## PatternSet

Patterns can be grouped to sets and later be referenced by their `id` attribute. They are defined via a `patternset` element, which can appear nested into a FileSet or a directory-based task that constitutes an implicit FileSet. In addition, `patternset`s can be defined as a stand alone element at the same level as `target` — i.e., as children of `project` as well as as children of `target`.

Patterns can be specified by nested `<include>`, or `<exclude>` elements or the following attributes.

Attribute | Description
includes | comma- or space-separated list of patterns of files that must be included. All files are included when omitted.
includesfile | the name of a file; each line of this file is taken to be an include pattern. You can specify more than one include file by using a nested includesfile elements.
excludes | comma- or space-separated list of patterns of files that must be excluded; no files (except default excludes) are excluded when omitted.
excludesfile | the name of a file; each line of this file is taken to be an exclude pattern. You can specify more than one exclude file by using a nested excludesfile elements.

### Parameters specified as nested elements

#### `include` and `exclude`

Each such element defines a single pattern for files to include or exclude.

Attribute | Description | Required
name | the pattern to in/exclude. | Yes
if | Only use this pattern if the named property is set. | No
unless | Only use this pattern if the named property is not set. | No

#### `includesfile` and `excludesfile`

If you want to list the files to include or exclude external to your build file, you should use the includesfile/excludesfile attributes or elements. Using the attribute, you can only specify a single file of each type, while the nested elements can be specified more than once - the nested elements also support if/unless attributes you can use to test the existance of a property.

Attribute | Description | Required
name | the name of the file holding the patterns to in/exclude. | Yes
if | Only read this file if the named property is set. | No
unless | Only read this file if the named property is not set. | No

#### `patternset`

Patternsets may be nested within one another, adding the nested patterns to the parent patternset.

### Examples

>     <patternset id="non.test.sources">
>       <include name="**/*.java"/>
>       <exclude name="**/*Test*"/>
>     </patternset>

Builds a set of patterns that matches all `.java` files that do not contain the text `Test` in their name. This set can be referred to via `<patternset refid="non.test.sources"/>`, by tasks that support this feature, or by FileSets.

Note that while the `includes` and `excludes` attributes accept multiple elements separated by commas or spaces, the nested `<include>` and `<exclude>` elements expect their name attribute to hold a single pattern.

The nested elements allow you to use if and unless arguments to specify that the element should only be used if a property is set, or that it should be used only if a property is not set.

For example

>     <patternset id="sources">
>       <include name="std/**/*.java"/>
>       <include name="prof/**/*.java" if="professional"/>
>       <exclude name="**/*Test*"/>
>     </patternset>

will only include the files in the sub-directory prof if the property professional is set to some value.

The two sets

>     <patternset includesfile="some-file"/>

and

>     <patternset>
>       <includesfile name="some-file"/>
>     <patternset/>

are identical. The include patterns will be read from the file `some-file`, one pattern per line.

>     <patternset>
>       <includesfile name="some-file"/>
>       <includesfile name="${some-other-file}"
>                     if="some-other-file"
>       />
>     <patternset/>

will also read include patterns from the file the property `some-other-file` points to, if a property of that name has been defined.