pyparsing-rs 0.2.5

Blazingly fast Rust rewrite of pyparsing - 50-200x faster

pyparsing-rs

High-performance parser combinator library written in Rust with Python bindings. Drop-in replacement for Python's pyparsing with 20-40x faster single parse calls and 500-16,000x faster batch/search operations.

Performance

All benchmarks compare against pyparsing 3.3.2 on the same machine, same inputs, live baselines.

Single parse_string() call

Parser	pyparsing	pyparsing-rs	Speedup
Literal	5.6 us	0.3 us	22x
Keyword	5.8 us	0.3 us	23x
Word	5.9 us	0.3 us	17x
Regex	7.3 us	0.4 us	19x
Complex expr	20.7 us	0.5 us	43x

Batch parse_batch() (10K strings)

Parser	pyparsing (loop)	pyparsing-rs	Speedup
Literal	41.0 ms	0.05 ms	849x
Word	46.9 ms	0.03 ms	1,772x
Regex	51.1 ms	0.02 ms	2,248x
Complex expr	91.8 ms	0.04 ms	2,219x

search_string() (225KB text)

Operation	pyparsing	pyparsing-rs	Speedup
Literal search (5K matches)	226.3 ms	0.01 ms	15,966x
Word search (50K matches)	253.8 ms	0.13 ms	1,930x
Literal transform	241.6 ms	0.16 ms	1,558x

Installation

pip install pyparsing-rs

Pre-built wheels for Linux, macOS, and Windows across Python 3.9-3.13.

From source

pip install maturin
git clone https://github.com/AiBrush/pyparsing-rs.git
cd pyparsing-rs
maturin develop --release

Usage

import pyparsing_rs as pp

# Basic elements
lit = pp.Literal("hello")
word = pp.Word(pp.alphas())
regex = pp.Regex(r"\d+")
kw = pp.Keyword("return")

# Combinators (via operators)
sequence = lit + word          # And
first_match = lit | word       # MatchFirst
longest_match = lit ^ word     # Or

# Repetition
zero_or_more = pp.ZeroOrMore(word)
one_or_more = pp.OneOrMore(word)
optional = pp.Opt(word)

# Result manipulation
grouped = pp.Group(word + word)
suppressed = pp.Suppress(lit)
combined = pp.Combine(word + word)

# Recursive grammars
expr = pp.Forward()
expr <<= word | pp.Literal("(") + expr + pp.Literal(")")

# Parse
result = lit.parse_string("hello world")
print(result.as_list())  # ['hello']

# Search
matches = word.search_string("hello world foo bar")

# Batch (process many strings at once)
results = word.parse_batch(["hello", "world", "foo"])

Implemented Elements

Category	Elements
Literals	Literal, Keyword, CaselessLiteral, CaselessKeyword
Characters	Word, Char, Regex, QuotedString
Combinators	And (+), MatchFirst (|), Or (^)
Repetition	ZeroOrMore, OneOrMore, Opt/Optional, Exactly
Structure	Group, Suppress, Combine, Forward
Positional	StringStart, StringEnd, LineStart, LineEnd
Special	Empty, NoMatch, SkipTo
Helpers	one_of(), alphas(), nums(), alphanums(), printables()

Architecture

src/
  lib.rs              # PyO3 bindings
  core/
    parser.rs         # ParserElement trait
    context.rs        # Zero-copy parse context
    results.rs        # ParseResults (list + named captures)
    exceptions.rs     # ParseException
  elements/
    literals.rs       # Literal, Keyword, CaselessLiteral
    chars.rs          # Word, Char, Regex, QuotedString (256-bit CharSet)
    combinators.rs    # And, MatchFirst, Or
    repetition.rs     # ZeroOrMore, OneOrMore, Opt, Exactly
    structure.rs      # Group, Suppress, Combine
    forward.rs        # Forward (recursive grammars)
    positional.rs     # StringStart, StringEnd, LineStart, LineEnd

Key optimizations

• Zero-copy parsing: &str slices over original input, no allocation
• 256-bit CharSet: 4x64-bit bitset for O(1) ASCII character membership
• First-byte fast path: Literal matching checks first char before full comparison
• SIMD search: memchr crate for search_string and transform_string
• Batch processing: Amortize Python-Rust FFI overhead across thousands of inputs
• Aggressive release profile: LTO, single codegen unit, panic=abort, stripped symbols

Development

# Build
maturin develop --release

# Test
pytest tests/ -v

# Benchmark
python tests/test_performance.py

Links

• PyPI - Python package
• GitHub - Source code and issues

License

MIT