/*

 * Copyright (c) 2003, 2017, 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 com.sun.tools.javac.code.*;

import com.sun.tools.javac.code.Attribute.Compound;

import com.sun.tools.javac.code.Attribute.TypeCompound;

import com.sun.tools.javac.code.Scope.WriteableScope;

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

import com.sun.tools.javac.code.TypeMetadata.Entry.Kind;

import com.sun.tools.javac.resources.CompilerProperties.Errors;

import com.sun.tools.javac.tree.JCTree;

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

import com.sun.tools.javac.tree.TreeInfo;

import com.sun.tools.javac.tree.TreeMaker;

import com.sun.tools.javac.tree.TreeScanner;

import com.sun.tools.javac.util.*;

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;

import com.sun.tools.javac.util.List;

import javax.tools.JavaFileObject;

import java.util.*;

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

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

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

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

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

import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;

import static com.sun.tools.javac.code.TypeTag.ARRAY;

import static com.sun.tools.javac.code.TypeTag.CLASS;

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

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

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

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

import com.sun.tools.javac.util.JCDiagnostic.DiagnosticFlag;

/** Enter annotations onto symbols and types (and trees).

 *

 *  This is also a pseudo stage in the compiler taking care of scheduling when annotations are

 *  entered.

 *

 *  <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 Annotate {

    protected static final Context.Key<Annotate> annotateKey = new Context.Key<>();

    public static Annotate instance(Context context) {

        Annotate instance = context.get(annotateKey);

        if (instance == null)

            instance = new Annotate(context);

        return instance;

    }

    private final Attr attr;

    private final Check chk;

    private final ConstFold cfolder;

    private final DeferredLintHandler deferredLintHandler;

    private final Enter enter;

    private final Lint lint;

    private final Log log;

    private final Names names;

    private final Resolve resolve;

    private final TreeMaker make;

    private final Symtab syms;

    private final TypeEnvs typeEnvs;

    private final Types types;

    private final Attribute theUnfinishedDefaultValue;

    private final boolean allowRepeatedAnnos;

    private final String sourceName;

    protected Annotate(Context context) {

        context.put(annotateKey, this);

        attr = Attr.instance(context);

        chk = Check.instance(context);

        cfolder = ConstFold.instance(context);

        deferredLintHandler = DeferredLintHandler.instance(context);

        enter = Enter.instance(context);

        log = Log.instance(context);

        lint = Lint.instance(context);

        make = TreeMaker.instance(context);

        names = Names.instance(context);

        resolve = Resolve.instance(context);

        syms = Symtab.instance(context);

        typeEnvs = TypeEnvs.instance(context);

        types = Types.instance(context);

        theUnfinishedDefaultValue =  new Attribute.Error(syms.errType);

        Source source = Source.instance(context);

        allowRepeatedAnnos = source.allowRepeatedAnnotations();

        sourceName = source.name;

        blockCount = 1;

    }

    /** Semaphore to delay annotation processing */

    private int blockCount = 0;

    /** Called when annotations processing needs to be postponed. */

    public void blockAnnotations() {

        blockCount++;

    }

    /** Called when annotation processing can be resumed. */

    public void unblockAnnotations() {

        blockCount--;

        if (blockCount == 0)

            flush();

    }

    /** Variant which allows for a delayed flush of annotations.

     * Needed by ClassReader */

    public void unblockAnnotationsNoFlush() {

        blockCount--;

    }

    /** are we blocking annotation processing? */

    public boolean annotationsBlocked() {return blockCount > 0; }

    public void enterDone() {

        unblockAnnotations();

    }

    public List<TypeCompound> fromAnnotations(List<JCAnnotation> annotations) {

        if (annotations.isEmpty()) {

            return List.nil();

        }

        ListBuffer<TypeCompound> buf = new ListBuffer<>();

        for (JCAnnotation anno : annotations) {

            Assert.checkNonNull(anno.attribute);

            buf.append((TypeCompound) anno.attribute);

        }

        return buf.toList();

    }

    /** Annotate (used for everything else) */

    public void normal(Runnable r) {

        q.append(r);

    }

    /** Validate, triggers after 'normal' */

    public void validate(Runnable a) {

        validateQ.append(a);

    }

    /** Flush all annotation queues */

    public void flush() {

        if (annotationsBlocked()) return;

        if (isFlushing()) return;

        startFlushing();

        try {

            while (q.nonEmpty()) {

                q.next().run();

