Java example source code file (Printer.java)

This example Java source code file (Printer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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Java - Java tags/keywords

arraytype, classtype, compound, listbuffer, locale, object, override, prime, printer, string, stringbuilder, symbol, type, unbound, util

The Printer.java Java example source code

/*
 * Copyright (c) 2009, 2013, 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.code;

import java.util.Locale;

import com.sun.tools.javac.api.Messages;
import com.sun.tools.javac.code.Type.AnnotatedType;
import com.sun.tools.javac.code.Type.ArrayType;
import com.sun.tools.javac.code.Symbol.*;
import com.sun.tools.javac.code.Type.*;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.ListBuffer;

import static com.sun.tools.javac.code.BoundKind.*;
import static com.sun.tools.javac.code.Flags.*;
import static com.sun.tools.javac.code.TypeTag.CLASS;
import static com.sun.tools.javac.code.TypeTag.FORALL;

/**
 * A combined type/symbol visitor for generating non-trivial localized string
 * representation of types and symbols.
 *
 * <p>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 abstract class Printer implements Type.Visitor<String, Locale>, Symbol.Visitor {

    List<Type> seenCaptured = List.nil();
    static final int PRIME = 997;  // largest prime less than 1000

    protected Printer() { }

    /**
     * This method should be overriden in order to provide proper i18n support.
     *
     * @param locale the locale in which the string is to be rendered
     * @param key the key corresponding to the message to be displayed
     * @param args a list of optional arguments
     * @return localized string representation
     */
    protected abstract String localize(Locale locale, String key, Object... args);

    /**
     * Maps a captured type into an unique identifier.
     *
     * @param t the captured type for which an id is to be retrieved
     * @param locale locale settings
     * @return unique id representing this captured type
     */
    protected abstract String capturedVarId(CapturedType t, Locale locale);

    /**
     * Create a printer with default i18n support provided by Messages. By default,
     * captured types ids are generated using hashcode.
     *
     * @param messages Messages class to be used for i18n
     * @return printer visitor instance
     */
    public static Printer createStandardPrinter(final Messages messages) {
        return new Printer() {
            @Override
            protected String localize(Locale locale, String key, Object... args) {
                return messages.getLocalizedString(locale, key, args);
            }

            @Override
            protected String capturedVarId(CapturedType t, Locale locale) {
                return (t.hashCode() & 0xFFFFFFFFL) % PRIME + "";
        }};
    }

    /**
     * Get a localized string representation for all the types in the input list.
     *
     * @param ts types to be displayed
     * @param locale the locale in which the string is to be rendered
     * @return localized string representation
     */
    public String visitTypes(List<Type> ts, Locale locale) {
        ListBuffer<String> sbuf = new ListBuffer<>();
        for (Type t : ts) {
            sbuf.append(visit(t, locale));
        }
        return sbuf.toList().toString();
    }

    /**
     * * Get a localized string representation for all the symbols in the input list.
     *
     * @param ts symbols to be displayed
     * @param locale the locale in which the string is to be rendered
     * @return localized string representation
     */
    public String visitSymbols(List<Symbol> ts, Locale locale) {
        ListBuffer<String> sbuf = new ListBuffer<>();
        for (Symbol t : ts) {
            sbuf.append(visit(t, locale));
        }
        return sbuf.toList().toString();
    }

    /**
     * Get a localized string representation for a given type.
     *
     * @param t type to be displayed
     * @param locale the locale in which the string is to be rendered
     * @return localized string representation
     */
    public String visit(Type t, Locale locale) {
        return t.accept(this, locale);
    }

    /**
     * Get a localized string representation for a given symbol.
     *
     * @param s symbol to be displayed
     * @param locale the locale in which the string is to be rendered
     * @return localized string representation
     */
    public String visit(Symbol s, Locale locale) {
        return s.accept(this, locale);
    }

    @Override
    public String visitCapturedType(CapturedType t, Locale locale) {
        if (seenCaptured.contains(t))
            return localize(locale, "compiler.misc.type.captureof.1",
                capturedVarId(t, locale));
        else {
            try {
                seenCaptured = seenCaptured.prepend(t);
                return localize(locale, "compiler.misc.type.captureof",
                    capturedVarId(t, locale),
                    visit(t.wildcard, locale));
            }
            finally {
                seenCaptured = seenCaptured.tail;
            }
        }
    }

