encode: Begone with encodeTODO

2 files changed, 59 insertions, 13 deletions

diff --git a/borrowed_misc.go b/borrowed_misc.go
index 59c49aa..52f4a12 100644
--- a/borrowed_misc.go
+++ b/borrowed_misc.go
@@ -7,7 +7,10 @@
 package lowmemjson
 
 import (
+	"io"
+	"math"
 	"reflect"
+	"strconv"
 )
 
 // isEmptyValue is borrowed from encode.go.
@@ -28,3 +31,43 @@ func isEmptyValue(v reflect.Value) bool {
 	}
 	return false
 }
+
+// encodeFloat is lightly modified from
+// encode.go:floatEncoder.encode().
+func encodeFloat(w io.Writer, bits int, v reflect.Value) error {
+	var scratch [64]byte
+
+	f := v.Float()
+	if math.IsInf(f, 0) || math.IsNaN(f) {
+		return &EncodeValueError{Value: v, Str: strconv.FormatFloat(f, 'g', -1, bits)}
+	}
+
+	// Convert as if by ES6 number to string conversion.
+	// This matches most other JSON generators.
+	// See golang.org/issue/6384 and golang.org/issue/14135.
+	// Like fmt %g, but the exponent cutoffs are different
+	// and exponents themselves are not padded to two digits.
+	b := scratch[:0]
+	abs := math.Abs(f)
+	fmt := byte('f')
+	// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
+	if abs != 0 {
+		if bits == 64 && (abs < 1e-6 || abs >= 1e21) || bits == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
+			fmt = 'e'
+		}
+	}
+	b = strconv.AppendFloat(b, f, fmt, -1, bits)
+	if fmt == 'e' {
+		// clean up e-09 to e-9
+		n := len(b)
+		if n >= 4 && b[n-4] == 'e' && b[n-3] == '-' && b[n-2] == '0' {
+			b[n-2] = b[n-1]
+			b = b[:n-1]
+		}
+	}
+
+	if _, err := w.Write(b); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/encode.go b/encode.go
index 2830ace..492b40f 100644
--- a/encode.go
+++ b/encode.go
@@ -246,13 +246,27 @@ func encode(w *ReEncoder, val reflect.Value, escaper BackslashEscaper, quote boo
 					return err
 				}
 			}
-		case reflect.Float32, reflect.Float64:
+		case reflect.Float32:
 			if quote {
 				if err := w.WriteByte('"'); err != nil {
 					return err
 				}
 			}
-			if err := encodeTODO(w, val); err != nil {
+			if err := encodeFloat(w, 32, val); err != nil {
+				return err
+			}
+			if quote {
+				if err := w.WriteByte('"'); err != nil {
+					return err
+				}
+			}
+		case reflect.Float64:
+			if quote {
+				if err := w.WriteByte('"'); err != nil {
+					return err
+				}
+			}
+			if err := encodeFloat(w, 64, val); err != nil {
 				return err
 			}
 			if quote {
@@ -522,14 +536,3 @@ func encodeArray(w *ReEncoder, val reflect.Value, escaper BackslashEscaper, cycl
 	}
 	return nil
 }
-
-func encodeTODO(w io.Writer, val reflect.Value) error {
-	bs, err := json.Marshal(val.Interface())
-	if err != nil {
-		return err
-	}
-	if _, err := w.Write(bs); err != nil {
-		return err
-	}
-	return nil
-}