pe · PyPI

Library for Parsing Expression Grammars (PEG)

These details have not been verified by PyPI

Project links

Project description

pe logo
Parsing Expressions
Python Support

pe is a library for parsing expressions, including parsing expression grammars (PEGs). It aims to join the expressive power of parsing expressions with the familiarity of regular expressions. For example:

>>> import pe
>>> m = pe.match(r'["] (!["\\] . / "\\" .)* ["]',
...              '"escaped \\"string\\"" ...')
>>> m.group()
'"escaped \\"string\\""'

Quick Links

Features and Goals

Grammar notation is backward-compatible with standard PEG with few extensions
A specification describes the semantic effect of parsing (e.g., for mapping expressions to function calls)
Parsers are often faster than other parsing libraries, sometimes by a lot; see the benchmarks
The API is intuitive and familiar; it's modeled on the standard API's re module
Grammar definitions and parser implementations are separate
- Optimizations target the abstract grammar definitions
- Multiple parsers are available (currently packrat for recursive descent and machine for an iterative "parsing machine" as from Medeiros and Ierusalimschy, 2008 and implemented in LPeg).

Syntax Overview

pe is backward compatible with standard PEG syntax and it is conservative with extensions.

# terminals
.            # any single character
"abc"        # string literal
'abc'        # string literal
[abc]        # character class

# repeating expressions
e            # exactly one
e?           # zero or one (optional)
e*           # zero or more
e+           # one or more

# combining expressions
e1 e2        # sequence of e1 and e2
e1 / e2      # ordered choice of e1 and e2
(e)          # subexpression

# lookahead
&e           # positive lookahead
!e           # negative lookahead

# (extension) capture substring
~e           # result of e is matched substring

# (extension) binding
name:e       # bind result of e to 'name'

# grammars
Name <- ...  # define a rule named 'Name'
... <- Name  # refer to rule named 'Name'

Matching Inputs with Parsing Expressions

When a parsing expression matches an input, it returns a Match object, which is similar to those of Python's re module for regular expressions. By default, nothing is captured, but the capture operator (~) emits the substring of the matching expression, similar to regular expression's capturing groups:

>>> e = pe.compile(r'[0-9] [.] [0-9]')
>>> m = e.match('1.4')
>>> m.group()
'1.4'
>>> m.groups()
()
>>> e = pe.compile(r'~([0-9] [.] [0-9])')
>>> m = e.match('1.4')
>>> m.group()
'1.4'
>>> m.groups()
('1.4',)

Value Bindings

A value binding extracts the emitted values of a match and associates it with a name that is made available in the Match.groupdict() dictionary. This is similar to named-capture groups in regular expressions, except that it extracts the emitted values and not the substring of the bound expression.

>>> e = pe.compile(r'~[0-9] x:(~[.]) ~[0-9]')
>>> m = e.match('1.4')
>>> m.groups()
('1', '4')
>>> m.groupdict()
{'x': '.'}

Actions

Actions (also called "semantic actions") are callables that transform parse results. When an arbitrary function is given, it is called as follows:

func(*match.groups(), **match.groupdict())

The result of this function call becomes the only emitted value going forward and all bound values are cleared.

For more control, pe provides the Action class and a number of subclasses for various use-cases. These actions have access to more information about a parse result and more control over the match. For example, the Pack class takes a function and calls it with the emitted values packed into a list:

func(match.groups())

And the Join class joins all emitted strings with a separator:

func(sep.join(match.groups()), **match.groupdict())

Example

Here is one way to parse a list of comma-separated integers:

>>> from pe.actions import Pack
>>> p = pe.compile(
...   r'''
...     Start  <- "[" Values? "]"
...     Values <- Int ("," Int)*
...     Int    <- ~( "-"? ("0" / [1-9] [0-9]*) )
...   ''',
...   actions={'Values': Pack(list), 'Int': int})
>>> m = p.match('[5,10,-15]')
>>> m.value()
[5, 10, -15]

Similar Projects

Lark (Python)
nom (Rust)
Parsimonious (Python)
Rosie (Multiple bindings)
TatSu (Python)
PEG.js (Javascript)
Pegged (D)
pegen (Python / C)
LPeg (Lua)

