perf(formatter): replace String buffer with byte-oriented CodeBuffer by Boshen · Pull Request #14752 · oxc-project/oxc

Boshen · 2025-10-18T12:52:39Z

Use CodeBuffer (Vec) instead of String for internal buffer
SIMD-optimized indentation via CodeBuffer.print_indent()
Unified byte-level iteration eliminates .chars() iterator overhead
ASCII fast-path (95%+ of JavaScript) handled inline without UTF-8 decoding
Multi-byte UTF-8 decoded on-demand only when needed
Maintains Unicode width calculation correctness

🤖 Generated with Claude Code

graphite-app · 2025-10-18T12:52:46Z

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Pull Request Overview

Refactors the formatter's printer to use byte-oriented CodeBuffer instead of String buffer for significant performance improvements in ASCII-heavy code.

Replaces String buffer with CodeBuffer for optimized byte-level operations
Implements ASCII fast-paths for character and string printing
Uses SIMD-optimized indentation via CodeBuffer.print_indent()

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
crates/oxc_formatter/src/formatter/printer/mod.rs	Core refactoring replacing String buffer with CodeBuffer, implementing ASCII fast-paths, and optimizing indentation logic
crates/oxc_formatter/Cargo.toml	Adds "code_buffer" feature dependency to oxc_data_structures

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crates/oxc_formatter/src/formatter/printer/mod.rs

codspeed-hq · 2025-10-18T13:20:21Z

CodSpeed Performance Report

Merging #14752 will not alter performance

_{Comparing perf/formatter-byte-oriented-codebuffer (d5f4e84) with main (f30ce4b)¹}

Summary

✅ 33 untouched
⏩ 4 skipped²

No successful run was found on graphite-base/14752 (82cd55e) during the generation of this report, so main (f30ce4b) was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩
4 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. ↩

Dunqing · 2025-11-04T15:01:32Z

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Dunqing · 2025-11-07T02:09:17Z

Merge activity

Nov 7, 2:09 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Nov 7, 2:14 AM UTC: Dunqing added this pull request to the Graphite merge queue.
Nov 7, 2:22 AM UTC: Merged by the Graphite merge queue.

…14752) - Use CodeBuffer (Vec<u8>) instead of String for internal buffer - SIMD-optimized indentation via CodeBuffer.print_indent() - Unified byte-level iteration eliminates .chars() iterator overhead - ASCII fast-path (95%+ of JavaScript) handled inline without UTF-8 decoding - Multi-byte UTF-8 decoded on-demand only when needed - Maintains Unicode width calculation correctness 🤖 Generated with [Claude Code](https://claude.com/claude-code)

…ntation (#15406) I forgot this APi in #14752

Boshen requested a review from Dunqing as a code owner October 18, 2025 12:52

Copilot AI review requested due to automatic review settings October 18, 2025 12:52

github-actions bot added A-formatter Area - Formatter C-performance Category - Solution not expected to change functional behavior, only performance labels Oct 18, 2025

Copilot AI reviewed Oct 18, 2025

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crates/oxc_formatter/src/formatter/printer/mod.rs Outdated Show resolved Hide resolved

crates/oxc_formatter/src/formatter/printer/mod.rs Outdated Show resolved Hide resolved

Boshen force-pushed the perf/formatter-byte-oriented-codebuffer branch 2 times, most recently from b6de98e to 3995aef Compare October 18, 2025 13:15

Boshen changed the title ~~perf(formatter): refactor printer to use byte-oriented CodeBuffer~~ perf(formatter): replace String buffer with byte-oriented CodeBuffer Oct 18, 2025

Boshen assigned Dunqing Oct 18, 2025

Dunqing force-pushed the perf/formatter-byte-oriented-codebuffer branch from 3995aef to 255cc18 Compare November 4, 2025 15:01

Dunqing force-pushed the perf/formatter-byte-oriented-codebuffer branch from 510fc6e to 1992c8c Compare November 4, 2025 16:21

Dunqing changed the base branch from main to graphite-base/14752 November 7, 2025 01:53

Dunqing changed the base branch from graphite-base/14752 to main November 7, 2025 01:53

Dunqing force-pushed the perf/formatter-byte-oriented-codebuffer branch from c42af69 to 76ae84b Compare November 7, 2025 01:57

Dunqing changed the base branch from main to graphite-base/14752 November 7, 2025 01:58

Dunqing force-pushed the perf/formatter-byte-oriented-codebuffer branch from 76ae84b to e8f05f4 Compare November 7, 2025 01:58

Dunqing changed the base branch from graphite-base/14752 to 11-07-perf_formatter_add_text_without_whitespace_for_text_that_can_never_have_whitespace November 7, 2025 01:58

Dunqing force-pushed the perf/formatter-byte-oriented-codebuffer branch from e8f05f4 to d5f4e84 Compare November 7, 2025 02:08

Dunqing added the 0-merge Merge with Graphite Merge Queue label Nov 7, 2025

graphite-app bot changed the base branch from 11-07-perf_formatter_add_text_without_whitespace_for_text_that_can_never_have_whitespace to graphite-base/14752 November 7, 2025 02:09

Dunqing approved these changes Nov 7, 2025

View reviewed changes

graphite-app bot changed the base branch from graphite-base/14752 to main November 7, 2025 02:15

graphite-app bot force-pushed the perf/formatter-byte-oriented-codebuffer branch from d5f4e84 to b92deb4 Compare November 7, 2025 02:16

graphite-app bot merged commit b92deb4 into main Nov 7, 2025
20 checks passed

graphite-app bot deleted the perf/formatter-byte-oriented-codebuffer branch November 7, 2025 02:22

graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Nov 7, 2025

Dunqing mentioned this pull request Nov 7, 2025

perf(formatter): use CodeBuffer's built-in print_indent to print indentation #15406

Merged

graphite-app bot pushed a commit that referenced this pull request Nov 7, 2025

perf(formatter): use CodeBuffer's built-in print_indent to print inde…

2515045

…ntation (#15406) I forgot this APi in #14752

Boshen mentioned this pull request Nov 10, 2025

release(apps): oxlint v1.27.0 && oxfmt v0.12.0 #15547

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perf(formatter): replace String buffer with byte-oriented CodeBuffer#14752

perf(formatter): replace String buffer with byte-oriented CodeBuffer#14752
graphite-app[bot] merged 1 commit intomainfrom
perf/formatter-byte-oriented-codebuffer

Boshen commented Oct 18, 2025 •

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edited by Boshen

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Pull Request Overview

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CodSpeed Performance Report

Merging #14752 will not alter performance

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Boshen commented Oct 18, 2025 •

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Dunqing commented Nov 4, 2025 •

edited by Boshen

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Dunqing commented Nov 7, 2025 •

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