 e = e.next()) {

                if (e.sym.kind == TYP &&

                    (e.sym.owner.kind & (VAR | MTH)) != 0 &&

                    c.name != names.error) {

                    duplicateError(pos, e.sym);

                    return;

                }

            }

        }

    }

    /** Check that class does not have the same name as one of

     *  its enclosing classes, or as a class defined in its enclosing scope.

     *  return true if class is unique in its enclosing scope.

     *  @param pos           Position for error reporting.

     *  @param name          The class name.

     *  @param s             The enclosing scope.

     */

    boolean checkUniqueClassName(DiagnosticPosition pos, Name name, Scope s) {

        for (Scope.Entry e = s.lookup(name); e.scope == s; e = e.next()) {

            if (e.sym.kind == TYP && e.sym.name != names.error) {

                duplicateError(pos, e.sym);

                return false;

            }

        }

        for (Symbol sym = s.owner; sym != null; sym = sym.owner) {

            if (sym.kind == TYP && sym.name == name && sym.name != names.error) {

                duplicateError(pos, sym);

                return true;

            }

        }

        return true;

    }

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

 * Class name generation

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

    /** Return name of local class.

     *  This is of the form    <enclClass> $ n <classname>

     *  where

     *    enclClass is the flat name of the enclosing class,

     *    classname is the simple name of the local class

     */

    Name localClassName(ClassSymbol c) {

        for (int i=1; ; i++) {

            Name flatname = names.

                fromString("" + c.owner.enclClass().flatname +

                           syntheticNameChar + i +

                           c.name);

            if (compiled.get(flatname) == null) return flatname;

        }

    }

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

 * Type Checking

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

    /** Check that a given type is assignable to a given proto-type.

     *  If it is, return the type, otherwise return errType.

     *  @param pos        Position to be used for error reporting.

     *  @param found      The type that was found.

     *  @param req        The type that was required.

     */

    Type checkType(DiagnosticPosition pos, Type found, Type req) {

        if (req.tag == ERROR)

            return req;

        if (req.tag == NONE)

            return found;

        if (types.isAssignable(found, req, convertWarner(pos, found, req)))

            return found;

        if (found.tag <= DOUBLE && req.tag <= DOUBLE)

            return typeError(pos, diags.fragment("possible.loss.of.precision"), found, req);

        if (found.isSuperBound()) {

            log.error(pos, "assignment.from.super-bound", found);

            return types.createErrorType(found);

        }

        if (req.isExtendsBound()) {

            log.error(pos, "assignment.to.extends-bound", req);

            return types.createErrorType(found);

        }

        return typeError(pos, diags.fragment("incompatible.types"), found, req);

    }

    Type checkReturnType(DiagnosticPosition pos, Type found, Type req) {

        if (found.tag == FORALL) {

            try {

                return instantiatePoly(pos, (ForAll) found, req, convertWarner(pos, found, req));

            } catch (Infer.NoInstanceException ex) {

                if (ex.isAmbiguous) {

                    JCDiagnostic d = ex.getDiagnostic();

                    log.error(pos,

                            "undetermined.type" + (d != null ? ".1" : ""),

                            found, d);

                    return types.createErrorType(req);

                } else {

                    JCDiagnostic d = ex.getDiagnostic();

                    return typeError(pos,

                            diags.fragment("incompatible.types" + (d != null ? ".1" : ""), d),

                            found, req);

                }

            } catch (Infer.InvalidInstanceException ex) {

                JCDiagnostic d = ex.getDiagnostic();

                log.error(pos, "invalid.inferred.types", ((ForAll)found).tvars, d);

                return types.createErrorType(req);

            }

        } else {

            return checkType(pos, found, req);

        }

    }

    /** Instantiate polymorphic type to some prototype, unless

     *  prototype is `anyPoly' in which case polymorphic type

     *  is returned unchanged.

     */

    Type instantiatePoly(DiagnosticPosition pos, ForAll t, Type pt, Warner warn) throws Infer.NoInstanceException {

        if (pt == Infer.anyPoly && complexInference) {

            return t;

        } else if (pt == Infer.anyPoly || pt.tag == NONE) {

            Type newpt = t.qtype.tag <= VOID ? t.qtype : syms.objectType;

            return instantiatePoly(pos, t, newpt, warn);

        } else if (pt.tag == ERROR) {

            return pt;

        } else {

            return infer.instantiateExpr(t, pt, warn);

        }

     }

    /** Check that a given type can be cast to a given target type.

     *  Return the result of the cast.

     *  @param pos        Position to be used for error reporting.

     *  @param found      The type that is being cast.

     *  @param req        The target type of the cast.

     */

    Type checkCastable(DiagnosticPosition pos, Type found, Type req) {

        if (found.tag == FORALL) {

            instantiatePoly(pos, (ForAll) found, req, castWarner(pos, found, req));

            return req;

        } else if (types.isCastable(found, req, castWarner(pos, found, req))) {

            return req;

        } else {

            return typeError(pos,

                             diags.fragment("inconvertible.types"),

                             found, req);

        }

    }

//where

        /** Is type a type variable, or a (possibly multi-dimensional) array of

         *  type variables?

         */

        boolean isTypeVar(Type t) {

            return t.tag == TYPEVAR || t.tag == ARRAY && isTypeVar(types.elemtype(t));

        }

    /** Check that a type is within some bounds.

     *

     *  Used in TypeApply to verify that, e.g., X in V<X> is a valid

     *  type argument.

     *  @param pos           Position to be used for error reporting.

     *  @param a             The type that should be bounded by bs.

     *  @param bs            The bound.

     */

    private void checkExtends(DiagnosticPosition pos, Type a, TypeVar bs) {

         if (a.isUnbound()) {

             return;

         } else if (a.tag != WILDCARD) {

             a = types.upperBound(a);

             for (List<Type> l = types.getBounds(bs); l.nonEmpty(); l = l.tail) {

                 if (!types.isSubtype(a, l.head)) {

                     log.error(pos, "not.within.bounds", a);

                     return;

                 }

             }

         } else if (a.isExtendsBound()) {

             if (!types.isCastable(bs.getUpperBound(), types.upperBound(a), Warner.noWarnings))

                 log.error(pos, "not.within.bounds", a);

         } else if (a.isSuperBound()) {

             if (types.notSoftSubtype(types.lowerBound(a), bs.getUpperBound()))

                 log.error(pos, "not.within.bounds", a);

         }

     }

    /** Check that a type is within some bounds.

     *

     *  Used in TypeApply to verify that, e.g., X in V<X> is a valid

     *  type argument.

     *  @param pos           Position to be used for error reporting.

     *  @param a             The type that should be bounded by bs.

     *  @param bs            The bound.

     */

    private void checkCapture(JCTypeApply tree) {

        List<JCExpression> args = tree.getTypeArguments();

        for (Type arg : types.capture(tree.type).getTypeArguments()) {

            if (arg.tag == TYPEVAR && arg.getUpperBound().isErroneous()) {

                log.error(args.head.pos, "not.within.bounds", args.head.type);

                break;

            }

            args = args.tail;

        }

     }

    /** Check that type is different from 'void'.

     *  @param pos           Position to be used for error reporting.

     *  @param t             The type to be checked.

     */