Encode and decode fields of union type.

mojom/generators/go/translator/mojom_file.go

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package translator
 
 // TmplFile contains all of the information needed by the templates to generate
 // the go bindings for one mojom file.
 type TmplFile struct {
         PackageName string
@@ skipping 93 matching lines @@
 
         // IsHandle returns true if the field is a handle type.
         IsHandle() bool
 
         // IsPointer returns true if the field is a pointer: struct, array, map or string.
         IsPointer() bool
 
         // IsStruct returns true if the field is a struct.
         IsStruct() bool
 
+        // IsUnion returns true if the field is a union.
+        IsUnion() bool
+
         // IsArray returns true if the field is an array.
         IsArray() bool
 
         // IsMap returns true if the field is a map.
         IsMap() bool
 
         // IsNullable returns true if the field is nullable.
         IsNullable() bool
         setNullable(nullable bool)
 
@@ skipping 52 matching lines @@
 }
 
 func (b *baseEncodingInfo) IsPointer() bool {
         return false
 }
 
 func (b *baseEncodingInfo) IsStruct() bool {
         return false
 }
 
+func (b *baseEncodingInfo) IsUnion() bool {
+        return false
+}
+
 func (b *baseEncodingInfo) IsArray() bool {
         return false
 }
 
 func (b *baseEncodingInfo) IsMap() bool {
         return false
 }
 
 func (b *baseEncodingInfo) ElementEncodingInfo() EncodingInfo {
         panic("Only arrays have elements!")
@@ skipping 185 matching lines @@
         return true
 }
 
 func (t *structTypeEncodingInfo) WriteFunction() string {
         panic("Structs don't have a write function.")
 }
 
 func (t *structTypeEncodingInfo) ReadFunction() string {
         panic("Structs don't have a read function.")
 }
+
+////////////////////////////////////////////////////////////////////////////////
+
+// unionTypeEncodingInfo is the EncodingInfo for a union.
+type unionTypeEncodingInfo struct {
+        baseEncodingInfo
+        nestedUnion bool
+        nullable    bool
+}
+
+func (t *unionTypeEncodingInfo) BitSize() uint32 {
+        if t.nestedUnion {
+                return uint32(64)
+        }
+        return uint32(128)
+}
+
+func (t *unionTypeEncodingInfo) IsUnion() bool {
+        return true
+}
+
+func (t *unionTypeEncodingInfo) IsPointer() bool {
+        return t.nestedUnion
+}
+
+func (b *unionTypeEncodingInfo) IsNullable() bool {
+        return b.nullable
+}
+
+func (b *unionTypeEncodingInfo) setNullable(nullable bool) {
+        b.nullable = nullable
+}
+
+func (t *unionTypeEncodingInfo) WriteFunction() string {
+        panic("Unions don't have a write function.")
+}
+
+func (t *unionTypeEncodingInfo) ReadFunction() string {
+        panic("Unions don't have a read function.")
+}