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Module:Fallbacklist>Awesome Aasim: remove header but link to MIT license

2026-06-08T03:21:07Z

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--- Lexer for Lua source code written in pure Lua.
-- @script lexer
-- @license [https://github.com/LoganDark/lua-lexer/blob/master/LICENSE MIT]
-- @author https://github.com/LoganDark
-- @param {string} text Lua source code to lex.
-- @return {string} Table of line arrays containing lexemes.

--- Mapper for individual token list string.
-- @param {string} src List of characters or keywords to map.
-- @param[opt] {table} list Table to extend by reference.
-- @return {{char=true,...}}, map
-- @local
local function lookupify(src, list)
list = list or {}

if type(src) == 'string' then
for i = 1, src:len() do
list[src:sub(i, i)] = true
end
elseif type(src) == 'table' then
for i = 1, #src do
list[src[i]] = true
end
end

return list
end

--- Base identifier character set.
-- @variable {string} base_ident
local base_ident = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_'

--- Base identifier character set.
-- @variable {string} base_digits
local base_digits = '0123456789'

--- Base identifier character set.
-- @variable {string} base_operators
local base_operators = '+-*/^%#'

--- Map of Lua character patterns.
-- @table chars
-- @field {table} whitespace Boolean map of whitespace
-- tokens.
-- @field {table} validEscapes Boolean map of valid escape
-- characters.
-- @field {table} ident Boolean map of valid identifier
-- characters.
-- @field {table} symbols Boolean map of valid symbol and
-- operator characters.
-- @local
local chars = {
whitespace = lookupify(' \n\t\r'),
validEscapes = lookupify('abfnrtv"\'\\'),
ident = lookupify(
base_ident .. base_digits,
{
start = lookupify(base_ident),
}
),

digits = lookupify(
base_digits,
{
hex = lookupify(base_digits .. 'abcdefABCDEF')
}
),

symbols = lookupify(
base_operators .. ',{}[]();.:', {
equality = lookupify('~=><'),
operators = lookupify(base_operators)
}
)
}

--- List of Lua keywords.
-- @table keywords
-- @field structure Boolean map of structure keywords.
-- @field values Boolean map of primitive keywords.
local keywords = {
structure = lookupify({
'and', 'break', 'do', 'else', 'elseif', 'end', 'for', 'function',
'goto', 'if', 'in', 'local', 'not', 'or', 'repeat', 'return', 'then',
'until', 'while'
}),

values = lookupify({
'true', 'false', 'nil'
})
}

-- Lexer function export.
return function(text)
local pos = 1
local start = 1
local buffer = {}
local lines = {}

local function look(delta)
delta = pos + (delta or 0)

return text:sub(delta, delta)
end

local function get()
pos = pos + 1

return look(-1)
end

local function getDataLevel()
local num = 0

while look(num) == '=' do
num = num + 1
end

if look(num) == '[' then
pos = pos + num + 1

return num
end
end

local function getCurrentTokenText()
return text:sub(start, pos - 1)
end

local currentLineLength = 0
local lineoffset = 0

local function pushToken(type, text)
text = text or getCurrentTokenText()

local tk = buffer[#buffer]

if not tk or tk.type ~= type then
tk = {
type = type,
data = text,
posFirst = start - lineoffset,
posLast = pos - 1 - lineoffset
}

if tk.data ~= '' then
buffer[#buffer + 1] = tk
end
else
tk.data = tk.data .. text
tk.posLast = tk.posLast + text:len()
end

currentLineLength = currentLineLength + text:len()
start = pos

return tk
end

local function newline()
lines[#lines + 1] = buffer
buffer = {}

get()
pushToken('newline')
buffer[1] = nil

lineoffset = lineoffset + currentLineLength
currentLineLength = 0
end

local function getData(level, type)
while true do
local char = get()

if char == '' then
return
elseif char == '\n' then
pos = pos - 1
pushToken(type)
newline()
elseif char == ']' then
local valid = true

for i = 1, level do
if look() == '=' then
pos = pos + 1
else
valid = false
break
end
end

