content: /*
   * Copyright (c) 2018-2020, the Alpha Team.
   * All rights reserved.
   *
   * Additional changes made by Siemens.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1) Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2) Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package at.ac.tuwien.kr.alpha.core.parser;
  
  import java.util.Collections;
  
  import org.antlr.v4.runtime.CharStreams;
  import org.antlr.v4.runtime.CommonTokenStream;
  import org.antlr.v4.runtime.ParserRuleContext;
  import org.antlr.v4.runtime.RecognitionException;
  import org.antlr.v4.runtime.misc.ParseCancellationException;
  
  import at.ac.tuwien.kr.alpha.api.programs.atoms.BasicAtom;
  import at.ac.tuwien.kr.alpha.api.programs.literals.Literal;
  import at.ac.tuwien.kr.alpha.api.programs.terms.Term;
  import at.ac.tuwien.kr.alpha.core.antlr.ASPCore2Lexer;
  import at.ac.tuwien.kr.alpha.core.antlr.ASPCore2Parser;
  
  /**
   * A parser that, in contrast to {@link ProgramParserImpl}, does not parse full programs but only program parts like
   * atoms, terms and such.
   */
  public class ProgramPartParser {
  	private final ParseTreeVisitor visitor = new ParseTreeVisitor(Collections.emptyMap(), true);
  
  	public Term parseTerm(String s) {
  		final ASPCore2Parser parser = getASPCore2Parser(s);
  		return (Term)parse(parser.term());
  	}
  
  	public BasicAtom parseBasicAtom(String s) {
  		final ASPCore2Parser parser = getASPCore2Parser(s);
  		return (BasicAtom) parse(parser.classical_literal());
  	}
  
  	public Literal parseLiteral(String s) {
  		final ASPCore2Parser parser = getASPCore2Parser(s);
  		return (Literal)parse(parser.naf_literal());
  	}
  
  	private ASPCore2Parser getASPCore2Parser(String s) {
  		return new ASPCore2Parser(new CommonTokenStream(new ASPCore2Lexer(CharStreams.fromString(s))));
  	}
  
  	private Object parse(ParserRuleContext context) {
  		try {
  			return visitor.visit(context);
  		} catch (RecognitionException | ParseCancellationException e) {
  			// If there were issues parsing the given string, we
  			// throw something that suggests that the input string
  			// is malformed.
  			throw new IllegalArgumentException("Could not parse term.", e);
  		}
  	}
  }
  