Implement dictionary data serialization to improve startup times

dict/.gitignore

@@ -1 +1,2 @@
 JMdict.xml
+dict.bin

dict/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/gob"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -16,6 +17,21 @@ import (
 var dict map[string]Entry
 
 func LoadDict() error {
+	// Loading from binary
+	const binaryFile = "dict.bin"
+	file, err := os.Open(binaryFile)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return err
+		}
+	} else {
+		defer file.Close()
+		decoder := gob.NewDecoder(file)
+		err = decoder.Decode(&dict)
+		return err
+	}
+
+	// Loading from JMdict
 	const jmdictFile = "JMdict.xml"
 	reader, err := os.Open(jmdictFile)
 	if err != nil {
@@ -30,6 +46,19 @@ func LoadDict() error {
 		entry := ParseEntry(&jmdictEntry)
 		dict[entry.Kanji] = entry
 	}
+
+	// Encoding to binary
+	file, err = os.Create(binaryFile)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	encoder := gob.NewEncoder(file)
+	err = encoder.Encode(&dict)
+	if err != nil {
+		return err
+	}
+
 	return nil
 }