feat(plc4go): provide finer interfaces

+ A *Contract interface for parents declaring methods which are implemented by that parent
+ A *Requirements interface for parents which defines which methods the parent needs to properly function.
+ A interface which combines the two above to give a full picture
+ A type assertion to ensure the struct implements the right interface

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

@@ -84,37 +84,71 @@ const ${type.name}_${field.name?upper_case} ${helper.getLanguageTypeNameForField
 
 // ${type.name} is the corresponding interface of ${type.name?cap_first}
 type ${type.name} interface {
+<#if type.isDiscriminatedParentTypeDefinition()>
+	${type.name}Contract
+	${type.name}Requirements
 	fmt.Stringer<@emitImport import="fmt" />
 	utils.LengthAware
 	utils.Serializable
-<#if type.isDiscriminatedChildTypeDefinition()>
-	${type.parentType.orElseThrow().name?cap_first}
+<#else>
+	fmt.Stringer<@emitImport import="fmt" />
+	utils.LengthAware
+	utils.Serializable
+	<#if type.isDiscriminatedChildTypeDefinition()>
+		${type.parentType.orElseThrow().name?cap_first}
+	</#if>
+	<#list type.propertyFields as field>
+		<#assign typeRef=field.asTypedField().orElseThrow().type>
+	// Get${field.name?cap_first} returns ${field.name?cap_first} (property field)
+	Get${field.name?cap_first}() <#if helper.needsPointerAccess(field)>*</#if>${helper.getLanguageTypeNameForTypeReference(typeRef)}
+	</#list>
+	<#list type.virtualFields as field>
+		<#assign typeRef=field.asTypedField().orElseThrow().type>
+	// Get${field.name?cap_first} returns ${field.name?cap_first} (virtual field)
+	Get${field.name?cap_first}() <#if helper.needsPointerAccess(field)>*</#if>${helper.getLanguageTypeNameForTypeReference(typeRef)}
+	</#list>
+	<#list type.abstractFields as field>
+		<#assign namedField=field.asNamedField().orElseThrow()>
+	// Get${namedField.name?cap_first} returns ${namedField.name?cap_first} (abstract field)
+	Get${namedField.name?cap_first}() ${helper.getLanguageTypeNameForField(field)}
+	</#list>
 </#if>
+}
+
 <#if type.isDiscriminatedParentTypeDefinition()>
+// ${type.name}Contract provides a set of functions which can be overwritten by a sub struct
+type ${type.name}Contract interface {
+	<#if type.isDiscriminatedChildTypeDefinition()>
+	${type.parentType.orElseThrow().name?cap_first}
+	</#if>
+	<#list type.propertyFields as field>
+		<#assign typeRef=field.asTypedField().orElseThrow().type>
+	// Get${field.name?cap_first} returns ${field.name?cap_first} (property field)
+	Get${field.name?cap_first}() <#if helper.needsPointerAccess(field)>*</#if>${helper.getLanguageTypeNameForTypeReference(typeRef)}
+	</#list>
+	<#list type.virtualFields as field>
+		<#assign typeRef=field.asTypedField().orElseThrow().type>
+	// Get${field.name?cap_first} returns ${field.name?cap_first} (virtual field)
+	Get${field.name?cap_first}() <#if helper.needsPointerAccess(field)>*</#if>${helper.getLanguageTypeNameForTypeReference(typeRef)}
+	</#list>
+	<#list type.abstractFields as field>
+		<#assign namedField=field.asNamedField().orElseThrow()>
+	// Get${namedField.name?cap_first} returns ${namedField.name?cap_first} (abstract field)
+	Get${namedField.name?cap_first}() ${helper.getLanguageTypeNameForField(field)}
+	</#list>
+}
+
+// ${type.name}Requirements provides a set of functions which need to be implemented by a sub struct
+type ${type.name}Requirements interface {
 	<#list helper.getDiscriminatorTypes() as discriminatorName, discriminatorType>
 	<#-- If the discriminator name matches that of another field, suppress the methods generation -->
 		<#if !type.isNonDiscriminatorField(discriminatorName)>
 	// Get${discriminatorName?cap_first} returns ${discriminatorName?cap_first} (discriminator field)
 	Get${discriminatorName?cap_first}() ${helper.getLanguageTypeNameForTypeReference(discriminatorType)}
 		</#if>
 	</#list>
-</#if>
-<#list type.propertyFields as field>
-    <#assign typeRef=field.asTypedField().orElseThrow().type>
-	// Get${field.name?cap_first} returns ${field.name?cap_first} (property field)
-	Get${field.name?cap_first}() <#if helper.needsPointerAccess(field)>*</#if>${helper.getLanguageTypeNameForTypeReference(typeRef)}
-</#list>
-<#list type.virtualFields as field>
-    <#assign typeRef=field.asTypedField().orElseThrow().type>
-	// Get${field.name?cap_first} returns ${field.name?cap_first} (virtual field)
-	Get${field.name?cap_first}() <#if helper.needsPointerAccess(field)>*</#if>${helper.getLanguageTypeNameForTypeReference(typeRef)}
-</#list>
-<#list type.abstractFields as field>
-	<#assign namedField=field.asNamedField().orElseThrow()>
-	// Get${namedField.name?cap_first} returns ${namedField.name?cap_first} (abstract field)
-	Get${namedField.name?cap_first}() ${helper.getLanguageTypeNameForField(field)}
-</#list>
 }
+</#if>
 
