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/*
 * Copyright (c) 2005, 2016, 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
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package com.sun.tools.javac.model;

import java.util.Collection;
import java.util.Collections;
import java.util.EnumSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

import javax.lang.model.element.*;
import javax.lang.model.type.*;

import com.sun.tools.javac.code.*;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.util.*;
import com.sun.tools.javac.util.DefinedBy.Api;

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


Utility methods for operating on types.

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.


/**
 * Utility methods for operating on types.
 *
 * <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></p>
 */
public class JavacTypes implements javax.lang.model.util.Types {

    private final Symtab syms;
    private final Types types;

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

    protected JavacTypes(Context context) {
        context.put(JavacTypes.class, this);
        syms = Symtab.instance(context);
        types = Types.instance(context);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public Element asElement(TypeMirror t) {
        switch (t.getKind()) {
            case DECLARED:
            case INTERSECTION:
            case ERROR:
            case TYPEVAR:
                Type type = cast(Type.class, t);
                return type.asElement();
            default:
                return null;
        }
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public boolean isSameType(TypeMirror t1, TypeMirror t2) {
        if (t1.getKind() == TypeKind.WILDCARD || t2.getKind() == TypeKind.WILDCARD) {
            return false;
        }
        return types.isSameType((Type) t1, (Type) t2);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public boolean isSubtype(TypeMirror t1, TypeMirror t2) {
        validateTypeNotIn(t1, EXEC_OR_PKG_OR_MOD);
        validateTypeNotIn(t2, EXEC_OR_PKG_OR_MOD);
        return types.isSubtype((Type) t1, (Type) t2);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public boolean isAssignable(TypeMirror t1, TypeMirror t2) {
        validateTypeNotIn(t1, EXEC_OR_PKG_OR_MOD);
        validateTypeNotIn(t2, EXEC_OR_PKG_OR_MOD);
        return types.isAssignable((Type) t1, (Type) t2);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public boolean contains(TypeMirror t1, TypeMirror t2) {
        validateTypeNotIn(t1, EXEC_OR_PKG_OR_MOD);
        validateTypeNotIn(t2, EXEC_OR_PKG_OR_MOD);
        return types.containsType((Type) t1, (Type) t2);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public boolean isSubsignature(ExecutableType m1, ExecutableType m2) {
        return types.isSubSignature((Type) m1, (Type) m2);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public List<Type> directSupertypes(TypeMirror t) {
        validateTypeNotIn(t, EXEC_OR_PKG_OR_MOD);
        Type ty = (Type)t;
        return types.directSupertypes(ty).stream()
                .map(Type::stripMetadataIfNeeded)
                .collect(Collectors.toList());
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public TypeMirror erasure(TypeMirror t) {
        TypeKind kind = t.getKind();
        if (kind == TypeKind.PACKAGE || kind == TypeKind.MODULE)
            throw new IllegalArgumentException(t.toString());
        return types.erasure((Type)t).stripMetadataIfNeeded();
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public TypeElement boxedClass(PrimitiveType p) {
        return types.boxedClass((Type) p);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public PrimitiveType unboxedType(TypeMirror t) {
        if (t.getKind() != TypeKind.DECLARED)
            throw new IllegalArgumentException(t.toString());
        Type unboxed = types.unboxedType((Type) t);
        if (! unboxed.isPrimitive())    // only true primitives, not void
            throw new IllegalArgumentException(t.toString());
        return (PrimitiveType)unboxed;
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public TypeMirror capture(TypeMirror t) {
        validateTypeNotIn(t, EXEC_OR_PKG_OR_MOD);
        return types.capture((Type)t).stripMetadataIfNeeded();
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public PrimitiveType getPrimitiveType(TypeKind kind) {
        switch (kind) {
        case BOOLEAN:   return syms.booleanType;
        case BYTE:      return syms.byteType;
        case SHORT:     return syms.shortType;
        case INT:       return syms.intType;
        case LONG:      return syms.longType;
        case CHAR:      return syms.charType;
        case FLOAT:     return syms.floatType;
        case DOUBLE:    return syms.doubleType;
        default:
            throw new IllegalArgumentException("Not a primitive type: " + kind);
        }
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public NullType getNullType() {
        return (NullType) syms.botType;
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public NoType getNoType(TypeKind kind) {
        switch (kind) {
        case VOID:      return syms.voidType;
        case NONE:      return Type.noType;
        default:
            throw new IllegalArgumentException(kind.toString());
        }
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public ArrayType getArrayType(TypeMirror componentType) {
        switch (componentType.getKind()) {
        case VOID:
        case EXECUTABLE:
        case WILDCARD:  // heh!
        case PACKAGE:
        case MODULE:
            throw new IllegalArgumentException(componentType.toString());
        }
        return new Type.ArrayType((Type) componentType, syms.arrayClass);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public WildcardType getWildcardType(TypeMirror extendsBound,
                                        TypeMirror superBound) {
        BoundKind bkind;
        Type bound;
        if (extendsBound == null && superBound == null) {
            bkind = BoundKind.UNBOUND;
            bound = syms.objectType;
        } else if (superBound == null) {
            bkind = BoundKind.EXTENDS;
            bound = (Type) extendsBound;
        } else if (extendsBound == null) {
            bkind = BoundKind.SUPER;
            bound = (Type) superBound;
        } else {
            throw new IllegalArgumentException(
                    "Extends and super bounds cannot both be provided");
        }
        switch (bound.getKind()) {
        case ARRAY:
        case DECLARED:
        case ERROR:
        case TYPEVAR:
            return new Type.WildcardType(bound, bkind, syms.boundClass);
        default:
            throw new IllegalArgumentException(bound.toString());
        }
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public DeclaredType getDeclaredType(TypeElement typeElem,
                                        TypeMirror... typeArgs) {
        ClassSymbol sym = (ClassSymbol) typeElem;

