110 lines
3.0 KiB
Lua
110 lines
3.0 KiB
Lua
--
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-- A primitive code minifier
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--
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-- © 2019 by luk3yx
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--
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-- Find multiple patterns
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local function find_multiple(text, ...)
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local n = select('#', ...)
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local s, e, pattern
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for i = 1, n do
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local p = select(i, ...)
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local s2, e2 = text:find(p)
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if s2 and (not s or s2 < s) then
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s, e, pattern = s2, e2 or s2, p
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end
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end
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return s, e, pattern
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end
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-- Matches
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-- These take 2-3 arguments (code, res, char) and should return code and res.
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local matches = {
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-- Handle multi-line strings
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['%[=*%['] = function(code, res, char)
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res = res .. char
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char = char:sub(2, -2)
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local s, e = code:find(']' .. char .. ']', nil, true)
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if not s or not e then return code, res end
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return code:sub(e + 1), res .. code:sub(1, e)
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end,
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-- Handle regular comments
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['--'] = function(code, res, char)
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local s, e = code:find('\n', nil, true)
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if not s or not e then return code, res end
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-- Shift trailing spaces back
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local spaces = res:match('(%s*)$') or ''
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return spaces .. code:sub(e), res:sub(1, #res - #spaces)
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end,
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-- Handle multi-line comments
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['%-%-%[=*%['] = function(code, res, char)
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char = char:sub(4, -2)
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local s, e = code:find(']' .. char .. ']', nil, true)
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if not s or not e then return code, res end
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-- Shift trailing spaces back
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local spaces = res:match('(%s*)$') or ''
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return spaces .. code:sub(e + 1), res:sub(1, #res - #spaces)
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end,
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-- Handle quoted text
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['"'] = function(code, res, char)
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res = res .. char
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-- Handle backslashes
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repeat
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local s, e, pattern = find_multiple(code, '\\', char)
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if pattern == char then
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res = res .. code:sub(1, e)
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code = code:sub(e + 1)
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elseif pattern then
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res = res .. code:sub(1, e + 1)
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code = code:sub(e + 2)
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end
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until not pattern or pattern == char
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return code, res
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end,
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['%s*[\r\n]%s*'] = function(code, res, char)
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return code, res .. '\n'
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end,
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['[ \t]+'] = function(code, res, char)
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return code, res .. ' '
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end,
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}
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-- Give the functions alternate names
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matches["'"] = matches['"']
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-- The actual transpiler
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return function(code)
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assert(type(code) == 'string')
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local res = ''
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-- Split the code by "tokens"
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while true do
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-- Search for special characters
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local s, e, pattern = find_multiple(code, '[\'"\\]', '%-%-%[=*%[',
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'%-%-', '%[=*%[', '%s*[\r\n]%s*', '[ \t]+')
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if not s then break end
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-- Add non-matching characters
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res = res .. code:sub(1, math.max(s - 1, 0))
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-- Call the correct function
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local char = code:sub(s, e)
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local func = matches[char] or matches[pattern]
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assert(func, 'No function found for pattern!')
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code, res = func(code:sub(e + 1), res, char)
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end
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return (res .. code):trim()
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end
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