            }

            while (typesQ.nonEmpty()) {

                typesQ.next().run();

            }

            while (afterTypesQ.nonEmpty()) {

                afterTypesQ.next().run();

            }

            while (validateQ.nonEmpty()) {

                validateQ.next().run();

            }

        } finally {

            doneFlushing();

        }

    }

    private ListBuffer<Runnable> q = new ListBuffer<>();

    private ListBuffer<Runnable> validateQ = new ListBuffer<>();

    private int flushCount = 0;

    public boolean isFlushing() { return flushCount > 0; }

    private void startFlushing() { flushCount++; }

    private void doneFlushing() { flushCount--; }

    ListBuffer<Runnable> typesQ = new ListBuffer<>();

    ListBuffer<Runnable> afterTypesQ = new ListBuffer<>();

    public void typeAnnotation(Runnable a) {

        typesQ.append(a);

    }

    public void afterTypes(Runnable a) {

        afterTypesQ.append(a);

    }

    /**

     * Queue annotations for later attribution and entering. This is probably the method you are looking for.

     *

     * @param annotations the list of JCAnnotations to attribute and enter

     * @param localEnv    the enclosing env

     * @param s           ths Symbol on which to enter the annotations

     * @param deferPos    report errors here

     */

    public void annotateLater(List<JCAnnotation> annotations, Env<AttrContext> localEnv,

            Symbol s, DiagnosticPosition deferPos)

    {

        if (annotations.isEmpty()) {

            return;

        }

        s.resetAnnotations(); // mark Annotations as incomplete for now

        normal(() -> {

            // Packages are unusual, in that they are the only type of declaration that can legally appear

            // more than once in a compilation, and in all cases refer to the same underlying symbol.

            // This means they are the only kind of declaration that syntactically may have multiple sets

            // of annotations, each on a different package declaration, even though that is ultimately

            // forbidden by JLS 8 section 7.4.

            // The corollary here is that all of the annotations on a package symbol may have already

            // been handled, meaning that the set of annotations pending completion is now empty.

            Assert.check(s.kind == PCK || s.annotationsPendingCompletion());

            JavaFileObject prev = log.useSource(localEnv.toplevel.sourcefile);

            DiagnosticPosition prevLintPos =

                    deferPos != null

                            ? deferredLintHandler.setPos(deferPos)

                            : deferredLintHandler.immediate();

            Lint prevLint = deferPos != null ? null : chk.setLint(lint);

            try {

                if (s.hasAnnotations() && annotations.nonEmpty())

                    log.error(annotations.head.pos, "already.annotated", Kinds.kindName(s), s);

                Assert.checkNonNull(s, "Symbol argument to actualEnterAnnotations is null");

                // false is passed as fifth parameter since annotateLater is

                // never called for a type parameter

                annotateNow(s, annotations, localEnv, false, false);

            } finally {

                if (prevLint != null)

                    chk.setLint(prevLint);

                deferredLintHandler.setPos(prevLintPos);

                log.useSource(prev);

            }

        });

        validate(() -> { //validate annotations

            JavaFileObject prev = log.useSource(localEnv.toplevel.sourcefile);

            try {

                chk.validateAnnotations(annotations, s);

            } finally {

                log.useSource(prev);

            }

        });

    }

    /** Queue processing of an attribute default value. */

    public void annotateDefaultValueLater(JCExpression defaultValue, Env<AttrContext> localEnv,

            MethodSymbol m, DiagnosticPosition deferPos)

    {

        normal(() -> {

            JavaFileObject prev = log.useSource(localEnv.toplevel.sourcefile);

            DiagnosticPosition prevLintPos = deferredLintHandler.setPos(deferPos);

            try {

                enterDefaultValue(defaultValue, localEnv, m);

            } finally {

                deferredLintHandler.setPos(prevLintPos);

                log.useSource(prev);

            }

        });

        validate(() -> { //validate annotations

            JavaFileObject prev = log.useSource(localEnv.toplevel.sourcefile);

            try {

                // if default value is an annotation, check it is a well-formed

                // annotation value (e.g. no duplicate values, no missing values, etc.)

                chk.validateAnnotationTree(defaultValue);

            } finally {

                log.useSource(prev);

            }

        });

    }

    /** Enter a default value for an annotation element. */

    private void enterDefaultValue(JCExpression defaultValue,

            Env<AttrContext> localEnv, MethodSymbol m) {

        m.defaultValue = attributeAnnotationValue(m.type.getReturnType(), defaultValue, localEnv);

    }

    /**

     * Gather up annotations into a map from type symbols to lists of Compound attributes,

     * then continue on with repeating annotations processing.

