Selectors are a mechanism whereby the files that make up a fileset<depend>
    can be selected based on criteria other than filename as provided
    by the <include> and <exclude>
    tags.
A selector is an element of FileSet, and appears within it. It can
    also be defined outside of any target by using the <selector> tag
    and then using it as a reference.
    
Different selectors have different attributes. Some selectors can
    contain other selectors, and these are called
    Selector Containers.
    There is also a category of selectors that allow
    user-defined extensions, called
    Custom Selectors.
    The ones built in to Ant are called
    Core Selectors.
    
Core selectors are the ones that come standard with Ant. They can be used within a fileset and can be contained within Selector Containers.
The core selectors are:
<contains> - Select
        files that contain a particular text string<date> - Select files
        that have been modified either before or after a particular date
        and time<depend> - Select files
        that have been modified more recently than equivalent files
        elsewhere<depth> - Select files
        that appear so many directories down in a directory tree<different> - Select files
        that are different from those elsewhere<filename> - Select
        files whose name matches a particular pattern. Equivalent to
        the include and exclude elements of a patternset.<present> - Select
        files that either do or do not exist in some other location<containsregexp> - Select
        files that match a regular expression<size> - Select files
        that are larger or smaller than a particular number of bytes.<type> - Select files
        that are either regular files or directories.<modified> - Select files if
        the return value of the configured algorithm is different from that
        stored in a cache.The <contains> tag in a FileSet limits
    the files defined by that fileset to only those which contain the
    string specified by the text attribute.
    .
| Attribute | Description | Required | 
| text | Specifies the text that every file must contain | Yes | 
| casesensitive | Whether to pay attention to case when looking
          for the string in the textattribute. Default is
          true. | No | 
| ignorewhitespace | Whether to eliminate whitespace before checking
          for the string in the textattribute. Default is
          false. | No | 
Here is an example of how to use the Contains Selector:
<fileset dir="${doc.path}" includes="**/*.html">
    <contains text="script" casesensitive="no"/>
</fileset>
Selects all the HTML files that contain the string
    script.
The <date> tag in a FileSet will put
    a limit on the files specified by the include tag, so that tags
    whose last modified date does not meet the date limits specified
    by the selector will not end up being selected.
| Attribute | Description | Required | 
| datetime | Specifies the date and time to test for. Should be in the format MM/DD/YYYY HH:MM AM_or_PM, or an alternative pattern specified via the pattern attribute. | At least one of the two. | 
| millis | The number of milliseconds since 1970 that should be tested for. It is usually much easier to use the datetime attribute. | |
| when | Indicates how to interpret the date, whether
          the files to be selected are those whose last modified times should
          be before, after, or equal to the specified value. Acceptable
          values for this attribute are: 
 | No | 
| granularity | The number of milliseconds leeway to use when comparing file modification times. This is needed because not every file system supports tracking the last modified time to the millisecond level. Default is 0 milliseconds, or 2 seconds on DOS systems. | No | 
| pattern | The SimpleDateFormat-compatible pattern
          to use when interpreting the datetime attribute.
          Since Ant 1.6.2 | No | 
| checkdirs | Indicates whether or not to check dates on directories. | No, defaults to false | 
Here is an example of how to use the Date Selector:
<fileset dir="${jar.path}" includes="**/*.jar">
    <date datetime="01/01/2001 12:00 AM" when="before"/>
</fileset>
Selects all JAR files which were last modified before midnight January 1, 2001.
The <depend> tag selects files
    whose last modified date is later than another, equivalent file in
    another location.
The <depend> tag supports the use of a
    contained <mapper> element
    to define the location of the file to be compared against. If no
    <mapper> element is specified, the
    identity type mapper is used.
The <depend> selector is case-sensitive.
| Attribute | Description | Required | 
| targetdir | The base directory to look for the files to compare
          against. The precise location depends on a combination of this
          attribute and the <mapper>element, if any. | Yes | 
| granularity | The number of milliseconds leeway to give before deciding a file is out of date. This is needed because not every file system supports tracking the last modified time to the millisecond level. Default is 0 milliseconds, or 2 seconds on DOS systems. | No | 
Here is an example of how to use the Depend Selector:
<fileset dir="${ant.1.5}/src/main" includes="**/*.java">
    <depend targetdir="${ant.1.4.1}/src/main"/>
</fileset>
Selects all the Java source files which were modified in the 1.5 release.
The <depth> tag selects files based on
    how many directy levels deep they are in relation to the base
    directory of the fileset.
    
