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<!-- ErrorList user's guide -->
<!-- (C) 2001 Slava Pestov -->

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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">

<book>

<bookinfo><title>ErrorList plugin user's guide</title>

 <author><firstname>Slava</firstname><surname>Pestov</surname></author>

 <legalnotice><title>Legal Notice</title>
  <para>
   Permission is granted to copy, distribute and/or modify this document
   under the terms of the GNU Free Documentation License, Version 1.1 or
   any later version published by the Free Software Foundation; with no
   <quote>Invariant Sections</quote>, <quote>Front-Cover Texts</quote> or
   <quote>Back-Cover Texts</quote>, each as defined in the license. A copy of
   the license can be found in the file <filename>COPYING.DOC.txt</filename>
   included with jEdit.
  </para>
 </legalnotice>
</bookinfo>

<chapter id="intro"><title>Introduction</title>

 <para>
  The ErrorList plugin displays errors and warnings
  generated by other plugins. It does
  nothing on its own; for it to be useful, some plugins that support the
  error reporting API must be installed.
 </para>

 <para>
  The error reporting API is particularly well-suited to reporting compiler errors
  and such; plugins that use this API include Console, JCompiler, HTML and XML.
  If you would like to use it from your plugin, see <xref linkend="api" />.
 </para>

</chapter>

<chapter id="window"><title>The error list window</title>

 <para>
  <guimenu>Plugins</guimenu>&gt;<guisubmenu>Error
  List</guisubmenu>&gt;<guimenuitem>Error List</guimenuitem> displays the error
  list window. This window is floating by default, but it can be made to
  dock into the view in the <guibutton>Docking</guibutton> pane of the
  <guimenuitem>Global Options</guimenuitem> dialog box.
 </para>

 <para>
  Errors are shown in a tree control, with each branch being a file, and each
  leaf an error. Clicking on a file will open that file; clicking on an error
  will open the file containing the error and move the caret to its location.
 </para>

 <para>
  The error reporting API supports two types of errors; genuine errors and
  warnings. The two are differentiated with different-colored icons in the
  tree; errors have a red icon, warnings have a yellow one.
 </para>

 <para>
  For information on keyboard-based navigation of the tree, see
  <xref linkend="actions" />.
 </para>

</chapter>

<chapter id="highlight"><title>Error highlighting</title>

 <para>
  The ErrorList plugin also highlights errors in-place in the text area with
  a colored underline. The color depends on the error type; genuine errors
  have a red underline, warnings have a yellow one.
 </para>

 <para>
  Hovering the mouse over a line with an error highlight will show a tooltip
  with the error message.
 </para>

 <para>
  Error highlighting can be disabled in the <guibutton>Error List</guibutton> pane
  of the <guimenuitem>Global Options</guimenuitem> dialog box. The colors of
  the underlines can also be changed in that same option pane.
 </para>

</chapter>

<chapter id="actions"><title>Additional commands</title>

 <para>
  The ErrorList plugin provides a few additional commands that can be bound to
  keyboard shortcuts in the <guibutton>Shortcuts</guibutton> pane of the
  <guimenuitem>Global Options</guimenuitem> dialog box.
 </para>

 <para>
  <guimenu>Plugins</guimenu>&gt;<guisubmenu>Error
  List</guisubmenu>&gt;<guimenuitem>Go to Previous Error</guimenuitem> moves the
  caret to the error immediately before the one currently selected in the
  error list window. If no error is selected, the last error in the list is
  chosen. This will open the appropriate file if the error is in a
  different file.
 </para>

 <para>
  <guimenu>Plugins</guimenu>&gt;<guisubmenu>Error
  List</guisubmenu>&gt;<guimenuitem>Go to Next Error</guimenuitem> moves the
  caret to the error immediately after the one currently selected in the
  error list window. If no error is selected, the first error in the list is
  chosen. This will open the appropriate file if the error is in a
  different file.
 </para>