     */

    private <T extends Attribute.Compound> void annotateNow(Symbol toAnnotate,

            List<JCAnnotation> withAnnotations, Env<AttrContext> env, boolean typeAnnotations,

            boolean isTypeParam)

    {

        Map<TypeSymbol, ListBuffer<T>> annotated = new LinkedHashMap<>();

        Map<T, DiagnosticPosition> pos = new HashMap<>();

        for (List<JCAnnotation> al = withAnnotations; !al.isEmpty(); al = al.tail) {

            JCAnnotation a = al.head;

            T c;

            if (typeAnnotations) {

                @SuppressWarnings("unchecked")

                T tmp = (T)attributeTypeAnnotation(a, syms.annotationType, env);

                c = tmp;

            } else {

                @SuppressWarnings("unchecked")

                T tmp = (T)attributeAnnotation(a, syms.annotationType, env);

                c = tmp;

            }

            Assert.checkNonNull(c, "Failed to create annotation");

            if (annotated.containsKey(a.type.tsym)) {

                if (!allowRepeatedAnnos) {

                    log.error(DiagnosticFlag.SOURCE_LEVEL, a.pos(), "repeatable.annotations.not.supported.in.source", sourceName);

                }

                ListBuffer<T> l = annotated.get(a.type.tsym);

                l = l.append(c);

                annotated.put(a.type.tsym, l);

                pos.put(c, a.pos());

            } else {

                annotated.put(a.type.tsym, ListBuffer.of(c));

                pos.put(c, a.pos());

            }

            // Note: @Deprecated has no effect on local variables and parameters

            if (!c.type.isErroneous()

                    && (toAnnotate.kind == MDL || toAnnotate.owner.kind != MTH)

                    && types.isSameType(c.type, syms.deprecatedType)) {

                toAnnotate.flags_field |= (Flags.DEPRECATED | Flags.DEPRECATED_ANNOTATION);

                Attribute fr = c.member(names.forRemoval);

                if (fr instanceof Attribute.Constant) {

                    Attribute.Constant v = (Attribute.Constant) fr;

                    if (v.type == syms.booleanType && ((Integer) v.value) != 0) {

                        toAnnotate.flags_field |= Flags.DEPRECATED_REMOVAL;

                    }

                }

            }

        }

        List<T> buf = List.nil();

        for (ListBuffer<T> lb : annotated.values()) {

            if (lb.size() == 1) {

                buf = buf.prepend(lb.first());

            } else {

                AnnotationContext<T> ctx = new AnnotationContext<>(env, annotated, pos, typeAnnotations);

                T res = makeContainerAnnotation(lb.toList(), ctx, toAnnotate, isTypeParam);

                if (res != null)

                    buf = buf.prepend(res);

            }

        }

        if (typeAnnotations) {

            @SuppressWarnings("unchecked")

            List<TypeCompound> attrs = (List<TypeCompound>)buf.reverse();

            toAnnotate.appendUniqueTypeAttributes(attrs);

        } else {

            @SuppressWarnings("unchecked")

            List<Attribute.Compound> attrs =  (List<Attribute.Compound>)buf.reverse();

            toAnnotate.resetAnnotations();

            toAnnotate.setDeclarationAttributes(attrs);

        }

    }

    /**

     * Attribute and store a semantic representation of the annotation tree {@code tree} into the

     * tree.attribute field.

     *

     * @param tree the tree representing an annotation

     * @param expectedAnnotationType the expected (super)type of the annotation

     * @param env the current env in where the annotation instance is found

     */

    public Attribute.Compound attributeAnnotation(JCAnnotation tree, Type expectedAnnotationType,

                                                  Env<AttrContext> env)

    {

        // The attribute might have been entered if it is Target or Repetable

        // Because TreeCopier does not copy type, redo this if type is null

        if (tree.attribute != null && tree.type != null)

            return tree.attribute;

        List<Pair<MethodSymbol, Attribute>> elems = attributeAnnotationValues(tree, expectedAnnotationType, env);

        Attribute.Compound ac = new Attribute.Compound(tree.type, elems);

        return tree.attribute = ac;

    }

    /** Attribute and store a semantic representation of the type annotation tree {@code tree} into

     * the tree.attribute field.