| Attribute | Description | Required | 
| min | The minimum number of directory levels below the base directory that a file must be in order to be selected. Default is no limit. | At least one of the two. | 
| max | The maximum number of directory levels below the base directory that a file can be and still be selected. Default is no limit. | 
Here is an example of how to use the Depth Selector:
<fileset dir="${doc.path}" includes="**/*">
    <depth max="1"/>
</fileset>
Selects all files in the base directory and one directory below that.
The <different> tag selects files
    who are deemed to be 'different' from another, equivalent file in
    another location. The rules for determining difference between two
    files are as follows:
    
<copy> task, set the preservelastmodified to propagate the timestamp
    from source file to destintaion file.
    
    The <different> tag supports the use of a
    contained <mapper> element
    to define the location of the file to be compared against. If no
    <mapper> element is specified, the
    identity type mapper is used.
| Attribute | Description | Required | 
| targetdir | The base directory to look for the files to compare
          against. The precise location depends on a combination of this
          attribute and the <mapper>element, if any. | Yes | 
| ignoreFileTimes | Whether to use file times in the comparison or not. Default is true (time differences are ignored). | No | 
| ignoreContents | Whether to do a byte per byte compare. Default is false (contents are compared). Since ant 1.6.3 | No | 
| granularity | The number of milliseconds leeway to give before deciding a file is out of date. This is needed because not every file system supports tracking the last modified time to the millisecond level. Default is 0 milliseconds, or 2 seconds on DOS systems. | No | 
Here is an example of how to use the Different Selector:
<fileset dir="${ant.1.5}/src/main" includes="**/*.java">
    <different targetdir="${ant.1.4.1}/src/main"
        ignoreFileTimes="true"/>
</fileset>
Compares all the Java source files between the 1.4.1 and the 1.5 release and selects those who are different, disregarding file times.
The <filename> tag acts like the
    <include> and <exclude>
    tags within a fileset. By using a selector instead, however,
    one can combine it with all the other selectors using whatever
    selector container is desired.
    
The <filename> selector is
    case-sensitive.
| Attribute | Description | Required | 
| name | The name of files to select. The name parameter can contain the standard Ant wildcard characters. | Yes | 
| casesensitive | Whether to pay attention to case when looking at file names. Default is "true". | No | 
| negate | Whether to reverse the effects of this filename selection, therefore emulating an exclude rather than include tag. Default is "false". | No | 
Here is an example of how to use the Filename Selector:
<fileset dir="${doc.path}" includes="**/*">
    <filename name="**/*.css"/>
</fileset>
Selects all the cascading style sheet files.
The <present> tag selects files
    that have an equivalent file in another directory tree.
The <present> tag supports the use of a
    contained <mapper> element
    to define the location of the file to be tested against. If no
    <mapper> element is specified, the
    identity type mapper is used.
The <present> selector is case-sensitive.
| Attribute | Description | Required | 
| targetdir | The base directory to look for the files to compare
          against. The precise location depends on a combination of this
          attribute and the <mapper>element, if any. | Yes | 
| present | Whether we are requiring that a file is present in
          the src directory tree only, or in both the src and the target
          directory tree. Valid values are: 
 <not>selector container. | No | 
Here is an example of how to use the Present Selector:
<fileset dir="${ant.1.5}/src/main" includes="**/*.java">
    <present present="srconly" targetdir="${ant.1.4.1}/src/main"/>
</fileset>
Selects all the Java source files which are new in the 1.5 release.
The <containsregexp> tag in a FileSet limits
    the files defined by that fileset to only those which contain a
    match to the regular expression specified by the expression attribute.
    
