refactor(parser): switch parser to new `AstBuilder` by overlookmotel · Pull Request #23730 · oxc-project/oxc

overlookmotel · 2026-06-23T00:31:52Z

Part of #23043.

Switch over oxc_parser to use the new AstBuilder and builder methods on AST types themselves.

Vast majority performed by an ast-grep codemod generated by Claude (2nd commit - codemod here).

The last 2 commits are a few small fixes, and some manual changes to shorten code.

overlookmotel · 2026-06-23T00:32:15Z

refactor(parser): switch parser to new AstBuilder #23730 👈 (View in Graphite)
feat(ast): add custom builder methods to AST types #23651 : 1 other dependent PR (#23729 )
feat(ast): add AST creation methods to AST types #23650
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codspeed-hq · 2026-06-23T00:41:09Z

Merging this PR will not alter performance

✅ 62 untouched benchmarks
⏩ 9 skipped benchmarks¹

_{Comparing om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ (17a0f9e) with om/06-18-feat_ast_add_custom_builder_methods_to_ast_types (1e4a339)}

9 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

Copilot

Pull request overview

This PR migrates oxc_parser to the new AST builder API (builder methods on AST types + GetAstBuilder), aligning the parser with the ongoing AstBuilder redesign in #23043 and reducing reliance on the legacy self.ast.* constructor surface.

Changes:

Switch parser AST construction from self.ast.* methods to *_::new(...) / *_::boxed(...) builder methods across JS/TS/JSX parsing paths.
Update allocation patterns to use ArenaVec::{new_in, with_capacity_in, from_value_in} and ArenaBox::new_in(...) via GetAllocator.
Wire ParserImpl into the new builder system by implementing GetAstBuilder, and enable oxc_ast’s builder_new feature.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/oxc_parser/src/ts/types.rs	Convert TS type node construction to `TSType::`/`TS::new/boxed` builder methods and arena vec helpers.
crates/oxc_parser/src/ts/statement.rs	Convert TS statement/declaration parsing to new builder methods and arena vec allocation helpers.
crates/oxc_parser/src/lib.rs	Import new builder traits/types, construct `Program` via `Program::new`, update `alloc`, and implement `GetAstBuilder` for `ParserImpl`.
crates/oxc_parser/src/jsx/mod.rs	Convert JSX node creation to `JSX*::new/boxed` methods and arena vec helpers.
crates/oxc_parser/src/js/statement.rs	Convert statement node creation (and directive/hashbang) to new builder methods and arena vec helpers.
crates/oxc_parser/src/js/object.rs	Convert object expression/property construction to new builder methods; update shorthand/init tracking construction sites.
crates/oxc_parser/src/js/module.rs	Convert import/export/module AST construction to new builder methods and arena vec helpers.
crates/oxc_parser/src/js/grammar.rs	Update cover grammar conversions to new builder methods; replace `p.ast.vec()` with `ArenaVec::new_in(p)`.
crates/oxc_parser/src/js/function.rs	Convert function body/params/function nodes and yield expression construction to new builder methods.
crates/oxc_parser/src/js/expression.rs	Convert expression node creation to new builder methods; update arena vec helpers and `Str::from_in` usage.
crates/oxc_parser/src/js/declaration.rs	Convert variable declaration/declarator construction and list allocations to new builder methods.
crates/oxc_parser/src/js/class.rs	Convert class/class-body/heritage/method/property element construction to new builder methods and arena vec helpers.
crates/oxc_parser/src/js/binding.rs	Convert binding patterns/rest elements/properties/assignment patterns to new builder methods.
crates/oxc_parser/src/js/arrow.rs	Convert arrow function construction (params/body/expression) to new builder methods and arena vec helpers.
crates/oxc_parser/src/cursor.rs	Replace builder vec creation with `ArenaVec::new_in(self)` in list parsing helpers.
crates/oxc_parser/Cargo.toml	Enable `oxc_ast` feature `builder_new` for the parser crate.

overlookmotel · 2026-06-24T19:20:28Z

@camc314 @Dunqing I think this is ready to go now. Please could you take a look and see if you think it's OK?

The thing I'm not entirely happy with is that it makes code more verbose (especially self.ast.vec1(node) -> ArenaVec::from_value_in(node, self)), but I can't really see any good way to make it shorter.

I did try a macro, which is shorter syntax, but I felt it was a bit "mysterious":

ArenaVec::new_in(self) -> avec![self]
ArenaVec::from_value_in(node, self) -> avec![node; self]
ArenaVec::from_array_in([node1, node2, node3], self) -> avec![node1, node2, node3; self]

If we all think we should move forwards with this, I think we can merge, and I'll transition all the other crates over in separate PRs.

camc314

nice work! looks good to me!

camc314 · 2026-06-24T22:16:18Z

I'll transition all the other crates over in separate PRs.

I'm happy to work on this for the linter - would be helpful to get used to the new API. but if me working on that will slow you down, please go ahead!

overlookmotel · 2026-06-24T22:48:32Z

I'm happy to work on this for the linter - would be helpful to get used to the new API. but if me working on that will slow you down, please go ahead!

Thanks! That would be a great help. By all means try the codemod and see how far it gets.

We might need to convert some other Str and Ident methods to take &A where A: GetAllocator<'a> instead of &'a Allocator (like #23767, #23756, and #23755 did) to avoid very verbose code -Str::from_strs_array_in([...], self) not Str::from_strs_array_in([...], &self.ast.allocator).

Then again, the linter doesn't use AstBuilder much, and not with usual pattern of having a context object holding an AstBuilder, so the codemod may not be much help without modification.

