printing: commit some refactors (probably broken)

internal/prnt/printer.go

@@ -0,0 +1,40 @@
+package prnt
+
+import (
+	"bytes"
+	"fmt"
+)
+
+type Generator struct {
+	buf bytes.Buffer
+	err error
+}
+
+func (g *Generator) Printf(format string, args ...interface{}) {
+	if g.err != nil {
+		return
+	}
+	if _, err := fmt.Fprintf(&g.buf, format, args...); err != nil {
+		g.AddError(err)
+	}
+}
+
+func (g *Generator) NL() {
+	g.Printf("\n")
+}
+
+func (g *Generator) Comment(lines ...string) {
+	for _, line := range lines {
+		g.Printf("// %s\n", line)
+	}
+}
+
+func (g *Generator) AddError(err error) {
+	if err != nil && g.err == nil {
+		g.err = err
+	}
+}
+
+func (g *Generator) Result() ([]byte, error) {
+	return g.buf.Bytes(), g.err
+}