ezregex 1.6.1

A readable and intuitive way to generate Regular Expressions

EZRegex

A readable and intuitive way to generate Regular Expressions

Try my new frontend for this library at ezregex.org!

TLDR: This is to regular expressions what CMake is to makefiles

Table of Contents

• Usage
• Installation
• Invert
• Dialects
• Documentation
• Explanation
• Todo
• License

Usage

Quickstart

from ezregex import *
'foo' + number + optional(whitespace) + word
# Matches `foo123abc` and `foo123 abc`
# but not `abc123foo` or  `foo bar`

Importing as a named package is recommended

import ezregex as er
# ow is part of er already as optional whitespace
params = er.group(er.atLeastNone(er.ow + er.word + er.ow + er.optional(',') + er.ow))
function = er.word + er.ow + '(' + params + ')'
# Automatically calls the re.search() function for you
function % 'some string containing func( param1 , param2)'
# The test() method is helpful for debugging, and color codes groups for you
function.test('this should match func(param1,\tparam2 ), foo(), and bar( foo,)')

.test() will print all the matches, color coded to match and group:

╭───────────────────────────── Testing Regex ──────────────────────────────╮
│ Testing expression:                                                      │
│         \w+(?:\s+)?\(((?:(?:\s+)?\w+(?:\s+)?,?(?:\s+)?)*)\)              │
│ for matches in:                                                          │
│         this should matchfunc(param1,  param2 ), foo(), and bar( foo,)   │
│                                                                          │
│ Match = "func(param1,  param2 )" (18:39)                                 │
│ Unnamed Groups:                                                          │
│         1: "param1,     param2 " (23:38)                                 │
│                                                                          │
│ Match = "foo()" (41:46)                                                  │
│ Unnamed Groups:                                                          │
│         1: "" (45:45)                                                    │
│                                                                          │
│ Match = "bar( foo,)" (52:62)                                             │
│ Unnamed Groups:                                                          │
│         1: " foo," (56:61)                                               │
│                                                                          │
│                                                                          │
╰───────────────────────────────── Found  ─────────────────────────────────╯

Installation

EZRegex is distributed on PyPI as a universal wheel and is available on Linux/macOS and Windows and supports Python 3.10+ and PyPy.

$ pip install ezregex

Inverting

The invert function provided (available either as er.invert, or ~<expression>) is useful for debugging. You pass it an expression, and it returns an example of a string that is guaranteed to match the provided expression.

Dialects

As of version 1.6.0, the concepts of dialects was introduced. Different languages often have slight variations on the regular expression syntax. As this library is meant to be language independent (even though it's written in Python), you should be able to compile regular expressions to work with other languages as well. To do that, you can simply import a sub-package, and they should work identically (though some languages may have more features than others):

>>> import ezregex as er # The python dialect is the defualt dialect
>>> er.group(digit, 'name') + er.earlierGroup('name')
EZRegex("(?P<name>\d)(?P=name)")
>>> import ezregex.perl as er
>>> er.group(digit, 'name') + er.earlierGroup('name')
EZRegex("?P<name>\d)(\g<name>")

The currently implemented dialects are:

• Python
  • Well tested, ~98% implemented
• Perl
  • Almost identical to the Python dialect because I don't know Perl.

If you know a particular flavor of regex and would like to contribute, feel free to make a pull request! Or you can email me at [e-mail]

Documentation

Notes and Gotchas

This documentation is for the Python dialect specifically, as it really is the only one currently implemented.

• When using the re library, functions like search() and sub() don't accept EZRegexs as valid regex patterns. Be sure to call either .str() or .compile(), or cast to a string when passing to those. Also, be careful to call the function on the entire pattern: chunk + whitespace.str() is not the same as (chunk + whitespace).str().
• In regular Regex, a lot of random things capture groups for no reason. I find this annoying. All regexes in EZRegex intentionally capture passively, so to capture any groups, use group(), with the optional name parameter.
• All EZRegexs (except for raw) auto-sanitize strings given to them, so there's no need to escape characters or use r strings. This does mean, however, that you cannot pass actual regex strings to any of them, as they'll think you're talking about it literally (unless you want that, of course). To include already written regex strings, use raw
• Note that I have camelCase and snake_case versions of each of the functions, because I waver back and forth between which I like better. Both versions function identically.
• The input parameter can accept strings, other EZRegexs, or entire sequences of EZRegex patterns.
• A few of these have greedy and possessive optional parameters. They can be useful, but can get complicated. Refer to the Python re docs for details.