     *

     * @param a the tree representing an annotation

     * @param expectedAnnotationType the expected (super)type of the annotation

     * @param env the the current env in where the annotation instance is found

     */

    public Attribute.TypeCompound attributeTypeAnnotation(JCAnnotation a, Type expectedAnnotationType,

                                                          Env<AttrContext> env)

    {

        // The attribute might have been entered if it is Target or Repetable

        // Because TreeCopier does not copy type, redo this if type is null

        if (a.attribute == null || a.type == null || !(a.attribute instanceof Attribute.TypeCompound)) {

            // Create a new TypeCompound

            List<Pair<MethodSymbol,Attribute>> elems =

                    attributeAnnotationValues(a, expectedAnnotationType, env);

            Attribute.TypeCompound tc =

                    new Attribute.TypeCompound(a.type, elems, TypeAnnotationPosition.unknown);

            a.attribute = tc;

            return tc;

        } else {

            // Use an existing TypeCompound

            return (Attribute.TypeCompound)a.attribute;

        }

    }

    /**

     *  Attribute annotation elements creating a list of pairs of the Symbol representing that

     *  element and the value of that element as an Attribute. */

    private List<Pair<MethodSymbol, Attribute>> attributeAnnotationValues(JCAnnotation a,

            Type expected, Env<AttrContext> env)

    {

        // The annotation might have had its type attributed (but not

        // checked) by attr.attribAnnotationTypes during MemberEnter,

        // in which case we do not need to do it again.

        Type at = (a.annotationType.type != null ?

                a.annotationType.type : attr.attribType(a.annotationType, env));

        a.type = chk.checkType(a.annotationType.pos(), at, expected);

        boolean isError = a.type.isErroneous();

        if (!a.type.tsym.isAnnotationType() && !isError) {

            log.error(a.annotationType.pos(),

                    "not.annotation.type", a.type.toString());

            isError = true;

        }

        // List of name=value pairs (or implicit "value=" if size 1)

        List<JCExpression> args = a.args;

        boolean elidedValue = false;

        // special case: elided "value=" assumed

        if (args.length() == 1) {

            if (!args.head.hasTag(ASSIGN)) {

                args.head = make.at(Position.NOPOS).

                        Assign(make.Ident(names.value), args.head);

                elidedValue = true;

            } else if (args.head.pos == Position.NOPOS) {

                elidedValue = true;

            }

        }

        ListBuffer<Pair<MethodSymbol,Attribute>> buf = new ListBuffer<>();

        for (List<JCExpression> tl = args; tl.nonEmpty(); tl = tl.tail) {

            Pair<MethodSymbol, Attribute> p = attributeAnnotationNameValuePair(tl.head, a.type, isError, env, elidedValue);

            if (p != null && !p.fst.type.isErroneous())

                buf.append(p);

        }

        return buf.toList();

    }

    // where

    private Pair<MethodSymbol, Attribute> attributeAnnotationNameValuePair(JCExpression nameValuePair,

            Type thisAnnotationType, boolean badAnnotation, Env<AttrContext> env, boolean elidedValue)

    {

        if (!nameValuePair.hasTag(ASSIGN)) {

            log.error(nameValuePair.pos(), "annotation.value.must.be.name.value");

            attributeAnnotationValue(nameValuePair.type = syms.errType, nameValuePair, env);

            return null;

        }

        JCAssign assign = (JCAssign)nameValuePair;

        if (!assign.lhs.hasTag(IDENT)) {

            log.error(nameValuePair.pos(), "annotation.value.must.be.name.value");

            attributeAnnotationValue(nameValuePair.type = syms.errType, nameValuePair, env);

            return null;

        }

        // Resolve element to MethodSym

        JCIdent left = (JCIdent)assign.lhs;

        Symbol method = resolve.resolveQualifiedMethod(elidedValue ? assign.rhs.pos() : left.pos(),

                env, thisAnnotationType,

                left.name, List.nil(), null);

        left.sym = method;

        left.type = method.type;

        if (method.owner != thisAnnotationType.tsym && !badAnnotation)

            log.error(left.pos(), "no.annotation.member", left.name, thisAnnotationType);

        Type resultType = method.type.getReturnType();

        // Compute value part

        Attribute value = attributeAnnotationValue(resultType, assign.rhs, env);

        nameValuePair.type = resultType;

        return method.type.isErroneous() ? null : new Pair<>((MethodSymbol)method, value);

    }

    /** Attribute an annotation element value */

    private Attribute attributeAnnotationValue(Type expectedElementType, JCExpression tree,

            Env<AttrContext> env)

