Elixir grammar for the Lezer parser system.
This grammar is based directly on tree-sitter-elixir and closely mirrors its syntax tree and decisions. All the test cases are adapted from there as well. Refer to the corresponding repository for further documentation.
The Elixir syntax tree is very generic. Most of the language built-ins, such as a function definition, are no different than user-defined functions. It is only for the purpose of highlighting, where it makes sense to distinguish certain keywords.
tree-sitter allows pattern matching on arbitrary fragments of the syntax tree, which is flexible enough to correctly tag nodes for highlighting in all cases. On the other hand, in Lezer the highlighting queries are more strict, for performance reasons. Under these restrictions, we need a more specialized syntax tree that, for example, uses separate nodes for function definition call and regular function call. Additionally, Lezer does not support annotating nodes with "fields", for example, to distinguish between operator left and right expression. In cases where we need those, an explicit nodes are required.
Given that, this grammar describes a syntax tree that is a superset of the tree-sitter one. The following additional nodes are present:
-
Identifier
specializationsSpecialIdentifier
(__MODULE__
)UnderscoredIdentifier
(_x
)
-
Call
specializationsFunctionDefinitionCall
(def fun(x), do: 1
)KernelCall
(if
) - in addition toCall
-
UnaryOperator
specializationsAtOperator
(@x
)DocOperator
(@doc "..."
)CaptureOperator
(&fun/1
)CaptureOperand
(&1
)
-
BinaryOperator
specializationsWhenOperator
(left when right
)PipeOperator
(left |> right
)
-
Sigil
specializationsStringSigil
(~s"string"
,~S"string"
)
-
named operator groups
Operator
(+
)WordOperator
(and
)
-
explicitly included tokens
do
,end
,fn
,after
,else
,catch
,rescue
- all brackets
-
fields:
Right
node inWhenOperator
,PipeOperator
andDot
to distinguish the left and right operand (note that this is enough to make the distinction, we don't needLeft
, which would result in more conflicts when introduced)- we do not need an explicit "target" node for calls, because arguments are already
separated under the
Arguments
node, hence anything else on that level is the target
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