docs/token-is-on-new-line - Branch - oxc-project/oxc

docs(parser): document is_on_new_line and read_bool performance characteristics

#13867Merged

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docs/token-is-on-new-line

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Untouched: 37

Benchmarks

Passed

minifier[cal.com.tsx]

tasks/benchmark/benches/minifier.rs::minifier::bench_minifier

+3%

31.9 ms31 ms

semantic[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/semantic.rs::semantic::bench_semantic

75.4 µs75.2 µs

transformer[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/transformer.rs::transformer::bench_transformer

134.1 µs133.8 µs

codegen[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/codegen.rs::codegen::bench_codegen

120 µs119.9 µs

transformer[cal.com.tsx]

tasks/benchmark/benches/transformer.rs::transformer::bench_transformer

26.4 ms26.3 ms

transformer[react.development.js]

tasks/benchmark/benches/transformer.rs::transformer::bench_transformer

714.4 µs714 µs

semantic[cal.com.tsx]

tasks/benchmark/benches/semantic.rs::semantic::bench_semantic

27.8 ms27.7 ms

minifier[react.development.js]

tasks/benchmark/benches/minifier.rs::minifier::bench_minifier

2.4 ms2.4 ms

isolated-declarations[vue-id.ts]

tasks/benchmark/benches/transformer.rs::transformer::bench_isolated_declarations

56.4 ms56.4 ms

parser[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/parser.rs::parser::bench_parser

84.5 µs84.4 µs

formatter[cal.com.tsx]

tasks/benchmark/benches/formatter.rs::formatter::bench_formatter

208.8 ms208.7 ms

mangler[react.development.js]

tasks/benchmark/benches/minifier.rs::minifier::bench_mangler

259.2 µs259.2 µs

mangler[cal.com.tsx]

tasks/benchmark/benches/minifier.rs::minifier::bench_mangler

2.8 ms2.8 ms

linter[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/linter.rs::linter::bench_linter

1.7 ms1.7 ms

mangler[binder.ts]

tasks/benchmark/benches/minifier.rs::minifier::bench_mangler

733.8 µs733.7 µs

linter[cal.com.tsx]

tasks/benchmark/benches/linter.rs::linter::bench_linter

801.9 ms801.8 ms

codegen[binder.ts]

tasks/benchmark/benches/codegen.rs::codegen::bench_codegen

4 ms4 ms

estree[checker.ts]

tasks/benchmark/benches/parser.rs::parser::bench_estree

104.5 ms104.5 ms

lexer[cal.com.tsx]

tasks/benchmark/benches/lexer.rs::lexer::bench_lexer

5.3 ms5.3 ms

linter[binder.ts]

tasks/benchmark/benches/linter.rs::linter::bench_linter

96 ms96 ms

parser[react.development.js]

tasks/benchmark/benches/parser.rs::parser::bench_parser

1.3 ms1.3 ms

lexer[binder.ts]

tasks/benchmark/benches/lexer.rs::lexer::bench_lexer

870.3 µs870.3 µs

parser[cal.com.tsx]

tasks/benchmark/benches/parser.rs::parser::bench_parser

26.7 ms26.7 ms

formatter[binder.ts]

tasks/benchmark/benches/formatter.rs::formatter::bench_formatter

23 ms23 ms

parser[binder.ts]

tasks/benchmark/benches/parser.rs::parser::bench_parser

3.3 ms3.3 ms

codegen[react.development.js]

tasks/benchmark/benches/codegen.rs::codegen::bench_codegen

1.9 ms1.9 ms

lexer[react.development.js]

tasks/benchmark/benches/lexer.rs::lexer::bench_lexer

356.9 µs356.9 µs

transformer[binder.ts]

tasks/benchmark/benches/transformer.rs::transformer::bench_transformer

1.7 ms1.7 ms

semantic[binder.ts]

tasks/benchmark/benches/semantic.rs::semantic::bench_semantic

4.3 ms4.3 ms

codegen[cal.com.tsx]

tasks/benchmark/benches/codegen.rs::codegen::bench_codegen

34.3 ms34.4 ms

linter[react.development.js]

tasks/benchmark/benches/linter.rs::linter::bench_linter

34.7 ms34.7 ms

minifier[binder.ts]

tasks/benchmark/benches/minifier.rs::minifier::bench_minifier

3.8 ms3.8 ms

semantic[react.development.js]

tasks/benchmark/benches/semantic.rs::semantic::bench_semantic

1.7 ms1.7 ms

lexer[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/lexer.rs::lexer::bench_lexer

19.9 µs19.9 µs

formatter[react.development.js]

tasks/benchmark/benches/formatter.rs::formatter::bench_formatter

11.6 ms11.7 ms

formatter[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/formatter.rs::formatter::bench_formatter

-1%

575.2 µs579.3 µs

mangler[RadixUIAdoptionSection.jsx]

tasks/benchmark/benches/minifier.rs::minifier::bench_mangler

-1%

11.5 µs11.6 µs

Commits

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main

fa866b3

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docs(parser): document is_on_new_line and read_bool performance characteristics (#13867) ## Summary This PR adds comprehensive documentation to the `is_on_new_line` and `read_bool` methods in the lexer's Token implementation, based on the performance analysis from PR #13788. ## Changes - Document `is_on_new_line`'s purpose for ASI and JavaScript parsing rules - Add detailed performance analysis to `read_bool` showing assembly code comparison - Explain why unsafe pointer arithmetic is used (3 instructions vs 4 for bit operations) - Reference PR #13788's benchmarking discussion for historical context ## Context As discussed in #13788, the unsafe pointer arithmetic implementation was retained because it generates one fewer CPU instruction on this hot path. This documentation helps future contributors understand this design decision. ### Assembly Comparison **Unsafe pointer arithmetic (current):** ```asm movzx eax, BYTE PTR [rdi+9] ; 3 instructions total and eax, 1 ret ``` **Safe bit operations (proposed but rejected):** ```asm mov rax, QWORD PTR [rdi+8] ; 4 instructions total shr rax, 8 and eax, 1 ret ``` 🤖 Generated with [Claude Code](https://claude.ai/code)

5d4e4f0

2 months ago

by Boshen

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