    {

        //first, try completing the symbol for the annotation value - if acompletion

        //error is thrown, we should recover gracefully, and display an

        //ordinary resolution diagnostic.

        try {

            expectedElementType.tsym.complete();

        } catch(CompletionFailure e) {

            log.error(tree.pos(), "cant.resolve", Kinds.kindName(e.sym), e.sym);

            expectedElementType = syms.errType;

        }

        if (expectedElementType.hasTag(ARRAY)) {

            return getAnnotationArrayValue(expectedElementType, tree, env);

        }

        //error recovery

        if (tree.hasTag(NEWARRAY)) {

            if (!expectedElementType.isErroneous())

                log.error(tree.pos(), "annotation.value.not.allowable.type");

            JCNewArray na = (JCNewArray)tree;

            if (na.elemtype != null) {

                log.error(na.elemtype.pos(), "new.not.allowed.in.annotation");

            }

            for (List<JCExpression> l = na.elems; l.nonEmpty(); l=l.tail) {

                attributeAnnotationValue(syms.errType,

                        l.head,

                        env);

            }

            return new Attribute.Error(syms.errType);

        }

        if (expectedElementType.tsym.isAnnotationType()) {

            if (tree.hasTag(ANNOTATION)) {

                return attributeAnnotation((JCAnnotation)tree, expectedElementType, env);

            } else {

                log.error(tree.pos(), "annotation.value.must.be.annotation");

                expectedElementType = syms.errType;

            }

        }

        //error recovery

        if (tree.hasTag(ANNOTATION)) {

            if (!expectedElementType.isErroneous())

                log.error(tree.pos(), "annotation.not.valid.for.type", expectedElementType);

            attributeAnnotation((JCAnnotation)tree, syms.errType, env);

            return new Attribute.Error(((JCAnnotation)tree).annotationType.type);

        }

        if (expectedElementType.isPrimitive() ||

                (types.isSameType(expectedElementType, syms.stringType) && !expectedElementType.hasTag(TypeTag.ERROR))) {

            return getAnnotationPrimitiveValue(expectedElementType, tree, env);

        }

        if (expectedElementType.tsym == syms.classType.tsym) {

            return getAnnotationClassValue(expectedElementType, tree, env);

        }

        if (expectedElementType.hasTag(CLASS) &&

                (expectedElementType.tsym.flags() & Flags.ENUM) != 0) {

            return getAnnotationEnumValue(expectedElementType, tree, env);

        }

        //error recovery:

        if (!expectedElementType.isErroneous())

            log.error(tree.pos(), "annotation.value.not.allowable.type");

        return new Attribute.Error(attr.attribExpr(tree, env, expectedElementType));

    }

    private Attribute getAnnotationEnumValue(Type expectedElementType, JCExpression tree, Env<AttrContext> env) {

        Type result = attr.attribExpr(tree, env, expectedElementType);

        Symbol sym = TreeInfo.symbol(tree);

        if (sym == null ||

                TreeInfo.nonstaticSelect(tree) ||

                sym.kind != VAR ||

                (sym.flags() & Flags.ENUM) == 0) {

            log.error(tree.pos(), "enum.annotation.must.be.enum.constant");

            return new Attribute.Error(result.getOriginalType());

        }

        VarSymbol enumerator = (VarSymbol) sym;

        return new Attribute.Enum(expectedElementType, enumerator);

    }

    private Attribute getAnnotationClassValue(Type expectedElementType, JCExpression tree, Env<AttrContext> env) {

        Type result = attr.attribExpr(tree, env, expectedElementType);

        if (result.isErroneous()) {

            // Does it look like an unresolved class literal?

            if (TreeInfo.name(tree) == names._class &&

                    ((JCFieldAccess) tree).selected.type.isErroneous()) {

                Name n = (((JCFieldAccess) tree).selected).type.tsym.flatName();

                return new Attribute.UnresolvedClass(expectedElementType,

                        types.createErrorType(n,

                                syms.unknownSymbol, syms.classType));

            } else {

                return new Attribute.Error(result.getOriginalType());

            }

        }

        // Class literals look like field accesses of a field named class

        // at the tree level

        if (TreeInfo.name(tree) != names._class) {

            log.error(tree.pos(), "annotation.value.must.be.class.literal");

            return new Attribute.Error(syms.errType);

        }

        return new Attribute.Class(types,

                (((JCFieldAccess) tree).selected).type);