 <para>
  <guimenu>Plugins</guimenu>&gt;<guisubmenu>Error
  List</guisubmenu>&gt;<guimenuitem>Go to Previous File With Errors</guimenuitem>
  opens the file immediately before the one currently selected in the error
  list window. If no file is selected, the last file with errors is chosen.
 </para>

 <para>
  <guimenu>Plugins</guimenu>&gt;<guisubmenu>Error
  List</guisubmenu>&gt;<guimenuitem>Go to Next File With Errors</guimenuitem>
  opens the file immediately after the one currently selected in the error
  list window. If no file is selected, the first file with errors is chosen.
 </para>

</chapter>

<chapter id="api"><title>The error reporting API</title>

 <para>
  The error reporting API is very simple. A plugin that wishes to use it must
  do these three things:
 </para>

 <itemizedlist>

  <listitem><para>Specify that it requires the ErrorList and EditBus plugins.
  The error reporting API is spread between these two plugins for historical
  reasons.</para></listitem>

  <listitem><para>Register an <quote>error source</quote> at some stage,
  usually during startup.</para></listitem>

  <listitem><para>Add errors to the error source when they occur.</para></listitem>

 </itemizedlist>

 <para>
  The classes of the error reporting API, and the ErrorList plugin itself handle
  the rest automatically; displaying errors in a list, error highlighting, and
  so on.
 </para>

 <sect1 id="api-deps"><title>Specifying dependencies</title>

  <para>
   In order to give the user a helpful error message if the ErrorList
   plugin is not installed, your plugin should specify dependency properties.
   If your plugin's core class is named <classname>MyPlugin</classname>, the
   corresponding dependencies might look like so:
  </para>

  <programlisting>plugin.MyPlugin.depend.0=jedit 04.00.01.00
plugin.MyPlugin.depend.2=plugin ErrorListPlugin 1.2</programlisting>

  <para>
   Note that the current version of the ErrorList plugin requires jEdit 4.0pre1
   or later, so your plugin should also require at least that jEdit version.
   If a newer version of the ErrorList plugin is available, you can
   specify higher version numbers than in the example above. However, all the
   API calls in this chapter are guaranteed to work with the above version,
   so in most cases you shouldn't worry about it.
  </para>

 </sect1>

 <sect1 id="api-register"><title>Creating and registering an error source</title>

  <para>
   Errors are managed by implementations of the
   <classname>errorlist.ErrorSource</classname> abstract class.
   Extending this class is a bit involved and requires writing a lot of
   low-level code; most
   plugins can use the <classname>errorlist.DefaultErrorSource</classname>
   class instead, which provides a very easy-to-use front-end.
  </para>

  <para>
   The constructor for the <classname>DefaultErrorSource</classname> class
   accepts one parameter; a string that will identify the error source.
   Currently, this identifier is not used, but in the future the ErrorList plugin
   might show which error comes from which plugin, for example.
  </para>

  <para>
   Typically, error sources will be registered in your plugin's
   <function>start()</function> method, but that does not have to be the case.
   The Console plugin, for example, maintains a separate error source for each
   console window, and registers an unregisters them as consoles are opened
   and closed.
  </para>

  <para>
   To add an error source to the list of registered error sources, you must call
   the static <function>registerErrorSource()</function> method of the
   <classname>errorlist.ErrorSource</classname> class.
  </para>

  <para>
   A corresponding <function>unregisterErrorSource()()</function> method also
   exists, for advanced uses of the API, like the Console plugin mentioned
   above.
  </para>

  <para>
   Putting all this together, a simple plugin core class
   <function>start()</function> method
   might look as follows:
  </para>

  <programlisting>public void start()
{
    errorSource = new DefaultErrorSource("MyPlugin");
    ErrorSource.registerErrorSource(errorSource);

    // any other initialization your plugin
    // needs to perform
}</programlisting>

  <para>
   Note that the newly-created error source is assigned to an instance variable.
   This allows the error source instance to be called upon later, when
   compiler errors are actually generated.
  </para>

