133 lines
2.3 KiB
Lua
Executable File
133 lines
2.3 KiB
Lua
Executable File
local require,table
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= require,table
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module((...))
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local parse = require(_PACKAGE.."parser")
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local gen = {}
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gen.preamble = [[
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local fd,data = ...
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local stack = {}
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local index = 1
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local start = fd:seek()
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local len = 0
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local function push(key)
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if not key then
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key = index
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index = index + 1
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end
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stack[#stack+1] = { index, data }
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data = data[key]
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index = 1
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end
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local function pop(key)
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local saved = stack[#stack]
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stack[#stack] = nil
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index = saved[1]
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data = saved[2]
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end
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local function update_len()
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len = len + fd:seek() - start
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end
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local function update_start()
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start = fd:seek()
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end
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hostendian()
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]]
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gen.postamble = [[
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update_len()
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return fd,len
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]]
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-- control:
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-- <<type>>(fd, <<args>>)
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function gen.control(token)
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local tr = {
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["<"] = "littleendian";
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[">"] = "bigendian";
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["="] = "hostendian";
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["+"] = "seekforward";
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["-"] = "seekback";
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["@"] = "seekto";
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}
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local fn = tr[token[1]] or token[1]
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local args = token[2]:gsub('%.', ', ')
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if #args == 0 then args = "nil" end
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return "update_len(); "..fn.."(fd, "..args..")".."; update_start()"
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end
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-- atom:
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-- <<type>>(fd, data[index], <<args>>)
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-- ++index
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function gen.atom(token)
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local fn = token[1]
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local args = token[2]:gsub('%.', ', ')
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if #args == 0 then args = "nil" end
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return fn.."(fd, data[index], "..args..")\nindex = index+1"
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end
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-- table:
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-- push()
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-- <<table contents>>
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-- pop()
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function gen.table(token)
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return "push()\n"
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..parse(token[1]:sub(2,-2), gen)
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.."\npop()"
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end
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-- group:
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-- <<group contents>>
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function gen.group(token)
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return parse(token[1]:sub(2,-2), gen)
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end
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-- named atom:
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-- <<type>>(fd, data.<<name>>, <<args>>)
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function gen.name_atom(token)
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local fn = token[2]
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local args = token[3]:gsub('%.', ', ')
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if #args == 0 then args = "nil" end
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return fn.."(fd, data."..token[1]..", "..args..")"
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end
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-- named table:
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-- push(<<name>>)
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-- <<table contents>>
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-- pop()
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function gen.name_table(token)
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return "push('"..token[1].."')\n"
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..parse(token[2]:sub(2,-2), gen)
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.."\npop()"
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end
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function gen.prerepeat(token, get)
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local next = get()
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local src = gen[next.type](next, get)
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return "for _idx=1,"..token[1].." do\n\n"..src.."\nend"
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end
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function gen.postrepeat(token, get, asl)
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local src = table.remove(asl)
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return "for _idx=1,"..token[1].." do\n\n"..src.."\nend"
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end
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return gen
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