subtree(users/wpcarro): docking briefcase at '24f5a642'

git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c
git-subtree-split: 24f5a642af
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789

users/wpcarro/gopkgs/kv/default.nix

@@ -0,0 +1,8 @@
+{ depot, ... }:
+
+depot.buildGo.package {
+  name = "kv";
+  srcs = [
+    ./kv.go
+  ];
+}

users/wpcarro/gopkgs/kv/kv.go

@@ -0,0 +1,39 @@
+// Supporting reading and writing key-value pairs to disk.
+package kv
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"path"
+)
+
+// Return the decoded store from disk.
+func getStore(storePath string) map[string]interface{} {
+	b, err := ioutil.ReadFile(path.Join(storePath, "kv.json"))
+	if err != nil {
+		log.Fatal("Could not read store: ", err)
+	}
+	var state map[string]interface{}
+	err = json.Unmarshal(b, &state)
+	if err != nil {
+		log.Fatal("Could not decode store as JSON: ", err)
+	}
+	return state
+}
+
+// Set `key` to `value` in the store.
+func Set(storePath string, key string, value interface{}) error {
+	state := getStore(storePath)
+	state[key] = value
+	b, err := json.Marshal(state)
+	if err != nil {
+		log.Fatal("Could not encode state as JSON: ", err)
+	}
+	return ioutil.WriteFile(path.Join(storePath, "kv.json"), b, 0644)
+}
+
+// Get `key` from the store.
+func Get(storePath string, key string) interface{} {
+	return getStore(path.Join(storePath, "kv.json"))[key]
+}