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| local LEFT_PLACEHOLDER = '__LEFT_BRACE__' | |
| local RIGHT_PLACEHOLDER = '__RIGHT_BRACE__' | |
| local function template(str) | |
| local parts = {} | |
| local last = 1 | |
| str = str:gsub('{{', LEFT_PLACEHOLDER) | |
| str = str:gsub('}}', RIGHT_PLACEHOLDER) | |
| for start, _, expr, finish in str:gmatch('()({(.-)})()') do | |
| local code = str:sub(last, start - 1) | |
| :gsub(LEFT_PLACEHOLDER, '{') | |
| :gsub(RIGHT_PLACEHOLDER, '}') | |
| table.insert(parts, string.format('%q', code)) | |
| table.insert(parts, '(' .. expr .. ')') | |
| last = finish | |
| end | |
| local remaining = str:sub(last) | |
| :gsub(LEFT_PLACEHOLDER, '{') | |
| :gsub(RIGHT_PLACEHOLDER, '}') | |
| table.insert(parts, string.format('%q', remaining)) | |
| local source = | |
| 'return function() return table.concat({' | |
| .. table.concat(parts, ',') | |
| .. '}) end' | |
| local env = setmetatable({}, { | |
| __index = function(t, k) | |
| if _G[k] then | |
| return _G[k] | |
| else | |
| local level = 1 | |
| while true do | |
| local info = debug.getinfo(level, "f") | |
| if not info then break end -- no more stack frames | |
| local i = 1 | |
| while true do | |
| local name, value = debug.getlocal(level, i) | |
| if not name then break end | |
| if name == k then | |
| -- cache value | |
| rawset(t, k, value) | |
| return value | |
| end | |
| i = i + 1 | |
| end | |
| level = level + 1 | |
| end | |
| rawset(t, k, '???') | |
| return '???' | |
| end | |
| end | |
| }) | |
| local fn, err = load(source, 'template', 't', env) | |
| if not fn then error('template compile error: ' .. err) end | |
| local tpl = fn() | |
| return function(vars) | |
| for k, v in next, vars do env[k] = v end | |
| return tpl() | |
| end | |
| end |
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