if valid and look() == ']' then
pos = pos - level - 1

return
end
end
end
end

local function chompWhitespace()
while true do
local char = look()

if char == '\n' then
pushToken('whitespace')
newline()
elseif chars.whitespace[char] then
pos = pos + 1
else
break
end
end

pushToken('whitespace')
end

while true do
chompWhitespace()

local char = get()

if char == '' then
break
elseif char == '-' and look() == '-' then
pos = pos + 1

if look() == '[' then
pos = pos + 1

local level = getDataLevel()

if level then
getData(level, 'comment')

pos = pos + level + 2
pushToken('comment')
else
while true do
local char2 = get()

if char2 == '' or char2 == '\n' then
pos = pos - 1
pushToken('comment')

if char2 == '\n' then
newline()
end

break
end
end
end
else
while true do
local char2 = get()

if char2 == '' or char2 == '\n' then
pos = pos - 1
pushToken('comment')

if char2 == '\n' then
newline()
end

break
end
end
end

pushToken('comment')
elseif char == '\'' or char == '"' then
pushToken('string_start')

while true do
local char2 = get()

if char2 == '\\' then
pos = pos - 1
pushToken('string')
get()

local char3 = get()

if chars.digits[char3] then
for i = 1, 2 do
if chars.digits[look()] then
pos = pos + 1
end
end
elseif char3 == 'x' then
if chars.digits.hex[look()] and chars.digits.hex[look(1)] then
pos = pos + 2
else
pushToken('unidentified')
end
elseif char3 == '\n' then
pos = pos - 1
pushToken('escape')
newline()
elseif not chars.validEscapes[char3] then
pushToken('unidentified')
end

pushToken('escape')
elseif char2 == '\n' then
pos = pos - 1
pushToken('string')
newline()

break
elseif char2 == char or char2 == '' then
pos = pos - 1
pushToken('string')
get()

break
end
end

pushToken('string_end')
elseif chars.ident.start[char] then
while chars.ident[look()] do
pos = pos + 1
end

local word = getCurrentTokenText()

if keywords.structure[word] then
pushToken('keyword')
elseif keywords.values[word] then
pushToken('value')
else
pushToken('ident')
end
elseif chars.digits[char] or (char == '.' and chars.digits[look()]) then
if char == '0' and look() == 'x' then
pos = pos + 1

while chars.digits.hex[look()] do
pos = pos + 1
end
else
while chars.digits[look()] do
pos = pos + 1
end

if look() == '.' then
pos = pos + 1

while chars.digits[look()] do
pos = pos + 1
end
end

if look():lower() == 'e' then
pos = pos + 1

if look() == '-' then
pos = pos + 1
end

while chars.digits[look()] do
pos = pos + 1
end
end
end

pushToken('number')
elseif char == '[' then
local level = getDataLevel()

if level then
pushToken('string_start')

getData(level, 'string')
pushToken('string')

pos = pos + level + 2
pushToken('string_end')
else
pushToken('symbol')
end
elseif char == '.' then
if look() == '.' then
pos = pos + 1

if look() == '.' then
pos = pos + 1
end
end

if getCurrentTokenText():len() == 3 then
pushToken('vararg')
else
pushToken('symbol')
end
elseif char == ':' and look() == ':' then
get()

pushToken('label_start')

chompWhitespace()

if chars.ident.start[look()] then
get()

while chars.ident[look()] do
get()
end

pushToken('label')

chompWhitespace()

if look() == ':' and look(1) == ':' then
get()
get()

pushToken('label_end')
end
end
elseif chars.symbols.equality[char] then
if look() == '=' then
pos = pos + 1
end

pushToken('operator')
elseif chars.symbols[char] then
if chars.symbols.operators[char] then
pushToken('operator')
else
pushToken('symbol')
end
else
pushToken('unidentified')
end
end

lines[#lines + 1] = buffer

return lines
end

Module:Lua lexer - Revision history

Austenasia: 1 revision imported

Module:Fallbacklist>Awesome Aasim: remove header but link to MIT license