/*

 * Copyright (c) 2014, 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 jdk.jshell;

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

import com.sun.tools.javac.parser.JavacParser;

import com.sun.tools.javac.parser.ParserFactory;

import com.sun.tools.javac.parser.Tokens.Comment;

import com.sun.tools.javac.parser.Tokens.Comment.CommentStyle;

import com.sun.tools.javac.parser.Tokens.Token;

import static com.sun.tools.javac.parser.Tokens.TokenKind.CLASS;

import static com.sun.tools.javac.parser.Tokens.TokenKind.COLON;

import static com.sun.tools.javac.parser.Tokens.TokenKind.ENUM;

import static com.sun.tools.javac.parser.Tokens.TokenKind.EOF;

import static com.sun.tools.javac.parser.Tokens.TokenKind.IMPORT;

import static com.sun.tools.javac.parser.Tokens.TokenKind.INTERFACE;

import static com.sun.tools.javac.parser.Tokens.TokenKind.LPAREN;

import static com.sun.tools.javac.parser.Tokens.TokenKind.MONKEYS_AT;

import static com.sun.tools.javac.parser.Tokens.TokenKind.SEMI;

import static com.sun.tools.javac.parser.Tokens.TokenKind.VOID;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

/**

 * This is a subclass of JavacParser which overrides one method with a modified

 * verson of that method designed to allow parsing of one "snippet" of Java

 * code without the surrounding context of class, method, etc.

 * Accepts an expression, a statement, an import, or the declaration of a

 * method, variable, or type (class, interface, ...).

 */

class ReplParser extends JavacParser {

    // force starting in expression mode

    private final boolean forceExpression;

    public ReplParser(ParserFactory fac,

            com.sun.tools.javac.parser.Lexer S,

            boolean keepDocComments,

            boolean keepLineMap,

            boolean keepEndPositions,

            boolean forceExpression) {

        super(fac, S, keepDocComments, keepLineMap, keepEndPositions);

        this.forceExpression = forceExpression;

    }

    /**

     * As faithful a clone of the overridden method as possible while still

     * achieving the goal of allowing the parse of a stand-alone snippet.

     * As a result, some variables are assigned and never used, tests are

     * always true, loops don't, etc.  This is to allow easy transition as the

     * underlying method changes.

     * @return a snippet wrapped in a compilation unit

     */

    @Override

    public JCCompilationUnit parseCompilationUnit() {

        Token firstToken = token;

        JCModifiers mods = null;

        boolean seenImport = false;

        boolean seenPackage = false;

        ListBuffer<JCTree> defs = new ListBuffer<>();

        if (token.kind == MONKEYS_AT) {

            mods = modifiersOpt();

        }

        boolean firstTypeDecl = true;

        while (token.kind != EOF) {

            if (token.pos > 0 && token.pos <= endPosTable.errorEndPos) {

                // error recovery

                skip(true, false, false, false);

                if (token.kind == EOF) {

                    break;

                }

            }

            if (mods == null && token.kind == IMPORT) {

                seenImport = true;

                defs.append(importDeclaration());

            } else {

                Comment docComment = token.comment(CommentStyle.JAVADOC);

                if (firstTypeDecl && !seenImport && !seenPackage) {

                    docComment = firstToken.comment(CommentStyle.JAVADOC);

                }

                List<? extends JCTree> udefs = replUnit(mods, docComment);

               // if (def instanceof JCExpressionStatement)

                //     def = ((JCExpressionStatement)def).expr;

                for (JCTree def : udefs) {

                    defs.append(def);

                }

                mods = null;

                firstTypeDecl = false;

            }

            break;  // Remove to process more than one snippet

        }

        List<JCTree> rdefs = defs.toList();

        class ReplUnit extends JCCompilationUnit {

            public ReplUnit(List<JCTree> defs) {

                super(defs);

            }

        }

        JCCompilationUnit toplevel = new ReplUnit(rdefs);

        if (rdefs.isEmpty()) {

            storeEnd(toplevel, S.prevToken().endPos);

        }

        toplevel.lineMap = S.getLineMap();

        this.endPosTable.setParser(null); // remove reference to parser

        toplevel.endPositions = this.endPosTable;

        return toplevel;

    }

    @SuppressWarnings("fallthrough")

