/*
    * SPDX-FileCopyrightText: none
    * SPDX-License-Identifier: CC0-1.0
    */
   
   package gov.nist.secauto.metaschema.core.metapath.cst;
   
   import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
   import gov.nist.secauto.metaschema.core.metapath.IExpression;
  import gov.nist.secauto.metaschema.core.metapath.item.IItem;
  import gov.nist.secauto.metaschema.core.metapath.item.ISequence;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  /**
   * A common base class for Metapath expression implementations, providing common
   * utility functions.
   */
  public abstract class AbstractExpression implements IExpression {
    @NonNull
    private final String text;
  
    /**
     * Construct a new expression.
     *
     * @param text
     *          the parsed text of the expression
     */
    public AbstractExpression(@NonNull String text) {
      this.text = text;
    }
  
    @Override
    public String getText() {
      return text;
    }
  
    @Override
    public String toString() {
      return CSTPrinter.toString(this);
    }
  
    @Override
    public ISequence<?> accept(DynamicContext dynamicContext, ISequence<?> focus) {
      dynamicContext.pushExecutionStack(this);
      try {
        return evaluate(dynamicContext, focus);
      } finally {
        dynamicContext.popExecutionStack(this);
      }
    }
  
    /**
     * Evaluate this expression, producing a sequence result.
     *
     * @param dynamicContext
     *          the dynamic evaluation context
     * @param focus
     *          the outer focus of the expression
     * @return the result of evaluation
     */
    @NonNull
    protected abstract ISequence<? extends IItem> evaluate(
        @NonNull DynamicContext dynamicContext,
        @NonNull ISequence<?> focus);
  }