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refactor to hide structs behind an interface

pull/6/head
Daniel Smith 2014-11-26 11:13:37 -08:00
parent 564c087062
commit 3c1d51b19d
1 changed files with 87 additions and 32 deletions
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119
pkg/conversion/converter.go
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@ -361,7 +361,7 @@ func (c *Converter) convert(sv, dv reflect.Value, scope *scope) error {
switch dv.Kind() {
case reflect.Struct:
return c.convertStruct(sv, dv, scope)
return c.convertKV(toKVValue(sv), toKVValue(dv), scope)
case reflect.Slice:
if sv.IsNil() {
// Don't make a zero-length slice.
@ -408,46 +408,99 @@ func (c *Converter) convert(sv, dv reflect.Value, scope *scope) error {
return nil
}
func (c *Converter) convertStruct(sv, dv reflect.Value, scope *scope) error {
dt, st := dv.Type(), sv.Type()
listType := dt
if scope.flags.IsSet(SourceToDest) {
listType = st
func toKVValue(v reflect.Value) kvValue {
switch v.Kind() {
case reflect.Struct:
return structAdaptor(v)
}
for i := 0; i < listType.NumField(); i++ {
f := listType.Field(i)
if found, err := c.checkStructField(f.Name, sv, dv, scope); found {
return nil
}
// kvValue lets us write the same conversion logic to work with both maps
// and structs. Only maps with string keys make sense for this.
type kvValue interface {
// returns all keys, as a []string.
keys() []string
// Will just return "" for maps.
tagOf(key string) reflect.StructTag
// Will return the zero Value if the key doesn't exist.
value(key string) reflect.Value
// Maps require explict setting-- will do nothing for structs.
// Returns false on failure.
confirmSet(key string, v reflect.Value) bool
}
type structAdaptor reflect.Value
func (sa structAdaptor) len() int {
v := reflect.Value(sa)
return v.Type().NumField()
}
func (sa structAdaptor) keys() []string {
v := reflect.Value(sa)
t := v.Type()
keys := make([]string, t.NumField())
for i := range keys {
keys[i] = t.Field(i).Name
}
return keys
}
func (sa structAdaptor) tagOf(key string) reflect.StructTag {
v := reflect.Value(sa)
field, ok := v.Type().FieldByName(key)
if ok {
return field.Tag
}
return ""
}
func (sa structAdaptor) value(key string) reflect.Value {
v := reflect.Value(sa)
return v.FieldByName(key)
}
func (sa structAdaptor) confirmSet(key string, v reflect.Value) bool {
return true
}
// convertKV can convert things that consist of key/value pairs, like structs
// and some maps.
func (c *Converter) convertKV(skv, dkv kvValue, scope *scope) error {
if skv == nil || dkv == nil {
// TODO: add keys to stack to support really understandable error messages.
return fmt.Errorf("Unable to convert %#v to %#v", skv, dkv)
}
lister := dkv
if scope.flags.IsSet(SourceToDest) {
lister = skv
}
for _, key := range lister.keys() {
if found, err := c.checkField(key, skv, dkv, scope); found {
if err != nil {
return err
}
continue
}
df := dv.FieldByName(f.Name)
sf := sv.FieldByName(f.Name)
if sf.IsValid() {
// No need to check error, since we know it's valid.
field, _ := st.FieldByName(f.Name)
scope.srcStack.top().tag = field.Tag
}
if df.IsValid() {
field, _ := dt.FieldByName(f.Name)
scope.destStack.top().tag = field.Tag
}
// TODO: set top level of scope.src/destTagStack with these field tags here.
df := dkv.value(key)
sf := skv.value(key)
if !df.IsValid() || !sf.IsValid() {
switch {
case scope.flags.IsSet(IgnoreMissingFields):
// No error.
case scope.flags.IsSet(SourceToDest):
return scope.error("%v not present in dest (%v to %v)", f.Name, st, dt)
return scope.error("%v not present in dest", key)
default:
return scope.error("%v not present in src (%v to %v)", f.Name, st, dt)
return scope.error("%v not present in src", key)
}
continue
}
scope.srcStack.top().key = f.Name
scope.srcStack.top().key = f.Name
scope.srcStack.top().key = key
scope.srcStack.top().tag = skv.tagOf(key)
scope.destStack.top().key = key
scope.destStack.top().tag = dkv.tagOf(key)
if err := c.convert(sf, df, scope); err != nil {
return err
}
@ -455,12 +508,12 @@ func (c *Converter) convertStruct(sv, dv reflect.Value, scope *scope) error {
return nil
}
// checkStructField returns true if the field name matches any of the struct
// checkField returns true if the field name matches any of the struct
// field copying rules. The error should be ignored if it returns false.
func (c *Converter) checkStructField(fieldName string, sv, dv reflect.Value, scope *scope) (bool, error) {
func (c *Converter) checkField(fieldName string, skv, dkv kvValue, scope *scope) (bool, error) {
replacementMade := false
if scope.flags.IsSet(DestFromSource) {
df := dv.FieldByName(fieldName)
df := dkv.value(fieldName)
if !df.IsValid() {
return false, nil
}
@ -468,7 +521,7 @@ func (c *Converter) checkStructField(fieldName string, sv, dv reflect.Value, sco
// Check each of the potential source (type, name) pairs to see if they're
// present in sv.
for _, potentialSourceKey := range c.structFieldSources[destKey] {
sf := sv.FieldByName(potentialSourceKey.fieldName)
sf := skv.value(potentialSourceKey.fieldName)
if !sf.IsValid() {
continue
}
@ -479,13 +532,14 @@ func (c *Converter) checkStructField(fieldName string, sv, dv reflect.Value, sco
if err := c.convert(sf, df, scope); err != nil {
return true, err
}
dkv.confirmSet(fieldName, df)
replacementMade = true
}
}
return replacementMade, nil
}
sf := sv.FieldByName(fieldName)
sf := skv.value(fieldName)
if !sf.IsValid() {
return false, nil
}
@ -493,7 +547,7 @@ func (c *Converter) checkStructField(fieldName string, sv, dv reflect.Value, sco
// Check each of the potential dest (type, name) pairs to see if they're
// present in dv.
for _, potentialDestKey := range c.structFieldDests[srcKey] {
df := dv.FieldByName(potentialDestKey.fieldName)
df := dkv.value(potentialDestKey.fieldName)
if !df.IsValid() {
continue
}
@ -504,6 +558,7 @@ func (c *Converter) checkStructField(fieldName string, sv, dv reflect.Value, sco
if err := c.convert(sf, df, scope); err != nil {
return true, err
}
dkv.confirmSet(potentialDestKey.fieldName, df)
replacementMade = true
}
}