From da633fb3048d576c63bb1faf6f0e09aea55867e9 Mon Sep 17 00:00:00 2001
From: John Jeffery <jjeffery@sp.com.au>
Date: Sun, 22 Jan 2017 11:22:45 +1000
Subject: [PATCH] Uses package kv to serialize key/value pairs.

This package already depended on package kv for kv.Flatten, so it seems OK to use this new functionality from package kv.
---
 context.go     | 152 ++-----------------------------------------------
 errors_test.go |   4 +-
 2 files changed, 7 insertions(+), 149 deletions(-)

diff --git a/context.go b/context.go
index 446a7e1..1b82e75 100644
--- a/context.go
+++ b/context.go
@@ -2,9 +2,6 @@ package errors
 
 import (
 	"bytes"
-	"encoding"
-	"fmt"
-	"reflect"
 	"strings"
 
 	"github.com/jjeffery/kv"
@@ -104,152 +101,13 @@ func (ctx context) appendKeyvals(keyvals []interface{}) []interface{} {
 
 // writeToBuf writes the context's key/value pairs to a buffer.
 func (ctx context) writeToBuf(buf *bytes.Buffer) {
-	keyvals := kv.Flatten(ctx.keyvals)
-	for i := 0; i < len(keyvals); i += 2 {
-		// kv.Flatten guarantees that every even-numbered index
-		// will contain a string, and that it will be followed by
-		// an odd-numbered index
-		key := keyvals[i].(string)
-		value := keyvals[i+1]
-
-		if buf.Len() > 0 {
-			buf.WriteRune(' ')
-		}
-		buf.WriteString(key)
-		buf.WriteRune('=')
-		writeValue(buf, value)
-	}
-}
-
-// constant byte values
-var (
-	bytesNull  = []byte("null")
-	bytesPanic = []byte(`"<PANIC>"`)
-	bytesError = []byte(`"<ERROR>"`)
-)
-
-func writeValue(buf *bytes.Buffer, value interface{}) {
-	defer func() {
-		if r := recover(); r != nil {
-			if buf != nil {
-				buf.Write(bytesPanic)
-			}
-		}
-	}()
-	switch v := value.(type) {
-	case nil:
-		writeBytesValue(buf, bytesNull)
-		return
-	case []byte:
-		writeBytesValue(buf, v)
-		return
-	case string:
-		writeStringValue(buf, v)
-		return
-	case bool, byte, int8, int16, uint16, int32, uint32, int64, uint64, int, uint, uintptr, float32, float64, complex64, complex128:
-		fmt.Fprint(buf, v)
-		return
-	case encoding.TextMarshaler:
-		writeTextMarshalerValue(buf, v)
-		return
-	case error:
-		writeStringValue(buf, v.Error())
-		return
-	case fmt.Stringer:
-		writeStringValue(buf, v.String())
-		return
-	default:
-		// handle pointer to any of the above
-		rv := reflect.ValueOf(value)
-		if rv.Kind() == reflect.Ptr {
-			if rv.IsNil() {
-				buf.Write(bytesNull)
-				return
-			}
-			writeValue(buf, rv.Elem().Interface())
-			return
-		}
-		writeStringValue(buf, fmt.Sprint(value))
-	}
-}
-
-func writeBytesValue(buf *bytes.Buffer, b []byte) {
-	if b == nil {
-		buf.Write(bytesNull)
+	if len(ctx.keyvals) == 0 {
 		return
 	}
-	index := bytes.IndexFunc(b, needsQuote)
-	if index < 0 {
-		buf.Write(b)
-		return
-	}
-	buf.WriteRune('"')
-	if index > 0 {
-		buf.Write(b[0:index])
-		b = b[index:]
-	}
-	for {
-		index = bytes.IndexFunc(b, needsBackslash)
-		if index < 0 {
-			break
-		}
-		if index > 0 {
-			buf.Write(b[:index])
-			b = b[index:]
-		}
-		buf.WriteRune('\\')
-		// we know that the rune will be a single byte
-		buf.WriteByte(b[0])
-		b = b[1:]
+	kvlist := kv.List(ctx.keyvals)
+	b, _ := kvlist.MarshalText()
+	if buf.Len() > 0 {
+		buf.WriteRune(' ')
 	}
 	buf.Write(b)
-	buf.WriteRune('"')
-}
-
-func writeStringValue(buf *bytes.Buffer, s string) {
-	index := strings.IndexFunc(s, needsQuote)
-	if index < 0 {
-		buf.WriteString(s)
-		return
-	}
-	buf.WriteRune('"')
-	if index > 0 {
-		buf.WriteString(s[0:index])
-		s = s[index:]
-	}
-	for {
-		index = strings.IndexFunc(s, needsBackslash)
-		if index < 0 {
-			break
-		}
-		if index > 0 {
-			buf.WriteString(s[0:index])
-			s = s[index:]
-		}
-		buf.WriteRune('\\')
-		// we know that the rune will be a single byte
-		buf.WriteByte(s[0])
-		s = s[1:]
-	}
-	buf.WriteString(s)
-	buf.WriteRune('"')
-}
-
-func writeTextMarshalerValue(buf *bytes.Buffer, t encoding.TextMarshaler) {
-	b, err := t.MarshalText()
-	if err != nil {
-		buf.Write(bytesError)
-		return
-	}
-	writeBytesValue(buf, b)
-}
-
-func needsQuote(c rune) bool {
-	// the single quote '\'' is not strictly necessary, but
-	// is more human readable if quoted
-	return c <= ' ' || c == '"' || c == '\\' || c == '\''
-}
-
-func needsBackslash(c rune) bool {
-	return c == '\\' || c == '"'
 }
diff --git a/errors_test.go b/errors_test.go
index d24b310..29d5695 100644
--- a/errors_test.go
+++ b/errors_test.go
@@ -71,7 +71,7 @@ func TestNew(t *testing.T) {
 			opts: []interface{}{
 				"f1", failingTextMarshaler(0),
 			},
-			expect: `msg f1="<ERROR>"`,
+			expect: `msg f1=<ERROR>`,
 		},
 		{
 			msg: "msg",
@@ -108,7 +108,7 @@ func TestNew(t *testing.T) {
 			opts: []interface{}{
 				"p1", panicingStringer("I can't do this"),
 			},
-			expect: `msg p1="<PANIC>"`,
+			expect: `msg p1=<PANIC>`,
 		},
 	}