I noticed a pattern in linter where it creates an Allocator, creates an AstBuilder, uses that to generate a StringLiteral, and then passes the StringLiteral to Codegen to print it - by looks of things, it's doing all that just to escape a string. Surely there's a simpler way? Maybe oxc_codegen could just expose the function which escapes strings, independent of all the AST stuff?

But all that said, let's wait for Dunqing to have a look and see if he's happy with this before we go any further.

Dunqing

Great!

Dunqing · 2026-06-25T01:44:54Z

Merge activity

Jun 25, 1:44 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Jun 25, 1:45 AM UTC: Dunqing added this pull request to the Graphite merge queue.
Jun 25, 1:55 AM UTC: Merged by the Graphite merge queue.

Part of #23043. Switch over `oxc_parser` to use the new `AstBuilder` and builder methods on AST types themselves. Vast majority performed by an ast-grep codemod generated by Claude (2nd commit - [codemod here](https://github.com/oxc-project/oxc/tree/overlookmotel/ast-builder-codemod)). The last 2 commits are a few small fixes, and some manual changes to shorten code.

I created this ontop of #23781 just to avoid any potential conflicts. Follows on from #23730 It was relatively pain free! Thanks @ overlookmotel for the migration script!

Part of #23043. Switch over `oxc_parser` to use the new `AstBuilder` and builder methods on AST types themselves. Vast majority performed by an ast-grep codemod generated by Claude (2nd commit - [codemod here](https://github.com/oxc-project/oxc/tree/overlookmotel/ast-builder-codemod)). The last 2 commits are a few small fixes, and some manual changes to shorten code.

I created this ontop of #23781 just to avoid any potential conflicts. Follows on from #23730 It was relatively pain free! Thanks @ overlookmotel for the migration script!

overlookmotel mentioned this pull request Jun 23, 2026

feat(ast): add methods to create primitives to new AstBuilder #23729

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github-actions Bot added the A-parser Area - Parser label Jun 23, 2026

overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from de11062 to e769418 Compare June 23, 2026 00:56

overlookmotel force-pushed the om/06-22-feat_ast_add_methods_to_create_primitives_to_new_astbuilder_ branch from 27489b3 to e512626 Compare June 23, 2026 00:56

graphite-app Bot force-pushed the om/06-22-feat_ast_add_methods_to_create_primitives_to_new_astbuilder_ branch from e512626 to c5d5217 Compare June 23, 2026 01:09

graphite-app Bot force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from e769418 to 16f04a9 Compare June 23, 2026 01:10

overlookmotel commented Jun 23, 2026

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Comment thread crates/oxc_parser/src/js/arrow.rs Outdated

overlookmotel force-pushed the om/06-22-feat_ast_add_methods_to_create_primitives_to_new_astbuilder_ branch from c5d5217 to 6b2bb22 Compare June 23, 2026 10:46

overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from 16f04a9 to 53147e2 Compare June 23, 2026 10:46

overlookmotel mentioned this pull request Jun 23, 2026

feat(ast)!: put AstBuilder behind builder Cargo feature #23739

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overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from 53147e2 to 6afe9e0 Compare June 23, 2026 12:07

overlookmotel force-pushed the om/06-22-feat_ast_add_methods_to_create_primitives_to_new_astbuilder_ branch from 6b2bb22 to 431ba1e Compare June 23, 2026 12:07

overlookmotel mentioned this pull request Jun 23, 2026

refactor(ast): add builder Cargo feature #23743

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overlookmotel changed the base branch from om/06-22-feat_ast_add_methods_to_create_primitives_to_new_astbuilder_ to graphite-base/23730 June 24, 2026 16:53

overlookmotel force-pushed the graphite-base/23730 branch from 431ba1e to dd42174 Compare June 24, 2026 16:53

overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from 6afe9e0 to 36eb2c7 Compare June 24, 2026 16:53

overlookmotel changed the base branch from graphite-base/23730 to om/06-18-feat_ast_add_custom_builder_methods_to_ast_types June 24, 2026 16:54

overlookmotel requested a review from Copilot June 24, 2026 16:56

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overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from 36eb2c7 to e8278a2 Compare June 24, 2026 16:56

overlookmotel force-pushed the om/06-18-feat_ast_add_custom_builder_methods_to_ast_types branch from dd42174 to 5ef81a0 Compare June 24, 2026 16:56

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overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from e8278a2 to 858a6ba Compare June 24, 2026 17:49

overlookmotel force-pushed the om/06-18-feat_ast_add_custom_builder_methods_to_ast_types branch from 5ef81a0 to 1e4a339 Compare June 24, 2026 17:50

overlookmotel marked this pull request as ready for review June 24, 2026 17:51

overlookmotel force-pushed the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch from 858a6ba to 17a0f9e Compare June 24, 2026 19:16

overlookmotel requested a review from Dunqing June 24, 2026 19:17

overlookmotel self-assigned this Jun 24, 2026

overlookmotel requested a review from camc314 June 24, 2026 19:17

camc314 approved these changes Jun 24, 2026

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graphite-app Bot force-pushed the om/06-18-feat_ast_add_custom_builder_methods_to_ast_types branch from 1e4a339 to 785461b Compare June 25, 2026 01:45

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Base automatically changed from om/06-18-feat_ast_add_custom_builder_methods_to_ast_types to main June 25, 2026 01:53

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graphite-app Bot deleted the om/06-23-refactor_parser_switch_parser_to_new_astbuilder_ branch June 25, 2026 01:55

This was referenced Jun 25, 2026

linter: avoid constructing an AST to print a string #23780

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refactor(linter): migrate to new AstBuilder #23782

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refactor(parser): switch parser to new `AstBuilder`#23730

refactor(parser): switch parser to new `AstBuilder`#23730
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