Support forcing a specific language from the command-line

Store the language version provided by a -force-language command-line argument and use that as the default language before falling back to the filename

pmd-core/src/main/java/net/sourceforge/pmd/PMDConfiguration.java

@@ -88,6 +88,7 @@ public class PMDConfiguration extends AbstractConfiguration {
     private int threads = Runtime.getRuntime().availableProcessors();
     private ClassLoader classLoader = getClass().getClassLoader();
     private LanguageVersionDiscoverer languageVersionDiscoverer = new LanguageVersionDiscoverer();
+    private LanguageVersion forceLanguageVersion;
 
     // Rule and source file options
     private String ruleSets;
@@ -210,6 +211,26 @@ public class PMDConfiguration extends AbstractConfiguration {
         return languageVersionDiscoverer;
     }
 
+    /**
+     * Get the LanguageVersion specified by the force-language parameter. This overrides detection based on file
+     * extensions
+     *
+     * @return The LanguageVersion.
+     */
+    public LanguageVersion getForceLanguageVersion() {
+        return forceLanguageVersion;
+    }
+
+    /**
+     * Set the LanguageVersion specified by the force-language parameter. This overrides detection based on file
+     * extensions
+     *
+     * @param forceLanguageVersion the language version
+     */
+    public void setForceLanguageVersion(LanguageVersion forceLanguageVersion) {
+        this.forceLanguageVersion = forceLanguageVersion;
+    }
+
     /**
      * Set the given LanguageVersion as the current default for it's Language.
      *

pmd-core/src/main/java/net/sourceforge/pmd/SourceCodeProcessor.java

@@ -203,8 +203,10 @@ public class SourceCodeProcessor {
     private void determineLanguage(RuleContext ctx) {
         // If LanguageVersion of the source file is not known, make a
         // determination
-        if (ctx.getLanguageVersion() == null) {
-            LanguageVersion languageVersion = configuration.getLanguageVersionOfFile(ctx.getSourceCodeFilename());
+        LanguageVersion languageVersion = ctx.getLanguageVersion();
+        if (languageVersion == null) {
+            languageVersion = configuration.getForceLanguageVersion();
+            languageVersion = languageVersion != null ? languageVersion : configuration.getLanguageVersionOfFile(ctx.getSourceCodeFilename());
             ctx.setLanguageVersion(languageVersion);
         }
     }

pmd-core/src/main/java/net/sourceforge/pmd/cli/PMDParameters.java

@@ -101,6 +101,9 @@ public class PMDParameters {
     @Parameter(names = { "-language", "-l" }, description = "Specify a language PMD should use.")
     private String language = null;
 
+    @Parameter(names = "-force-language", description = "Force a language to be used for all input files, irrespective of filenames.")
+    private String forceLanguage = null;
+
     @Parameter(names = "-auxclasspath",
             description = "Specifies the classpath for libraries used by the source code. "
                     + "This is used by the type resolution. The platform specific path delimiter "
@@ -215,8 +218,11 @@ public class PMDParameters {
         configuration.setIgnoreIncrementalAnalysis(this.isIgnoreIncrementalAnalysis());
 
         LanguageVersion languageVersion = LanguageRegistry
-                .findLanguageVersionByTerseName(this.getLanguage() + ' ' + this.getVersion());
+                .findLanguageVersionByTerseName(forceLanguage != null ? forceLanguage : (this.getLanguage()) + ' ' + this.getVersion());
         if (languageVersion != null) {
+            if (forceLanguage != null) {
+                configuration.setForceLanguageVersion(languageVersion);
+            }
             configuration.getLanguageVersionDiscoverer().setDefaultLanguageVersion(languageVersion);
         }
         try {

pmd-core/src/test/java/net/sourceforge/pmd/lang/LanguageParameterTest.java

@@ -0,0 +1,26 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import net.sourceforge.pmd.cli.PMDCommandLineInterface;
+import net.sourceforge.pmd.cli.PMDParameters;
+
+public class LanguageParameterTest {
+
+    /** Test that language parameters from the CLI are correctly passed through to the PMDConfiguration. Although this is a
+     * CLI test, it resides here to take advantage of {@link net.sourceforge.pmd.lang.DummyLanguageModule}
+     */
+    @Test
+    public void testLanguageFromCliToConfiguration() {
+        PMDParameters params = new PMDParameters();
+        String[] args = { "-d", "source_folder", "-f", "ideaj", "-P", "sourcePath=/home/user/source/", "-R", "java-empty", "-force-language", "dummy"};
+        PMDCommandLineInterface.extractParameters(params, args, "PMD");
+
+        Assert.assertEquals(new DummyLanguageModule().getDefaultVersion().getName(), params.toConfiguration().getForceLanguageVersion().getName());
+    }
+}