Merge pull request #87 from jmattheis/dont-copy

README.md

@@ -32,10 +32,11 @@ use reflection.
 ## Features
 
 - **Fast execution**: No reflection is used at runtime
-- Automatically [deep
-  copies](https://en.wikipedia.org/wiki/Object_copying#Deep_copy) builtin
-  types: slices, maps, named types, primitive types, pointers, structs with
-  same fields
+- Automatically converts builtin types: slices, maps, named types, primitive
+  types, pointers, structs with same fields
+- [Deep copies](https://en.wikipedia.org/wiki/Object_copying#Deep_copy) per
+  default and supports [shallow
+  copying](https://en.wikipedia.org/wiki/Object_copying#Shallow_copy)
 - **Customizable**: [You can implement custom converter methods](https://goverter.jmattheis.de/#/conversion/custom)
 - [Clear errors when generating the conversion methods](https://goverter.jmattheis.de/#/conversion/?id=error-early) if
   - the target struct has unmapped fields
@@ -86,7 +87,7 @@ use reflection.
 1. Run `goverter`:
 
     ```bash
-    $ go run github.com/jmattheis/goverter/cmd/goverter@v0.17.4 ./
+    $ go run github.com/jmattheis/goverter/cmd/goverter@v0.18.0 ./
     ```
 
     See [Installation](https://goverter.jmattheis.de/#/install) for more information.

builder/flags.go

@@ -8,6 +8,7 @@ const (
 	FlagMatchIgnoreCase
 	FlagIgnoreUnexported
 	FlagZeroValueOnPtrInconsistency
+	FlagSkipCopySameType
 )
 
 type ConversionFlags map[ConversionFlag]bool

builder/skipcopy.go

@@ -0,0 +1,19 @@
+package builder
+
+import (
+	"github.com/dave/jennifer/jen"
+	"github.com/jmattheis/goverter/xtype"
+)
+
+// SkipCopy handles FlagSkipCopySameType.
+type SkipCopy struct{}
+
+// Matches returns true, if the builder can create handle the given types.
+func (*SkipCopy) Matches(ctx *MethodContext, source, target *xtype.Type) bool {
+	return ctx.Flags.Has(FlagSkipCopySameType) && source.T.String() == target.T.String()
+}
+
+// Build creates conversion source code for the given source and target type.
+func (*SkipCopy) Build(_ Generator, _ *MethodContext, sourceID *xtype.JenID, _, _ *xtype.Type) ([]jen.Code, *xtype.JenID, *Error) {
+	return nil, sourceID, nil
+}

comments/parse_docs.go

@@ -226,6 +226,9 @@ func parseConverterComment(comment string, config ConverterConfig) (ConverterCon
 			case "ignoreMissing":
 				config.Flags.Set(builder.FlagIgnoreMissing)
 				continue
+			case "skipCopySameType":
+				config.Flags.Set(builder.FlagSkipCopySameType)
+				continue
 			case "useZeroValueOnPointerInconsistency":
 				config.Flags.Set(builder.FlagZeroValueOnPtrInconsistency)
 				continue
@@ -318,6 +321,9 @@ func parseMethodComment(comment string) (Method, error) {
 			case "useZeroValueOnPointerInconsistency":
 				m.Flags.Set(builder.FlagZeroValueOnPtrInconsistency)
 				continue
+			case "skipCopySameType":
+				m.Flags.Set(builder.FlagSkipCopySameType)
+				continue
 			case "wrapErrors":
 				if strings.TrimSpace(remaining) != "" {
 					return m, fmt.Errorf("invalid %s:wrapErrors, parameters not supported", prefix)

