generate the instruction table

internal/gen/gen.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"go/format"
+	"strings"
 
 	"github.com/mmcloughlin/avo/internal/inst"
 )
@@ -18,6 +19,24 @@ func (f Func) Generate(is []*inst.Instruction) ([]byte, error) {
 	return f(is)
 }
 
+type Config struct {
+	Name string
+	Argv []string
+}
+
+func (c Config) GeneratedBy() string {
+	if c.Argv == nil {
+		return c.Name
+	}
+	return fmt.Sprintf("command: %s", strings.Join(c.Argv, " "))
+}
+
+func (c Config) GeneratedWarning() string {
+	return fmt.Sprintf("Code generated by %s. DO NOT EDIT.", c.GeneratedBy())
+}
+
+type Builder func(Config) Interface
+
 // GoFmt formats Go code produced from the given generator.
 func GoFmt(i Interface) Interface {
 	return Func(func(is []*inst.Instruction) ([]byte, error) {