Project details

These details have not been verified by PyPI

Project links

Release history Release notifications | RSS feed

0.5.3

Jun 19, 2024

0.5.2

Apr 3, 2024

0.5.1

Dec 31, 2023

0.5.0

Jul 27, 2023

0.4.0

Jun 4, 2023

0.3.2

Oct 6, 2021

0.3.1

Sep 30, 2021

This version

0.3.0

Sep 29, 2021

0.2.0

Apr 28, 2020

0.1.0

Apr 14, 2020

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

pe-0.3.0.tar.gz (185.1 kB view details)

Uploaded Sep 29, 2021 Source

Built Distributions

pe-0.3.0-cp310-cp310-win_amd64.whl (150.8 kB view details)

Uploaded Sep 29, 2021 CPython 3.10 Windows x86-64

pe-0.3.0-cp310-cp310-musllinux_1_1_x86_64.whl (777.3 kB view details)

Uploaded Sep 29, 2021 CPython 3.10 musllinux: musl 1.1+ x86-64

pe-0.3.0-cp310-cp310-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (703.7 kB view details)

Uploaded Sep 29, 2021 CPython 3.10 manylinux: glibc 2.12+ x86-64 manylinux: glibc 2.5+ x86-64

pe-0.3.0-cp310-cp310-macosx_10_9_x86_64.whl (165.2 kB view details)

Uploaded Sep 29, 2021 CPython 3.10 macOS 10.9+ x86-64

pe-0.3.0-cp39-cp39-win_amd64.whl (150.5 kB view details)

Uploaded Sep 29, 2021 CPython 3.9 Windows x86-64

pe-0.3.0-cp39-cp39-musllinux_1_1_x86_64.whl (773.9 kB view details)

Uploaded Sep 29, 2021 CPython 3.9 musllinux: musl 1.1+ x86-64

pe-0.3.0-cp39-cp39-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (699.6 kB view details)

Uploaded Sep 29, 2021 CPython 3.9 manylinux: glibc 2.12+ x86-64 manylinux: glibc 2.5+ x86-64

pe-0.3.0-cp39-cp39-macosx_10_9_x86_64.whl (165.0 kB view details)

Uploaded Sep 29, 2021 CPython 3.9 macOS 10.9+ x86-64

pe-0.3.0-cp38-cp38-win_amd64.whl (150.7 kB view details)

Uploaded Sep 29, 2021 CPython 3.8 Windows x86-64

pe-0.3.0-cp38-cp38-musllinux_1_1_x86_64.whl (825.0 kB view details)

Uploaded Sep 29, 2021 CPython 3.8 musllinux: musl 1.1+ x86-64

pe-0.3.0-cp38-cp38-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (755.2 kB view details)

Uploaded Sep 29, 2021 CPython 3.8 manylinux: glibc 2.12+ x86-64 manylinux: glibc 2.5+ x86-64

pe-0.3.0-cp38-cp38-macosx_10_9_x86_64.whl (162.5 kB view details)

Uploaded Sep 29, 2021 CPython 3.8 macOS 10.9+ x86-64

pe-0.3.0-cp37-cp37m-win_amd64.whl (145.4 kB view details)

Uploaded Sep 29, 2021 CPython 3.7m Windows x86-64

pe-0.3.0-cp37-cp37m-musllinux_1_1_x86_64.whl (706.7 kB view details)

Uploaded Sep 29, 2021 CPython 3.7m musllinux: musl 1.1+ x86-64

pe-0.3.0-cp37-cp37m-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (629.8 kB view details)

Uploaded Sep 29, 2021 CPython 3.7m manylinux: glibc 2.12+ x86-64 manylinux: glibc 2.5+ x86-64

pe-0.3.0-cp37-cp37m-macosx_10_9_x86_64.whl (159.4 kB view details)

Uploaded Sep 29, 2021 CPython 3.7m macOS 10.9+ x86-64

pe-0.3.0-cp36-cp36m-win_amd64.whl (145.2 kB view details)

Uploaded Sep 29, 2021 CPython 3.6m Windows x86-64

pe-0.3.0-cp36-cp36m-musllinux_1_1_x86_64.whl (707.9 kB view details)

Uploaded Sep 29, 2021 CPython 3.6m musllinux: musl 1.1+ x86-64

pe-0.3.0-cp36-cp36m-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (632.6 kB view details)

Uploaded Sep 29, 2021 CPython 3.6m manylinux: glibc 2.12+ x86-64 manylinux: glibc 2.5+ x86-64

pe-0.3.0-cp36-cp36m-macosx_10_9_x86_64.whl (159.2 kB view details)

Uploaded Sep 29, 2021 CPython 3.6m macOS 10.9+ x86-64

File details

Details for the file pe-0.3.0.tar.gz.

