[tarantool-patches] Fwd: Re[3]: [PATCH] lua: add string.fromhex method

["Nikita Tatunov" <n.tatunov@tarantool.org>]

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-------- Пересылаемое сообщение --------
От кого: Nikita Tatunov <n.tatunov@tarantool.org>
Кому: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Копия: tarantool-patches@freelists.org, Alexander Turenko <alexander.turenko@tarantool.org>
Дата: Четверг,  9 августа 2018, 13:08 +03:00
Тема: Re[3]: [PATCH] lua: add string.fromhex method

Diff:

diff --git a/src/lua/string.lua b/src/lua/string.lua
index 5ff64c9f6..f6accb42c 100644
--- a/src/lua/string.lua
+++ b/src/lua/string.lua
@@ -292,6 +292,54 @@ local function string_hex(inp)
return ffi.string(res, len)
end

+local hexadecimal_chars = {
+ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',
+ 'a', 'B', 'b', 'C', 'c', 'D', 'd', 'E', 'e', 'F', 'f'}
+
+local hexadecimal_values = {
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
+ 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15}
+
+local hexadecimals_mapping = {}
+
+local function chars_to_hex(chars, values, mapping)
+ for i, char in ipairs(chars) do
+ mapping[string.byte(char)] = values[i]
+ end
+end
+
+chars_to_hex(hexadecimal_chars, hexadecimal_values, hexadecimals_mapping)
+
+--- Match a hexadecimal representation of a string to its
+-- string representation.
+-- @function fromhex
+-- @string inp the string of hexadecimals
+-- @returns formatted string
+local function string_fromhex(inp)
+ if type(inp) ~= 'string' then
+ error(err_string_arg:format(1, 'string.fromhex', 'string',
+ type(inp)), 2)
+ end
+ if inp:len() % 2 ~= 0 then
+ error(err_string_arg:format(1, 'string.fromhex',
+ 'even amount of chars',
+ 'odd amount'), 2)
+ end
+ local len = inp:len() / 2
+ local casted_inp = ffi.cast('const char *', inp)
+ local res = ffi.new('char[?]', len)
+ for i = 0, len - 1 do
+ local first = hexadecimals_mapping[casted_inp[i * 2]]
+ local second = hexadecimals_mapping[casted_inp[i * 2 + 1]]
+ if first == nil or second == nil then
+ error(err_string_arg:format(1, 'string.fromhex', 'hex string',
+ 'non hex chars'), 2)
+ end
+ res[i] = first * 16 + second
+ end
+ return ffi.string(res, len)
+end
+
local function string_strip(inp)
if type(inp) ~= 'string' then
error(err_string_arg:format(1, "string.strip", 'string', type(inp)), 2)
@@ -323,6 +371,7 @@ string.center = string_center
string.startswith = string_startswith
string.endswith = string_endswith
string.hex = string_hex
+string.fromhex = string_fromhex
string.strip = string_strip
string.lstrip = string_lstrip
string.rstrip = string_rstrip
diff --git a/test/app-tap/string.test.lua b/test/app-tap/string.test.lua
index 1d10dcfc9..32333bff1 100755
--- a/test/app-tap/string.test.lua
+++ b/test/app-tap/string.test.lua
@@ -3,7 +3,7 @@
local tap = require('tap')
local test = tap.test("string extensions")

-test:plan(6)
+test:plan(7)

test:test("split", function(test)
test:plan(10)
@@ -114,6 +114,25 @@ test:test("hex", function(test)
test:is(string.hex(""), "", "hex empty string")
end)

+test:test("fromhex", function(test)
+ test:plan(11)
+ test:is(string.fromhex("48656c6c6f"), "Hello", "from hex to bin")
+ test:is(string.fromhex("4c696e7578"), "Linux", "from hex to bin")
+ test:is(string.fromhex("6C6F72656D"), "lorem", "from hex to bin")
+ test:is(string.fromhex("697073756D"), "ipsum", "from hex to bin")
+ test:is(string.fromhex("6c6f72656d"), "lorem", "from hex to bin")
+ test:is(string.fromhex("697073756d"), "ipsum", "from hex to bin")
+ test:is(string.fromhex("6A6B6C6D6E6F"), "jklmno", "from hex to bin")
+ test:is(string.fromhex("6a6b6c6d6e6f"), "jklmno", "from hex to bin")
+ local _, err = pcall(string.fromhex, "aaa")
+ test:ok(err and err:match("(even amount of chars expected," ..
+ " got odd amount)"))
+ local _, err = pcall(string.fromhex, "qq")
+ test:ok(err and err:match("(hex string expected, got non hex chars)"))
+ local _, err = pcall(string.fromhex, 795)
+ test:ok(err and err:match("(string expected, got number)"))
+end)
+
test:test("strip", function(test)
test:plan(6)
local str = " hello hello "

----------------------------------------------------------------------

-- 
WBR, Nikita Tatunov.

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