    @Override
    public String visitForAll(ForAll t, Locale locale) {
        return "<" + visitTypes(t.tvars, locale) + ">" + visit(t.qtype, locale);
    }

    @Override
    public String visitUndetVar(UndetVar t, Locale locale) {
        if (t.inst != null) {
            return visit(t.inst, locale);
        } else {
            return visit(t.qtype, locale) + "?";
        }
    }

    @Override
    public String visitArrayType(ArrayType t, Locale locale) {
        StringBuilder res = new StringBuilder();
        printBaseElementType(t, res, locale);
        printBrackets(t, res, locale);
        return res.toString();
    }

    void printBaseElementType(Type t, StringBuilder sb, Locale locale) {
        Type arrel = t;
        while (arrel.hasTag(TypeTag.ARRAY)) {
            arrel = arrel.unannotatedType();
            arrel = ((ArrayType) arrel).elemtype;
        }
        sb.append(visit(arrel, locale));
    }

    void printBrackets(Type t, StringBuilder sb, Locale locale) {
        Type arrel = t;
        while (arrel.hasTag(TypeTag.ARRAY)) {
            if (arrel.isAnnotated()) {
                sb.append(' ');
                sb.append(arrel.getAnnotationMirrors());
                sb.append(' ');
            }
            sb.append("[]");
            arrel = arrel.unannotatedType();
            arrel = ((ArrayType) arrel).elemtype;
        }
    }

    @Override
    public String visitClassType(ClassType t, Locale locale) {
        StringBuilder buf = new StringBuilder();
        if (t.getEnclosingType().hasTag(CLASS) && t.tsym.owner.kind == Kinds.TYP) {
            buf.append(visit(t.getEnclosingType(), locale));
            buf.append('.');
            buf.append(className(t, false, locale));
        } else {
            buf.append(className(t, true, locale));
        }
        if (t.getTypeArguments().nonEmpty()) {
            buf.append('<');
            buf.append(visitTypes(t.getTypeArguments(), locale));
            buf.append('>');
        }
        return buf.toString();
    }

    @Override
    public String visitMethodType(MethodType t, Locale locale) {
        return "(" + printMethodArgs(t.argtypes, false, locale) + ")" + visit(t.restype, locale);
    }

    @Override
    public String visitPackageType(PackageType t, Locale locale) {
        return t.tsym.getQualifiedName().toString();
    }

    @Override
    public String visitWildcardType(WildcardType t, Locale locale) {
        StringBuilder s = new StringBuilder();
        s.append(t.kind);
        if (t.kind != UNBOUND) {
            s.append(visit(t.type, locale));
        }
        return s.toString();
    }

    @Override
    public String visitErrorType(ErrorType t, Locale locale) {
        return visitType(t, locale);
    }

    @Override
    public String visitTypeVar(TypeVar t, Locale locale) {
        return visitType(t, locale);
    }

    @Override
    public String visitAnnotatedType(AnnotatedType t, Locale locale) {
        if (t.getAnnotationMirrors().nonEmpty()) {
            if (t.unannotatedType().hasTag(TypeTag.ARRAY)) {
                StringBuilder res = new StringBuilder();
                printBaseElementType(t, res, locale);
                printBrackets(t, res, locale);
                return res.toString();
            } else if (t.unannotatedType().hasTag(TypeTag.CLASS) &&
                    t.unannotatedType().getEnclosingType() != Type.noType) {
                return visit(t.unannotatedType().getEnclosingType(), locale) +
                        ". " +
                        t.getAnnotationMirrors() +
                        " " + className((ClassType)t.unannotatedType(), false, locale);
            } else {
                return t.getAnnotationMirrors() + " " + visit(t.unannotatedType(), locale);
            }
        } else {
            return visit(t.unannotatedType(), locale);
        }
    }

    public String visitType(Type t, Locale locale) {
        String s = (t.tsym == null || t.tsym.name == null)
                ? localize(locale, "compiler.misc.type.none")
                : t.tsym.name.toString();
        return s;
    }

