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 * Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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package com.sun.tools.javah;

import java.util.*;
import javax.lang.model.element.Name;
import javax.lang.model.element.TypeElement;
import javax.lang.model.type.ArrayType;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.NoType;
import javax.lang.model.type.PrimitiveType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.type.TypeVariable;
import javax.lang.model.type.TypeVisitor;
import javax.lang.model.util.Elements;
import javax.lang.model.util.SimpleTypeVisitor9;

import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;

Returns internal type signature.
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.
Author:
Sucheta Dambalkar/**
 * Returns internal type signature.
 *
 * <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>
 *
 * @author Sucheta Dambalkar
 */

public class TypeSignature {
    static class SignatureException extends Exception {
        private static final long serialVersionUID = 1L;
        SignatureException(String reason) {
            super(reason);
        }
    }

    Elements elems;

    /* Signature Characters */

    private static final String SIG_VOID                   = "V";
    private static final String SIG_BOOLEAN                = "Z";
    private static final String SIG_BYTE                   = "B";
    private static final String SIG_CHAR                   = "C";
    private static final String SIG_SHORT                  = "S";
    private static final String SIG_INT                    = "I";
    private static final String SIG_LONG                   = "J";
    private static final String SIG_FLOAT                  = "F";
    private static final String SIG_DOUBLE                 = "D";
    private static final String SIG_ARRAY                  = "[";
    private static final String SIG_CLASS                  = "L";



    public TypeSignature(Elements elems){
        this.elems = elems;
    }

    /*
     * Returns the type signature of a field according to JVM specs
     */
    public String getTypeSignature(String javasignature) throws SignatureException {
        return getParamJVMSignature(javasignature);
    }

    /*
     * Returns the type signature of a method according to JVM specs
     */
    public String getTypeSignature(String javasignature, TypeMirror returnType)
            throws SignatureException {
        String signature = null; //Java type signature.
        String typeSignature = null; //Internal type signature.
        List<String> params = new ArrayList<>(); //List of parameters.
        String paramsig = null; //Java parameter signature.
        String paramJVMSig = null; //Internal parameter signature.
        String returnSig = null; //Java return type signature.
        String returnJVMType = null; //Internal return type signature.
        int dimensions = 0; //Array dimension.

        int startIndex = -1;
        int endIndex = -1;
        StringTokenizer st = null;
        int i = 0;

        // Gets the actual java signature without parentheses.
        if (javasignature != null) {
            startIndex = javasignature.indexOf("(");
            endIndex = javasignature.indexOf(")");
        }

        if (((startIndex != -1) && (endIndex != -1))
            &&(startIndex+1 < javasignature.length())
            &&(endIndex < javasignature.length())) {
            signature = javasignature.substring(startIndex+1, endIndex);
        }

        // Separates parameters.
        if (signature != null) {
            if (signature.contains(",")) {
                st = new StringTokenizer(signature, ",");
                if (st != null) {
                    while (st.hasMoreTokens()) {
                        params.add(st.nextToken());
                    }
                }
            } else {
                params.add(signature);
            }
        }

        /* JVM type signature. */
        typeSignature = "(";

        // Gets indivisual internal parameter signature.
        while (params.isEmpty() != true) {
            paramsig = params.remove(i).trim();
            paramJVMSig  = getParamJVMSignature(paramsig);
            if (paramJVMSig != null) {
                typeSignature += paramJVMSig;
            }
        }

        typeSignature += ")";

        // Get internal return type signature.

        returnJVMType = "";
        if (returnType != null) {
            dimensions = dimensions(returnType);
        }

        //Gets array dimension of return type.
        while (dimensions-- > 0) {
            returnJVMType += "[";
        }
        if (returnType != null) {
            returnSig = qualifiedTypeName(returnType);
            returnJVMType += getComponentType(returnSig);
        } else {
            System.out.println("Invalid return type.");
        }

        typeSignature += returnJVMType;

        return typeSignature;
    }

    /*
     * Returns internal signature of a parameter.
     */
    private String getParamJVMSignature(String paramsig) throws SignatureException {
        String paramJVMSig = "";
        String componentType ="";

        if(paramsig != null){

            if(paramsig.contains("[]")) {
                // Gets array dimension.
                int endindex = paramsig.indexOf("[]");
                componentType = paramsig.substring(0, endindex);
                String dimensionString =  paramsig.substring(endindex);
                if(dimensionString != null){
                    while(dimensionString.contains("[]")){
                        paramJVMSig += "[";
                        int beginindex = dimensionString.indexOf("]") + 1;
                        if(beginindex < dimensionString.length()){
                            dimensionString = dimensionString.substring(beginindex);
                        }else
                            dimensionString = "";
                    }
                }
            } else componentType = paramsig;

            paramJVMSig += getComponentType(componentType);
        }
        return paramJVMSig;
    }

    /*
     * Returns internal signature of a component.
     */
    private String getComponentType(String componentType) throws SignatureException {

        String JVMSig = "";

        if(componentType != null){
            switch (componentType) {
                case "void":    JVMSig += SIG_VOID;    break;
                case "boolean": JVMSig += SIG_BOOLEAN; break;
                case "byte":    JVMSig += SIG_BYTE;    break;
                case "char":    JVMSig += SIG_CHAR;    break;
                case "short":   JVMSig += SIG_SHORT;   break;
                case "int":     JVMSig += SIG_INT;     break;
                case "long":    JVMSig += SIG_LONG;    break;
                case "float":   JVMSig += SIG_FLOAT;   break;
                case "double":  JVMSig += SIG_DOUBLE;  break;
                default:
                    if (!componentType.equals("")) {
                        TypeElement classNameDoc = elems.getTypeElement(componentType);

                        if (classNameDoc == null) {
                            throw new SignatureException(componentType);
                        }
                        else {
                            String classname = classNameDoc.getQualifiedName().toString();
                            String newclassname = classname.replace('.', '/');
                            JVMSig += "L";
                            JVMSig += newclassname;
                            JVMSig += ";";
                        }
                    }
                    break;
            }
        }
        return JVMSig;
    }

    int dimensions(TypeMirror t) {
        if (t.getKind() != TypeKind.ARRAY)
            return 0;
        return 1 + dimensions(((ArrayType) t).getComponentType());
    }


    String qualifiedTypeName(TypeMirror type) {
        TypeVisitor<Name, Void> v = new SimpleTypeVisitor9<Name, Void>() {
            @Override @DefinedBy(Api.LANGUAGE_MODEL)
            public Name visitArray(ArrayType t, Void p) {
                return t.getComponentType().accept(this, p);
            }

            @Override @DefinedBy(Api.LANGUAGE_MODEL)
            public Name visitDeclared(DeclaredType t, Void p) {
                return ((TypeElement) t.asElement()).getQualifiedName();
            }

            @Override @DefinedBy(Api.LANGUAGE_MODEL)
            public Name visitPrimitive(PrimitiveType t, Void p) {
                return elems.getName(t.toString());
            }

            @Override @DefinedBy(Api.LANGUAGE_MODEL)
            public Name visitNoType(NoType t, Void p) {
                if (t.getKind() == TypeKind.VOID)
                    return elems.getName("void");
                return defaultAction(t, p);
            }

            @Override @DefinedBy(Api.LANGUAGE_MODEL)
            public Name visitTypeVariable(TypeVariable t, Void p) {
                return t.getUpperBound().accept(this, p);
            }
        };
        return v.visit(type).toString();
    }
}