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Description
Did you check the tree-sitter docs?
- I have read all the tree-sitter docs if it relates to using the parser
Is your feature request related to a problem? Please describe.
Currently, else if blocks are parsed as nested if statements. For example,
int main() {
if (0) {
;
} else if (0) {
;
} else if (0) {
;
}
}(translation_unit ; [0, 0] - [9, 0]
(function_definition ; [0, 0] - [8, 1]
type: (primitive_type) ; [0, 0] - [0, 3]
declarator: (function_declarator ; [0, 4] - [0, 10]
declarator: (identifier) ; [0, 4] - [0, 8]
parameters: (parameter_list)) ; [0, 8] - [0, 10]
body: (compound_statement ; [0, 11] - [8, 1]
(if_statement ; [1, 2] - [7, 3]
condition: (parenthesized_expression ; [1, 5] - [1, 8]
(number_literal)) ; [1, 6] - [1, 7]
consequence: (compound_statement ; [1, 9] - [3, 3]
(expression_statement)) ; [2, 4] - [2, 5]
alternative: (else_clause ; [3, 4] - [7, 3]
(if_statement ; [3, 9] - [7, 3]
condition: (parenthesized_expression ; [3, 12] - [3, 15]
(number_literal)) ; [3, 13] - [3, 14]
consequence: (compound_statement ; [3, 16] - [5, 3]
(expression_statement)) ; [4, 4] - [4, 5]
alternative: (else_clause ; [5, 4] - [7, 3]
(if_statement ; [5, 9] - [7, 3]
condition: (parenthesized_expression ; [5, 12] - [5, 15]
(number_literal)) ; [5, 13] - [5, 14]
consequence: (compound_statement ; [5, 16] - [7, 3]
(expression_statement)))))))))) ; [6, 4] - [6, 5]
This structure is suboptimal for various reasons.
-
If the source contains very long
else ifchain, and a query pattern has a (editor-specific) predicate that climbs up the tree, processing the predicate can be very slow. For example, Neovim's#has-ancestor?predicate can be slow: Poor performance with Treesitter highlighting on deep if-else in c neovim/neovim#24965. -
Naively folding each
(if_statement)would create a nested fold for eachelse if, resulting in deeply nested folds. What user would want is to have fold for each body ofelse if.
Describe the solution you'd like
The entire if-else if-else should be parsed as flat list. Something like this:
(if_statement
(alternative (condition) (consequence)) ; the first `if`
(alternative (condition) (consequence)) ; the first `else if`
(alternative (condition) (consequence)) ; the second `else if`
...
(else (consequence)) ; `else`
)
Describe alternatives you've considered
- For predicate performance, the predicate implementor can limit the traversal length. See perf(treesitter): bound
has-ancestor?for highlighter neovim/neovim#27783. Other solutions: Poor performance with Treesitter highlighting on deep if-else in c neovim/neovim#24965 (comment) - For folds, one could fold each
consequence: (compound_statement)instead ofif_statement.
Additional context
No response