ae.sys.persistence.json source code

1 /**
2  * ae.sys.persistence.json
3  *
4  * License:
5  *   This Source Code Form is subject to the terms of
6  *   the Mozilla Public License, v. 2.0. If a copy of
7  *   the MPL was not distributed with this file, You
8  *   can obtain one at http://mozilla.org/MPL/2.0/.
9  *
10  * Authors:
11  *   Vladimir Panteleev <ae@cy.md>
12  */
13 
14 module ae.sys.persistence.json;
15 
16 import ae.sys.persistence.core;
17 
18 // ****************************************************************************
19 
20 /// `FileCache` wrapper which stores a D type as JSON serialization.
21 template JsonFileCache(T, FlushPolicy flushPolicy = FlushPolicy.none)
22 {
23 	import std.file;
24 	import ae.utils.json;
25 
26 	static T getJson(T)(string fileName)
27 	{
28 		return fileName.readText.jsonParse!T;
29 	}
30 
31 	static void putJson(T)(string fileName, in T t)
32 	{
33 		std.file.write(fileName, t.toJson());
34 	}
35 
36 	alias JsonFileCache = FileCache!(getJson!T, putJson!T, flushPolicy);
37 }
38 
39 unittest
40 {
41 	import std.file;
42 
43 	enum FN = "test1.json";
44 	std.file.write(FN, "{}");
45 	scope(exit) remove(FN);
46 
47 	auto cache = JsonFileCache!(string[string])(FN);
48 	assert(cache.length == 0);
49 }
50 
51 unittest
52 {
53 	import std.file;
54 
55 	enum FN = "test2.json";
56 	scope(exit) if (FN.exists) remove(FN);
57 
58 	auto cache = JsonFileCache!(string[string], FlushPolicy.manual)(FN);
59 	assert(cache.length == 0);
60 	cache["foo"] = "bar";
61 	cache.save();
62 
63 	auto cache2 = JsonFileCache!(string[string])(FN);
64 	assert(cache2["foo"] == "bar");
65 }
66 
67 unittest
68 {
69 	import std.file;
70 
71 	enum FN = "test3.json";
72 	scope(exit) if (FN.exists) remove(FN);
73 
74 	{
75 		auto cache = JsonFileCache!(string[string], FlushPolicy.atScopeExit)(FN);
76 		cache["foo"] = "bar";
77 	}
78 
79 	auto cache2 = JsonFileCache!(string[string])(FN);
80 	assert(cache2["foo"] == "bar");
81 }