From 9d1b2b2df58741f32885bc733e4cf5defccfdf36 Mon Sep 17 00:00:00 2001
From: Jordan Orelli <jordanorelli@gmail.com>
Date: Tue, 21 Apr 2015 23:21:15 -0400
Subject: [PATCH] new subcommand: eval

---
 cmd/moon/main.go | 28 +++++++++++++++++++++++++---
 lib/doc.go       | 19 +++++++++++++++++++
 lib/emit.go      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+), 3 deletions(-)

diff --git a/cmd/moon/main.go b/cmd/moon/main.go
index 506d630..875aaec 100644
--- a/cmd/moon/main.go
+++ b/cmd/moon/main.go
@@ -43,7 +43,9 @@ func to() {
 }
 
 func to_json(n int) {
-	doc, err := moon.Read(input(n))
+	in := input(n)
+	defer in.Close()
+	doc, err := moon.Read(in)
 	if err != nil {
 		bail(1, "input error: %s", err)
 	}
@@ -56,7 +58,10 @@ func to_json(n int) {
 
 func get() {
 	docpath := flag.Arg(1)
-	doc, err := moon.Read(input(2))
+	in := input(2)
+	defer in.Close()
+
+	doc, err := moon.Read(in)
 	if err != nil {
 		bail(1, "input error: %s", err)
 	}
@@ -71,6 +76,21 @@ func get() {
 	os.Stdout.Write(b)
 }
 
+func eval() {
+	in := input(1)
+	defer in.Close()
+
+	doc, err := moon.Read(in)
+	if err != nil {
+		bail(1, "input error: %s", err)
+	}
+	b, err := moon.Encode(doc)
+	if err != nil {
+		bail(1, "output error: %s", err)
+	}
+	os.Stdout.Write(b)
+}
+
 func bail(status int, t string, args ...interface{}) {
 	var w io.Writer
 	if status == 0 {
@@ -91,8 +111,10 @@ func main() {
 		to()
 	case "get":
 		get()
+	case "eval":
+		eval()
 	case "":
-		bail(1, "must specify an action.\nvalid actions: check to get")
+		bail(1, "must specify an action.\nvalid actions: check to get eval")
 	default:
 		bail(1, "no such action:%s", flag.Arg(0))
 	}
diff --git a/lib/doc.go b/lib/doc.go
index 21def1b..33ea28f 100644
--- a/lib/doc.go
+++ b/lib/doc.go
@@ -1,6 +1,7 @@
 package moon
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"reflect"
@@ -16,6 +17,24 @@ func (d *Doc) MarshalJSON() ([]byte, error) {
 	return json.Marshal(d.items)
 }
 
+func (d *Doc) MarshalMoon() ([]byte, error) {
+	var buf bytes.Buffer
+	for k, v := range d.items {
+		buf.WriteString(k)
+		buf.WriteByte(':')
+		buf.WriteByte(' ')
+		b, err := Encode(v)
+		if err != nil {
+			return nil, err
+		}
+		if _, err := buf.Write(b); err != nil {
+			return nil, err
+		}
+		buf.WriteByte('\n')
+	}
+	return buf.Bytes(), nil
+}
+
 func (d *Doc) Get(path string, dest interface{}) error {
 	if d.items == nil {
 		return fmt.Errorf("no item found at path %s (doc is empty)", path)
diff --git a/lib/emit.go b/lib/emit.go
index 5438e2f..397d78d 100644
--- a/lib/emit.go
+++ b/lib/emit.go
@@ -9,6 +9,10 @@ import (
 	"strconv"
 )
 
+type Marshaler interface {
+	MarshalMoon() ([]byte, error)
+}
+
 func Encode(v interface{}) ([]byte, error) {
 	e := &encoder{}
 	if err := e.encode(v); err != nil {
@@ -52,7 +56,15 @@ func valueEncoder(v reflect.Value) encodeFn {
 	return typeEncoder(v.Type())
 }
 
+var (
+	marshalerType = reflect.TypeOf(new(Marshaler)).Elem()
+)
+
 func typeEncoder(t reflect.Type) encodeFn {
+	if t.Implements(marshalerType) {
+		return marshalerEncoder
+	}
+
 	switch t.Kind() {
 	case reflect.Bool:
 		return encodeBool
@@ -70,6 +82,8 @@ func typeEncoder(t reflect.Type) encodeFn {
 		return encodeSlice
 	case reflect.Interface:
 		return encodeInterface
+	case reflect.Ptr:
+		return encodePointer
 	case reflect.Map:
 		return encodeMap
 	default:
@@ -187,3 +201,24 @@ func encodeMap(e *encoder, v reflect.Value) {
 	}
 	e.WriteByte('}')
 }
+
+func encodePointer(e *encoder, v reflect.Value) {
+	if v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	e.encodeValue(v.Elem())
+}
+
+func marshalerEncoder(e *encoder, v reflect.Value) {
+	if v.Kind() == reflect.Ptr && v.IsNil() {
+		e.WriteString("null")
+		return
+	}
+	m := v.Interface().(Marshaler)
+	b, err := m.MarshalMoon()
+	if err != nil {
+		panic(err)
+	}
+	e.Write(b)
+}