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resources/[housing]/brutal_housing/client/object_placing/dataview.lua

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+-- Credit: https://github.com/citizenfx/lua/blob/luaglm-dev/cfx/libs/scripts/examples/dataview.lua
+local dataView = setmetatable({
+    EndBig = ">",
+    EndLittle = "<",
+    Types = {
+        Int8 = { code = "i1" },
+        Uint8 = { code = "I1" },
+        Int16 = { code = "i2" },
+        Uint16 = { code = "I2" },
+        Int32 = { code = "i4" },
+        Uint32 = { code = "I4" },
+        Int64 = { code = "i8" },
+        Uint64 = { code = "I8" },
+        Float32 = { code = "f", size = 4 }, -- a float (native size)
+        Float64 = { code = "d", size = 8 }, -- a double (native size)
+
+        LuaInt = { code = "j" }, -- a lua_Integer
+        UluaInt = { code = "J" }, -- a lua_Unsigned
+        LuaNum = { code = "n" }, -- a lua_Number
+        String = { code = "z", size = -1, }, -- zero terminated string
+    },
+
+    FixedTypes = {
+        String = { code = "c" }, -- a fixed-sized string with n bytes
+        Int = { code = "i" }, -- a signed int with n bytes
+        Uint = { code = "I" }, -- an unsigned int with n bytes
+    },
+}, {
+    __call = function(_, length)
+        return dataView.ArrayBuffer(length)
+    end
+})
+dataView.__index = dataView
+
+--[[ Create an ArrayBuffer with a size in bytes --]]
+function dataView.ArrayBuffer(length)
+    return setmetatable({
+        blob = string.blob(length),
+        length = length,
+        offset = 1,
+        cangrow = true,
+    }, dataView)
+end
+
+--[[ Wrap a non-internalized string --]]
+function dataView.Wrap(blob)
+    return setmetatable({
+        blob = blob,
+        length = blob:len(),
+        offset = 1,
+        cangrow = true,
+    }, dataView)
+end
+
+--[[ Return the underlying bytebuffer --]]
+function dataView:Buffer() return self.blob end
+function dataView:ByteLength() return self.length end
+function dataView:ByteOffset() return self.offset end
+function dataView:SubView(offset, length)
+    return setmetatable({
+        blob = self.blob,
+        length = length or self.length,
+        offset = 1 + offset,
+        cangrow = false,
+    }, dataView)
+end
+
+--[[ Return the Endianness format character --]]
+function ef(big) return (big and dataView.EndBig) or dataView.EndLittle end
+
+--[[ Helper function for setting fixed datatypes within a buffer --]]
+function packblob(self, offset, value, code)
+    -- If cangrow is false the dataview represents a subview, i.e., a subset
+    -- of some other string view. Ensure the references are the same before
+    -- updating the subview
+    local packed = self.blob:blob_pack(offset, code, value)
+    if self.cangrow or packed == self.blob then
+        self.blob = packed
+        self.length = packed:len()
+        return true
+    else
+        return false
+    end
+end
+
+--[[
+    Create the API by using dataView.Types
+--]]
+for label,datatype in pairs(dataView.Types) do
+    if not datatype.size then  -- cache fixed encoding size
+        datatype.size = string.packsize(datatype.code)
+    elseif datatype.size >= 0 and string.packsize(datatype.code) ~= datatype.size then
+        local msg = "Pack size of %s (%d) does not match cached length: (%d)"
+        error(msg:format(label, string.packsize(datatype.code), datatype.size))
+        return nil
+    end
+
+    dataView["Get" .. label] = function(self, offset, endian)
+        offset = offset or 0
+        if offset >= 0 then
+            local o = self.offset + offset
+            local v,_ = self.blob:blob_unpack(o, ef(endian) .. datatype.code)
+            return v
+        end
+        return nil
+    end
+
+    dataView["Set" .. label] = function(self, offset, value, endian)
+        if offset >= 0 and value then
+            local o = self.offset + offset
+            local v_size = (datatype.size < 0 and value:len()) or datatype.size
+            if self.cangrow or ((o + (v_size - 1)) <= self.length) then
+                if not packblob(self, o, value, ef(endian) .. datatype.code) then
+                    error("cannot grow subview")
+                end
+            else
+                error("cannot grow dataview")
+            end
+        end
+        return self
+    end
+end
+
+for label,datatype in pairs(dataView.FixedTypes) do
+    datatype.size = -1 -- Ensure cached encoding size is invalidated
+
+    dataView["GetFixed" .. label] = function(self, offset, typelen, endian)
+        if offset >= 0 then
+            local o = self.offset + offset
+            if (o + (typelen - 1)) <= self.length then
+                local code = ef(endian) .. "c" .. tostring(typelen)
+                local v,_ = self.blob:blob_unpack(o, code)
+                return v
+            end
+        end
+        return nil -- Out of bounds
+    end
+
+    dataView["SetFixed" .. label] = function(self, offset, typelen, value, endian)
+        if offset >= 0 and value then
+            local o = self.offset + offset
+            if self.cangrow or ((o + (typelen - 1)) <= self.length) then
+                local code = ef(endian) .. "c" .. tostring(typelen)
+                if not packblob(self, o, value, code) then
+                    error("cannot grow subview")
+                end
+            else
+                error("cannot grow dataview")
+            end
+        end
+        return self
+    end
+end
+
+return dataView