go-json/cmd/generator/main.go

package main

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"path/filepath"
	"runtime"
	"strings"
	"text/template"
)

type opType struct {
	Op       string
	IndentOp string
	Code     string
}

type headType struct {
	Head                      string
	PtrHead                   string
	AnonymousHead             string
	AnonymousPtrHead          string
	OmitEmptyHead             string
	OmitEmptyPtrHead          string
	AnonymousOmitEmptyHead    string
	AnonymousOmitEmptyPtrHead string
	StringTagHead             string
	StringTagPtrHead          string
	AnonymousStringTagHead    string
	AnonymousStringTagPtrHead string
}

type fieldType struct {
	Field          string
	OmitEmptyField string
	StringTagField string
}

func _main() error {
	tmpl, err := template.New("").Parse(`// Code generated by cmd/generator. DO NOT EDIT!
package json

type codeType int

const (
{{- range $index, $type := .CodeTypes }}
  code{{ $type }} codeType = {{ $index }}
{{- end }}
)

type opType int

const (
{{- range $index, $type := .OpTypes }}
  op{{ $type.Op }} opType = {{ $index }}
{{- end }}
)

func (t opType) String() string {
  switch t {
{{- range $type := .OpTypes }}
  case op{{ $type.Op }}:
    return "{{ $type.Op }}"
{{- end }}
  }
  return ""
}

func (t opType) codeType() codeType {
  switch t {
{{- range $type := .OpTypes }}
  case op{{ $type.Op }}:
    return code{{ $type.Code }}
{{- end }}
  }
  return codeOp
}

func (t opType) toIndent() opType {
  switch t {
{{- range $type := .OpTypes }}
  case op{{ $type.Op }}:
    return op{{ $type.IndentOp }}
{{- end }}
  }
  return t
}

func (t opType) headToPtrHead() opType {
  switch t {
{{- range $type := .HeadTypes }}
  case op{{ $type.Head }}:
    return op{{ $type.PtrHead }}
  case op{{ $type.AnonymousHead }}:
    return op{{ $type.AnonymousPtrHead }}
  case op{{ $type.OmitEmptyHead }}:
    return op{{ $type.OmitEmptyPtrHead }}
  case op{{ $type.AnonymousOmitEmptyHead }}:
    return op{{ $type.AnonymousOmitEmptyPtrHead }}
  case op{{ $type.StringTagHead }}:
    return op{{ $type.StringTagPtrHead }}
  case op{{ $type.AnonymousStringTagHead }}:
    return op{{ $type.AnonymousStringTagPtrHead }}
{{- end }}
  }
  return t
}

func (t opType) headToAnonymousHead() opType {
  switch t {
{{- range $type := .HeadTypes }}
  case op{{ $type.Head }}:
    return op{{ $type.AnonymousHead }}
  case op{{ $type.PtrHead }}:
    return op{{ $type.AnonymousPtrHead }}
  case op{{ $type.OmitEmptyHead }}:
    return op{{ $type.AnonymousOmitEmptyHead }}
  case op{{ $type.OmitEmptyPtrHead }}:
    return op{{ $type.AnonymousOmitEmptyPtrHead }}
  case op{{ $type.StringTagHead }}:
    return op{{ $type.AnonymousStringTagHead }}
  case op{{ $type.StringTagPtrHead }}:
    return op{{ $type.AnonymousStringTagPtrHead }}
{{- end }}
  }
  return t
}

func (t opType) headToOmitEmptyHead() opType {
  switch t {
{{- range $type := .HeadTypes }}
  case op{{ $type.Head }}:
    return op{{ $type.OmitEmptyHead }}
  case op{{ $type.PtrHead }}:
    return op{{ $type.OmitEmptyPtrHead }}
{{- end }}
  }
  return t
}

func (t opType) headToStringTagHead() opType {
  switch t {
{{- range $type := .HeadTypes }}
  case op{{ $type.Head }}:
    return op{{ $type.StringTagHead }}
  case op{{ $type.PtrHead }}:
    return op{{ $type.StringTagPtrHead }}
{{- end }}
  }
  return t
}

