Lua 5.4

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Feature Flag

[dependencies]
full_moon = { version = "2.1", features = ["lua54"] }

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Version-Specific Nodes

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Attribute

pub struct Attribute {
    #[node(full_range)]
    #[visit(contains = "name")]
    pub(crate) brackets: ContainedSpan,
    pub(crate) name: TokenReference,
}

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Methods

• new(name: TokenReference) -> Self - Creates a new Attribute with the given name
• name(&self) -> &TokenReference - The attribute name (e.g., const or close)
• brackets(&self) -> &ContainedSpan - The angle brackets (< and >) surrounding the attribute
• with_name(self, name: TokenReference) -> Self - Returns a new Attribute with the given name
• with_brackets(self, brackets: ContainedSpan) -> Self - Returns a new Attribute with the given brackets

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Attribute Types

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<const> Attribute

local x <const> = 10
-- x = 20  -- Error: attempt to assign to const variable

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<close> Attribute

local file <close> = io.open("test.txt", "r")
-- file is automatically closed when it goes out of scope

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Examples

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Constant Variables

local PI <const> = 3.14159
local MAX_SIZE <const> = 1000

function calculateArea(radius)
  return PI * radius * radius
end

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To-Be-Closed Variables

do
  local file <close> = io.open("data.txt", "r")
  local content = file:read("*a")
  print(content)
  -- file:close() is called automatically here
end

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Multiple Attributes

local x <const> = 5
local y <close> = setmetatable({}, {
  __close = function()
    print("Cleaning up")
  end
})

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Usage

use full_moon::parse;
use full_moon::ast::lua54::Attribute;

let ast = parse(r#"
  local x <const> = 10
  local file <close> = io.open("test.txt")
"#)?;

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Inherited Features

• Bitwise operators (see Lua 5.3)
• Goto statements and labels (see Lua 5.2)
• All Lua 5.2 and 5.3 syntax features

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Notes

• Attributes are only valid on local variable declarations
• A variable can only have one attribute
• The attribute must immediately follow the variable name
• Constant variables must be initialized when declared
• To-be-closed variables require a value with a __close metamethod (or nil/false)