79 lines
2.3 KiB
Lua
79 lines
2.3 KiB
Lua
local tinsert, tconcat, infinity = table.insert, table.concat, math.huge
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return function (value)
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local intro, outro, ready, known = {}, {}, {}, {}
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local knownCount = 0
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local writer = {}
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-- get writer delegate for this value's type
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local function getWriter (value)
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return writer[type(value)]
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end
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-- check if a value has a representation yet
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local function isReady (value)
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return type(value) ~= 'table' or ready[value]
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end
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-- serialize tables
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function writer.table (value)
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if known[value] then
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return known[value]
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end
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knownCount = knownCount + 1
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local variable = ('v%i'):format(knownCount)
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known[value] = variable
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local parts = {}
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for k, v in pairs(value) do
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local writeKey, writeValue = getWriter(k), getWriter(v)
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if writeKey and writeValue then
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local key, value = writeKey(k), writeValue(v)
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if isReady(k) and isReady(v) then
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tinsert(parts, ('[%s]=%s'):format(key, value))
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else
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tinsert(outro, ('%s[%s]=%s'):format(variable, key, value))
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end
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end
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end
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local fields = tconcat(parts, ',')
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tinsert(intro, ('local %s={%s}'):format(variable, fields))
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ready[value] = true
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return variable
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end
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-- preserve sign bit on NaN, since Lua prints "nan" or "-nan"
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local function writeNan (n)
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return tostring(n) == tostring(0/0) and '0/0' or '-(0/0)'
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end
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-- serialize numbers
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function writer.number (value)
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return value == infinity and '1/0'
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or value == -infinity and '-1/0'
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or value ~= value and writeNan(value)
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or ('%.17G'):format(value)
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end
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-- serialize strings
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function writer.string (value)
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return ('%q'):format(value)
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end
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-- serialize booleans
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writer.boolean = tostring
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-- concatenate array, joined by and terminated with line break
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local function lines (t)
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return #t == 0 and '' or tconcat(t, '\n') .. '\n'
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end
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-- generate serialized result
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local write = getWriter(value)
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local result = write and write(value) or 'nil'
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return lines(intro) .. lines(outro) .. 'return ' .. result
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end
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