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110 lines
2.5 KiB
110 lines
2.5 KiB
local m = {}
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local mt = {}
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local mt_name = "flatbuffers.view.mt"
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local N = require("flatbuffers.numTypes")
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local binaryarray = require("flatbuffers.binaryarray")
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local function enforceOffset(off)
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if off < 0 or off > 42949672951 then
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error("Offset is not valid")
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end
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end
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local unpack = string.unpack
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local function unPackUoffset(bytes, off)
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return unpack("<I4", bytes.str, off + 1)
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end
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local function unPackVoffset(bytes, off)
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return unpack("<I2", bytes.str, off + 1)
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end
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function m.New(buf, pos)
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enforceOffset(pos)
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-- need to convert from a string buffer into
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-- a binary array
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local o = {
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bytes = type(buf) == "string" and binaryarray.New(buf) or buf,
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pos = pos,
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}
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setmetatable(o, {__index = mt, __metatable = mt_name})
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return o
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end
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function mt:Offset(vtableOffset)
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local vtable = self.vtable
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if not vtable then
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vtable = self.pos - self:Get(N.SOffsetT, self.pos)
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self.vtable = vtable
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self.vtableEnd = self:Get(N.VOffsetT, vtable)
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end
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if vtableOffset < self.vtableEnd then
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return unPackVoffset(self.bytes, vtable + vtableOffset)
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end
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return 0
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end
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function mt:Indirect(off)
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enforceOffset(off)
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return off + unPackUoffset(self.bytes, off)
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end
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function mt:String(off)
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enforceOffset(off)
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off = off + unPackUoffset(self.bytes, off)
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local start = off + 4
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local length = unPackUoffset(self.bytes, off)
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return self.bytes:Slice(start, start+length)
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end
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function mt:VectorLen(off)
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enforceOffset(off)
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off = off + self.pos
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off = off + unPackUoffset(self.bytes, off)
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return unPackUoffset(self.bytes, off)
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end
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function mt:Vector(off)
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enforceOffset(off)
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off = off + self.pos
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return off + self:Get(N.UOffsetT, off) + 4
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end
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function mt:Union(t2, off)
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assert(getmetatable(t2) == mt_name)
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enforceOffset(off)
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off = off + self.pos
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t2.pos = off + self:Get(N.UOffsetT, off)
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t2.bytes = self.bytes
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end
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function mt:Get(flags, off)
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enforceOffset(off)
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return flags:Unpack(self.bytes, off)
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end
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function mt:GetSlot(slot, d, validatorFlags)
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N.VOffsetT:EnforceNumber(slot)
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if validatorFlags then
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validatorFlags:EnforceNumber(d)
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end
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local off = self:Offset(slot)
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if off == 0 then
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return d
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end
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return self:Get(validatorFlags, self.pos + off)
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end
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function mt:GetVOffsetTSlot(slot, d)
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N.VOffsetT:EnforceNumbers(slot, d)
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local off = self:Offset(slot)
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if off == 0 then
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return d
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end
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return off
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end
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return m |