1 files changed, 17 insertions, 4 deletions
diff --git a/src/pkg/math/big/rat.go b/src/pkg/math/big/rat.go
index 7faee61a4..f0973b390 100644
--- a/src/pkg/math/big/rat.go
+++ b/src/pkg/math/big/rat.go
@@ -47,7 +47,7 @@ func (z *Rat) SetFloat64(f float64) *Rat {
 
 	shift := 52 - exp
 
-	// Optimisation (?): partially pre-normalise.
+	// Optimization (?): partially pre-normalise.
 	for mantissa&1 == 0 && shift > 0 {
 		mantissa >>= 1
 		shift--
@@ -477,7 +477,7 @@ func (z *Rat) SetString(s string) (*Rat, bool) {
 	return z, true
 }
 
-// String returns a string representation of z in the form "a/b" (even if b == 1).
+// String returns a string representation of x in the form "a/b" (even if b == 1).
 func (x *Rat) String() string {
 	s := "/1"
 	if len(x.b.abs) != 0 {
@@ -486,7 +486,7 @@ func (x *Rat) String() string {
 	return x.a.String() + s
 }
 
-// RatString returns a string representation of z in the form "a/b" if b != 1,
+// RatString returns a string representation of x in the form "a/b" if b != 1,
 // and in the form "a" if b == 1.
 func (x *Rat) RatString() string {
 	if x.IsInt() {
@@ -495,7 +495,7 @@ func (x *Rat) RatString() string {
 	return x.String()
 }
 
-// FloatString returns a string representation of z in decimal form with prec
+// FloatString returns a string representation of x in decimal form with prec
 // digits of precision after the decimal point and the last digit rounded.
 func (x *Rat) FloatString(prec int) string {
 	if x.IsInt() {
@@ -585,3 +585,16 @@ func (z *Rat) GobDecode(buf []byte) error {
 	z.b.abs = z.b.abs.setBytes(buf[i:])
 	return nil
 }
+
+// MarshalText implements the encoding.TextMarshaler interface
+func (r *Rat) MarshalText() (text []byte, err error) {
+	return []byte(r.RatString()), nil
+}
+
+// UnmarshalText implements the encoding.TextUnmarshaler interface
+func (r *Rat) UnmarshalText(text []byte) error {
+	if _, ok := r.SetString(string(text)); !ok {
+		return fmt.Errorf("math/big: cannot unmarshal %q into a *big.Rat", text)
+	}
+	return nil
+}