140 lines
3.7 KiB
Go
140 lines
3.7 KiB
Go
package data
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import (
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"os"
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"maps"
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"errors"
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"encoding/json"
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)
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// A very simple datastructure, implementing the IDatastore interface. It uses
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// a simple text file to the data as json.
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type FileDatastore struct {
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path string
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data map[string]string
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}
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// Creates a new FileDatastore object, creating the storage file in the
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// process.
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func NewFileDatastore(path string) (*FileDatastore, error) {
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fds := &FileDatastore{ path: path }
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if _, err := fds.readMapObj(); err != nil {
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if err := fds.writeMapObj(make(map[string]string)); err != nil { return nil, err }
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}
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return fds, nil
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}
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// Read the contents of the storage file and convert to a map object. May throw
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// an error, if the file does not exit or the file content can not be
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// converted.
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func (fds *FileDatastore) readMapObj() (map[string]string, error) {
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if fds.data != nil {
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return fds.data, nil
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}
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dat, err := os.ReadFile(fds.path)
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if err != nil { return nil, err }
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var mapobj map[string]string
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err = json.Unmarshal(dat, &mapobj)
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if err != nil { return nil, err }
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return mapobj, nil
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}
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// Write the map object to the storage file. Will overwrite the content of the
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// file. May throw an error, if the file cannot be created or written to.
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func (fds *FileDatastore) writeMapObj(m map[string]string) error {
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file, err := os.Create(fds.path)
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if err != nil { return err }
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defer file.Close()
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encoder := json.NewEncoder(file)
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if err := encoder.Encode(m); err != nil { return err }
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fds.data = m
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return nil
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}
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// --- implement IDatastore interface ---
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// Sets the key value pair given, overwriting if the key already exists. May
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// through an error if the file cannot be opened or the contents cannot be
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// decoded correctly.
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func (fds *FileDatastore) Set(key string, val string) error {
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m, err := fds.readMapObj()
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if err != nil { return err }
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m[key] = val
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err = fds.writeMapObj(m)
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if err != nil { return err }
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return nil
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}
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// Check if for the given key a entry does exit. May through an error if the
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// file cannot be opened or the contents cannot be decoded correctly.
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func (fds *FileDatastore) KeyExists(key string) (bool, error) {
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m, err := fds.readMapObj()
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if err != nil { return false, err }
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_, ok := m[key]
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return ok, nil
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}
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// Gets the value for the given key. May through an error if the key does not
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// exit, the file cannot be opened or the contents cannot be decoded
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// correctly.
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func (fds *FileDatastore) Get(key string) (string, error) {
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m, err := fds.readMapObj()
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if err != nil { return "", err }
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val, ok := m[key]
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if !ok { return "", errors.New("key not found") }
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return val, nil
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}
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// Gets all the key value pairs from the file and returns them as a map object.
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// May through an error if the file cannot be opened or the contents cannot be
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// decoded correctly.
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func (fds *FileDatastore) GetAll() (map[string]string, error) {
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return fds.readMapObj()
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}
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// Gets all the key the file and returns them as a map object. May through an
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// error if the file cannot be opened or the contents cannot be decoded
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// correctly.
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func (fds *FileDatastore) GetAllKeys() (map[string]bool, error) {
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m, err := fds.readMapObj()
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if err != nil { return nil, err }
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out := make(map[string]bool)
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for key := range maps.Keys(m) {
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out[key] = true
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}
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return out, nil
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}
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// Deletes the entry with the given key. May through an error if the file
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// cannot be opened or the contents cannot be decoded or encoded correctly.
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func (fds *FileDatastore) Delete(key string) error {
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m, err := fds.readMapObj()
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if err != nil { return err }
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delete(m, key)
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err = fds.writeMapObj(m)
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if err != nil { return err }
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return nil
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}
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