    }

    private Attribute getAnnotationPrimitiveValue(Type expectedElementType, JCExpression tree, Env<AttrContext> env) {

        Type result = attr.attribExpr(tree, env, expectedElementType);

        if (result.isErroneous())

            return new Attribute.Error(result.getOriginalType());

        if (result.constValue() == null) {

            log.error(tree.pos(), "attribute.value.must.be.constant");

            return new Attribute.Error(expectedElementType);

        }

        result = cfolder.coerce(result, expectedElementType);

        return new Attribute.Constant(expectedElementType, result.constValue());

    }

    private Attribute getAnnotationArrayValue(Type expectedElementType, JCExpression tree, Env<AttrContext> env) {

        // Special case, implicit array

        if (!tree.hasTag(NEWARRAY)) {

            tree = make.at(tree.pos).

                    NewArray(null, List.nil(), List.of(tree));

        }

        JCNewArray na = (JCNewArray)tree;

        if (na.elemtype != null) {

            log.error(na.elemtype.pos(), "new.not.allowed.in.annotation");

        }

        ListBuffer<Attribute> buf = new ListBuffer<>();

        if (na.elems != null) {

            for (List<JCExpression> l = na.elems; l.nonEmpty(); l=l.tail) {

                buf.append(attributeAnnotationValue(types.elemtype(expectedElementType),

                        l.head,

                        env));

            }

        }

        na.type = expectedElementType;

        return new Attribute.

                Array(expectedElementType, buf.toArray(new Attribute[buf.length()]));

    }

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

     * Support for repeating annotations

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

    /**

     * This context contains all the information needed to synthesize new

     * annotations trees for repeating annotations.

     */

    private class AnnotationContext<T extends Attribute.Compound> {

        public final Env<AttrContext> env;

        public final Map<Symbol.TypeSymbol, ListBuffer<T>> annotated;

        public final Map<T, JCDiagnostic.DiagnosticPosition> pos;

        public final boolean isTypeCompound;

        public AnnotationContext(Env<AttrContext> env,

                                 Map<Symbol.TypeSymbol, ListBuffer<T>> annotated,

                                 Map<T, JCDiagnostic.DiagnosticPosition> pos,

                                 boolean isTypeCompound) {

            Assert.checkNonNull(env);

            Assert.checkNonNull(annotated);

            Assert.checkNonNull(pos);

            this.env = env;

            this.annotated = annotated;

            this.pos = pos;

            this.isTypeCompound = isTypeCompound;

        }

    }

    /* Process repeated annotations. This method returns the

     * synthesized container annotation or null IFF all repeating

     * annotation are invalid.  This method reports errors/warnings.

     */

    private <T extends Attribute.Compound> T processRepeatedAnnotations(List<T> annotations,

            AnnotationContext<T> ctx, Symbol on, boolean isTypeParam)

    {

        T firstOccurrence = annotations.head;

        List<Attribute> repeated = List.nil();

        Type origAnnoType = null;

        Type arrayOfOrigAnnoType = null;

        Type targetContainerType = null;

        MethodSymbol containerValueSymbol = null;

        Assert.check(!annotations.isEmpty() && !annotations.tail.isEmpty()); // i.e. size() > 1

        int count = 0;

        for (List<T> al = annotations; !al.isEmpty(); al = al.tail) {

            count++;

            // There must be more than a single anno in the annotation list

            Assert.check(count > 1 || !al.tail.isEmpty());

            T currentAnno = al.head;

            origAnnoType = currentAnno.type;

            if (arrayOfOrigAnnoType == null) {

                arrayOfOrigAnnoType = types.makeArrayType(origAnnoType);

            }

            // Only report errors if this isn't the first occurrence I.E. count > 1

            boolean reportError = count > 1;

            Type currentContainerType = getContainingType(currentAnno, ctx.pos.get(currentAnno), reportError);

            if (currentContainerType == null) {

                continue;

            }

            // Assert that the target Container is == for all repeated

            // annos of the same annotation type, the types should

            // come from the same Symbol, i.e. be '=='

            Assert.check(targetContainerType == null || currentContainerType == targetContainerType);

            targetContainerType = currentContainerType;

            containerValueSymbol = validateContainer(targetContainerType, origAnnoType, ctx.pos.get(currentAnno));

            if (containerValueSymbol == null) { // Check of CA type failed

                // errors are already reported

                continue;

            }

            repeated = repeated.prepend(currentAnno);

