docs/manual/tasks/for.html


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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>Ant-contrib Tasks: For</title>
  </head>

  <body>
    <h1>For</h1>

    <p>The for task iterates over a list, a list of paths, or
      any type that has a public iterator() method.
      The list will be evaluated first.
      Nested paths are evaluated in the order they
      appear in the task.
      Nested types will then be evalulated.
    </p>
    <p>
      This task is the same as the &lt;foreach&gt; task, except that
      <ul>
        <li>it uses a nested sequential for each iteration; and
        <li>it implements an additional &quot;keepgoing&quot; attribute.
      </ul>
      &lt;for&gt; makes use of ant's macrodef task, so the @{} notation
      is used for parameter substition.
    </p>
    <p><em>
      This task only works for ant version greater than or equal
      to ant 1.6.0.
      </em>
    </p>

    <h2>Parameters</h2>
    <table border="1" cellpadding="2" cellspacing="0">
      <tr>
        <th>Attribute</th>
        <th>Description</th>
        <th>Required</th>
      </tr>
      <tr>
        <td valign="top">list</td>
        <td valign="top">The list of values to process, with the
        delimiter character, indicated by the &quot;delimiter&quot;
        attribute, separating each value.</td>
        <td align="center" valign="top" rowspan="2">Yes, one of these needs to
          be set, unless a nested path
          has been specified.</td>
      </tr>
      <tr>
        <td valign="top">end</td>
        <td valign="top">
          Sets the ending index value. If this attribute is
          set, the &lt;for&gt; task will loop from "start" (default 1)
          to "end", using "step" (default 1) increments.
        </td>
      </tr>
      <tr>
        <td valign="top">param</td>
        <td valign="top">Name of the parameter to pass the tokens or
        files in as to the sequential.</td>
        <td align="center" valign="top">Yes</td>
      </tr>
      <tr>
        <td valign="top">delimiter</td>
        <td valign="top">The delimiter characters that separates the
        values in the &quot;list&quot; attribute.  Each character in the
        supplied string can act as a delimiter.  This follows the semantics
        of the StringTokenizer class.</td>
        <td align="center" valign="top">No, defaults to &quot;,&quot;.</td>
      </tr>
      <tr>
        <td valign="top">parallel</td>
        <td valign="top">If <code>true</code>, all iterations of the nested
          &lt;sequential&gt;
          will execute in parallel.  Defaults to <code>false</code>,
        which forces sequential execution of the iterations.  It is up to
        the caller to ensure that parallel execution is safe.
        <td align="center" valign="top">No</td>
      </tr>
      <tr>
        <td valign="top">keepgoing</td>
        <td valign="top">If <code>true</code>, all iterations of the called
          &lt;sequential&gt; will be executed, even if a task in one or more of them fails.
          Defaults
          to <code>false</code>, which forces execution to stop as soon as a
          task fails.  At the end, if any iterator has failed, the &lt;for&gt;
          task will fail, otherwise &lt;for&gt; will succeed.
          <p>
            Note that execution does not proceed keepgoing from one task
            to the next within the &lt;sequential&gt, but rather from one iteration to the
            next.
          </p>
          <p>It is up to the caller to ensure that keepgoing execution is safe.</p>
        </td>
        <td align="center" valign="top">No</td>
      </tr>
      <tr>
        <td valign="top">threadCount</td>
        <td valign="top">The maximum number of allowable threads when executing
            in parallel.
        <td align="center" valign="top">No. Defaults to 5.</td>
      </tr>
      <tr>
        <td valign="top">trim</td>
        <td valign="top">If <code>true</code>, any leading or trailing
        whitespace will be removed from the list item before it is passed
        to the sequential.
        </td>
        <td align="center" valign="top">No. Defaults to false.</td>
      </tr>
      <tr>
        <td valign="top">begin</td>
        <td valign="top">
          Sets the starting index value. This in only used
          if the "end" attribute is set.
        </td>
        <td align="center" valign="top">No. Defaults to "1".</td>
      </tr>
      <tr>
        <td valign="top">step</td>
        <td valign="top">
          Sets the index increment step.
          This in only used if the "end" attribute is set.
        </td>
        <td align="center" valign="top">No. Defaults to "1".</td>
      </tr>
    </table>

    <h2>Parameters specified as nested elements</h2>

    <a name="path"><h3>path</h3></a>

    <p><a href="http://ant.apache.org/manual/using.html#path">Path</a>s
    are used to select sets of files or directories to iterate over.</p>