 // ${type.name}Exactly can be used when we want exactly this type and not a type which fulfills ${type.name}.
 // This is useful for switch cases.
@@ -157,6 +191,12 @@ type _${type.name} struct {
 </#if>
 }
 
+<#if type.isDiscriminatedParentTypeDefinition()>
+var _ ${type.name}Contract = (*_${type.name})(nil)
+<#else>
+var _ ${type.name} = (*_${type.name})(nil)
+</#if>
+
 <#if type.isDiscriminatedParentTypeDefinition()>
 type _${type.name}ChildRequirements interface {
 	utils.Serializable
@@ -847,7 +887,7 @@ func ${type.name}ParseWithBuffer(ctx context.Context, readBuffer utils.ReadBuffe
 				<#assign typedField = field.asTypedField().orElseThrow()>
 				<#assign namedField = field.asNamedField().orElseThrow()>
 
-	${namedField.name} := Read${field.typeName?cap_first}Field[${helper.getLanguageTypeNameForField(field)}](ctx, "${namedField.name}", ${helper.getDataReaderCall(typedField.type)}, ${helper.toParseExpression(assertField, assertField.type, assertField.conditionExpression, parserArguments)}${helper.getFieldOptions(typedField, parserArguments)})
+	${namedField.name},err := Read${field.typeName?cap_first}Field[${helper.getLanguageTypeNameForField(field)}](ctx, "${namedField.name}", ${helper.getDataReaderCall(typedField.type)}, ${helper.toParseExpression(assertField, assertField.type, assertField.conditionExpression, parserArguments)}${helper.getFieldOptions(typedField, parserArguments)})
 	if err != nil {
 		return nil, errors.Wrap(err, fmt.Sprintf("Error parsing '${namedField.name}' field"))<@emitImport import="github.com/pkg/errors" />
 	}
@@ -1066,7 +1106,7 @@ func ${type.name}ParseWithBuffer(ctx context.Context, readBuffer utils.ReadBuffe
 				<#assign typedField = field.asTypedField().orElseThrow()>
 
 	if _, err := Read${field.typeName?cap_first}Field(ctx, "unknown", ${helper.getDataReaderCall(typedField.type)}${helper.getFieldOptions(typedField, parserArguments)}); err!=nil{
-			return nil, errors.Wrap(_UnknownErr, "Error parsing unknown field of ${type.name}")<@emitImport import="github.com/pkg/errors" />
+			return nil, errors.Wrap(err, "Error parsing unknown field of ${type.name}")<@emitImport import="github.com/pkg/errors" />
 	}
 				<#break>
 			<#case "virtual">${helper.emitRequiredImportRaw(". \"github.com/apache/plc4x/plc4go/spi/codegen/fields\"")}

