Improve the code generation even more ...

code-generation/language-base-freemarker/src/main/java/org/apache/plc4x/plugins/codegenerator/protocol/freemarker/FreemarkerLanguageOutput.java

@@ -21,6 +21,7 @@
 import freemarker.cache.ClassTemplateLoader;
 import freemarker.template.*;
 import org.apache.plc4x.plugins.codegenerator.language.LanguageOutput;
+import org.apache.plc4x.plugins.codegenerator.types.definitions.ConstantsTypeDefinition;
 import org.apache.plc4x.plugins.codegenerator.types.definitions.EnumTypeDefinition;
 import org.apache.plc4x.plugins.codegenerator.types.definitions.DataIoTypeDefinition;
 import org.apache.plc4x.plugins.codegenerator.types.definitions.TypeDefinition;
@@ -31,10 +32,7 @@
 import java.io.*;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 public abstract class FreemarkerLanguageOutput implements LanguageOutput {
 
@@ -53,13 +51,15 @@ public void generate(File outputDir, String version, String languageName, String
         freemarkerConfiguration.setTemplateLoader(classTemplateLoader);
 
         // Initialize all templates
-        List<Template> specTemplates;
+        List<Template> specTemplatesList;
+        List<Template> constantsTemplateList;
         List<Template> complexTypesTemplateList;
         List<Template> enumTypesTemplateList;
         List<Template> dataIoTemplateList;
         List<Template> miscTemplateList;
         try {
-            specTemplates = getSpecTemplates(freemarkerConfiguration);
+            specTemplatesList = getSpecTemplates(freemarkerConfiguration);
+            constantsTemplateList = getConstantsTemplates(freemarkerConfiguration);
             complexTypesTemplateList = getComplexTypeTemplates(freemarkerConfiguration);
             enumTypesTemplateList = getEnumTypeTemplates(freemarkerConfiguration);
             dataIoTemplateList = getDataIoTemplates(freemarkerConfiguration);
@@ -69,7 +69,7 @@ public void generate(File outputDir, String version, String languageName, String
         }
 
         // Generate output that's global for the entire mspec
-        if (!specTemplates.isEmpty()) {
+        if (!specTemplatesList.isEmpty()) {
             Map<String, Object> typeContext = new HashMap<>();
             typeContext.put("languageName", languageName);
             typeContext.put("protocolName", protocolName);
@@ -78,7 +78,7 @@ public void generate(File outputDir, String version, String languageName, String
             typeContext.put("tracer", Tracer.start("global"));
             typeContext.putAll(options);
 
-            for (Template template : specTemplates) {
+            for (Template template : specTemplatesList) {
                 try {
                     renderTemplate(outputDir, template, typeContext);
                 } catch (IOException | TemplateException e) {
@@ -87,8 +87,36 @@ public void generate(File outputDir, String version, String languageName, String
             }
         }
 
+        // Generate constants types
+        Optional<TypeDefinition> constantsTypeDefinition = types.values().stream().filter(type -> type instanceof ConstantsTypeDefinition).findFirst();
+        if (!constantsTemplateList.isEmpty() && constantsTypeDefinition.isPresent()) {
+            TypeDefinition typeDefinition = constantsTypeDefinition.get();
+            Map<String, Object> typeContext = new HashMap<>();
+            typeContext.put("languageName", languageName);
+            typeContext.put("protocolName", protocolName);
+            typeContext.put("outputFlavor", outputFlavor);
+            typeContext.put("typeName", typeDefinition.getName());
+            typeContext.put("type", typeDefinition);
+            typeContext.put("helper", getHelper(typeDefinition, protocolName, outputFlavor, types, options));
+            typeContext.put("tracer", Tracer.start("global"));
+            typeContext.putAll(options);
+
+            for (Template template : constantsTemplateList) {
+                try {
+                    renderTemplate(outputDir, template, typeContext);
+                } catch (IOException | TemplateException e) {
+                    throw new GenerationException("Error generating constants.", e);
+                }
+            }
+        }
+
         // Iterate over the types and have content generated for each one
         for (Map.Entry<String, TypeDefinition> typeEntry : types.entrySet()) {
+            // "Constants" types are handled separately.
+            if (typeEntry.getValue() instanceof ConstantsTypeDefinition) {
+                continue;
+            }
+
             // Prepare a new generation context
             Map<String, Object> typeContext = new HashMap<>();
             typeContext.put("languageName", languageName);
@@ -202,6 +230,8 @@ private Configuration getFreemarkerConfiguration() throws GenerationException {
 
