mirror of
https://github.com/appgurueu/modlib.git
synced 2024-07-07 08:35:15 +02:00
86 lines
2.7 KiB
Lua
86 lines
2.7 KiB
Lua
local assert, error, select, string_char, table_concat
|
|
= assert, error, select, string.char, table.concat
|
|
|
|
local utf8 = {}
|
|
|
|
function utf8.is_valid_codepoint(codepoint)
|
|
-- Must be in bounds & must not be a surrogate
|
|
return codepoint <= 0x10FFFF and (codepoint < 0xD800 or codepoint > 0xDFFF)
|
|
end
|
|
|
|
local function utf8_bytes(codepoint)
|
|
if codepoint <= 0x007F then
|
|
return codepoint
|
|
end if codepoint <= 0x7FF then
|
|
local payload_2 = codepoint % 0x40
|
|
codepoint = (codepoint - payload_2) / 0x40
|
|
return 0xC0 + codepoint, 0x80 + payload_2
|
|
end if codepoint <= 0xFFFF then
|
|
local payload_3 = codepoint % 0x40
|
|
codepoint = (codepoint - payload_3) / 0x40
|
|
local payload_2 = codepoint % 0x40
|
|
codepoint = (codepoint - payload_2) / 0x40
|
|
return 0xE0 + codepoint, 0x80 + payload_2, 0x80 + payload_3
|
|
end if codepoint <= 0x10FFFF then
|
|
local payload_4 = codepoint % 0x40
|
|
codepoint = (codepoint - payload_4) / 0x40
|
|
local payload_3 = codepoint % 0x40
|
|
codepoint = (codepoint - payload_3) / 0x40
|
|
local payload_2 = codepoint % 0x40
|
|
codepoint = (codepoint - payload_2) / 0x40
|
|
return 0xF0 + codepoint, 0x80 + payload_2, 0x80 + payload_3, 0x80 + payload_4
|
|
end error"codepoint out of range"
|
|
end
|
|
|
|
function utf8.char(...)
|
|
local n_args = select("#", ...)
|
|
if n_args == 0 then
|
|
return
|
|
end if n_args == 1 then
|
|
return string_char(utf8_bytes(...))
|
|
end
|
|
local chars = {}
|
|
for i = 1, n_args do
|
|
chars[i] = string_char(utf8_bytes(select(i, ...)))
|
|
end
|
|
return table_concat(chars)
|
|
end
|
|
|
|
-- Overly permissive pattern that greedily matches a single UTF-8 codepoint
|
|
utf8.charpattern = "[%z-\127\194-\253][\128-\191]*"
|
|
|
|
local function utf8_codepoint(str)
|
|
local first_byte = str:byte()
|
|
if first_byte < 0x80 then
|
|
assert(#str == 1, "invalid UTF-8")
|
|
return first_byte
|
|
end
|
|
|
|
local len, head_bits
|
|
if first_byte >= 0xC0 and first_byte <= 0xDF then -- 110_00000 to 110_11111
|
|
len, head_bits = 2, first_byte % 0x20 -- last 5 bits
|
|
elseif first_byte >= 0xE0 and first_byte <= 0xEF then -- 1110_0000 to 1110_1111
|
|
len, head_bits = 3, first_byte % 0x10 -- last 4 bits
|
|
elseif first_byte >= 0xF0 and first_byte <= 0xF7 then -- 11110_000 to 11110_111
|
|
len, head_bits = 4, first_byte % 0x8 -- last 3 bits
|
|
else error"invalid UTF-8" end
|
|
assert(#str == len, "invalid UTF-8")
|
|
|
|
local codepoint = 0
|
|
local pow = 1
|
|
for i = len, 2, -1 do
|
|
local byte = str:byte(i)
|
|
local val_bits = byte % 0x40 -- extract last 6 bits xxxxxx from 10xxxxxx
|
|
assert(byte - val_bits == 0x80) -- assert that first two bits are 10
|
|
codepoint = codepoint + val_bits * pow
|
|
pow = pow * 0x40
|
|
end
|
|
return codepoint + head_bits * pow
|
|
end
|
|
|
|
function utf8.codepoint(...)
|
|
if select("#", ...) == 0 then return end
|
|
return utf8_codepoint(...), utf8.codepoint(select(2, ...))
|
|
end
|
|
|
|
return utf8 |