mirror of
https://github.com/appgurueu/modlib.git
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115 lines
2.9 KiB
Markdown
115 lines
2.9 KiB
Markdown
# Bluon
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Binary Lua object notation.
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## `new(def)`
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```lua
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def = {
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aux_is_valid = function(object)
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return is_valid
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end,
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aux_len = function(object)
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return length_in_bytes
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end,
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-- read type byte, stream providing :read(count), map of references -> id
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aux_read = function(type, stream, references)
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... = stream:read(...)
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return object
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end,
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-- object to be written, stream providing :write(text), list of references
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aux_write = function(object, stream, references)
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stream:write(...)
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end
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}
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```
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## `:is_valid(object)`
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Returns whether the given object can be represented by the instance as boolean.
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## `:len(object)`
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Returns the expected length of the object if serialized by the current instance in bytes.
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## `:write(object, stream)`
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Writes the object to a stream supporting `:write(text)`. Throws an error if invalid.
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## `:read(stream)`
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Reads a single bluon object from a stream supporting `:read(count)`. Throws an error if invalid bluon.
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Checking whether the stream has been fully consumed by doing `assert(not stream:read(1))` is left up to the user.
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## Format
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* `nil`: nothing (`""`)
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* `false`: 0
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* `true`: 1
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* Numbers:
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* Constants: 0, nan, +inf, -inf
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* Integers: Little endian `U8`, `U16`, `U32`, `U64`, `-U8`, `-U16`, `-U32`, `-U64`
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* Floats: Little endian `F32`, `F64`
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* Strings:
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* Constant: `""`
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* Length as unsigned integer: `T8`, `T16`, `T32`, `T64`
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* Tables:
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* List and map part count as unsigned integers
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* `L0`, `L8`, `L16`, `L32`, `L64` times `M0`, `M8`, `M16`, `M32`, `M64`
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* Reference:
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* Reference ID as unsigned integer: `R8`, `R16`, `R32`, `R64`
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* Reserved types:
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* Everything <= 55 => 200 free types
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## Features
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* Embeddable: Written in pure Lua
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* Storage efficient: No duplication of strings or reference-equal tables
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* Flexible: Can serialize circular references and strings containing null
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## Simple example
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```lua
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local object = ...
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-- Write to file
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local file = io.open(..., "wb")
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modlib.bluon:write(object, file)
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file:close()
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-- Write to text
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local rope = modlib.table.rope{}
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modlib.bluon:write(object, rope)
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text = rope:to_text()
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-- Read from text
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local inputstream = modlib.text.inputstream"\1"
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assert(modlib.bluon:read(object, rope) == true)
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```
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## Advanced example
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```lua
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-- Serializes all userdata to a constant string:
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local custom_bluon = bluon.new{
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aux_is_valid = function(object)
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return type(object) == "userdata"
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end,
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aux_len = function(object)
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return 1 + ("userdata"):len())
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end,
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aux_read = function(type, stream, references)
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assert(type == 100, "unsupported type")
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assert(stream:read(("userdata"):len()) == "userdata")
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return userdata()
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end,
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-- object to be written, stream providing :write(text), list of references
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aux_write = function(object, stream, references)
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assert(type(object) == "userdata")
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stream:write"\100userdata"
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end
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}
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-- Write to text
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local rope = modlib.table.rope{}
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custom_bluon:write(userdata(), rope)
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assert(rope:to_text() == "\100userdata")
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```
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