| Attribute | Description | Required | 
| expression | Specifies the regular expression that must match true in every file | Yes | 
Here is an example of how to use the regular expression Selector:
<fileset dir="${doc.path}" includes="*.txt">
    <containsregexp expression="[4-6]\.[0-9]"/>
</fileset>
Selects all the text files that match the regular expression (have a 4,5 or 6 followed by a period and a number from 0 to 9).
The <size> tag in a FileSet will put
    a limit on the files specified by the include tag, so that tags
    which do not meet the size limits specified by the selector will not
    end up being selected.
| Attribute | Description | Required | 
| value | The size of the file which should be tested for. | Yes | 
| units | The units that the valueattribute
          is expressed in. When using the standard single letter SI
          designations, such as "k","M", or
          "G", multiples of 1000 are used. If you want to use
          power of 2 units, use the IEC standard: "Ki" for 1024,
          "Mi" for 1048576, and so on. The default is no units,
          which means thevalueattribute expresses the exact
          number of bytes. | No | 
| when | Indicates how to interpret the size, whether
          the files to be selected should be larger, smaller, or equal to
          that value. Acceptable values for this attribute are: 
 | No | 
Here is an example of how to use the Size Selector:
<fileset dir="${jar.path}">
  <patternset>
    <include name="**/*.jar"/>
  </patternset>
  <size value="4" units="Ki" when="more"/>
</fileset>
Selects all JAR files that are larger than 4096 bytes.
The <type> tag selects files of a certain type:
    directory or regular.
| Attribute | Description | Required | 
| type | The type of file which should be tested for.
            Acceptable values are: 
 | Yes | 
Here is an example of how to use the Type Selector to select only
    directories in ${src}
<fileset dir="${src}">
  <type type="dir"/>
</fileset>
The Type Selector is often used in conjunction with other selectors.
    For example, to select files that also exist in a template
    directory, but avoid selecting empty directories, use:
<fileset dir="${src}">
    <and>
        <present targetdir="template"/>
        <type type="file"/>
    </and>
</fileset>
The <modified> selector computes a value for a file, compares that
    to the value stored in a cache and select the file, if these two values
    differ.
Because this selector is highly configurable the order in which the selection is done is:
| Attribute | Description | Required | 
| algorithm | The type of algorithm should be used.
            Acceptable values are (further information see later): 
 | No, defaults to digest | 
| cache | The type of cache should be used.
            Acceptable values are (further information see later): 
 | No, defaults to propertyfile | 
| comparator | The type of comparator should be used.
            Acceptable values are (further information see later): 
 | No, defaults to equal | 
| update | Should the cache be updated when values differ? (boolean) | No, defaults to true | 
| seldirs | Should directories be selected? (boolean) | No, defaults to true | 
These attributes can be set with nested <param/> tags. With <param/>
    tags you can set other values too - as long as they are named according to
    the following rules: 
| Algorithm's | |
| Name | Description | 
| hashvalue | Reads the content of a file into a java.lang.String and use thats hashValue(). No additional configuration required. | 
| digest | Uses java.security.MessageDigest. This Algorithm supports
          the following attributes: 
 | 
| Cache's | |
| propertyfile | Use the java.util.Properties class and its possibility
          to load and store to file.
          This Cache implementation supports the following attributes: 
 | 
| Comparator's | |
| equal | Very simple object comparison. | 
| rule | Uses java.text.RuleBasedCollator for Object comparison. | 
Here are some examples of how to use the Modified Selector:
    <copy todir="dest">
        <fileset dir="src">
            <modified/>
        </fileset>
    </copy>
    This will copy all files from src to dest which content has changed. Using an updating PropertyfileCache with cache.properties and MD5-DigestAlgorithm.
    <copy todir="dest">
        <fileset dir="src">
            <modified update="true"
                      seldirs="true"
                      cache="propertyfile"
                      algorithm="digest"
                      comparator="equal">
                <param name="cache.cachefile"     value="cache.properties"/>
                <param name="algorithm.algorithm" value="MD5"/>
            </modified>
        </fileset>
    </copy>
    This is the same example rewritten as CoreSelector with setting the all the values (same as defaults are).
    <copy todir="dest">
        <fileset dir="src">
            <custom class="org.apache.tools.ant.types.selectors.modifiedselector.ModifiedSelector">
                <param name="update"     value="true"/>
                <param name="seldirs"    value="true"/>
                <param name="cache"      value="propertyfile"/>
                <param name="algorithm"  value="digest"/>
                <param name="comparator" value="equal"/>
                <param name="cache.cachefile"     value="cache.properties"/>
                <param name="algorithm.algorithm" value="MD5"/>
            </custom>
        </fileset>
    </copy>
    And this is the same rewritten as CustomSelector.
  <target name="generate-and-upload-site">
      <echo> generate the site using forrest </echo>
      <antcall target="site"/>
      <echo> upload the changed file </echo>
      <ftp server="${ftp.server}" userid="${ftp.user}" password="${ftp.pwd}">
          <fileset dir="htdocs/manual">
              <modified/>
          </fileset>
      </ftp>
  </target>
    A useful scenario for this selector inside a build environment for homepage generation (e.g. with Apache Forrest). Here all changed files are uploaded to the server. The CacheSelector saves therefore much upload time.
To create more complex selections, a variety of selectors that contain other selectors are available for your use. They combine the selections of their child selectors in various ways.
The selector containers are:
<and> - select a file only if all
        the contained selectors select it.
      <majority> - select a file
        if a majority of its selectors select it.
      <none> - select a file only if
        none of the contained selectors select it.
      <not> - can contain only one
        selector, and reverses what it selects and doesn't select.
      <or> - selects a file if any one
        of the contained selectors selects it.
      <selector> - contains only one
        selector and forwards all requests to it without alteration, provided
        that any "if" or
        "unless" conditions are met. This
        is the selector to use if you want to define a reference. It is
        usable as an element of <project>. It is also
        the one to use if you want selection of files to be dependent on
        Ant property settings.
    All selector containers can contain any other selector, including other containers, as an element. Using containers, the selector tags can be arbitrarily deep. Here is a complete list of allowable selector elements within a container:
<and><contains><custom><date><depend><depth><filename><majority><none><not><or><present><selector><size>The <and> tag selects files that are
    selected by all of the elements it contains. It returns as
    soon as it finds a selector that does not select the file,
    so it is not guaranteed to check every selector.
    