func (t opType) ptrHeadToHead() opType {
  switch t {
{{- range $type := .HeadTypes }}
  case op{{ $type.PtrHead }}:
    return op{{ $type.Head }}
  case op{{ $type.AnonymousPtrHead }}:
    return op{{ $type.AnonymousHead }}
  case op{{ $type.OmitEmptyPtrHead }}:
    return op{{ $type.OmitEmptyHead }}
  case op{{ $type.AnonymousOmitEmptyPtrHead }}:
    return op{{ $type.AnonymousOmitEmptyHead }}
  case op{{ $type.StringTagPtrHead }}:
    return op{{ $type.StringTagHead }}
  case op{{ $type.AnonymousStringTagPtrHead }}:
    return op{{ $type.AnonymousStringTagHead }}
{{- end }}
  }
  return t
}

func (t opType) fieldToOmitEmptyField() opType {
  switch t {
{{- range $type := .FieldTypes }}
  case op{{ $type.Field }}:
    return op{{ $type.OmitEmptyField }}
{{- end }}
  }
  return t
}

func (t opType) fieldToStringTagField() opType {
  switch t {
{{- range $type := .FieldTypes }}
  case op{{ $type.Field }}:
    return op{{ $type.StringTagField }}
{{- end }}
  }
  return t
}

