Allow regex based exclusions

README.md

@@ -31,6 +31,9 @@ Default phase of execution is `verify`. The following is an example of a configu
               <configLocation>${project.basedir}/lib/scalastyle_config.xml</configLocation>
               <outputFile>${project.basedir}/scalastyle-output.xml</outputFile>
               <outputEncoding>UTF-8</outputEncoding>
+              <exclusions>
+                <exclusion>.*directory.*</exclusion>
+              </exclusions>
             </configuration>
             <executions>
               <execution>
@@ -55,3 +58,14 @@ You can also specify multiple source directories if necessary. Replace the <sour
 ```
 
 and similarly for `testSourceDirectory` & `testSourceDirectories`.
+
+You can also specify multiple exclusion filters in form of regex if necessary. Add the <exclusion> element in <exclusions>:
+
+```xml
+    <exclusions>
+      <exclusion>.*testdir1.*</exclusion>
+      <exclusion>.*testdir2.*</exclusion>
+    </exclusions>
+```
+
+Only files that match **none** of the provided `exclusions` are processed.

src/it/exclusion/invoker.properties

@@ -0,0 +1,2 @@
+invoker.goals=clean compile
+invoker.buildResult=success

src/it/exclusion/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>it.scalastyle-maven-plugin</groupId>
+    <artifactId>basic</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>Test for basic criteria</name>
+    <description>Test for basic criteria</description>
+    <packaging>pom</packaging>
+    <dependencies>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>@project.groupId@</groupId>
+                <artifactId>@project.artifactId@</artifactId>
+                <version>@project.version@</version>
+                <configuration>
+                    <verbose>true</verbose>
+                    <failOnViolation>true</failOnViolation>
+                    <includeTestSourceDirectory>true</includeTestSourceDirectory>
+                    <failOnWarning>false</failOnWarning>
+                    <sourceDirectory>${src.it}/testsrc</sourceDirectory>
+                    <sourceDirectories>
+                        <dir>${src.it}/testsrc2</dir>
+                    </sourceDirectories>
+                    <configLocation>${src.it}/scalastyle_config.xml</configLocation>
+                    <exclusions>
+                        <exclusion>.*Foobar2.*</exclusion>
+                    </exclusions>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>scalastyle</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>check</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

src/it/exclusion/validate.groovy

@@ -0,0 +1,14 @@
+try {
+
+def file = new File(basedir, 'target')
+assert !file.exists()
+
+assert new File(basedir, "build.log").readLines().grep(~/.*excluded.*src\/it\/testsrc2\/Foobar2.scala.*/).size() == 1
+assert new File(basedir, "build.log").readLines().grep(~/.*Excluded 1 file.*/).size() == 1
+
+return true
+
+} catch(Throwable e) {
+  e.printStackTrace()
+  return false
+}

src/main/java/org/scalastyle/maven/plugin/ScalastyleViolationCheckMojo.java

@@ -171,6 +171,16 @@ public class ScalastyleViolationCheckMojo extends AbstractMojo {
     @Parameter(property = "scalastyle.input.encoding")
     private String inputEncoding;
 
+    /**
+     * Regex patterns to exclude files. Applies to all sources.
+     */
+    @Parameter(property = "scalastyle.exclusions")
+    private List<String> exclusions;
+
+    /**
+     * Number of excluded files
+     */
+    private int excludedFiles = 0;
 
     /**
      * The Maven Project Object.
@@ -201,6 +211,7 @@ public void execute() throws MojoFailureException, MojoExecutionException {
             getLog().debug("outputFile=" + outputFile);
             getLog().debug("outputEncoding=" + outputEncoding);
             getLog().debug("inputEncoding=" + inputEncoding);
+            getLog().debug("exclusions=" + exclusions);
 
             performCheck();
         }
@@ -225,6 +236,7 @@ private void performCheck() throws MojoFailureException, MojoExecutionException
 
             if (!quiet) {
                 System.out.println("Processed " + outputResult.files() + " file(s)");
+                System.out.println("Excluded " + excludedFiles + " file(s)");
                 System.out.println("Found " + outputResult.errors() + " errors");
                 System.out.println("Found " + outputResult.warnings() + " warnings");
                 System.out.println("Found " + outputResult.infos() + " infos");
@@ -313,7 +325,29 @@ private List<FileSpec> getFilesToProcess() {
         all.addAll(getFiles("sourceDirectory", sourceDirectoriesAsList(), inputEncoding));
         all.addAll(getFiles("testSourceDirectory", testSourceDirectoriesAsList(), inputEncoding));
 
-        return all;
+        List<FileSpec> filteredList = new ArrayList<FileSpec>();
+
+        if (exclusions != null && exclusions.size() != 0) {
+            for (FileSpec file : all) {
+                boolean check = true;
+
+                for (String exclusion : exclusions) {
+                    if (!check || file.name().matches(exclusion)) {
+                        check = false;
+                    }
+                }
+                if (check)
+                    filteredList.add(file);
+                else if (verbose)
+                    getLog().info("excluded file = " + file.name());
+            }
+        } else {
+            filteredList = all;
+        }
+
+        excludedFiles = all.size() - filteredList.size();
+
+        return filteredList;
     }
 
     private List<FileSpec> getFiles(String name, List<File> dirs, String encoding) {