Class Mapping

basex-core/src/main/java/org/basex/query/expr/Mapping.java:21–248

Mapping expression. @author BaseX Team, BSD License @author Christian Gruen

 * @author Christian Gruen
 */
public abstract class Mapping extends Arr {
  /**
   * Constructor.
   * @param info input info (can be {@code null})
   * @param seqType sequence type
   * @param exprs expressions
   */
  Mapping(final InputInfo info, final SeqType seqType, final Expr... exprs) {
    super(info, seqType, exprs);
  }

  @Override
  public final void checkUp() throws QueryException {
    final int el = exprs.length;
    for(int e = 0; e < el - 1; e++) checkNoUp(exprs[e]);
    exprs[el - 1].checkUp();
  }

  @Override
  public final boolean vacuous() {
    return exprs[exprs.length - 1].vacuous();
  }

  @Override
  public final Expr compile(final CompileContext cc) throws QueryException {
    final int el = exprs.length;
    final boolean items = items();
    for(int e = 0; e < el; e++) {
      final Expr expr = cc.compileOrError(exprs[e], e == 0);
      if(e == 0) cc.pushFocus(expr, items);
      else cc.updateFocus(expr, items);
      exprs[e] = expr;
    }
    cc.removeFocus();
    return optimize(cc);
  }

  /**
   * Indicates if the expression maps items or values.
   * @return result of check
   */
  abstract boolean items();

  @Override
  public final boolean has(final Flag... flags) {
    // Context dependency, positional access: only check first expression.
    // Examples: . ! abc, position() ! a
    return Flag.FCS.oneOf(flags) ||
           Flag.CTX.oneOf(flags) && exprs[0].has(Flag.CTX) ||
           Flag.POS.oneOf(flags) && exprs[0].has(Flag.POS) ||
           super.has(Flag.remove(flags, Flag.POS, Flag.CTX));
  }

  @Override
  public final boolean accept(final ASTVisitor visitor) {
    visitor.enterFocus();
    if(!visitAll(visitor, exprs)) return false;
    visitor.exitFocus();