82 lines
3.0 KiB
Markdown
82 lines
3.0 KiB
Markdown
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Use in Lua {#flatbuffers_guide_use_lua}
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=============
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## Before you get started
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Before diving into the FlatBuffers usage in Lua, it should be noted that the
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[Tutorial](@ref flatbuffers_guide_tutorial) page has a complete guide to general
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FlatBuffers usage in all of the supported languages (including Lua). This
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page is designed to cover the nuances of FlatBuffers usage, specific to
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Lua.
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You should also have read the [Building](@ref flatbuffers_guide_building)
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documentation to build `flatc` and should be familiar with
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[Using the schema compiler](@ref flatbuffers_guide_using_schema_compiler) and
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[Writing a schema](@ref flatbuffers_guide_writing_schema).
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## FlatBuffers Lua library code location
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The code for the FlatBuffers Lua library can be found at
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`flatbuffers/lua`. You can browse the library code on the
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[FlatBuffers GitHub page](https://github.com/google/flatbuffers/tree/master/lua).
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## Testing the FlatBuffers Lua library
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The code to test the Lua library can be found at `flatbuffers/tests`.
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The test code itself is located in [luatest.lua](https://github.com/google/
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flatbuffers/blob/master/tests/luatest.lua).
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To run the tests, use the [LuaTest.sh](https://github.com/google/flatbuffers/
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blob/master/tests/LuaTest.sh) shell script.
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*Note: This script requires [Lua 5.3](https://www.lua.org/) to be
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installed.*
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## Using the FlatBuffers Lua library
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*Note: See [Tutorial](@ref flatbuffers_guide_tutorial) for a more in-depth
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example of how to use FlatBuffers in Lua.*
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There is support for both reading and writing FlatBuffers in Lua.
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To use FlatBuffers in your own code, first generate Lua classes from your
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schema with the `--lua` option to `flatc`. Then you can include both
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FlatBuffers and the generated code to read or write a FlatBuffer.
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For example, here is how you would read a FlatBuffer binary file in Lua:
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First, require the module and the generated code. Then read a FlatBuffer binary
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file into a `string`, which you pass to the `GetRootAsMonster` function:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.lua}
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-- require the library
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local flatbuffers = require("flatbuffers")
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-- require the generated code
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local monster = require("MyGame.Sample.Monster")
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-- read the flatbuffer from a file into a string
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local f = io.open('monster.dat', 'rb')
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local buf = f:read('*a')
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f:close()
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-- parse the flatbuffer to get an instance to the root monster
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local monster1 = monster.GetRootAsMonster(buf, 0)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Now you can access values like this:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.lua}
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-- use the : notation to access member data
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local hp = monster1:Hp()
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local pos = monster1:Pos()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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## Text Parsing
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There currently is no support for parsing text (Schema's and JSON) directly
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from Lua, though you could use the C++ parser through SWIG or ctypes. Please
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see the C++ documentation for more on text parsing.
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<br>
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