Support multidimensional subscripts #221
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grammar.js
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| subscript_expression: $ => prec(PREC.SUBSCRIPT, seq( | ||
| field('argument', $._expression), | ||
| subscript_argument_list: $ => seq( | ||
| '[', | ||
| field('index', choice($._expression, $.initializer_list)), | ||
| commaSep(choice($._expression, $.initializer_list)), | ||
| ']', | ||
| )), | ||
| ), | ||
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| subscript_expression: $ => prec(PREC.SUBSCRIPT, seq( | ||
| field('argument', $._expression), | ||
| field('indices', $.subscript_argument_list), | ||
| )), |
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I don't think there's a particular need to segment the argument list out into their own node - let's just keep it contained in subscript_expression instead.
Otherwise this looks good.
So, just changing it to commaSep(field('index', choice($._expression, $.initializer_list))) would be good.
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OK - I can do that easily enough. However the reason to present the argument list as its own node is to make it easier for higher-level code to treat it semantically like a list of function args. For example imagine an editor having a function to swap arguments around - not an uncommon operation when refactoring code.
I've written code to do this in my editor and it's useful to have a similar parent-node-child-node structure for:
- function parameter lists
- function argument lists
- template parameter lists
- template argument lists
- subscript argument lists
Which was my rationale for doing it this way. Do you still want to change it back?
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Hm, you have a valid point, this is ok as is then
Can you just move the argument list below the expression then? Just a stylistic preference
This change allows commas inside subscripts. ```cpp auto x = a[1, 2, 3]; ``` From C++23, array subscripts work like arguments to `operator[]` as an n-ary function. Before C++23, `operator[]` must be a unary function, but before C++20, it's possible to use the comma operator inside subscript expressions - and this is done in libraries that use expression templates to achieve multidimensional array syntax. Use of the comma operator in subscript expressions was deprecated in C++20 to make way for the C++23 change to n-ary `operator[]`.
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This change allows commas inside subscripts.
From C++23, array subscripts work like arguments to
operator[]as an n-ary function.Before C++23,
operator[]must be a unary function, but before C++20, it's possible to use the comma operator inside subscript expressions - and this is done in libraries that use expression templates to achieve multidimensional array syntax.Use of the comma operator in subscript expressions was deprecated in C++20 to make way for the C++23 change to n-ary
operator[].