 </sect1>

 <sect1 id="api-report"><title>Reporting errors</title>

  <para>
   A custom <classname>ErrorSource</classname> implementation would need to
   send the appropriate EditBus message when an error arrives, and then
   provide implementations of various <quote>getter</quote> methods that
   the ErrorList plugin would later call to obtain the error.
   Using <classname>DefaultErrorSource</classname> makes the task much easier.
   In fact, all that is involved is calling a single method on the appropriate
   <classname>DefaultErrorSource</classname> instance:
  </para>

  <funcsynopsis>
   <funcprototype>
    <funcdef>public void <function>addError</function></funcdef>
    <paramdef>DefaultErrorSource.DefaultError <parameter>error</parameter></paramdef>
   </funcprototype>
  </funcsynopsis>

  <para>
   The constructor of the <classname>DefaultErrorSource.DefaultError</classname>
   class is as follows:
  </para>

  <funcsynopsis>
   <funcprototype>
    <funcdef>public <function>DefaultError</function></funcdef>
    <paramdef>int <parameter>type</parameter></paramdef>
    <paramdef>String <parameter>path</parameter></paramdef>
    <paramdef>int <parameter>line</parameter></paramdef>
    <paramdef>int <parameter>start</parameter></paramdef>
    <paramdef>int <parameter>end</parameter></paramdef>
    <paramdef>String <parameter>message</parameter></paramdef>
   </funcprototype>
  </funcsynopsis>

  <itemizedlist>
   <listitem><para><varname>type</varname> - this should be either
   <classname>ErrorSource.ERROR</classname> or
   <classname>ErrorSource.WARNING</classname>.</para></listitem>
   <listitem><para><varname>path</varname> - the path name or URL of
   the file containing the error. If this is a relative path, it will
   be qualified relative to the current working directory
   (<literal>user.dir</literal> system property). However, it is best to qualify
   it beforehand, using the <function>MiscUtilities.constructPath()</function>
   method.</para></listitem>
   <listitem><para><varname>line</varname> - the line number in the file
   where the error occurred. Lines are numbered starting from zero; since most
   tools and compilers report line numbers starting from 1, you might need to
   subtract 1 from the number before passing it to this method.</para></listitem>
   <listitem><para><varname>start</varname> - an offset in the line where
   the error begins.</para></listitem>
   <listitem><para><varname>end</varname> - an offset in the line where
   the error ends. These two values are only used to give a more exact
   display for error highlighting, and if both are zero, the entire line will be
   highlighted.</para></listitem>
   <listitem><para><varname>message</varname> - the error message itself,
   as shown in the error list window and error highlighting tooltips.
   </para></listitem>
  </itemizedlist>

  <para>
   This method is fully thread safe; if your plugin generates errors from
   another thread, it can call this method without having to use any of the
   usual <function>SwingUtilities.invokeLater()</function> tricks required
   when calling non-thread safe methods.
  </para>

  <para>
   Here are two examples of <function>addError()</function> calls. The first
   adds a warning, covering the entire line, the second adds an error that
   only applies to a subset of the specified line:
  </para>

  <programlisting>errorSource.addError(new ErrorSource.DefaultError(
    ErrorSource.WARNING,path,line,0,0,
    "Are you sure this is what you intended?"));
errorSource.addError(new ErrorSource.DefaultError(
    ErrorSource.WARNING,
    MiscUtilities.constructPath(directory,"input.src"),
    line,0,5,"First five characters of line are bad"));</programlisting>

  <para>
   Multiple-line messages can be created by calling the following method
   on the <classname>DefaultError</classname> instance before it is added
   to the error source (the last part is important, otherwise the extra
   messages will not be shown):
  </para>

  <funcsynopsis>
   <funcprototype>
    <funcdef>public void <function>addExtraMessage</function></funcdef>
    <paramdef>String <parameter>extra</parameter></paramdef>
   </funcprototype>
  </funcsynopsis>

  <para>
   That's basically all there is to it. There is one more method in the
   <classname>DefaultErrorSource</classname> class that needs to be mentioned:
  </para>