        }

        if (!repeated.isEmpty() && targetContainerType == null) {

            log.error(ctx.pos.get(annotations.head), "duplicate.annotation.invalid.repeated", origAnnoType);

            return null;

        }

        if (!repeated.isEmpty()) {

            repeated = repeated.reverse();

            DiagnosticPosition pos = ctx.pos.get(firstOccurrence);

            TreeMaker m = make.at(pos);

            Pair<MethodSymbol, Attribute> p =

                    new Pair<MethodSymbol, Attribute>(containerValueSymbol,

                            new Attribute.Array(arrayOfOrigAnnoType, repeated));

            if (ctx.isTypeCompound) {

                /* TODO: the following code would be cleaner:

                Attribute.TypeCompound at = new Attribute.TypeCompound(targetContainerType, List.of(p),

                        ((Attribute.TypeCompound)annotations.head).position);

                JCTypeAnnotation annoTree = m.TypeAnnotation(at);

                at = attributeTypeAnnotation(annoTree, targetContainerType, ctx.env);

                */

                // However, we directly construct the TypeCompound to keep the

                // direct relation to the contained TypeCompounds.

                Attribute.TypeCompound at = new Attribute.TypeCompound(targetContainerType, List.of(p),

                        ((Attribute.TypeCompound)annotations.head).position);

                JCAnnotation annoTree = m.TypeAnnotation(at);

                if (!chk.validateAnnotationDeferErrors(annoTree))

                    log.error(annoTree.pos(), Errors.DuplicateAnnotationInvalidRepeated(origAnnoType));

                if (!chk.isTypeAnnotation(annoTree, isTypeParam)) {

                    log.error(pos, isTypeParam ? Errors.InvalidRepeatableAnnotationNotApplicable(targetContainerType, on)

                                               : Errors.InvalidRepeatableAnnotationNotApplicableInContext(targetContainerType));

                }

                at.setSynthesized(true);

                @SuppressWarnings("unchecked")

                T x = (T) at;

                return x;

            } else {

                Attribute.Compound c = new Attribute.Compound(targetContainerType, List.of(p));

                JCAnnotation annoTree = m.Annotation(c);

                if (!chk.annotationApplicable(annoTree, on)) {

                    log.error(annoTree.pos(),

                              Errors.InvalidRepeatableAnnotationNotApplicable(targetContainerType, on));

                }

                if (!chk.validateAnnotationDeferErrors(annoTree))

                    log.error(annoTree.pos(), "duplicate.annotation.invalid.repeated", origAnnoType);

                c = attributeAnnotation(annoTree, targetContainerType, ctx.env);

                c.setSynthesized(true);

                @SuppressWarnings("unchecked")

                T x = (T) c;

                return x;

            }

        } else {

            return null; // errors should have been reported elsewhere

        }

    }

    /**

     * Fetches the actual Type that should be the containing annotation.

     */

    private Type getContainingType(Attribute.Compound currentAnno,

                                   DiagnosticPosition pos,

                                   boolean reportError)

    {

        Type origAnnoType = currentAnno.type;

        TypeSymbol origAnnoDecl = origAnnoType.tsym;

        // Fetch the Repeatable annotation from the current

        // annotation's declaration, or null if it has none

        Attribute.Compound ca = origAnnoDecl.getAnnotationTypeMetadata().getRepeatable();

        if (ca == null) { // has no Repeatable annotation

            if (reportError)

                log.error(pos, "duplicate.annotation.missing.container", origAnnoType, syms.repeatableType);

            return null;

        }

        return filterSame(extractContainingType(ca, pos, origAnnoDecl),

                origAnnoType);

    }

    // returns null if t is same as 's', returns 't' otherwise

    private Type filterSame(Type t, Type s) {

        if (t == null || s == null) {

            return t;

        }

        return types.isSameType(t, s) ? null : t;

    }

    /** Extract the actual Type to be used for a containing annotation. */

    private Type extractContainingType(Attribute.Compound ca,

                                       DiagnosticPosition pos,

                                       TypeSymbol annoDecl)

    {

        // The next three checks check that the Repeatable annotation

        // on the declaration of the annotation type that is repeating is

        // valid.