    /**
     * Converts a class name into a (possibly localized) string. Anonymous
     * inner classes get converted into a localized string.
     *
     * @param t the type of the class whose name is to be rendered
     * @param longform if set, the class' fullname is displayed - if unset the
     * short name is chosen (w/o package)
     * @param locale the locale in which the string is to be rendered
     * @return localized string representation
     */
    protected String className(ClassType t, boolean longform, Locale locale) {
        Symbol sym = t.tsym;
        if (sym.name.length() == 0 && (sym.flags() & COMPOUND) != 0) {
            StringBuilder s = new StringBuilder(visit(t.supertype_field, locale));
            for (List<Type> is = t.interfaces_field; is.nonEmpty(); is = is.tail) {
                s.append('&');
                s.append(visit(is.head, locale));
            }
            return s.toString();
        } else if (sym.name.length() == 0) {
            String s;
            ClassType norm = (ClassType) t.tsym.type;
            if (norm == null) {
                s = localize(locale, "compiler.misc.anonymous.class", (Object) null);
            } else if (norm.interfaces_field != null && norm.interfaces_field.nonEmpty()) {
                s = localize(locale, "compiler.misc.anonymous.class",
                        visit(norm.interfaces_field.head, locale));
            } else {
                s = localize(locale, "compiler.misc.anonymous.class",
                        visit(norm.supertype_field, locale));
            }
            return s;
        } else if (longform) {
            return sym.getQualifiedName().toString();
        } else {
            return sym.name.toString();
        }
    }

    /**
     * Converts a set of method argument types into their corresponding
     * localized string representation.
     *
     * @param args arguments to be rendered
     * @param varArgs if true, the last method argument is regarded as a vararg
     * @param locale the locale in which the string is to be rendered
     * @return localized string representation
     */
    protected String printMethodArgs(List<Type> args, boolean varArgs, Locale locale) {
        if (!varArgs) {
            return visitTypes(args, locale);
        } else {
            StringBuilder buf = new StringBuilder();
            while (args.tail.nonEmpty()) {
                buf.append(visit(args.head, locale));
                args = args.tail;
                buf.append(',');
            }
            if (args.head.unannotatedType().hasTag(TypeTag.ARRAY)) {
                buf.append(visit(((ArrayType) args.head.unannotatedType()).elemtype, locale));
                if (args.head.getAnnotationMirrors().nonEmpty()) {
                    buf.append(' ');
                    buf.append(args.head.getAnnotationMirrors());
                    buf.append(' ');
                }
                buf.append("...");
            } else {
                buf.append(visit(args.head, locale));
            }
            return buf.toString();
        }
    }

    @Override
    public String visitClassSymbol(ClassSymbol sym, Locale locale) {
        return sym.name.isEmpty()
                ? localize(locale, "compiler.misc.anonymous.class", sym.flatname)
                : sym.fullname.toString();
    }

    @Override
    public String visitMethodSymbol(MethodSymbol s, Locale locale) {
        if (s.isStaticOrInstanceInit()) {
            return s.owner.name.toString();
        } else {
            String ms = (s.name == s.name.table.names.init)
                    ? s.owner.name.toString()
                    : s.name.toString();
            if (s.type != null) {
                if (s.type.hasTag(FORALL)) {
                    ms = "<" + visitTypes(s.type.getTypeArguments(), locale) + ">" + ms;
                }
                ms += "(" + printMethodArgs(
                        s.type.getParameterTypes(),
                        (s.flags() & VARARGS) != 0,
                        locale) + ")";
            }
            return ms;
        }
    }

    @Override
    public String visitOperatorSymbol(OperatorSymbol s, Locale locale) {
        return visitMethodSymbol(s, locale);
    }

    @Override
    public String visitPackageSymbol(PackageSymbol s, Locale locale) {
        return s.isUnnamed()
                ? localize(locale, "compiler.misc.unnamed.package")
                : s.fullname.toString();
    }

    @Override
    public String visitTypeSymbol(TypeSymbol s, Locale locale) {
        return visitSymbol(s, locale);
    }

    @Override
    public String visitVarSymbol(VarSymbol s, Locale locale) {
        return visitSymbol(s, locale);
    }

    @Override
    public String visitSymbol(Symbol s, Locale locale) {
        return s.name.toString();
    }
}