        if (typeArgs.length == 0)
            return (DeclaredType) sym.erasure(types);
        if (sym.type.getEnclosingType().isParameterized())
            throw new IllegalArgumentException(sym.toString());

        return getDeclaredType0(sym.type.getEnclosingType(), sym, typeArgs);
    }

    @DefinedBy(Api.LANGUAGE_MODEL)
    public DeclaredType getDeclaredType(DeclaredType enclosing,
                                        TypeElement typeElem,
                                        TypeMirror... typeArgs) {
        if (enclosing == null)
            return getDeclaredType(typeElem, typeArgs);

        ClassSymbol sym = (ClassSymbol) typeElem;
        Type outer = (Type) enclosing;

        if (outer.tsym != sym.owner.enclClass())
            throw new IllegalArgumentException(enclosing.toString());
        if (!outer.isParameterized())
            return getDeclaredType(typeElem, typeArgs);

        return getDeclaredType0(outer, sym, typeArgs);
    }
    // where
        private DeclaredType getDeclaredType0(Type outer,
                                              ClassSymbol sym,
                                              TypeMirror... typeArgs) {
            if (typeArgs.length != sym.type.getTypeArguments().length())
                throw new IllegalArgumentException(
                "Incorrect number of type arguments");

            ListBuffer<Type> targs = new ListBuffer<>();
            for (TypeMirror t : typeArgs) {
                if (!(t instanceof ReferenceType || t instanceof WildcardType))
                    throw new IllegalArgumentException(t.toString());
                targs.append((Type) t);
            }
            // TODO: Would like a way to check that type args match formals.

            return (DeclaredType) new Type.ClassType(outer, targs.toList(), sym);
        }

    
Returns the type of an element when that element is viewed as a member of, or otherwise directly contained by, a given type. For example, when viewed as a member of the parameterized type Set<String>, the Set.add method is an ExecutableType whose parameter is of type String. 
Params:
  • containing –  the containing type
  • element –     the element
Throws:
Returns:the type of the element as viewed from the containing type
/**
     * Returns the type of an element when that element is viewed as
     * a member of, or otherwise directly contained by, a given type.
     * For example,
     * when viewed as a member of the parameterized type {@code Set<String>},
     * the {@code Set.add} method is an {@code ExecutableType}
     * whose parameter is of type {@code String}.
     *
     * @param containing  the containing type
     * @param element     the element
     * @return the type of the element as viewed from the containing type
     * @throws IllegalArgumentException if the element is not a valid one
     *          for the given type
     */
    @DefinedBy(Api.LANGUAGE_MODEL)
    public TypeMirror asMemberOf(DeclaredType containing, Element element) {
        Type site = (Type)containing;
        Symbol sym = (Symbol)element;
        if (types.asSuper(site, sym.getEnclosingElement()) == null)
            throw new IllegalArgumentException(sym + "@" + site);
        return types.memberType(site, sym);
    }


    private static final Set<TypeKind> EXEC_OR_PKG_OR_MOD =
        EnumSet.of(TypeKind.EXECUTABLE, TypeKind.PACKAGE, TypeKind.MODULE);

    
Throws an IllegalArgumentException if a type's kind is one of a set.

/**
     * Throws an IllegalArgumentException if a type's kind is one of a set.
     */
    private void validateTypeNotIn(TypeMirror t, Set<TypeKind> invalidKinds) {
        if (invalidKinds.contains(t.getKind()))
            throw new IllegalArgumentException(t.toString());
    }

    
Returns an object cast to the specified type.

Throws:
/**
     * Returns an object cast to the specified type.
     * @throws NullPointerException if the object is {@code null}
     * @throws IllegalArgumentException if the object is of the wrong type
     */
    private static <T> T cast(Class<T> clazz, Object o) {
        if (! clazz.isInstance(o))
            throw new IllegalArgumentException(o.toString());
        return clazz.cast(o);
    }

    public Set<MethodSymbol> getOverriddenMethods(Element elem) {
        if (elem.getKind() != ElementKind.METHOD
                || elem.getModifiers().contains(Modifier.STATIC)
                || elem.getModifiers().contains(Modifier.PRIVATE))
            return Collections.emptySet();

        if (!(elem instanceof MethodSymbol))
            throw new IllegalArgumentException();

        MethodSymbol m = (MethodSymbol) elem;
        ClassSymbol origin = (ClassSymbol) m.owner;

        Set<MethodSymbol> results = new LinkedHashSet<>();
        for (Type t : types.closure(origin.type)) {
            if (t != origin.type) {
                ClassSymbol c = (ClassSymbol) t.tsym;
                for (Symbol sym : c.members().getSymbolsByName(m.name)) {
                    if (sym.kind == MTH && m.overrides(sym, origin, types, true)) {
                        results.add((MethodSymbol) sym);
                    }
                }
            }
        }

        return results;
    }
}