File metadata

Download URL: pe-0.3.0.tar.gz
Upload date: Sep 29, 2021
Size: 185.1 kB
Tags: Source
Uploaded using Trusted Publishing? No
Uploaded via: twine/3.4.2 importlib_metadata/4.8.1 pkginfo/1.7.1 requests/2.26.0 requests-toolbelt/0.9.1 tqdm/4.62.3 CPython/3.9.7

File hashes

Hashes for pe-0.3.0.tar.gz
Algorithm	Hash digest
SHA256	`ae51d93870c06bf637674bc46b0ad4007a258d4b6960ed85cc6424407e51b792`
MD5	`b75de2e1dd8b8528c8446316e8ef7a30`
BLAKE2b-256	`31a7f4e8862a27e7829e51adf90ec3a6a5bce91b5835db80ecba38bc3bacc2b5`

Algorithm	Hash digest
SHA256	`b6eeadaa70aedf1be700429fa7719dfdc464f53eb06484915a875d188e58a1a5`
MD5	`8fc6d7455c37d07a3d0b4bbb31944185`
BLAKE2b-256	`aba62c953a0f60718de321f77077290da9b98a26bf855aa8c72cad9684f424a6`

Algorithm	Hash digest
SHA256	`b4777b0a81bd324293ebdf485e75faf68794b6d2580f238473f91e1c63754e13`
MD5	`0b0fc9855bbf976aef504d5abd1c5fef`
BLAKE2b-256	`3c3f48a00bc1d263f54d41549d8cc4870e8cafc2e84227a4dec44e67e38c2e67`

Algorithm	Hash digest
SHA256	`fd2dad798114fc55f9fbcb95e41844a747938a4988abac9d1460bf9e3a40f9bd`
MD5	`d3f1b8bf85afce7f12bd77900a964f4e`
BLAKE2b-256	`8cc7d7cac58926fbd1da667e8675248bc1551ec0621a57c187a6536ebfd1f2bc`

Algorithm	Hash digest
SHA256	`015059187560c9041d97530cb54425ffe355a5a63eebfd9a4e5054dee3e6da55`
MD5	`1703b94508373dad663c5e4e961719da`
BLAKE2b-256	`caa5c6153256078e00868d455953d481a9253d4593732c52dbf080374b41c91a`

Algorithm	Hash digest
SHA256	`b147611ad970d4c4987a545187fa6593b2d35270ab1c32b397bb09585fb529b6`
MD5	`8a686f38b8084d8e8206d0c635f66e06`
BLAKE2b-256	`195fbfc513b91329bc058a00c9682fec50b1d71629aa083b9d726603b3a32776`

Algorithm	Hash digest
SHA256	`7595f874fa54dbece1360239eae6ae9048a4753dc69e7c7b79e0532db34b5836`
MD5	`7fc727863bf93caa2ded469020f9958e`
BLAKE2b-256	`18241141d59881d11ec3a493b203641d7701aa62c77e395b9c51c4eac76022f2`

Algorithm	Hash digest
SHA256	`f0ef8f9690c451abab46692d550856cd787525f22e45d2ef4f8e9a5f33534d0b`
MD5	`d81f28596d76379c157c5ccf9daa8476`
BLAKE2b-256	`7eb34f27f06b2d53278dcb71b07285572296ecec6425d10046cd6e6d744698bf`

Algorithm	Hash digest
SHA256	`c73e798ff448ddd8f2400bb2ade8124bff611a17ce837ff25793e8a09dc4fe75`
MD5	`a168859a4487c1062554f06d693bafcb`
BLAKE2b-256	`cb4d67ad01d4af5c24ec64e4feae6716559db7f406b33c0fe0f1d912f57d9ad6`

Algorithm	Hash digest
SHA256	`2ce2f8efe0b46b4528866bd756678a10dcfa1bc027417717476f3c323d97ab5d`
MD5	`06d8efa0d1ac10041faefd0e80348434`
BLAKE2b-256	`f425923a98c2a6e7877eef6da077a53f074df79f3b546800b8597e5da9d8ecb4`

