Added a new mustache lambda to trim whitespace in fragments

Author: smasset

modules/swagger-codegen/src/main/java/io/swagger/codegen/mustache/TrimWhitespaceLambda.java

@@ -0,0 +1,34 @@
+package io.swagger.codegen.mustache;
+
+import java.io.IOException;
+import java.io.Writer;
+
+import com.samskivert.mustache.Mustache;
+import com.samskivert.mustache.Template.Fragment;
+
+/**
+ * Replaces duplicate whitespace characters in a fragment with single space.
+ *
+ * Register:
+ *
+ * <pre>
+ * additionalProperties.put("lambdaTrimWhitespace", new TrimWhitespaceLambda());
+ * </pre>
+ *
+ * Use:
+ *
+ * <pre>
+ * {{#lambdaTrimWhitespace}}{{summary}}{{/lambdaTrimWhitespace}}
+ * </pre>
+ */
+public class TrimWhitespaceLambda implements Mustache.Lambda {
+    private static final String SINGLE_SPACE = " ";
+
+    private static final String WHITESPACE_REGEX = "\\s+";
+
+    @Override
+    public void execute(Fragment fragment, Writer writer) throws IOException {
+        writer.write(fragment.execute().replaceAll(WHITESPACE_REGEX, SINGLE_SPACE));
+    }
+
+}

modules/swagger-codegen/src/test/java/io/swagger/codegen/mustache/TrimWhitespaceLambdaTest.java

@@ -0,0 +1,42 @@
+package io.swagger.codegen.mustache;
+
+import static org.mockito.Mockito.when;
+import static org.testng.Assert.assertEquals;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+import com.samskivert.mustache.Template.Fragment;
+
+public class TrimWhitespaceLambdaTest {
+
+    @Mock
+    private Fragment fragment;
+
+    @BeforeMethod
+    public void init() {
+        MockitoAnnotations.initMocks(this);
+    }
+
+    @AfterMethod
+    public void reset() {
+        Mockito.reset(fragment);
+    }
+
+    @Test
+    public void testTrimWhitespace() throws IOException {
+        when(fragment.execute()).thenReturn("\t a  b\t\tc \t");
+
+        StringWriter output = new StringWriter();
+        new TrimWhitespaceLambda().execute(fragment, output);
+        assertEquals(output.toString(), " a b c ");
+    }
+
+}