Here is an example of how to use the And Selector:
<fileset dir="${dist}" includes="**/*.jar">
    <and>
        <size value="4" units="Ki" when="more"/>
        <date datetime="01/01/2001 12:00 AM" when="before"/>
    </and>
</fileset>
Selects all the JAR file larger than 4096 bytes which haven't been update since the last millenium.
The <majority> tag selects files provided
    that a majority of the contained elements also select it. Ties are
    dealt with as specified by the allowtie attribute.
    
| Attribute | Description | Required | 
| allowtie | Whether files should be selected if there are an even number of selectors selecting them as are not selecting them. Default is true. | No | 
Here is an example of how to use the Majority Selector:
<fileset dir="${docs}" includes="**/*.html">
    <majority>
        <contains text="project" casesensitive="false"/>
        <contains text="taskdef" casesensitive="false"/>
        <contains text="IntrospectionHelper" casesensitive="true"/>
    </majority>
</fileset>
Selects all the HTML files which contain at least two of the three phrases "project", "taskdef", and "IntrospectionHelper" (this last phrase must match case exactly).
The <none> tag selects files that are
    not selected by any of the elements it contains. It returns as
    soon as it finds a selector that selects the file,
    so it is not guaranteed to check every selector.
    
Here is an example of how to use the None Selector:
<fileset dir="${src}" includes="**/*.java">
    <none>
        <present targetdir="${dest}"/>
        <present targetdir="${dest}">
            <mapper type="glob" from="*.java" to="*.class"/>
        </present>
    </none>
</fileset>
Selects only Java files which do not have equivalent java or class files in the dest directory.
The <not> tag reverses the meaning of the
    single selector it contains.
    
Here is an example of how to use the Not Selector:
<fileset dir="${src}" includes="**/*.java">
    <not>
        <contains text="test"/>
    </not>
</fileset>
Selects all the files in the src directory that do not contain the string "test".
The <or> tag selects files that are
    selected by any one of the elements it contains. It returns as
    soon as it finds a selector that selects the file,
    so it is not guaranteed to check every selector.
    