Algorithm	Hash digest
SHA256	`5f529386ce1c31289459ecb17ee26d589f9cfcc0e4a408370de743b6b1363a9e`
MD5	`487e40ba675bc3ca6c6564a1f10850b8`
BLAKE2b-256	`d24eca65ea09a0459f762c865e1f0e3e00984201b92a93725cba22def397d13d`

Algorithm	Hash digest
SHA256	`75b81e0eee1d0d209cb6ff48e26cf045346aa644617ae2a8a6e9b415d8fc4c00`
MD5	`3118cfa5b39fb4572b3ed154141dd135`
BLAKE2b-256	`97c718d9d6a9a749375219fb28acc713cb73c452e08f6c82e5e09e1c5470b33b`

Algorithm	Hash digest
SHA256	`6eb54bed25177d7360a1215384e5e03b59a4357c0b0ca88b6226ab0a35cc9d3c`
MD5	`af06da709a0e0c7c9e83eb85b66cc959`
BLAKE2b-256	`11e58f030f0a5aab0d2fe90c3afbaeca8dab72a26acf37cc73dc48446d6b16bb`

Algorithm	Hash digest
SHA256	`8dc373783aad76e562bcc9fea517cab8001bb467d50839db3b939cbfbe362288`
MD5	`4d2712e4ee01770e9a13a412b0822d01`
BLAKE2b-256	`56ccd449e058dd3443cc73d02b0f1ef4f02856c1e04eb985d31e9ad8e71c53af`

Algorithm	Hash digest
SHA256	`308f77cd64ec345cca8cd6578de4c7bc1b5a3691022bc6fbfe8c1f34a6eaa993`
MD5	`896b1eb383730514106fe21acd1ea4ba`
BLAKE2b-256	`e6291d6d1b59437e0137191341bcff6a682f27fa3cbd64d22f5b63d25e2019ee`

Algorithm	Hash digest
SHA256	`242b712c5dfba37f4fb0c88cec9e0ca5023e90a43d193f14c254eb50e0b45bc0`
MD5	`34e23e79d8c4bd5a008c8fc56d89ed05`
BLAKE2b-256	`cbf4fb281295ab3f7665df24ab5cda1aae314f9440db7bb5075b8b21a6789dde`

Algorithm	Hash digest
SHA256	`f521781198b92da6591de0403d31106761764639b3223e8963110ac94fe09e1a`
MD5	`559752a05db4c1438dc2291707e011f2`
BLAKE2b-256	`fb52770202dfd964530749e5a755d23bd406cac5a24cb578fc7a54139472d644`

Algorithm	Hash digest
SHA256	`b1a3226265001ce8b6dfe8bb9711c6b20b281074db0d734240bef7fb6429afbb`
MD5	`ab55491e57cc1e47fd99cbc97ececc19`
BLAKE2b-256	`fa7dff968dd7290540b21850b4d837229b6e1a64089f11bfc3c16ae0e5d17ed3`

Algorithm	Hash digest
SHA256	`0ace00558761bfb3c7305a8598318ca386e307c585ef9903b93a928cfbddeff8`
MD5	`1ec4b34b4b84d4c2305428622dd810b0`
BLAKE2b-256	`4431ded3d3dbbc561b71145b0a2fd9d25d7207323155a37c5bd75a221d6d2872`

Algorithm	Hash digest
SHA256	`d2418dfe67592b343dab8501e3f4d5d7997dbf8b06d1aaa483caba3390f05e5a`
MD5	`a856115a8dabdba46062a8b3c48e3ce7`
BLAKE2b-256	`b9aa77c1d493275804034723e1ec2dfebb1211b0026f612766c988b020e2aad9`

Algorithm	Hash digest
SHA256	`88bb6eb25382e99ac9c94493a77eeacbd4337a8f8a3eb0e3953ef4f175c7edea`
MD5	`9ad461d8f6c2c37c1fcc2aea19559901`
BLAKE2b-256	`65a998354b95181a22e61c203e085d5f069d0081f4b2621f158561c3f653689a`

pe 0.3.0

Navigation

Verified details

Maintainers

Unverified details

Project links

Meta

Classifiers

Project description

Features and Goals

Syntax Overview

Matching Inputs with Parsing Expressions

Value Bindings

Actions

Example

Similar Projects

Project details

Verified details

Maintainers

Unverified details

Project links

Meta

Classifiers

Release history Release notifications | RSS feed

Download files

Source Distribution

Built Distributions

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata

File hashes

File details

File metadata