[C++] Allow customizing header extension

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/CppGenerator.java

@@ -55,6 +55,7 @@ public class CppGenerator implements CodeGenerator
     private static final String INDENT = "    ";
     private static final String TWO_INDENT = INDENT + INDENT;
     private static final String THREE_INDENT = TWO_INDENT + INDENT;
+    private static final String DEFAULT_FILE_EXTENSION = ".h";
 
     private final Ir ir;
     private final OutputManager outputManager;
@@ -109,6 +110,15 @@ public CppGenerator(
         this.outputManager = outputManager;
     }
 
+    private String getFileExtension()
+    {
+        if (outputManager instanceof WithFileExtension)
+        {
+            return ((WithFileExtension)outputManager).getFileExtension();
+        }
+        return DEFAULT_FILE_EXTENSION;
+    }
+
     /**
      * Generate the composites for dealing with the message header.
      *
@@ -1818,7 +1828,7 @@ private CharSequence generateFileHeader(
             sb.append("\n");
             for (final String incName : typesToInclude)
             {
-                sb.append("#include \"").append(toUpperFirstChar(incName)).append(".h\"\n");
+                sb.append("#include \"").append(toUpperFirstChar(incName)).append(getFileExtension()).append("\"\n");
             }
         }
 

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/NamespaceOutputManager.java

@@ -28,8 +28,9 @@
  * {@link OutputManager} for managing the creation of C++11 source files as the target of code generation.
  * The character encoding for the {@link java.io.Writer} is UTF-8.
  */
-public class NamespaceOutputManager implements OutputManager
+public class NamespaceOutputManager implements OutputManager, WithFileExtension
 {
+    private String fileExt;
     private final File outputDir;
 
     /**
@@ -51,6 +52,9 @@ public NamespaceOutputManager(final String baseDirName, final String namespaceNa
         {
             throw new IllegalStateException("Unable to create directory: " + packageDirName);
         }
+
+        // Defaults to .h to maintain backward compatibility
+        fileExt = System.getProperty("sbe.cpp.file.extension", ".h");
     }
 
     /**
@@ -65,7 +69,19 @@ public NamespaceOutputManager(final String baseDirName, final String namespaceNa
      */
     public Writer createOutput(final String name) throws IOException
     {
-        final File targetFile = new File(outputDir, name + ".h");
+        final File targetFile = new File(outputDir, name + fileExt);
         return Files.newBufferedWriter(targetFile.toPath(), StandardCharsets.UTF_8);
     }
+
+    @Override
+    public void withFileExtension(final String fileExtension)
+    {
+        this.fileExt = fileExtension;
+    }
+
+    @Override
+    public String getFileExtension()
+    {
+        return this.fileExt;
+    }
 }

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/cpp/WithFileExtension.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2013-2025 Real Logic Limited.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package uk.co.real_logic.sbe.generation.cpp;
+
+/**
+ * Abstraction to provide file extension configuration and retrieval.
+ */
+public interface WithFileExtension
+{
+
+    /**
+     * Sets the file extension.
+     *
+     * @param fileExtension A valid file extension (e.g. ".hpp")
+     */
+    void withFileExtension(String fileExtension);
+
+    /**
+     * Gets a file extension.
+     *
+     * @return the configured file extension.
+     */
+    String getFileExtension();
+}

sbe-tool/src/test/java/uk/co/real_logic/sbe/generation/cpp/CppGeneratorTest.java

@@ -15,6 +15,7 @@
  */
 package uk.co.real_logic.sbe.generation.cpp;
 
+import org.agrona.generation.OutputManager;
 import org.agrona.generation.StringWriterOutputManager;
 import org.junit.jupiter.api.Test;
 import uk.co.real_logic.sbe.Tests;
@@ -24,11 +25,14 @@
 import uk.co.real_logic.sbe.xml.MessageSchema;
 import uk.co.real_logic.sbe.xml.ParserOptions;
 
+import java.io.IOException;
 import java.io.InputStream;
+import java.io.Writer;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.not;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static uk.co.real_logic.sbe.xml.XmlSchemaParser.parse;
 
@@ -140,4 +144,48 @@ void shouldUseConstexprWhenDefiningPrecedenceChecksLookupTables() throws Excepti
             assertThat(source, containsString("static constexpr const char *STATE_TRANSITIONS_LOOKUP[] ="));
         }
     }
+
+    @Test
+    void shouldAllowFileExtensionConfiguration() throws Exception
+    {
+        class OutputManagerWithExt extends StringWriterOutputManager implements WithFileExtension {
+            private String fileExtension;
+
+            @Override
+            public String getFileExtension() {
+                return fileExtension;
+            }
+
+            @Override
+            public void withFileExtension(String fileExtension) {
+                this.fileExtension = fileExtension;
+            }
+
+        }
+
+        try (InputStream in = Tests.getLocalResource("code-generation-schema.xml"))
+        {
+            final ParserOptions options = ParserOptions.builder().stopOnError(true).build();
+            final MessageSchema schema = parse(in, options);
+            final IrGenerator irg = new IrGenerator();
+            final Ir ir = irg.generate(schema);
+            final OutputManagerWithExt outputManager = new OutputManagerWithExt();
+            outputManager.setPackageName(ir.applicableNamespace());
+            outputManager.withFileExtension(".hpp");
+
+            assertEquals(outputManager.getFileExtension(), ".hpp");
+
+            final CppGenerator generator = new CppGenerator(
+                ir,
+                false,
+                PrecedenceChecks.newInstance(new PrecedenceChecks.Context().shouldGeneratePrecedenceChecks(true)),
+                false,
+                outputManager);
+            generator.generate();
+
+            final String source = outputManager.getSource("code.generation.test.Car").toString();
+            assertThat(source, containsString("#include \"MessageHeader.hpp\""));
+            assertThat(source,containsString("#include \"BoostType.hpp\""));
+        }
+    }
 }