     List<? extends JCTree> replUnit(JCModifiers pmods, Comment dc) {

        switch (token.kind) {

            case EOF:

                return List.nil();

            case RBRACE:

            case CASE:

            case DEFAULT:

                // These are illegal, fall through to handle as illegal statement

            case LBRACE:

            case IF:

            case FOR:

            case WHILE:

            case DO:

            case TRY:

            case SWITCH:

            case RETURN:

            case THROW:

            case BREAK:

            case CONTINUE:

            case SEMI:

            case ELSE:

            case FINALLY:

            case CATCH:

            case ASSERT:

                return List.<JCTree>of(parseStatement());

            case SYNCHRONIZED:

                if (peekToken(LPAREN)) {

                    return List.<JCTree>of(parseStatement());

                }

                //fall-through

            default:

                JCModifiers mods = modifiersOpt(pmods);

                if (token.kind == CLASS

                        || token.kind == INTERFACE

                        || token.kind == ENUM) {

                    return List.<JCTree>of(classOrInterfaceOrEnumDeclaration(mods, dc));

                } else {

                    int pos = token.pos;

                    List<JCTypeParameter> typarams = typeParametersOpt();

                    // if there are type parameters but no modifiers, save the start

                    // position of the method in the modifiers.

                    if (typarams.nonEmpty() && mods.pos == Position.NOPOS) {

                        mods.pos = pos;

                        storeEnd(mods, pos);

                    }

                    List<JCAnnotation> annosAfterParams = annotationsOpt(Tag.ANNOTATION);

                    if (annosAfterParams.nonEmpty()) {

                        checkAnnotationsAfterTypeParams(annosAfterParams.head.pos);

                        mods.annotations = mods.annotations.appendList(annosAfterParams);

                        if (mods.pos == Position.NOPOS) {

                            mods.pos = mods.annotations.head.pos;

                        }

                    }

                    Token prevToken = token;

                    pos = token.pos;

                    JCExpression t;

                    boolean isVoid = token.kind == VOID;

                    if (isVoid) {

                        t = to(F.at(pos).TypeIdent(TypeTag.VOID));

                        nextToken();

                    } else {

                        // return type of method, declared type of variable, or an expression

                        // unless expression is being forced

                        t = term(forceExpression

                                ? EXPR

                                : EXPR | TYPE);

                    }

                    if (token.kind == COLON && t.hasTag(IDENT)) {

                        // labelled statement

                        nextToken();

                        JCStatement stat = parseStatement();

                        return List.<JCTree>of(F.at(pos).Labelled(prevToken.name(), stat));

                    } else if ((isVoid || (lastmode & TYPE) != 0) && LAX_IDENTIFIER.accepts(token.kind)) {

                        // we have "Type Ident", so we can assume it is variable or method declaration

                        pos = token.pos;

                        Name name = ident();

                        if (token.kind == LPAREN) {

                        // method declaration

                            //mods.flags |= Flags.STATIC;

                            return List.of(methodDeclaratorRest(

                                    pos, mods, t, name, typarams,

                                    false, isVoid, dc));

                        } else if (!isVoid && typarams.isEmpty()) {

                        // variable declaration

                            //mods.flags |= Flags.STATIC;

                            List<JCTree> defs

                                    = variableDeclaratorsRest(pos, mods, t, name, false, dc,

                                            new ListBuffer<JCTree>()).toList();

                            accept(SEMI);

                            storeEnd(defs.last(), S.prevToken().endPos);

                            return defs;

                        } else {

                            // malformed declaration, return error

                            pos = token.pos;

                            List<JCTree> err = isVoid

                                    ? List.of(toP(F.at(pos).MethodDef(mods, name, t, typarams,

                                                            List.nil(), List.nil(), null, null)))

                                    : null;

                            return List.<JCTree>of(syntaxError(token.pos, err, "expected", LPAREN));

                        }

                    } else if (!typarams.isEmpty()) {

                        // type parameters on non-variable non-method -- error

                        return List.<JCTree>of(syntaxError(token.pos, "illegal.start.of.type"));

                    } else {

                        // expression-statement or expression to evaluate

                        JCExpressionStatement expr = toP(F.at(pos).Exec(t));

                        return List.<JCTree>of(expr);

                    }

                }

        }

    }

}