Here is an example of how to use the Or Selector:
<fileset dir="${basedir}">
    <or>
        <depth max="0"/>
        <filename name="*.png"/>
        <filename name="*.gif"/>
        <filename name="*.jpg"/>
    </or>
</fileset>
Selects all the files in the top directory along with all the image files below it.
The <selector> tag is used to create selectors
    that can be reused through references. It is the only selector which can
    be used outside of
    any target, as an element of the <project> tag. It
    can contain only one other selector, but of course that selector can
    be a container.
    
The <selector> tag can also be used to select
    files conditionally based on whether an Ant property exists or not.
    This functionality is realized using the "if" and
    "unless" attributes in exactly the same way they
    are used on targets or on the <include> and
    <exclude> tags within a
    <patternset>.
| Attribute | Description | Required | 
| if | Allow files to be selected only if the named property is set. | No | 
| unless | Allow files to be selected only if the named property is not set. | No | 
Here is an example of how to use the Selector Reference:
<project default="all" basedir="./ant">
    <selector id="completed">
        <none>
            <depend targetdir="build/classes">
                <mapper type="glob" from="*.java" to="*.class"/>
            </depend>
            <depend targetdir="docs/manual/api">
                <mapper type="glob" from="*.java" to="*.html"/>
            </depend>
        </none>
    </selector>
    <target>
        <zip>
            <fileset dir="src/main" includes="**/*.java">
                <selector refid="completed"/>
            </fileset>
        </zip>
    </target>
</project>
Zips up all the Java files which have an up-to-date equivalent class file and javadoc file associated with them.
And an example of selecting files conditionally, based on whether properties are set:
<fileset dir="${working.copy}">
    <or>
        <selector if="include.tests">
            <filename name="**/*Test.class">
        </selector>
        <selector if="include.source">
            <and>
                <filename name="**/*.java">
                <not>
                    <selector unless="include.tests">
                        <filename name="**/*Test.java">
                    </selector>
                </not>
            </and>
        </selector>
    </or>
</fileset>
A fileset that conditionally contains Java source files and Test source and class files.
You can write your own selectors and use them within the selector
    containers by specifying them within the <custom> tag.
First, you have to write your selector class in Java. The only
    requirement it must meet in order to be a selector is that it implements
    the org.apache.tools.ant.types.selectors.FileSelector
    interface, which contains a single method. See
    Programming Selectors in Ant for
    more information.
Once that is written, you include it in your build file by using
    the <custom> tag.
    
| Attribute | Description | Required | 
| classname | The name of your class that implements org.apache.tools.ant.types.selectors.FileSelector. | Yes | 
| classpath | The classpath to use in order to load the custom selector class. If neither this classpath nor the classpathref are specified, the class will be loaded from the classpath that Ant uses. | No | 
| classpathref | A reference to a classpath previously defined. If neither this reference nor the classpath above are specified, the class will be loaded from the classpath that Ant uses. | No | 
Here is how you use <custom> to
    use your class as a selector:
    
<fileset dir="${mydir}" includes="**/*">
    <custom classname="com.mydomain.MySelector">
        <param name="myattribute" value="myvalue"/>
    </custom>
</fileset>
A number of core selectors can also be used as custom selectors
    by specifying their attributes using <param> elements. These
    are
org.apache.tools.ant.types.selectors.ContainsSelector
      org.apache.tools.ant.types.selectors.DateSelector
      org.apache.tools.ant.types.selectors.DepthSelector
      org.apache.tools.ant.types.selectors.FilenameSelector
      org.apache.tools.ant.types.selectors.SizeSelector
    Here is the example from the Depth Selector section rewritten
    to use the selector through <custom>.
<fileset dir="${doc.path}" includes="**/*">
    <custom classname="org.apache.tools.ant.types.selectors.DepthSelector">
        <param name="max" value="1"/>
    </custom>
</fileset>
Selects all files in the base directory and one directory below that.
For more details concerning writing your own selectors, consult Programming Selectors in Ant.
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