  <funcsynopsis>
   <funcprototype>
    <funcdef>public void <function>clear</function></funcdef>
    <void />
   </funcprototype>
  </funcsynopsis>

  <para>
   This method removes all errors from the error source. It is typically
   called before each invocation of the operation that generates errors;
   for example, the Console plugin clears its error source before each new
   command is run.
  </para>

  <para>
   This method reveals a limitation of the
   <classname>DefaultErrorSource</classname>
   class; errors cannot be removed selectively. The main reason this hasn't
   been implemented is lack of demand. If your plugin needs a means of only
   removing a subset of errors in an error source, feel free to modify the
   source for this class and contribute the changes back to the jEdit project.
  </para>

 </sect1>

</chapter>

<appendix id="changes"><title>Change log</title>

 <itemizedlist>

  <listitem><formalpara><title>Version 1.2.2</title><para>requires
  jEdit 4.0pre4.
  </para></formalpara>

  <itemizedlist>

    <listitem><para>Fixed possible <classname>NullPointerException</classname>
    under Java 2 version 1.4.
    </para></listitem>

    <listitem><para>Error highlight didn't work properly when soft wrap was
    enabled.
    </para></listitem>

    <listitem><para>If the <quote>show on error</quote> feature is enabled, the
    error list will now open in the currently focused view, not the most
    recently opened view as before.
    </para></listitem>

   </itemizedlist>

  </listitem>

  <listitem><formalpara><title>Version 1.2.1</title><para>requires
  jEdit 4.0pre4.
  </para></formalpara>

   <itemizedlist>
    <listitem><para>Updated to use jEdit 4.0pre4 text area extension API.
    </para></listitem>
   </itemizedlist>

  </listitem>

  <listitem><formalpara><title>Version 1.2</title><para>requires jEdit 4.0pre1.
  </para></formalpara>

   <itemizedlist>
    <listitem><para>Updated for jEdit 4.0 API changes.</para></listitem>
    <listitem><para>EditBus plugin merged with this one.</para></listitem>
    <listitem><para>Changes to error source API; see <xref linkend="api" />
    for details.</para></listitem>
   </itemizedlist>

  </listitem>

  <listitem><formalpara><title>Version 1.1.2</title><para>requires jEdit 3.2pre8
   and the EditBus plugin 1.1.</para></formalpara>

   <itemizedlist>
    <listitem><para>If the error list was open but not visible, the
    <guilabel>Show on error</guilabel> option would do nothing.</para></listitem>
    <listitem><para>If no error sources were registered, all highlights added
    after the error list would not be painted.</para></listitem>
   </itemizedlist>

  </listitem>

  <listitem><formalpara><title>Version 1.1.1</title><para>requires jEdit 3.2pre8
   and the EditBus plugin 1.1.</para></formalpara>

   <itemizedlist>
    <listitem><para>Line numbers in the tree are now increased by one, so that
    they match the textarea line numbers (Dirk Moebius)</para></listitem>
    <listitem><para>The commands "Next/Previous Error" and "Next/Previous File
    With Errors" now ensure that the newly selected error is visible
    (Dirk Moebius)</para></listitem>
    <listitem><para>Supports multiple-line error messages, introduced
    by EditBus 1.1</para></listitem>
   </itemizedlist>

  </listitem>

  <listitem><formalpara><title>Version 1.1</title><para>requires jEdit 3.2pre8
   and the EditBus plugin 1.0.1.</para></formalpara>

   <itemizedlist>
    <listitem><para>Errors are now shown in a tree, not a list</para></listitem>
    <listitem><para>Error highlighting does not highlight leading whitespace
    of lines, leading to better appearance</para></listitem>
    <listitem><para>Minor update for jEdit 3.2 selection API</para></listitem>
    <listitem><para>Documentation generated with DocBook</para></listitem>
    <listitem><para>Error reporting API documentation included</para></listitem>
   </itemizedlist>

  </listitem>

 </itemizedlist>

</appendix>

</book>