booleanvalue.java

A framework written in Java for implementing high-level and dynamic languages, compiling them into J

// Copyright (c) 2002, 2003, 2006  Per M.A. Bothner.
// This is free software;  for terms and warranty disclaimer see ./COPYING.

package gnu.xquery.util;
import gnu.mapping.*;
import gnu.lists.*;
import gnu.math.Numeric;
import gnu.math.RealNum;
import gnu.kawa.xml.UntypedAtomic;
import gnu.expr.*;
import gnu.bytecode.Type;
import gnu.kawa.xml.XDataType;
import gnu.xquery.lang.XQuery;

public class BooleanValue extends Procedure1 implements CanInline
{
  public static final BooleanValue booleanValue =
    new BooleanValue("boolean-value");

  public BooleanValue (String name)
  {
    super(name);
  }

  public static boolean booleanValue(Object value)
  {
    if (value instanceof Boolean)
      return ((Boolean) value).booleanValue();
    if (value instanceof Number
        && (value instanceof RealNum || ! (value instanceof Numeric)))
      {
        double d = ((Number) value).doubleValue();
        return d != 0 && ! Double.isNaN(d);
      }
    if (value instanceof SeqPosition)
      return true;
    if (value instanceof String
        || value instanceof gnu.text.Path
        || value instanceof UntypedAtomic)
      return value.toString().length() > 0;
    if (value instanceof Values)
      {
	Values values = (Values) value;
	Object value1 = values.getPosNext(0);
	if (value1 == Sequence.eofValue)
	  return false;
	int next = values.nextDataIndex(0);
	if (next < 0)
	  return booleanValue(value1);
        if (value1 instanceof SeqPosition)
          return true;
      }
    throw new WrongType("fn:boolean", 1, value, "boolean-convertible-value");
  }

  public static boolean not(Object value)
  {
    return ! booleanValue(value);
  }

  public Object apply1(Object arg)
  {
    return booleanValue(arg) ? Boolean.TRUE : Boolean.FALSE;
  }

  public Expression inline (ApplyExp exp, ExpWalker walker)
  {
    Expression[] args = exp.getArgs();
    if (args.length == 1)
      {
        Expression arg = args[0];
        Type type = arg.getType();
        if (type == XDataType.booleanType)
          return arg;
        if (type == null)
          exp.setType(XDataType.booleanType);
        if (arg instanceof QuoteExp)
          {
            Object value = ((QuoteExp) arg).getValue();
            try
              {
                return booleanValue(value) ? XQuery.trueExp : XQuery.falseExp;
              }
            catch (Throwable ex)
              {
                String message = "cannot convert to a boolean";
                walker.getMessages().error('e', message);
                return new ErrorExp(message);
              }
          }
      }
    return exp;
  }
}