`)
	if err != nil {
		return err
	}
	codeTypes := []string{
		"Op",
		"ArrayHead",
		"ArrayElem",
		"SliceHead",
		"SliceElem",
		"MapHead",
		"MapKey",
		"MapValue",
		"StructFieldRecursive",
		"StructField",
	}
	primitiveTypes := []string{
		"int", "int8", "int16", "int32", "int64",
		"uint", "uint8", "uint16", "uint32", "uint64",
		"float32", "float64", "bool", "string", "bytes",
		"array", "map", "mapLoad", "slice", "struct", "MarshalJSON", "MarshalText",
	}
	primitiveTypesUpper := []string{}
	for _, typ := range primitiveTypes {
		primitiveTypesUpper = append(primitiveTypesUpper, strings.ToUpper(string(typ[0]))+typ[1:])
	}
	opTypes := []opType{
		{"End", "EndIndent", "Op"},
		{"Interface", "InterfaceIndent", "Op"},
		{"Ptr", "PtrIndent", "Op"},
		{"SliceHead", "SliceHeadIndent", "SliceHead"},
		{"RootSliceHead", "RootSliceHeadIndent", "SliceHead"},
		{"SliceElem", "SliceElemIndent", "SliceElem"},
		{"RootSliceElem", "RootSliceElemIndent", "SliceElem"},
		{"SliceEnd", "SliceEndIndent", "Op"},
		{"ArrayHead", "ArrayHeadIndent", "ArrayHead"},
		{"ArrayElem", "ArrayElemIndent", "ArrayElem"},
		{"ArrayEnd", "ArrayEndIndent", "Op"},
		{"MapHead", "MapHeadIndent", "MapHead"},
		{"MapHeadLoad", "MapHeadLoadIndent", "MapHead"},
		{"RootMapHead", "RootMapHeadIndent", "MapHead"},
		{"MapKey", "MapKeyIndent", "MapKey"},
		{"RootMapKey", "RootMapKeyIndent", "MapKey"},
		{"MapValue", "MapValueIndent", "MapValue"},
		{"MapEnd", "MapEndIndent", "Op"},
		{"StructFieldHead", "StructFieldHeadIndent", "StructField"},
		{"StructFieldHeadOmitEmpty", "StructFieldHeadOmitEmptyIndent", "StructField"},
		{"StructFieldHeadStringTag", "StructFieldHeadStringTagIndent", "StructField"},
		{"StructFieldAnonymousHead", "StructFieldAnonymousHeadIndent", "StructField"},
		{"StructFieldAnonymousHeadOmitEmpty", "StructFieldAnonymousHeadOmitEmptyIndent", "StructField"},
		{"StructFieldPtrAnonymousHeadOmitEmpty", "StructFieldPtrAnonymousHeadOmitEmptyIndent", "StructField"},
		{"StructFieldAnonymousHeadStringTag", "StructFieldAnonymousHeadStringTagIndent", "StructField"},
		{"StructFieldPtrAnonymousHeadStringTag", "StructFieldPtrAnonymousHeadStringTagIndent", "StructField"},
		{"StructFieldPtrHead", "StructFieldPtrHeadIndent", "StructField"},
		{"StructFieldPtrHeadOmitEmpty", "StructFieldPtrHeadOmitEmptyIndent", "StructField"},
		{"StructFieldPtrHeadStringTag", "StructFieldPtrHeadStringTagIndent", "StructField"},
		{"StructFieldPtrAnonymousHead", "StructFieldPtrAnonymousHeadIndent", "StructField"},
		{"StructField", "StructFieldIndent", "StructField"},
		{"StructFieldOmitEmpty", "StructFieldOmitEmptyIndent", "StructField"},
		{"StructFieldStringTag", "StructFieldStringTagIndent", "StructField"},
		{"StructFieldRecursive", "StructFieldRecursiveIndent", "StructFieldRecursive"},
		{"StructEnd", "StructEndIndent", "StructField"},
		{"StructAnonymousEnd", "StructAnonymousEndIndent", "StructField"},
	}
	for _, typ := range primitiveTypesUpper {
		opTypes = append(opTypes, opType{
			Op:       typ,
			IndentOp: fmt.Sprintf("%sIndent", typ),
			Code:     "Op",
		})
	}
	for _, prefix := range []string{
		"StructFieldHead",
		"StructFieldHeadOmitEmpty",
		"StructFieldHeadStringTag",
		"StructFieldAnonymousHead",
		"StructFieldAnonymousHeadOmitEmpty",
		"StructFieldAnonymousHeadStringTag",
		"StructFieldPtrHead",
		"StructFieldPtrHeadOmitEmpty",
		"StructFieldPtrHeadStringTag",
		"StructFieldPtrAnonymousHead",
		"StructFieldPtrAnonymousHeadOmitEmpty",
		"StructFieldPtrAnonymousHeadStringTag",
		"StructField",
		"StructFieldOmitEmpty",
		"StructFieldStringTag",
	} {
		for _, typ := range primitiveTypesUpper {
			opTypes = append(opTypes, opType{
				Op:       fmt.Sprintf("%s%s", prefix, typ),
				IndentOp: fmt.Sprintf("%s%sIndent", prefix, typ),
				Code:     "StructField",
			})
		}
	}
	for _, typ := range opTypes {
		opTypes = append(opTypes, opType{
			Op:       typ.IndentOp,
			IndentOp: typ.IndentOp,
			Code:     typ.Code,
		})
	}
	base := headType{
		Head:                      "StructFieldHead",
		PtrHead:                   "StructFieldPtrHead",
		AnonymousHead:             "StructFieldAnonymousHead",
		AnonymousPtrHead:          "StructFieldPtrAnonymousHead",
		OmitEmptyHead:             "StructFieldHeadOmitEmpty",
		OmitEmptyPtrHead:          "StructFieldPtrHeadOmitEmpty",
		StringTagHead:             "StructFieldHeadStringTag",
		StringTagPtrHead:          "StructFieldPtrHeadStringTag",
		AnonymousOmitEmptyHead:    "StructFieldAnonymousHeadOmitEmpty",
		AnonymousOmitEmptyPtrHead: "StructFieldPtrAnonymousHeadOmitEmpty",
		AnonymousStringTagHead:    "StructFieldAnonymousHeadStringTag",
		AnonymousStringTagPtrHead: "StructFieldPtrAnonymousHeadStringTag",
	}
	headTypes := []headType{base}
	for _, prim := range primitiveTypesUpper {
		headTypes = append(headTypes, headType{
			Head:                      fmt.Sprintf("%s%s", base.Head, prim),
			PtrHead:                   fmt.Sprintf("%s%s", base.PtrHead, prim),
			AnonymousHead:             fmt.Sprintf("%s%s", base.AnonymousHead, prim),
			AnonymousPtrHead:          fmt.Sprintf("%s%s", base.AnonymousPtrHead, prim),
			OmitEmptyHead:             fmt.Sprintf("%s%s", base.OmitEmptyHead, prim),
			OmitEmptyPtrHead:          fmt.Sprintf("%s%s", base.OmitEmptyPtrHead, prim),
			AnonymousOmitEmptyHead:    fmt.Sprintf("%s%s", base.AnonymousOmitEmptyHead, prim),
			AnonymousOmitEmptyPtrHead: fmt.Sprintf("%s%s", base.AnonymousOmitEmptyPtrHead, prim),
			StringTagHead:             fmt.Sprintf("%s%s", base.StringTagHead, prim),
			StringTagPtrHead:          fmt.Sprintf("%s%s", base.StringTagPtrHead, prim),
			AnonymousStringTagHead:    fmt.Sprintf("%s%s", base.AnonymousStringTagHead, prim),
			AnonymousStringTagPtrHead: fmt.Sprintf("%s%s", base.AnonymousStringTagPtrHead, prim),
		})
	}
	for _, typ := range headTypes {
		headTypes = append(headTypes, headType{
			Head:                      fmt.Sprintf("%sIndent", typ.Head),
			PtrHead:                   fmt.Sprintf("%sIndent", typ.PtrHead),
			AnonymousHead:             fmt.Sprintf("%sIndent", typ.AnonymousHead),
			AnonymousPtrHead:          fmt.Sprintf("%sIndent", typ.AnonymousPtrHead),
			OmitEmptyHead:             fmt.Sprintf("%sIndent", typ.OmitEmptyHead),
			OmitEmptyPtrHead:          fmt.Sprintf("%sIndent", typ.OmitEmptyPtrHead),
			AnonymousOmitEmptyHead:    fmt.Sprintf("%sIndent", typ.AnonymousOmitEmptyHead),
			AnonymousOmitEmptyPtrHead: fmt.Sprintf("%sIndent", typ.AnonymousOmitEmptyPtrHead),
			StringTagHead:             fmt.Sprintf("%sIndent", typ.StringTagHead),
			StringTagPtrHead:          fmt.Sprintf("%sIndent", typ.StringTagPtrHead),
			AnonymousStringTagHead:    fmt.Sprintf("%sIndent", typ.AnonymousStringTagHead),
			AnonymousStringTagPtrHead: fmt.Sprintf("%sIndent", typ.AnonymousStringTagPtrHead),
		})
	}

