aboutsummaryrefslogtreecommitdiffstats
path: root/util/format.lua
blob: 1cd8d81bad66186547a64c09c0f9f8d59275a366 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
--
-- A string.format wrapper that gracefully handles invalid arguments
--

local tostring = tostring;
local unpack = table.unpack or unpack; -- luacheck: ignore 113/unpack
local pack = require "util.table".pack; -- TODO table.pack in 5.2+
local valid_utf8 = require "util.encodings".utf8.valid;
local type = type;
local dump = require "util.serialization".new("debug");
local num_type = math.type or function (n)
	return n % 1 == 0 and n <= 9007199254740992 and n >= -9007199254740992 and "integer" or "float";
end

-- In Lua 5.3+ these formats throw an error if given a float
local expects_integer = { c = true, d = true, i = true, o = true, u = true, X = true, x = true, };
-- In Lua 5.2 these throw an error given a negative number
local expects_positive = { o = true; u = true; x = true; X = true };
-- Printable Unicode replacements for control characters
local control_symbols = {
	-- 0x00 .. 0x1F --> U+2400 .. U+241F, 0x7F --> U+2421
	["\000"] = "\226\144\128", ["\001"] = "\226\144\129", ["\002"] = "\226\144\130",
	["\003"] = "\226\144\131", ["\004"] = "\226\144\132", ["\005"] = "\226\144\133",
	["\006"] = "\226\144\134", ["\007"] = "\226\144\135", ["\008"] = "\226\144\136",
	["\009"] = "\226\144\137", ["\010"] = "\226\144\138", ["\011"] = "\226\144\139",
	["\012"] = "\226\144\140", ["\013"] = "\226\144\141", ["\014"] = "\226\144\142",
	["\015"] = "\226\144\143", ["\016"] = "\226\144\144", ["\017"] = "\226\144\145",
	["\018"] = "\226\144\146", ["\019"] = "\226\144\147", ["\020"] = "\226\144\148",
	["\021"] = "\226\144\149", ["\022"] = "\226\144\150", ["\023"] = "\226\144\151",
	["\024"] = "\226\144\152", ["\025"] = "\226\144\153", ["\026"] = "\226\144\154",
	["\027"] = "\226\144\155", ["\028"] = "\226\144\156", ["\029"] = "\226\144\157",
	["\030"] = "\226\144\158", ["\031"] = "\226\144\159", ["\127"] = "\226\144\161",
};
local supports_p = pcall(string.format, "%p", ""); -- >= Lua 5.4
local supports_a = pcall(string.format, "%a", 0.0); -- > Lua 5.1

local function format(formatstring, ...)
	local args = pack(...);
	local args_length = args.n;

	-- format specifier spec:
	-- 1. Start: '%%'
	-- 2. Flags: '[%-%+ #0]'
	-- 3. Width: '%d?%d?'
	-- 4. Precision: '%.?%d?%d?'
	-- 5. Option: '[cdiouxXaAeEfgGqs%%]'
	--
	-- The options c, d, E, e, f, g, G, i, o, u, X, and x all expect a number as argument, whereas q and s expect a string.
	-- This function does not accept string values containing embedded zeros, except as arguments to the q option.
	-- a and A are only in Lua 5.2+
	-- Lua 5.4 adds a p format that produces a pointer


	-- process each format specifier
	local i = 0;
	formatstring = formatstring:gsub("%%[^cdiouxXaAeEfgGpqs%%]*[cdiouxXaAeEfgGpqs%%]", function(spec)
		if spec == "%%" then return end
		i = i + 1;
		local arg = args[i];

		if arg == nil then
			args[i] = "nil";
			return "(%s)";
		end

		local option = spec:sub(-1);
		local t = type(arg);

		if option == "s" and t == "string" and not arg:find("[%z\1-\31\128-\255]") then
			-- No UTF-8 or control characters, assumed to be the common case.
			return
		elseif t == "number" then
			if option == "g" or (option == "d" and num_type(arg) == "integer") then return end
		elseif option == "s" and t ~= "string" then
			arg = tostring(arg);
			t = "string";
		end

		if option ~= "s" and option ~= "q" and option ~= "p" then
			-- all other options expect numbers
			if t ~= "number" then
				-- arg isn't number as expected?
				arg = tostring(arg);
				option = "s";
				spec = "[%s]";
				t = "string";
			elseif expects_integer[option] and num_type(arg) ~= "integer" then
				args[i] = tostring(arg);
				return "[%s]";
			elseif expects_positive[option] and arg < 0 then
				args[i] = tostring(arg);
				return "[%s]";
			elseif (option == "a" or option == "A") and not supports_a then
				return "%x";
			else
				return -- acceptable number
			end
		end


		if option == "p" and not supports_p then
			arg = tostring(arg);
			option = "s";
			spec = "[%s]";
			t = "string";
		end

		if t == "string" and option ~= "p" then
			if not valid_utf8(arg) then
				option = "q";
			else
				args[i] = arg:gsub("[%z\1-\8\11-\31\127]", control_symbols):gsub("\n\t?", "\n\t");
				return spec;
			end
		end

		if option == "q" then
			args[i] = dump(arg);
			return "%s";
		end

		if option == "p" and (t == "boolean" or t == "number") then
			args[i] = tostring(arg);
			return "[%s]";
		end
	end);

	-- process extra args
	while i < args_length do
		i = i + 1;
		local arg = args[i];
		if arg == nil then
			args[i] = "(nil)";
		else
			args[i] = tostring(arg):gsub("[%z\1-\8\11-\31\127]", control_symbols):gsub("\n\t?", "\n\t");
		end
		formatstring = formatstring .. " [%s]"
	end

	return formatstring:format(unpack(args));
end

return {
	format = format;
};