/*

 * Copyright (c) 1999, 2012, Oracle and/or its affiliates. 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.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.Flags.ANNOTATION;

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

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

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

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

import static com.sun.tools.javac.tree.JCTree.Tag.*;

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

 *

 *  <p><b>This is NOT part of any supported API.

 *  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 Resolve rs;

    private final Symtab syms;

    private final Enter enter;

    private final Infer infer;

    private final Types types;

    private final JCDiagnostic.Factory diags;

    private boolean warnOnSyntheticConflicts;

    private boolean suppressAbortOnBadClassFile;

    private boolean enableSunApiLintControl;

    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;

    // The method being analyzed in Attr - it is set/reset as needed by

    // Attr as it visits new method declarations.

    private MethodSymbol method;

    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);

        rs = Resolve.instance(context);

        syms = Symtab.instance(context);

        enter = Enter.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();

        allowVarargs = source.allowVarargs();

        allowAnnotations = source.allowAnnotations();

        allowCovariantReturns = source.allowCovariantReturns();

        allowSimplifiedVarargs = source.allowSimplifiedVarargs();

        complexInference = options.isSet("complexinference");

        warnOnSyntheticConflicts = options.isSet("warnOnSyntheticConflicts");

        suppressAbortOnBadClassFile = options.isSet("suppressAbortOnBadClassFile");

        enableSunApiLintControl = options.isSet("enableSunApiLintControl");

        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", LintCategory.DEPRECATION);

        uncheckedHandler = new MandatoryWarningHandler(log, verboseUnchecked,

                enforceMandatoryWarnings, "unchecked", LintCategory.UNCHECKED);

        sunApiHandler = new MandatoryWarningHandler(log, verboseSunApi,

                enforceMandatoryWarnings, "sunapi", null);

        deferredLintHandler = DeferredLintHandler.immediateHandler;

    }

    /** Switch: generics enabled?

     */

    boolean allowGenerics;

    /** Switch: varargs enabled?

     */

    boolean allowVarargs;

    /** Switch: annotations enabled?

     */

    boolean allowAnnotations;

    /** Switch: covariant returns enabled?

     */

    boolean allowCovariantReturns;

    /** Switch: simplified varargs enabled?

     */

    boolean allowSimplifiedVarargs;

    /** 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 proprietary API.

     */

    private MandatoryWarningHandler sunApiHandler;

    /** A handler for deferred lint warnings.

     */

    private DeferredLintHandler deferredLintHandler;

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

 * Errors and Warnings

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

    Lint setLint(Lint newLint) {

        Lint prev = lint;

        lint = newLint;

        return prev;

    }

    DeferredLintHandler setDeferredLintHandler(DeferredLintHandler newDeferredLintHandler) {

        DeferredLintHandler prev = deferredLintHandler;

        deferredLintHandler = newDeferredLintHandler;

        return prev;

    }

    MethodSymbol setMethod(MethodSymbol newMethod) {

        MethodSymbol prev = method;

        method = newMethod;

        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 unsafe vararg method decl.

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

     *  @param sym        The deprecated symbol.

     */

    void warnUnsafeVararg(DiagnosticPosition pos, String key, Object... args) {

        if (lint.isEnabled(LintCategory.VARARGS) && allowSimplifiedVarargs)

            log.warning(LintCategory.VARARGS, pos, key, args);

    }

    /** Warn about using 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);

    }

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

        if (lint.isEnabled(LintCategory.STATIC))

            log.warning(LintCategory.STATIC, 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

                && !suppressAbortOnBadClassFile) throw new Abort();

        else return syms.errType;

    }

    /** 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()) {

            Symbol location = sym.location();

            if (location.kind == MTH &&

                    ((MethodSymbol)location).isStaticOrInstanceInit()) {

                log.error(pos, "already.defined.in.clinit", kindName(sym), sym,

                        kindName(sym.location()), kindName(sym.location().enclClass()),

                        sym.location().enclClass());

            } else {

                log.error(pos, "already.defined", kindName(sym), sym,

                        kindName(sym.location()), 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.type.tag != TYPEVAR &&

                    (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

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

    /**

     * A check context is an object that can be used to perform compatibility

     * checks - depending on the check context, meaning of 'compatibility' might

     * vary significantly.

     */

    interface CheckContext {

        /**

         * Is type 'found' compatible with type 'req' in given context

         */

        boolean compatible(Type found, Type req, Warner warn);

        /**

         * Report a check error

         */

        void report(DiagnosticPosition pos, JCDiagnostic details);

        /**

         * Obtain a warner for this check context

         */

        public Warner checkWarner(DiagnosticPosition pos, Type found, Type req);

    }

    /**

     * This class represent a check context that is nested within another check

     * context - useful to check sub-expressions. The default behavior simply

     * redirects all method calls to the enclosing check context leveraging

     * the forwarding pattern.

     */

    static class NestedCheckContext implements CheckContext {

        CheckContext enclosingContext;

        NestedCheckContext(CheckContext enclosingContext) {

            this.enclosingContext = enclosingContext;

        }

        public boolean compatible(Type found, Type req, Warner warn) {

            return enclosingContext.compatible(found, req, warn);

        }

        public void report(DiagnosticPosition pos, JCDiagnostic details) {

            enclosingContext.report(pos, details);

        }

        public Warner checkWarner(DiagnosticPosition pos, Type found, Type req) {

            return enclosingContext.checkWarner(pos, found, req);

        }

    }

    /**

     * Check context to be used when evaluating assignment/return statements

     */

    CheckContext basicHandler = new CheckContext() {

        public void report(DiagnosticPosition pos, JCDiagnostic details) {

            log.error(pos, "prob.found.req", details);

        }

        public boolean compatible(Type found, Type req, Warner warn) {

            return types.isAssignable(found, req, warn);

        }

        public Warner checkWarner(DiagnosticPosition pos, Type found, Type req) {

            return convertWarner(pos, found, req);

        }

    };

    /** 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) {

        return checkType(pos, found, req, basicHandler);

    }

    Type checkType(final DiagnosticPosition pos, Type found, Type req, CheckContext checkContext) {

        if (req.tag == ERROR)

            return req;

        if (req.tag == NONE)

            return found;

        if (checkContext.compatible(found, req, checkContext.checkWarner(pos, found, req))) {

            return found;

        } else {

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

                checkContext.report(pos, diags.fragment("possible.loss.of.precision", found, req));

                return types.createErrorType(found);

            }

            checkContext.report(pos, diags.fragment("inconvertible.types", found, req));

            return types.createErrorType(found);

        }

    }

    /** 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.