refactor: merge big.Rat wrapper types (#1134)

Fixes #1133

Signed-off-by: Aurora Gaffney <[email protected]>

Author: agaffney

cbor/tags.go

@@ -15,6 +15,7 @@
 package cbor
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math/big"
@@ -150,6 +151,24 @@ func (r *Rat) MarshalCBOR() ([]byte, error) {
 	return Encode(&tmpData)
 }
 
+func (r *Rat) UnmarshalJSON(data []byte) error {
+	// Try as ratio
+	var tmpData struct {
+		Numerator   int64 `json:"numerator"`
+		Denominator int64 `json:"denominator"`
+	}
+	if err := json.Unmarshal(data, &tmpData); err == nil {
+		r.Rat = big.NewRat(tmpData.Numerator, tmpData.Denominator)
+		return nil
+	}
+	// Try as decimal value
+	r.Rat = new(big.Rat)
+	if _, ok := r.SetString(string(data)); !ok {
+		return fmt.Errorf("math/big: cannot unmarshal %q into a *big.Rat", data)
+	}
+	return nil
+}
+
 func (r *Rat) ToBigRat() *big.Rat {
 	return r.Rat
 }

cbor/tags_test.go

@@ -16,11 +16,13 @@ package cbor_test
 
 import (
 	"encoding/hex"
+	"encoding/json"
 	"math/big"
 	"reflect"
 	"testing"
 
 	"github.com/blinklabs-io/gouroboros/cbor"
+	"github.com/blinklabs-io/gouroboros/ledger/common"
 )
 
 var tagsTestDefs = []struct {
@@ -109,3 +111,31 @@ func TestTagsEncode(t *testing.T) {
 		}
 	}
 }
+
+func TestRatJsonUnmarshalNumDenom(t *testing.T) {
+	jsonData := `{"testRat": { "numerator": 721, "denominator": 10000 }}`
+	expectedRat := big.NewRat(721, 10000)
+	var testData struct {
+		TestRat common.GenesisRat `json:"testRat"`
+	}
+	if err := json.Unmarshal([]byte(jsonData), &testData); err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	if testData.TestRat.Cmp(expectedRat) != 0 {
+		t.Errorf("did not get expected value: got %s, wanted %s", testData.TestRat.String(), expectedRat.String())
+	}
+}
+
+func TestRatJsonUnmarshalFloat(t *testing.T) {
+	jsonData := `{"testRat": 0.0721}`
+	expectedRat := big.NewRat(721, 10000)
+	var testData struct {
+		TestRat common.GenesisRat `json:"testRat"`
+	}
+	if err := json.Unmarshal([]byte(jsonData), &testData); err != nil {
+		t.Fatalf("unexpected error: %s", err)
+	}
+	if testData.TestRat.Cmp(expectedRat) != 0 {
+		t.Errorf("did not get expected value: got %s, wanted %s", testData.TestRat.String(), expectedRat.String())
+	}
+}

ledger/common/common.go

@@ -439,3 +439,6 @@ type ExUnits struct {
 	Memory uint64
 	Steps  uint64
 }
+
+// GenesisRat is a convenience type for cbor.Rat
+type GenesisRat = cbor.Rat