gogo/protobuf pull #48 fix

gistfile1.diff

diff --git a/plugin/unmarshal/unmarshal.go b/plugin/unmarshal/unmarshal.go
index ef232d0..ffafc65 100644
--- a/plugin/unmarshal/unmarshal.go
+++ b/plugin/unmarshal/unmarshal.go
@@ -685,24 +685,21 @@ func (p *unmarshal) Generate(file *generator.FileDescriptor) {
 		}
 		p.atleastOne = true
 
-		// Count the required fields
-		var rfList []string
+		// build a map required field_id -> bitmask offset
+		rfMap := make(map[int32]uint)
+		rfNextId := uint(0)
 		for _, field := range message.Field {
 			if field.IsRequired() {
-				rfList = append(rfList, field.GetName())
+				rfMap[field.GetNumber()] = rfNextId
+				rfNextId++
 			}
 		}
+		rfCount := len(rfMap)
 
 		p.P(`func (m *`, ccTypeName, `) Unmarshal(data []byte) error {`)
 		p.In()
-		if len(rfList) > 0 {
-			p.P(`requiredFieldsPresent := map[string]bool{`)
-			p.In()
-			for _, fieldName := range rfList {
-				p.P(`"`, fieldName, `": false,`)
-			}
-			p.Out()
-			p.P(`}`)
+		if rfCount > 0 {
+			p.P(`var hasFields [`, strconv.Itoa(1+(rfCount-1)/64), `]uint64`)
 		}
 		p.P(`l := len(data)`)
 		p.P(`index := 0`)
@@ -759,7 +756,11 @@ func (p *unmarshal) Generate(file *generator.FileDescriptor) {
 			}
 
 			if field.IsRequired() {
-				p.P(`requiredFieldsPresent["`, field.GetName(), `"] = true`)
+				fieldBit, ok := rfMap[field.GetNumber()]
+				if !ok {
+					panic("field is required, but no bit registered")
+				}
+				p.P(`hasFields[`, strconv.Itoa(int(fieldBit/64)), `] |= uint64(`, fmt.Sprintf("0x%08x", 1<<(fieldBit%64)), `)`)
 			}
 		}
 		p.Out()
@@ -848,14 +849,20 @@ func (p *unmarshal) Generate(file *generator.FileDescriptor) {
 		p.P(`}`)
 		p.Out()
 		p.P(`}`)
-		if len(rfList) > 0 {
-			p.P(`for fieldName, present := range requiredFieldsPresent {`)
-			p.In()
-			p.P(`if !present {`)
+
+		for _, field := range message.Field {
+			if !field.IsRequired() {
+				continue
+			}
+
+			fieldBit, ok := rfMap[field.GetNumber()]
+			if !ok {
+				panic("field is required, but no bit registered")
+			}
+
+			p.P(`if hasFields[`, strconv.Itoa(int(fieldBit/64)), `] & uint64(`, fmt.Sprintf("0x%08x", 1<<(fieldBit%64)), `) == 0 {`)
 			p.In()
-			p.P(`return `, protoPkg.Use(), `.NewRequiredNotSetError(fieldName)`)
-			p.Out()
-			p.P(`}`)
+			p.P(`return `, protoPkg.Use(), `.NewRequiredNotSetError("`, field.GetName(), `")`)
 			p.Out()
 			p.P(`}`)
 		}