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// Copyright 2019 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package gomarshal
import (
"go/ast"
"go/token"
)
// interfaceGenerator generates marshalling interfaces for a single type.
//
// getState is not thread-safe.
type interfaceGenerator struct {
sourceBuffer
// The type we're serializing.
t *ast.TypeSpec
// Receiver argument for generated methods.
r string
// FileSet containing the tokens for the type we're processing.
f *token.FileSet
// is records external packages referenced by the generated implementation.
is map[string]struct{}
// ms records Marshallable types referenced by the generated implementation
// of t's interfaces.
ms map[string]struct{}
// as records embedded fields in t that are potentially not packed. The key
// is the accessor for the field.
as map[string]struct{}
}
// typeName returns the name of the type this g represents.
func (g *interfaceGenerator) typeName() string {
return g.t.Name.Name
}
// newinterfaceGenerator creates a new interface generator.
func newInterfaceGenerator(t *ast.TypeSpec, fset *token.FileSet) *interfaceGenerator {
g := &interfaceGenerator{
t: t,
r: receiverName(t),
f: fset,
is: make(map[string]struct{}),
ms: make(map[string]struct{}),
as: make(map[string]struct{}),
}
g.recordUsedMarshallable(g.typeName())
return g
}
func (g *interfaceGenerator) recordUsedMarshallable(m string) {
g.ms[m] = struct{}{}
}
func (g *interfaceGenerator) recordUsedImport(i string) {
g.is[i] = struct{}{}
}
func (g *interfaceGenerator) recordPotentiallyNonPackedField(fieldName string) {
g.as[fieldName] = struct{}{}
}
// abortAt aborts the go_marshal tool with the given error message, with a
// reference position to the input source. Same as abortAt, but uses g to
// resolve p to position.
func (g *interfaceGenerator) abortAt(p token.Pos, msg string) {
abortAt(g.f.Position(p), msg)
}
// scalarSize returns the size of type identified by t. If t isn't a primitive
// type, the size isn't known at code generation time, and must be resolved via
// the marshal.Marshallable interface.
func (g *interfaceGenerator) scalarSize(t *ast.Ident) (size int, unknownSize bool) {
switch t.Name {
case "int8", "uint8", "byte":
return 1, false
case "int16", "uint16":
return 2, false
case "int32", "uint32":
return 4, false
case "int64", "uint64":
return 8, false
default:
return 0, true
}
}
func (g *interfaceGenerator) shift(bufVar string, n int) {
g.emit("%s = %s[%d:]\n", bufVar, bufVar, n)
}
func (g *interfaceGenerator) shiftDynamic(bufVar, name string) {
g.emit("%s = %s[%s.SizeBytes():]\n", bufVar, bufVar, name)
}
// marshalScalar writes a single scalar to a byte slice.
func (g *interfaceGenerator) marshalScalar(accessor, typ, bufVar string) {
switch typ {
case "int8", "uint8", "byte":
g.emit("%s[0] = byte(%s)\n", bufVar, accessor)
g.shift(bufVar, 1)
case "int16", "uint16":
g.recordUsedImport("usermem")
g.emit("usermem.ByteOrder.PutUint16(%s[:2], uint16(%s))\n", bufVar, accessor)
g.shift(bufVar, 2)
case "int32", "uint32":
g.recordUsedImport("usermem")
g.emit("usermem.ByteOrder.PutUint32(%s[:4], uint32(%s))\n", bufVar, accessor)
g.shift(bufVar, 4)
case "int64", "uint64":
g.recordUsedImport("usermem")
g.emit("usermem.ByteOrder.PutUint64(%s[:8], uint64(%s))\n", bufVar, accessor)
g.shift(bufVar, 8)
default:
g.emit("%s.MarshalBytes(%s[:%s.SizeBytes()])\n", accessor, bufVar, accessor)
g.shiftDynamic(bufVar, accessor)
}
}
// unmarshalScalar reads a single scalar from a byte slice.
func (g *interfaceGenerator) unmarshalScalar(accessor, typ, bufVar string) {
switch typ {
case "byte":
g.emit("%s = %s[0]\n", accessor, bufVar)
g.shift(bufVar, 1)
case "int8", "uint8":
g.emit("%s = %s(%s[0])\n", accessor, typ, bufVar)
g.shift(bufVar, 1)
case "int16", "uint16":
g.recordUsedImport("usermem")
g.emit("%s = %s(usermem.ByteOrder.Uint16(%s[:2]))\n", accessor, typ, bufVar)
g.shift(bufVar, 2)
case "int32", "uint32":
g.recordUsedImport("usermem")
g.emit("%s = %s(usermem.ByteOrder.Uint32(%s[:4]))\n", accessor, typ, bufVar)
g.shift(bufVar, 4)
case "int64", "uint64":
g.recordUsedImport("usermem")
g.emit("%s = %s(usermem.ByteOrder.Uint64(%s[:8]))\n", accessor, typ, bufVar)
g.shift(bufVar, 8)
default:
g.emit("%s.UnmarshalBytes(%s[:%s.SizeBytes()])\n", accessor, bufVar, accessor)
g.shiftDynamic(bufVar, accessor)
g.recordPotentiallyNonPackedField(accessor)
}
}
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