File

util/human/units.lua @ 13146:771eb453e03a

util.sqlite3: Deduplicate query methods There were 3 very similar methods: - :execute() - :execute_query() - :execute_update() The first one returns the prepared statement and is mainly used internally in the library for CREATE statements. The later two only really differ in how the results are returned. Those two are one main method and one small one that only picks out the iterator.
author Kim Alvefur <zash@zash.se>
date Sat, 10 Jun 2023 22:02:15 +0200
parent 12589:39ae08180c81
line wrap: on
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local math_abs = math.abs;
local math_ceil = math.ceil;
local math_floor = math.floor;
local math_log = math.log;
local math_max = math.max;
local math_min = math.min;
local unpack = table.unpack;

local large = {
	"k", 1000,
	"M", 1000000,
	"G", 1000000000,
	"T", 1000000000000,
	"P", 1000000000000000,
	"E", 1000000000000000000,
	"Z", 1000000000000000000000,
	"Y", 1000000000000000000000000,
}
local small = {
	"m", 0.001,
	"μ", 0.000001,
	"n", 0.000000001,
	"p", 0.000000000001,
	"f", 0.000000000000001,
	"a", 0.000000000000000001,
	"z", 0.000000000000000000001,
	"y", 0.000000000000000000000001,
}

local binary = {
	"Ki", 2^10,
	"Mi", 2^20,
	"Gi", 2^30,
	"Ti", 2^40,
	"Pi", 2^50,
	"Ei", 2^60,
	"Zi", 2^70,
	"Yi", 2^80,
}

local function adjusted_unit(n, b)
	local round = math_floor;
	local prefixes = large;
	local logbase = 1000;
	if b == 'b' then
		prefixes = binary;
		logbase = 1024;
	elseif n < 1 then
		prefixes = small;
		round = math_ceil;
	end
	local m = math_max(0, math_min(8, round(math_abs(math_log(math_abs(n), logbase)))));
	local prefix, multiplier = unpack(prefixes, m * 2-1, m*2);
	return multiplier or 1, prefix;
end

-- n: number, the number to format
-- unit: string, the base unit
-- b: optional enum 'b', thousands base
local function format(n, unit, b) --> string
	local fmt = "%.3g %s%s";
	if n == 0 then
		return fmt:format(n, "", unit);
	end
	local multiplier, prefix = adjusted_unit(n, b);
	return fmt:format(n / multiplier, prefix or "", unit);
end

return {
	adjust = adjusted_unit;
	format = format;
};