     protected abstract List<Template> getSpecTemplates(Configuration freemarkerConfiguration) throws IOException;
 
+    protected abstract List<Template> getConstantsTemplates(Configuration freemarkerConfiguration) throws IOException;
+
     protected abstract List<Template> getComplexTypeTemplates(Configuration freemarkerConfiguration) throws IOException;
 
     protected abstract List<Template> getEnumTypeTemplates(Configuration freemarkerConfiguration) throws IOException;

code-generation/language/c/src/main/java/org/apache/plc4x/language/c/CLanguageOutput.java

@@ -53,11 +53,20 @@ protected List<Template> getSpecTemplates(Configuration freemarkerConfiguration)
         return Collections.emptyList();
     }
 
+    @Override
+    protected List<Template> getConstantsTemplates(Configuration freemarkerConfiguration) throws IOException {
+        return Arrays.asList(
+            freemarkerConfiguration.getTemplate("templates/c/constants-template.h.ftlh"),
+            freemarkerConfiguration.getTemplate("templates/c/constants-template.c.ftlh")
+        );
+    }
+
     @Override
     protected List<Template> getComplexTypeTemplates(Configuration freemarkerConfiguration) throws IOException {
         return Arrays.asList(
             freemarkerConfiguration.getTemplate("templates/c/complex-type-template.h.ftlh"),
-            freemarkerConfiguration.getTemplate("templates/c/complex-type-template.c.ftlh"));
+            freemarkerConfiguration.getTemplate("templates/c/complex-type-template.c.ftlh")
+        );
     }
 
     @Override

code-generation/language/c/src/main/java/org/apache/plc4x/language/c/CLanguageTemplateHelper.java

@@ -137,19 +137,25 @@ public String getLanguageTypeNameForField(Field field) {
         return getLanguageTypeNameForTypeReference(typeReference);
     }
 
-    public List<Pair<ConstField, ComplexTypeDefinition>> getAllConstFields() {
+    public List<Pair<ConstField, String>> getAllConstFields() {
         // Note: a map is not an option here as ConstFields are duplicated
-        List<Pair<ConstField, ComplexTypeDefinition>> constFields = new LinkedList<>();
-        ComplexTypeDefinition complexTypeDefinition = (ComplexTypeDefinition) this.thisType;
-        complexTypeDefinition.getConstFields()
-            .forEach(constField -> constFields.add(Pair.of(constField, complexTypeDefinition)));
-        complexTypeDefinition.getSwitchField()
-            .map(SwitchField::getCases)
-            .ifPresent(discriminatedComplexTypeDefinitions ->
-                discriminatedComplexTypeDefinitions.forEach(switchCase ->
-                    switchCase.getConstFields().forEach(constField -> constFields.add(Pair.of(constField, switchCase)))
-                )
-            );
+        List<Pair<ConstField, String>> constFields = new LinkedList<>();
+        if(this.thisType instanceof ComplexTypeDefinition) {
+            ComplexTypeDefinition complexTypeDefinition = (ComplexTypeDefinition) this.thisType;
+            complexTypeDefinition.getConstFields()
+                .forEach(constField -> constFields.add(Pair.of(constField, complexTypeDefinition.getName())));
+            complexTypeDefinition.getSwitchField()
+                .map(SwitchField::getCases)
+                .ifPresent(discriminatedComplexTypeDefinitions ->
+                    discriminatedComplexTypeDefinitions.forEach(switchCase ->
+                        switchCase.getConstFields().forEach(constField -> constFields.add(Pair.of(constField, switchCase.getName())))
+                    )
+                );
+        } else if (this.thisType instanceof ConstantsTypeDefinition) {
+            ConstantsTypeDefinition constantsTypeDefinition = (ConstantsTypeDefinition) this.thisType;
+            constantsTypeDefinition.getConstFields()
+                .forEach(constField -> constFields.add(Pair.of(constField, constantsTypeDefinition.getName())));
+        }
         return constFields;
     }
 

