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Allow default export for any declaration #160

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Allow default export for any declaration #160

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6d3dc1d
allow default export for any declaration
resolritter Mar 10, 2021
9928405
regenerate parser
resolritter Mar 10, 2021
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6 changes: 5 additions & 1 deletion grammar.js
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ module.exports = grammar({
[$.primary_expression, $.statement_block, 'object'],
[$.import_statement, $.import],
[$.export_statement, $.primary_expression],
[$.export_clause, $.object],
],

conflicts: $ => [
Expand All @@ -79,6 +80,9 @@ module.exports = grammar({
[$.assignment_expression, $.object_assignment_pattern],
[$.labeled_statement, $._property_name],
[$.computed_property_name, $.array],
[$.export_clause, $.object, $.object_pattern],
[$._import_export_specifier, $.object, $.object_pattern],
[$.export_statement, $._property_name],
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Could you report what error you get if you remove these conflicts? I'm assuming that, by allowing export <expression>, we're creating ambiguities between "export clauses (e.g. export {foo as bar, baz}) and exported object literals (e.g. export {foo: bar}).

I'm wondering if the latter case is really allowed, or if we should keep default as required when exporting an expression.

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@resolritter resolritter Mar 19, 2021 •
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The way I comprehend it, this syntax is for exporting identifiers, not objects. It's sugar for export const c = c so you don't have to repeat the c twice. Fairly common to see in the wild.

From what I've tested in the links above, the "object version" of export { foo: bar } is not valid.

The error I get by removing the conflicts is:

Unresolved conflict for symbol sequence:

  'export'  '{'  ','  •  '}'  …

Possible interpretations:

  1:  'export'  '{'  (object_pattern_repeat1  ',')  •  '}'  …
  2:  'export'  '{'  (object_repeat1  ',')  •  '}'  …
  3:  'export'  (export_clause  '{'  ','  •  '}')

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I pushed the suggested fix, consisting in allowing expressions only after export default, not directly after export.

I made a new PR for this: #168

],

word: $ => $.identifier,
Expand Down Expand Up @@ -107,10 +111,10 @@ module.exports = grammar({
seq(
repeat(field('decorator', $.decorator)),
'export',
optional('default'),
choice(
field('declaration', $.declaration),
seq(
'default',
field('value', $.expression),
$._semicolon
)
Expand Down
40 changes: 36 additions & 4 deletions src/grammar.json
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Expand Up @@ -112,6 +112,18 @@
"type": "STRING",
"value": "export"
},
{
"type": "CHOICE",
"members": [
{
"type": "STRING",
"value": "default"
},
{
"type": "BLANK"
}
]
},
{
"type": "CHOICE",
"members": [
Expand All @@ -126,10 +138,6 @@
{
"type": "SEQ",
"members": [
{
"type": "STRING",
"value": "default"
},
{
"type": "FIELD",
"name": "value",
Expand Down Expand Up @@ -6244,6 +6252,20 @@
[
"computed_property_name",
"array"
],
[
"export_clause",
"object",
"object_pattern"
],
[
"_import_export_specifier",
"object",
"object_pattern"
],
[
"export_statement",
"_property_name"
]
],
"precedences": [
Expand Down Expand Up @@ -6398,6 +6420,16 @@
"type": "SYMBOL",
"name": "primary_expression"
}
],
[
{
"type": "SYMBOL",
"name": "export_clause"
},
{
"type": "SYMBOL",
"name": "object"
}
]
],
"externals": [
Expand Down
16 changes: 16 additions & 0 deletions src/node-types.json
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Original file line number Diff line number Diff line change
Expand Up @@ -684,6 +684,14 @@
{
"type": "expression",
"named": true
},
{
"type": "identifier",
"named": true
},
{
"type": "member_expression",
"named": true
}
]
}
Expand Down Expand Up @@ -1804,6 +1812,14 @@
{
"type": "expression",
"named": true
},
{
"type": "identifier",
"named": true
},
{
"type": "member_expression",
"named": true
}
]
},
Expand Down
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