sample: indent request initialization (#43)

Fixes #41.

Author: pongad

cmd/gen-go-sample/main.go

@@ -271,34 +271,26 @@ func (g *generator) genSample(ifaceName, methName, regTag string, valSet SampleV
 	p("")
 	g.imports[pbinfo.ImportSpec{Path: "context"}] = true
 
-	for i, name := range argNames {
-		var sb strings.Builder
-		fmt.Fprintf(&sb, "// %s := ", name)
-		if err := argTrees[i].Print(&sb, g); err != nil {
-			return errors.E(err, "can't initializing parameter: %s", name)
-		}
-		s := sb.String()
-		s = strings.Replace(s, "\n", "\n//", -1)
-
-		w := g.pt.Writer()
-		if _, err := w.Write([]byte(s)); err != nil {
-			return err
-		}
-		if _, err := w.Write([]byte{'\n'}); err != nil {
-			return err
-		}
-	}
-
 	{
-		w := g.pt.Writer()
+		var buf bytes.Buffer
 
-		if _, err := w.Write([]byte("req := ")); err != nil {
-			return err
+		for i, name := range argNames {
+			fmt.Fprintf(&buf, "%s := ", name)
+			if err := argTrees[i].Print(&buf, g); err != nil {
+				return errors.E(err, "can't initialize parameter: %s", name)
+			}
+			buf.WriteByte('\n')
 		}
-		if err := itree.Print(g.pt.Writer(), g); err != nil {
-			return errors.E(err, "can't initializing request object")
+		prependLines(&buf, "// ")
+
+		buf.WriteString("req := ")
+		if err := itree.Print(&buf, g); err != nil {
+			return errors.E(err, "can't initialize request object")
 		}
-		if _, err := w.Write([]byte{'\n'}); err != nil {
+		buf.WriteByte('\n')
+		prependLines(&buf, "\t")
+
+		if _, err := buf.WriteTo(g.pt.Writer()); err != nil {
 			return err
 		}
 	}
@@ -433,3 +425,26 @@ func (g *generator) handleOut(meth *descriptor.MethodDescriptorProto, valSet Sam
 	}
 	return nil
 }
+
+// prependLines adds prefix to every line in b. A line is defined as a possibly empty run
+// of non-newlines terminated by a newline character.
+// If b doesn't end with a newline, prependLines panics.
+func prependLines(b *bytes.Buffer, prefix string) {
+	if b.Len() == 0 {
+		return
+	}
+	if b.Bytes()[b.Len()-1] != '\n' {
+		panic(errors.E(nil, "prependLines: must end with newline"))
+	}
+	// Don't split with b.Bytes; we have to make a copy of the content since we're overwriting the buffer.
+	lines := strings.SplitAfter(b.String(), "\n")
+	b.Reset()
+	for _, l := range lines {
+		// When splitting, we have an empty string after the last newline, ignore it.
+		if l == "" {
+			continue
+		}
+		b.WriteString(prefix)
+		b.WriteString(l)
+	}
+}

cmd/gen-go-sample/main_test.go

@@ -15,7 +15,6 @@
 package main
 
 import (
-	"fmt"
 	"path/filepath"
 	"testing"
 
@@ -29,7 +28,6 @@ func TestUnary(t *testing.T) {
 	t.Parallel()
 
 	g := initTestGenerator()
-	fmt.Println(g.descInfo.Serv)
 
 	vs := SampleValueSet{
 		ID: "my_value_set",

cmd/gen-go-sample/testdata/sample_empty.want

@@ -33,8 +33,8 @@ func sampleEmptyMethod() error {
 		return err
 	}
 
-req := &foopb.PageInType{
-}
+	req := &foopb.PageInType{
+	}
 	if err := c.EmptyMethod(ctx, req); err != nil {
 		return err
 	}

cmd/gen-go-sample/testdata/sample_paging.want

@@ -34,8 +34,8 @@ func samplePagingMethod() error {
 		return err
 	}
 
-req := &foopb.PageInType{
-}
+	req := &foopb.PageInType{
+	}
 	it := c.PagingMethod(ctx, req)
 	for {
 		resp, err := it.Next()

cmd/gen-go-sample/testdata/sample_unary.want

@@ -33,29 +33,29 @@ func sampleUnaryMethod(theX int64, theB string) error {
 		return err
 	}
 
-// theX := 42
-// theB := "foobar"
-req := &foopb.InputType{
-	A: &foopb.AType{
-		X: theX,
-		Y: 3.14159,
-	},
-	B: theB,
-	E: foopb.AType_FOO,
-	Group: &foopb.InputType_F{
-		F: "in a oneof",
-	},
-	AArray: []*foopb.AType{
-		&foopb.AType{
-			X: 0,
-			Y: 1,
+	// theX := 42
+	// theB := "foobar"
+	req := &foopb.InputType{
+		A: &foopb.AType{
+			X: theX,
+			Y: 3.14159,
 		},
-		&foopb.AType{
-			X: 2,
-			Y: 3,
+		B: theB,
+		E: foopb.AType_FOO,
+		Group: &foopb.InputType_F{
+			F: "in a oneof",
 		},
-	},
-}
+		AArray: []*foopb.AType{
+			&foopb.AType{
+				X: 0,
+				Y: 1,
+			},
+			&foopb.AType{
+				X: 2,
+				Y: 3,
+			},
+		},
+	}
 	resp, err := c.UnaryMethod(ctx, req)
 	if err != nil {
 		return err