code-generation/language/c/src/main/resources/templates/c/complex-type-template.c.ftlh

@@ -98,10 +98,10 @@ ${helper.getCTypeName(type.name)} ${helper.getCTypeName(type.name)}_null() {
 // Constant values.
     <#list helper.getAllConstFields() as entry>
         <#assign constField=entry.key>
-        <#assign parentType=entry.value>
-static const ${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentType.name)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}_const = ${helper.toParseExpression(type, constField, constField.referenceValue, parserArguments)};
-${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentType.name)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}() {
-  return ${helper.getCTypeName(parentType.name)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}_const;
+        <#assign parentTypeName=entry.value>
+static const ${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}_const = ${helper.toParseExpression(type, constField, constField.referenceValue, parserArguments)};
+${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}() {
+  return ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}_const;
 }
     </#list>
 </#if>

code-generation/language/c/src/main/resources/templates/c/complex-type-template.h.ftlh

@@ -122,8 +122,8 @@ ${helper.getCTypeName(type.name)}_discriminator ${helper.getCTypeName(type.name)
 // Constant values.
     <#list helper.getAllConstFields() as entry>
         <#assign constField=entry.key>
-        <#assign parentType=entry.value>
-${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentType.name)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}();
+        <#assign parentTypeName=entry.value>
+${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}();
     </#list>
 </#if>
 

code-generation/language/c/src/main/resources/templates/c/constants-template.c.ftlh

@@ -0,0 +1,76 @@
+<#--
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you 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.
+-->
+<#-- Prevent freemarker from escaping stuff -->
+<#outputformat "undefined">
+<#-- Declare the name and type of variables passed in to the template -->
+<#-- @ftlvariable name="languageName" type="java.lang.String" -->
+<#-- @ftlvariable name="protocolName" type="java.lang.String" -->
+<#-- @ftlvariable name="outputFlavor" type="java.lang.String" -->
+<#-- @ftlvariable name="helper" type="org.apache.plc4x.language.c.CLanguageTemplateHelper" -->
+<#-- @ftlvariable name="tracer" type="org.apache.plc4x.plugins.codegenerator.protocol.freemarker.Tracer" -->
+<#-- @ftlvariable name="type" type="org.apache.plc4x.plugins.codegenerator.types.definitions.ComplexTypeDefinition" -->
+<#-- Declare the name and type of variables declared locally inside the template -->
+<#-- @ftlvariable name="field" type="org.apache.plc4x.plugins.codegenerator.types.fields.Field" -->
+${helper.getSourceDirectory()?replace(".", "/")}/${helper.camelCaseToSnakeCase(type.name)}.c
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <plc4c/spi/context.h>
+#include <plc4c/spi/read_buffer.h>
+#include <plc4c/spi/write_buffer.h>
+#include <plc4c/utils/list.h>
+
+// Code generated by code-generation. DO NOT EDIT.
+
+<#--
+    When using const fields, output the constant reference values
+    as global const values so we can use them elsewhere.
+-->
+<#if helper.getAllConstFields()?has_content>
+
+// Constant values.
+    <#list helper.getAllConstFields() as entry>
+        <#assign constField=entry.key>
+        <#assign parentTypeName=entry.value>
+static const ${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}_const = ${helper.toParseExpression(type, constField, constField.referenceValue, parserArguments)};
+    ${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}() {
+    return ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}_const;
+}
+    </#list>
+</#if>
+
+</#outputformat>

code-generation/language/c/src/main/resources/templates/c/constants-template.h.ftlh

