package org.matheclipse.core.reflection.system;

import org.matheclipse.core.convert.AST2Expr;
import org.matheclipse.core.eval.exception.Validate;
import org.matheclipse.core.eval.interfaces.AbstractFunctionEvaluator;
import org.matheclipse.core.expression.F;
import org.matheclipse.core.interfaces.IAST;
import org.matheclipse.core.interfaces.IExpr;
import org.matheclipse.core.interfaces.IStringX;
import org.matheclipse.core.interfaces.ISymbol;
import org.matheclipse.parser.client.Parser;
import org.matheclipse.parser.client.SyntaxError;
import org.matheclipse.parser.client.ast.ASTNode;

import com.google.common.base.Predicate;

/**
 * Returns True, if the given expression is a string which has the
 * correct syntax
 * 
 */
public class SyntaxQ extends AbstractFunctionEvaluator implements Predicate {

	public SyntaxQ() {
	}

	@Override
	public IExpr evaluate(final IAST ast) {
		Validate.checkSize(ast, 2);
		
		if (!(ast.arg1() instanceof IStringX)) {
			return F.False;
		}
		return F.bool(apply(ast.arg1().toString()));
	}

	@Override
	public void setUp(final ISymbol symbol) {
		symbol.setAttributes(ISymbol.LISTABLE);
	}

	public boolean apply(final String str) {
		try {
			final Parser fParser = new Parser();
			final ASTNode parsedAST = fParser.parse(str);
			final IExpr parsedExpression = AST2Expr.CONST.convert(parsedAST);
			if (parsedExpression != null) {
				return true;
			}
		} catch (final SyntaxError e) {

		}
		return false;
	}

}