        // Repeatable must have at least one element

        if (ca.values.isEmpty()) {

            log.error(pos, "invalid.repeatable.annotation", annoDecl);

            return null;

        }

        Pair<MethodSymbol,Attribute> p = ca.values.head;

        Name name = p.fst.name;

        if (name != names.value) { // should contain only one element, named "value"

            log.error(pos, "invalid.repeatable.annotation", annoDecl);

            return null;

        }

        if (!(p.snd instanceof Attribute.Class)) { // check that the value of "value" is an Attribute.Class

            log.error(pos, "invalid.repeatable.annotation", annoDecl);

            return null;

        }

        return ((Attribute.Class)p.snd).getValue();

    }

    /* Validate that the suggested targetContainerType Type is a valid

     * container type for repeated instances of originalAnnoType

     * annotations. Return null and report errors if this is not the

     * case, return the MethodSymbol of the value element in

     * targetContainerType if it is suitable (this is needed to

     * synthesize the container). */

    private MethodSymbol validateContainer(Type targetContainerType,

                                           Type originalAnnoType,

                                           DiagnosticPosition pos) {

        MethodSymbol containerValueSymbol = null;

        boolean fatalError = false;

        // Validate that there is a (and only 1) value method

        Scope scope = targetContainerType.tsym.members();

        int nr_value_elems = 0;

        boolean error = false;

        for(Symbol elm : scope.getSymbolsByName(names.value)) {

            nr_value_elems++;

            if (nr_value_elems == 1 &&

                    elm.kind == MTH) {

                containerValueSymbol = (MethodSymbol)elm;

            } else {

                error = true;

            }

        }

        if (error) {

            log.error(pos,

                    "invalid.repeatable.annotation.multiple.values",

                    targetContainerType,

                    nr_value_elems);

            return null;

        } else if (nr_value_elems == 0) {

            log.error(pos,

                    "invalid.repeatable.annotation.no.value",

                    targetContainerType);

            return null;

        }

        // validate that the 'value' element is a method

        // probably "impossible" to fail this

        if (containerValueSymbol.kind != MTH) {

            log.error(pos,

                    "invalid.repeatable.annotation.invalid.value",

                    targetContainerType);

            fatalError = true;

        }

        // validate that the 'value' element has the correct return type

        // i.e. array of original anno

        Type valueRetType = containerValueSymbol.type.getReturnType();

        Type expectedType = types.makeArrayType(originalAnnoType);

        if (!(types.isArray(valueRetType) &&

                types.isSameType(expectedType, valueRetType))) {

            log.error(pos,

                    "invalid.repeatable.annotation.value.return",

                    targetContainerType,

                    valueRetType,

                    expectedType);

            fatalError = true;

        }

        return fatalError ? null : containerValueSymbol;

    }

    private <T extends Attribute.Compound> T makeContainerAnnotation(List<T> toBeReplaced,

            AnnotationContext<T> ctx, Symbol sym, boolean isTypeParam)

    {

        // Process repeated annotations

        T validRepeated =

                processRepeatedAnnotations(toBeReplaced, ctx, sym, isTypeParam);

        if (validRepeated != null) {

            // Check that the container isn't manually

            // present along with repeated instances of

            // its contained annotation.

            ListBuffer<T> manualContainer = ctx.annotated.get(validRepeated.type.tsym);

            if (manualContainer != null) {

                log.error(ctx.pos.get(manualContainer.first()),

                        "invalid.repeatable.annotation.repeated.and.container.present",

                        manualContainer.first().type.tsym);

            }

        }

        // A null return will delete the Placeholder

        return validRepeated;

    }

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

     * Type annotations *

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

    /**

     * Attribute the list of annotations and enter them onto s.

     */

    public void enterTypeAnnotations(List<JCAnnotation> annotations, Env<AttrContext> env,

            Symbol s, DiagnosticPosition deferPos, boolean isTypeParam)

    {

        Assert.checkNonNull(s, "Symbol argument to actualEnterTypeAnnotations is nul/");

        JavaFileObject prev = log.useSource(env.toplevel.sourcefile);

        DiagnosticPosition prevLintPos = null;

        if (deferPos != null) {

            prevLintPos = deferredLintHandler.setPos(deferPos);

        }

        try {

            annotateNow(s, annotations, env, true, isTypeParam);

        } finally {

            if (prevLintPos != null)

                deferredLintHandler.setPos(prevLintPos);

            log.useSource(prev);

        }

    }

    /**

     * Enqueue tree for scanning of type annotations, attaching to the Symbol sym.

     */

    public void queueScanTreeAndTypeAnnotate(JCTree tree, Env<AttrContext> env, Symbol sym,

            DiagnosticPosition deferPos)

    {

        Assert.checkNonNull(sym);

        normal(() -> tree.accept(new TypeAnnotate(env, sym, deferPos)));

    }

    /**