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gen-db.go
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gen-db.go
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/*
* mimedb: Mime Database, (C) 2015 Minio, Inc.
*
* 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 mimedb is a database of file extension to mime content-type.
// Definitions are imported from NodeJS mime-db project under MIT license.
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"strings"
"text/template"
)
const progTempl = `// DO NOT EDIT THIS FILE. IT IS AUTO-GENERATED BY "gen-db.go". //
/*
* mimedb: Mime Database, (C) 2016 Minio, Inc.
*
* 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 mimedb is a database of file extension to mime content-type.
// Definitions are imported from NodeJS mime-db project under MIT license.
package mimedb
// DB - Mime is a collection of mime types with extension as key and content-type as value.
var DB = map[string]struct {
ContentType string
Compressible bool
}{
{{range $extension, $entry := . }} "{{$extension}}": {
ContentType: "{{$entry.ContentType}}",
Compressible: {{$entry.Compressible}},
},
{{end}}}
`
type mimeEntry struct {
ContentType string `json:"contentType"`
Compressible bool `json:"compresible"`
}
type mimeDB map[string]mimeEntry
// JSON data from gobindata and parse them into extDB.
func convertDB(jsonFile string) (mimeDB, error) {
// Structure of JSON data from mime-db project.
type dbEntry struct {
Source string `json:"source"`
Compressible bool `json:"compresible"`
Extensions []string `json:"extensions"`
}
// Access embedded "db.json" inside go-bindata.
jsonDB, err := ioutil.ReadFile(jsonFile)
if err != nil {
return nil, err
}
// Convert db.json into go's typed structure.
db := make(map[string]dbEntry)
if err := json.Unmarshal(jsonDB, &db); err != nil {
return nil, err
}
mDB := make(mimeDB)
// Generate a new database from mime-db.
for key, val := range db {
if len(val.Extensions) > 0 {
/* Denormalize - each extension has its own
unique content-type now. Looks will be fast. */
for _, ext := range val.Extensions {
/* Single extension type may map to
multiple content-types. In that case,
simply prefer the longest content-type
to maintain some level of
consistency. Only guarantee is,
whatever content type is assigned, it
is appropriate and valid type. */
if strings.Compare(mDB[ext].ContentType, key) < 0 {
mDB[ext] = mimeEntry{
ContentType: key,
Compressible: val.Compressible,
}
}
}
}
}
return mDB, nil
}
func main() {
// Take input json file from command-line".
if len(os.Args) != 2 {
fmt.Print("Syntax:\n\tgen-db /path/to/db.json\n")
os.Exit(1)
}
// Load and convert db.json into new database with extension
// as key.
mDB, err := convertDB(os.Args[1])
if err != nil {
panic(err)
}
// Generate db embedded go program.
tmpl := template.New("mimedb")
mimeTmpl, err := tmpl.Parse(progTempl)
if err != nil {
panic(err)
}
err = mimeTmpl.Execute(os.Stdout, mDB)
if err != nil {
panic(err)
}
}