r.lang.primitive.parse.DeparsingVisitor.java Source code

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Here is the source code for r.lang.primitive.parse.DeparsingVisitor.java

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/*
 * R : A Computer Language for Statistical Data Analysis
 * Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 * Copyright (C) 1997--2008  The R Development Core Team
 * Copyright (C) 2003, 2004  The R Foundation
 * Copyright (C) 2010 bedatadriven
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package r.lang.primitive.parse;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.Iterables;
import r.lang.*;
import r.parser.ParseUtil;

import static com.google.common.collect.Iterables.transform;

public class DeparsingVisitor extends SexpVisitor<String> {

    private StringBuilder deparsed = new StringBuilder();

    public DeparsingVisitor(SEXP exp) {
        exp.accept(this);
    }

    @Override
    public void visit(CharExp charExp) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void visit(ComplexExp complexExp) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void visit(EnvExp envExp) {
        // this is somewhat random; it's isn't parsable in any case
        deparsed.append("<environment>");
    }

    @Override
    public void visit(ExpExp expSexp) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void visit(BuiltinExp builtinSexp) {
        throw new UnsupportedOperationException();
    }

    @Override
    public void visit(IntExp intExp) {
        appendVector(intExp, new ParseUtil.IntDeparser());
    }

    @Override
    public void visit(ListExp listExp) {
        deparsed.append("list(");
        boolean needsComma = false;
        for (SEXP sexp : listExp) {
            if (needsComma) {
                deparsed.append(", ");
            } else {
                needsComma = true;
            }
            sexp.accept(this);
        }
        deparsed.append(")");
    }

    @Override
    public void visit(NilExp nilExp) {
        deparsed.append("NULL");
    }

    @Override
    public void visit(PrimitiveSexp primitiveSexp) {
        super.visit(primitiveSexp);
    }

    @Override
    public void visit(PromExp promExp) {
        super.visit(promExp);
    }

    @Override
    public void visit(RealExp realExp) {
        appendVector(realExp, new ParseUtil.RealDeparser());
    }

    @Override
    public void visit(StringExp stringExp) {
        appendVector(stringExp, new ParseUtil.StringDeparser());
    }

    @Override
    public void visit(LogicalExp logicalExp) {
        appendVector(logicalExp, new ParseUtil.LogicalDeparser());
    }

    @Override
    public void visit(LangExp langExp) {
        super.visit(langExp);
    }

    @Override
    public void visit(SymbolExp symbolExp) {
        deparsed.append(symbolExp.getPrintName());
    }

    @Override
    public void visit(ClosureExp closureExp) {
        throw new UnsupportedOperationException("deparsing of closures not yet implemented");
    }

    @Override
    public String getResult() {
        return deparsed.toString();
    }

    public <T> void appendVector(Iterable<T> values, Function<T, String> deparser) {
        if (Iterables.size(values) == 1) {
            deparsed.append(deparser.apply(values.iterator().next()));
        } else {
            Joiner.on(", ").appendTo(deparsed, transform(values, deparser));
        }
    }

}