	baseField := fieldType{
		Field:          "StructField",
		OmitEmptyField: "StructFieldOmitEmpty",
		StringTagField: "StructFieldStringTag",
	}
	fieldTypes := []fieldType{baseField}
	for _, prim := range primitiveTypesUpper {
		fieldTypes = append(fieldTypes, fieldType{
			Field:          fmt.Sprintf("%s%s", baseField.Field, prim),
			OmitEmptyField: fmt.Sprintf("%s%s", baseField.OmitEmptyField, prim),
			StringTagField: fmt.Sprintf("%s%s", baseField.StringTagField, prim),
		})
	}
	for _, typ := range fieldTypes {
		fieldTypes = append(fieldTypes, fieldType{
			Field:          fmt.Sprintf("%sIndent", typ.Field),
			OmitEmptyField: fmt.Sprintf("%sIndent", typ.OmitEmptyField),
			StringTagField: fmt.Sprintf("%sIndent", typ.StringTagField),
		})
	}

	var b bytes.Buffer
	if err := tmpl.Execute(&b, struct {
		CodeTypes  []string
		OpTypes    []opType
		HeadTypes  []headType
		FieldTypes []fieldType
	}{
		CodeTypes:  codeTypes,
		OpTypes:    opTypes,
		HeadTypes:  headTypes,
		FieldTypes: fieldTypes,
	}); err != nil {
		return err
	}
	path := filepath.Join(repoRoot(), "encode_optype.go")
	return ioutil.WriteFile(path, b.Bytes(), 0644)
}

func repoRoot() string {
	_, file, _, _ := runtime.Caller(0)
	relativePathFromRepoRoot := filepath.Join("cmd", "generator")
	return strings.TrimSuffix(filepath.Dir(file), relativePathFromRepoRoot)
}

func main() {
	if err := _main(); err != nil {
		panic(err)
	}
}