docs/conversion/misc.md

@@ -151,3 +151,54 @@ func (c *ConverterImpl) Convert(source example.Input) example.Output {
 ```
 
 <!-- tabs:end -->
+
+## Skip copy same type
+
+Goverter deep copies instances when converting the source to the target type.
+With `goverter:skipCopySameType` you instruct Goverter to skip copying
+instances when the source and target type is the same.
+
+The setting can be enabled on both the converter interface and methods.
+
+<!-- tabs:start -->
+
+#### **input.go**
+
+```go
+package example
+
+// goverter:converter
+// goverter:skipCopySameType
+type Converter interface {
+	Convert(source Input) Output
+}
+
+type Input struct {
+	Name *string
+    ItemCounts map[string]int
+}
+
+type Output struct {
+	Name *string
+    ItemCounts map[string]int
+}
+```
+
+#### **generated/generated.go**
+
+```go
+package generated
+
+import example "goverter/example"
+
+type ConverterImpl struct{}
+
+func (c *ConverterImpl) Convert(source example.Input) example.Output {
+	var exampleOutput example.Output
+	exampleOutput.Name = source.Name
+	exampleOutput.ItemCounts = source.ItemCounts
+	return exampleOutput
+}
+```
+
+<!-- tabs:end -->

generator/generate.go

@@ -24,6 +24,7 @@ type Config struct {
 
 // BuildSteps that'll used for generation.
 var BuildSteps = []builder.Builder{
+	&builder.SkipCopy{},
 	&builder.BasicTargetPointerRule{},
 	&builder.Pointer{},
 	&builder.SourcePointer{},

generator/generator.go

@@ -423,6 +423,9 @@ func (g *generator) Build(
 		case source.Pointer && source.PointerInner.Named && !source.PointerInner.Basic:
 			createSubMethod = true
 		}
+		if ctx.Flags.Has(builder.FlagSkipCopySameType) && source.T.String() == target.T.String() {
+			createSubMethod = false
+		}
 	}
 	ctx.MarkSeen(source)
 

scenario/skipcopy_identity.yml

@@ -0,0 +1,19 @@
+input:
+    input.go: |
+        package skip
+
+        // goverter:converter
+        // goverter:skipCopySameType
+        type Converter interface {
+            Convert(source map[string]int) map[string]int
+        }
+success: |
+    // Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
+
+    package generated
+
+    type ConverterImpl struct{}
+
+    func (c *ConverterImpl) Convert(source map[string]int) map[string]int {
+    	return source
+    }

scenario/skipcopy_inner.yml

@@ -0,0 +1,56 @@
+input:
+    input.go: |
+        package skip
+
+        import "time"
+
+        // goverter:converter
+        // goverter:skipCopySameType
+        type Converter interface {
+            Convert(source Input) Output
+        }
+
+        type Input struct {
+            ID *int
+            Map map[string]int
+            MapDifferentType map[string]int
+            CreatedAt time.Time
+            Unnamed struct{Name string}
+        }
+        type Output struct {
+            ID *int
+            Map map[string]int
+            MapDifferentType map[string]ID
+            CreatedAt *time.Time
+            Unnamed struct{Name string}
+        }
+
+        type ID int
+success: |
+    // Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
+
+    package generated
+
+    import (
+    	execution "github.com/jmattheis/goverter/execution"
+    	"time"
+    )
+
+    type ConverterImpl struct{}
+
+    func (c *ConverterImpl) Convert(source execution.Input) execution.Output {
+    	var skipOutput execution.Output
+    	skipOutput.ID = source.ID
+    	skipOutput.Map = source.Map
+    	mapStringSkipID := make(map[string]execution.ID, len(source.MapDifferentType))
+    	for key, value := range source.MapDifferentType {
+    		mapStringSkipID[key] = execution.ID(value)
+    	}
+    	skipOutput.MapDifferentType = mapStringSkipID
+    	skipOutput.CreatedAt = c.timeTimeToPTimeTime(source.CreatedAt)
+    	skipOutput.Unnamed = source.Unnamed
+    	return skipOutput
+    }
+    func (c *ConverterImpl) timeTimeToPTimeTime(source time.Time) *time.Time {
+    	return &source
+    }

scenario/skipcopy_method.yml

@@ -0,0 +1,30 @@
+input:
+    input.go: |
+        package skip
+
+        // goverter:converter
+        type Converter interface {
+            // goverter:skipCopySameType
+            Convert(source Input) Output
+        }
+
+        type Input struct {
+            ID *int
+        }
+        type Output struct {
+            ID *int
+        }
+success: |
+    // Code generated by github.com/jmattheis/goverter, DO NOT EDIT.
+
+    package generated
+
+    import execution "github.com/jmattheis/goverter/execution"
+
+    type ConverterImpl struct{}
+
+    func (c *ConverterImpl) Convert(source execution.Input) execution.Output {
+    	var skipOutput execution.Output
+    	skipOutput.ID = source.ID
+    	return skipOutput
+    }