code-generation/language-go/src/test/resources/plc4go/go.mod

@@ -18,13 +18,15 @@
 //
 module github.com/apache/plc4x/plc4go
 
-go 1.16
+go 1.23
 
 require (
-	github.com/ajankovic/xdiff v0.0.1
-	github.com/icza/bitio v1.0.0
-	github.com/pkg/errors v0.9.1
-	github.com/rs/zerolog v1.20.0
-	github.com/subchen/go-xmldom v1.1.2
-	github.com/tebeka/go2xunit v1.4.10 // indirect
+    github.com/ajankovic/xdiff v0.0.1
+    github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e // indirect
+    github.com/icza/bitio v1.1.0
+    github.com/pkg/errors v0.9.1
+    github.com/rs/zerolog v1.33.0
+    github.com/subchen/go-xmldom v1.1.2
+    github.com/tebeka/go2xunit v1.4.10 // indirect
+    golang.org/x/tools v0.0.0-20190828213141-aed303cbaa74 // indirect
 )

code-generation/language-go/src/test/resources/plc4go/protocols/test/readwrite/model/StaticHelper.go

@@ -19,7 +19,10 @@
 
 package model
 
-import "github.com/apache/plc4x/plc4go/spi/utils"
+import (
+	"context"
+	"github.com/apache/plc4x/plc4go/spi/utils"
+)
 
 func ParseBit(io utils.ReadBuffer) int8 {
 	return 0
@@ -77,14 +80,19 @@ func Parse(io utils.ReadBuffer) int8 {
 func Serialize(io utils.WriteBuffer, data byte) {
 }
 
-func ReadManualField(io utils.ReadBuffer, simpleField uint8) (any, error) {
+func ReadAManualField(ctx context.Context, io utils.ReadBuffer, simpleField uint8) (any, error) {
 	return uint8(0), nil
 }
 
-func CrcInt8(num int) (int8, error) {
-	return int8(num), nil
+
+func CrcInt8(num int)  func() (int8, error) {
+	return func() (int8, error) {
+		return int8(num), nil
+	}
 }
 
-func CrcUint8(num int) (uint8, error) {
-	return uint8(num), nil
+func CrcUint8(num int) func() (uint8, error) {
+	return func() (uint8, error) {
+		return uint8(num), nil
+	}
 }

code-generation/protocol-test/src/main/resources/protocols/test/test.mspec

@@ -48,8 +48,8 @@
     //[manualArray    uint 8  manualArrayField count      '1'    ] // TODO: Implement ...
     //[manualArray    uint 8  manualArrayField length     '1'    ] // TODO: Implement ...
     //[manualArray    uint 8  manualArrayField terminated '1'    ] // TODO: Implement ...
-    [manual         uint 8  manualField 'STATIC_CALL("readManualField", readBuffer, simpleField)'
-                                        'STATIC_CALL("writeManualField", writeBuffer, simpleField)'
+    [manual         uint 8  manualField 'STATIC_CALL("readAManualField", readBuffer, simpleField)'
+                                        'STATIC_CALL("writeAManualField", writeBuffer, simpleField)'
                                         'simpleField*8'                   ]
     [optional       uint 8  optionalField 'simpleField == 5'   ]
     [padding        uint 8  paddingField  '0x00'  'simpleField']
@@ -476,6 +476,28 @@
 ////////////////////////////////////////////////////////////////
 
 /* Needs to be ported to C and GO
+[discriminatedType TTGranddad
+    [discriminator uint 8 dadNumber]
+    [simple uint 8 warStories]
+    [typeSwitch dadNumber
+        ['0x00' TTDad
+            [discriminator uint 8 sonNumber]
+            [simple uint 8 beerBottles]
+            [typeSwitch sonNumber
+                ['0x01' TTSon
+                    [simple uint 8 gameConsoles]
+                    [discriminator uint 8 babyNumber]
+                    [typeSwitch babyNumber
+                        ['0x02' TTBaby
+                            [simple uint 8 lalalala]
+                        ]
+                    ]
+                ]
+            ]
+        ]
+    ]
+]
+
 [discriminatedType TypeSwitchInTypeSwitchParentType
     [discriminator uint 8 typeNumber]
     [simple uint 8 parentFieldHurz]