@@ -0,0 +1,84 @@
+<#--
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you 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.
+-->
+<#-- Prevent freemarker from escaping stuff -->
+<#outputformat "undefined">
+<#-- Declare the name and type of variables passed in to the template -->
+<#-- @ftlvariable name="languageName" type="java.lang.String" -->
+<#-- @ftlvariable name="protocolName" type="java.lang.String" -->
+<#-- @ftlvariable name="outputFlavor" type="java.lang.String" -->
+<#-- @ftlvariable name="helper" type="org.apache.plc4x.language.c.CLanguageTemplateHelper" -->
+<#-- @ftlvariable name="tracer" type="org.apache.plc4x.plugins.codegenerator.protocol.freemarker.Tracer" -->
+<#-- @ftlvariable name="type" type="org.apache.plc4x.plugins.codegenerator.types.definitions.ComplexTypeDefinition" -->
+<#-- Declare the name and type of variables declared locally inside the template -->
+<#-- @ftlvariable name="field" type="org.apache.plc4x.plugins.codegenerator.types.fields.Field" -->
+${helper.getIncludesDirectory()?replace(".", "/")}/${helper.camelCaseToSnakeCase(type.name)}.h
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+#ifndef ${helper.getCTypeName(type.name)?upper_case}_H_
+#define ${helper.getCTypeName(type.name)?upper_case}_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <plc4c/spi/context.h>
+#include <plc4c/spi/read_buffer.h>
+#include <plc4c/spi/write_buffer.h>
+#include <plc4c/utils/list.h>
+
+// Code generated by code-generation. DO NOT EDIT.
+
+<#--#ifdef __cplusplus
+extern "C" {
+#endif-->
+
+<#--
+    When using const fields, output the constant reference values
+    as global const values so we can use them elsewhere.
+-->
+<#if helper.getAllConstFields()?has_content>
+
+// Constant values.
+    <#list helper.getAllConstFields() as entry>
+        <#assign constField=entry.key>
+        <#assign parentTypeName=entry.value>
+${helper.getLanguageTypeNameForField(constField)} ${helper.getCTypeName(parentTypeName)?upper_case}_${helper.camelCaseToSnakeCase(constField.name)?upper_case}();
+    </#list>
+</#if>
+
+<#--#ifdef __cplusplus
+}
+#endif-->
+#endif  // ${helper.getCTypeName(type.name)?upper_case}_H_
+</#outputformat>

code-generation/language/cs/src/main/java/org/apache/plc4x/language/cs/CsLanguageOutput.java

@@ -52,6 +52,11 @@ protected List<Template> getSpecTemplates(Configuration freemarkerConfiguration)
         return Collections.emptyList();
     }
 
+    @Override
+    protected List<Template> getConstantsTemplates(Configuration freemarkerConfiguration) throws IOException {
+        return Collections.emptyList();
+    }
+
     @Override
     protected List<Template> getComplexTypeTemplates(Configuration freemarkerConfiguration) throws IOException {
         return Collections.singletonList(

code-generation/language/go/src/main/java/org/apache/plc4x/language/go/GoLanguageOutput.java

@@ -53,6 +53,11 @@ protected List<Template> getSpecTemplates(Configuration freemarkerConfiguration)
             freemarkerConfiguration.getTemplate("templates/go/xml-parser-factory-template.go.ftlh"));
     }
 
+    @Override
+    protected List<Template> getConstantsTemplates(Configuration freemarkerConfiguration) throws IOException {
+        return List.of(freemarkerConfiguration.getTemplate("templates/go/constants-template.go.ftlh"));
+    }
+
     @Override
     protected List<Template> getComplexTypeTemplates(Configuration freemarkerConfiguration) throws IOException {
         return Collections.singletonList(