    <p>Using a path allows you to determine the order by which files
    are considered by using
    <a href="http://ant.apache.org/manual/CoreTypes/filelist.html">filelist</a>s
    or explicit <code>pathelements</code>.  You also can specify
    whether you want to iterate over files or directories by chosing
    either filesets or
    <a href="http://ant.apache.org/manual/CoreTypes/dirset.html">dirset</a>s.</p>
    <a name="fileset"><h3>fileset</h3></a>
    <p><a href="http://ant.apache.org/manual/CoreTypes/fileset.html">FileSet</a>s
    are used to select sets of files to iterate over.
    </p>
    <a name="fileset"><h3>dirset</h3></a>
    <p><a href="http://ant.apache.org/manual/CoreTypes/dirset.html">DirSet</a>s
    are used to select sets of directories to iterate over.
    </p>

    <a name="seqential"><h3>sequential</h3></a>
    This is the list of tasks to be run for each iteration of
    the list.
    <h3>Example</h3>
    <p>
      To print out the first five letters of the latin alphabet:
    </p>
    <blockquote>
      <pre>
&lt;echo message="The first five letters of the alphabet are:"/&gt;
&lt;for list="a,b,c,d,e" param="letter"&gt;
  &lt;sequential&gt;
    &lt;echo&gt;Letter @{letter}&lt;/echo&gt;
  &lt;/sequential&gt;
&lt;/for&gt;
        </pre>
      </blockquote>
      <p>
        A more complicated example to to iterate over a set
        of c++ source files and invoke the &lt;cc&gt; task on them:
      </p>
      <blockquote>
        <pre>
&lt;for param="file"&gt;
  &lt;path&gt;
    &lt;fileset dir="${test.dir}/mains" includes="*.cpp"/&gt;
  &lt;/path&gt;
  &lt;sequential&gt;
    &lt;propertyregex override="yes"
      property="program"  input="@{file}"
      regexp=".*/([^\.]*)\.cpp" replace="\1"/&gt;
    &lt;mkdir dir="${obj.dir}/${program}"/&gt;
    &lt;mkdir dir="${build.bin.dir}"/&gt;
    &lt;cc link="executable" objdir="${obj.dir}/${program}"
        outfile="${build.bin.dir}/${program}"&gt;
      &lt;compiler refid="compiler.options"/&gt;
      &lt;fileset file="@{file}"/&gt;
      &lt;linker refid="linker-libs"/&gt;
    &lt;/cc&gt;
  &lt;/sequential&gt;
&lt;/for&gt;
        </pre>
      </blockquote>
    The preceding example will stop as soon as one of the &lt;cc&gt; tasks fails.
    If you change the first line of the example to
        <pre>    &lt;for param="file" keepgoing="true"&gt;</pre>
    All iterations will be executed, and then &lt;for&gt; will fail if any one
    or more of the &lt;cc&gt; tasks failed.
    <p>
      The following example embeds an outofdate type and iterates over
      the sources that are newer than their corresponding targets.
    </p>

      <pre>
    &lt;ac:for param="xmlfile" xmlns:ac="antlib:net.sf.antcontrib"&gt;
      &lt;ac:outofdate&gt;
        &lt;ac:sourcefiles&gt;
          &lt;ac:fileset dir="${basedir}/xdocs" includes="**/*.xml"/&gt;
        &lt;/ac:sourcefiles&gt;
        &lt;ac:mapper dir="${basedir}/xdocs"
                   type="glob" from="*.xml" to="${basedir}/docs/*.html"/&gt;
      &lt;/ac:outofdate&gt;
      &lt;ac:sequential&gt;
        &lt;echo&gt;Need to generate a target html file from source file @{xmlfile}&lt;/echo&gt;
      &lt;/ac:sequential&gt;
    &lt;/ac:for&gt;
      </pre>

    <p>
      The following example loops from one to ten.
    </p>
    <pre>
    &lt;ac:for param="i" end="10"&gt;
      &lt;sequential&gt;
        &lt;echo&gt;i is @{i}&lt;/echo&gt;
      &lt;/sequential&gt;
    &lt;/ac:for&gt;
    </pre>
    <p>
      The following example counts down from 10 to 0 in steps of -2.
    </p>
    <pre>
    &lt;ac:for param="i" begin="10" step="-2" end="0"&gt;
      &lt;sequential&gt;
        &lt;echo&gt;i is @{i}&lt;/echo&gt;
      &lt;/sequential&gt;
    &lt;/ac:for&gt;
    </pre>
    <hr>
    <p align="center">Copyright &copy; 2003-2006 Ant-Contrib Project. All
    rights Reserved.</p>

  </body>
</html>