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These are Java extensions for use with the DocBook XML stylesheets and the Saxon XSLT engine.
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// UnwrapLinks.java - Saxon extension for unwrapping nested links

package com.nwalsh.saxon;

import javax.xml.transform.TransformerException;
import com.icl.saxon.Controller;
import com.icl.saxon.expr.Value;
import com.icl.saxon.expr.FragmentValue;
import com.icl.saxon.expr.NodeSetValue;
import com.icl.saxon.om.NamePool;
import com.icl.saxon.Context;
import com.icl.saxon.functions.Extensions;
import com.nwalsh.saxon.UnwrapLinksEmitter;

/**
 * Saxon extension for unwrapping nested links
 *
 * $Id: UnwrapLinks.java 8098 2008-08-03 13:27:07Z mzjn $
 *
 * Copyright (C) 2000, 2002 Norman Walsh.
 *
 * This class provides a
 * Saxon 6.*
 * implementation of a link unwrapper.
 *
 * Change Log:
 * 
 * 1.0
 * Initial release.
 * 
 *
 * @author Norman Walsh
 * [email protected]
 *
 * @version $Id: UnwrapLinks.java 8098 2008-08-03 13:27:07Z mzjn $
 *
 */
public class UnwrapLinks {
  /** True if the stylesheet is producing formatting objects */
  private static boolean foStylesheet = false;

  /**
   * Constructor for UnwrapLinks
   *
   * All of the methods are static, so the constructor does nothing.
   */
  public UnwrapLinks() {
  }

  /**
   * Find the string value of a stylesheet variable or parameter
   *
   * Returns the string value of varName in the current
   * context. Returns the empty string if the variable is
   * not defined.
   *
   * @param context The current stylesheet context
   * @param varName The name of the variable (without the dollar sign)
   *
   * @return The string value of the variable
   */
  protected static String getVariable(Context context, String varName) {
    Value variable = null;
    String varString = null;

    try {
      variable = Extensions.evaluate(context, "$" + varName);
      varString = variable.asString();
      return varString;
    } catch (TransformerException te) {
      System.out.println("Undefined variable: " + varName);
      return "";
    } catch (IllegalArgumentException iae) {
      System.out.println("Undefined variable: " + varName);
      return "";
    }
  }

  /**
   * Setup the parameters associated with unwrapping links
   *
   * @param context The current stylesheet context
   *
   */
  private static void setupUnwrapLinks(Context context) {
    // Get the stylesheet type
    String varString = getVariable(context, "stylesheet.result.type");
    foStylesheet = (varString.equals("fo"));
  }

  /**
   * Unwrap links
   *
   * @param context The current stylesheet context.
   * @param rtf_ns The result tree fragment of the verbatim environment.
   *
   * @return The modified result tree fragment.
   */
  public static NodeSetValue unwrapLinks (Context context,
					  NodeSetValue rtf_ns) {

    FragmentValue rtf = (FragmentValue) rtf_ns;
    boolean tryAgain = true;

    setupUnwrapLinks(context);

    try {
      Controller controller = context.getController();
      NamePool namePool = controller.getNamePool();

      while (tryAgain) {
	UnwrapLinksEmitter ulEmitter = new UnwrapLinksEmitter(controller,
							      namePool,
							      foStylesheet);
	rtf.replay(ulEmitter);
	tryAgain = ulEmitter.tryAgain();
	rtf = (FragmentValue) ulEmitter.getResultTreeFragment();
      }

      return rtf;

    } catch (TransformerException e) {
      // This "can't" happen.
      System.out.println("Transformer Exception in unwrapLinks");
      return rtf;
    }
  }
}