Positionals

These differentiate the string starting with a sequence, and a line starting with a sequence. Do note that the start of the string is also the start of a line. These can also be called without parameters to denote the start/end of a string/line without something specific having to be next to it.

• stringStart
• stringEnd
• lineStart
• lineEnd
• wordBoundary
  • Matches the boundary of a word, i.e. the empty space between a word character and not a word character, or the end of a string.
• notWordBoundary
  • The opposite of wordBoundary

Literals

• tab
• space
• spaceOrTab
• newline
• carriageReturn
• quote
  • Matches ', ", and `
• verticalTab
• formFeed
• comma
• period
• underscore

Not Literals

• notWhitespace
• notDigit
• notWord

Catagories

• whitespace
• whitechunk
  • A "chunk" of whitespace. Just any amount of whitespace together
• digit
• letter
  • Matches just a letter -- not numbers or _ like wordChar.
• number
  • Matches multiple digits next to each other. Does not match negatives or decimals
• word
• wordChar
  • Matches just a single "word character", defined as any letter, number, or _
• anything
  • Matches any single character, except a newline. To also match a newline, use literallyAnything
• chunk
  • A "chunk": Any clump of characters up until the next newline
• uppercase
• lowercase
• hexDigit
• octDigit
• punctuation
  • Matches punctuation. In the Python dialect, there isn't a built-in method of doing this, so I probably forgot a bunch of them.
• controller
  • Matches a metadata ASCII characters
• printable
  • Matches printable ASCII characters
• printableAndSpace
• alphaNum
• unicode
  • Matches a unicode character by name
• anyBetween(char, and_char)
  • Match any char between char and and_char, using the ASCII table for reference

Amounts

• matchMax(input)

  • Match as many of input in the string as you can. This is equivelent to using the unary + operator. If input is not provided, it works on the previous regex pattern. That's not recommended for clarity's sake though

• amt(num, input)

  • Match num amount of input in the string

• moreThan(min, input)

  • Match more than min sequences of input in the string

• matchRange(min, max, input, greedy=True, possessive=False)

  • Match between min and max sequences of input in the string. This also accepts greedy and possessive parameters Max can be an empty string to indicate no maximum greedy means it will try to match as many repititions as possible non-greedy will try to match as few repititions as possible possessive means it won't backtrack to try to find any repitions see https://docs.python.org/3/library/re.html for more help

• atLeast(min, input)

  • Match at least min sequences of input in the string

• atMost(max, input)

  • Match at most max instances of input in the string

• atLeastOne(input, greedy=True, possessive=False)

  • Match at least one of input in the string. This also accepts greedy and possessive parameters greedy means it will try to match as many repititions as possible non-greedy will try to match as few repititions as possible possessive means it won't backtrack to try to find any repitions see https://docs.python.org/3/library/re.html for more help

• atLeastNone(input, greedy=True, possessive=False)

  • Match 0 or more sequences of input. This also accepts greedy and possessive parameters greedy means it will try to match as many repititions as possible non-greedy will try to match as few repititions as possible possessive means it won't backtrack to try to find any repitions see https://docs.python.org/3/library/re.html for more help

Choices

• optional(input, greedy=True, possessive=False)

  • Match input if it's there. This also accepts greedy and possessive parameters greedy means it will try to match as many repititions as possible non-greedy will try to match as few repititions as possible possessive means it won't backtrack to try to find any repitions see https://docs.python.org/3/library/re.html for more help

• either(input, or_input)

• oneOf(*inputs, chars=None, split=None)

  • Match any of the given inputs. Note that inputs can be multiple parameters, or a single string. Can also accept parameters chars and split. If char is set to True, then inputs must only be a single string, it interprets inputs as characters, and splits it up to find any of the chars in the string. If split is set to true, it forces the ?(...) regex syntax instead of the [...] syntax. It should act the same way, but your output regex will look different. By default, it just optimizes it for you.

• anyCharExcept(*inputs)

  • This matches any char that is NOT in inputs. inputs can be multiple parameters, or a single string of chars to split.

• anyExcept(input, type='.*')

  • