json: encoder now has pretty print options.

... with no way to configure them yet, admittedly.

I don't want to further bifrucate the already alarming number of
top-level methods there are for setting up your marshallers and
unmarshallers.  It's probably time to get a move-on on those
options structs and actually make them do some work.

... oooh.  And we can make those a lot less ugly now that golang
has aliases.  That'll let us put the configuration struct types in
their relevant packages, and alias them out to the top level package
with all its other convenience methods.

Signed-off-by: Eric Myhre <hash@exultant.us>

Author: warpfork

json/jsonEncoder.go

@@ -25,7 +25,9 @@ func (d *Encoder) Reset() {
 	A json.Encoder is a TokenSink implementation that emits json bytes.
 */
 type Encoder struct {
-	wr io.Writer
+	wr     io.Writer
+	indent []byte
+	line   []byte
 
 	// Stack, tracking how many array and map opens are outstanding.
 	// (Values are only 'phase_mapExpectKeyOrEnd' and 'phase_arrExpectValueOrEnd'.)
@@ -74,6 +76,10 @@ func (d *Encoder) Step(tok *Token) (done bool, err error) {
 		case TArrOpen:
 			return true, fmt.Errorf("unexpected arrOpen; expected start of key or end of map")
 		case TMapClose:
+			d.wr.Write(d.line)
+			for i := 1; i < len(d.stack); i++ {
+				d.wr.Write(d.indent)
+			}
 			d.wr.Write(wordMapClose)
 			return d.popPhase()
 		case TArrClose:
@@ -126,6 +132,10 @@ func (d *Encoder) Step(tok *Token) (done bool, err error) {
 		case TMapClose:
 			return true, fmt.Errorf("unexpected mapClose; expected start of value or end of array")
 		case TArrClose:
+			d.wr.Write(d.line)
+			for i := 1; i < len(d.stack); i++ {
+				d.wr.Write(d.indent)
+			}
 			d.wr.Write(wordArrClose)
 			return d.popPhase()
 		default:
@@ -149,6 +159,7 @@ func (d *Encoder) pushPhase(p phase) {
 func (d *Encoder) popPhase() (bool, error) {
 	n := len(d.stack) - 1
 	if n == 0 {
+		d.wr.Write(d.line)
 		return true, nil
 	}
 	if n < 0 { // the state machines are supposed to have already errored better
@@ -167,6 +178,10 @@ func (d *Encoder) entrySep() {
 		d.wr.Write(wordComma)
 	}
 	d.some = true
+	d.wr.Write(d.line)
+	for i := 0; i < len(d.stack); i++ {
+		d.wr.Write(d.indent)
+	}
 }
 
 func (d *Encoder) flushValue(tok *Token) {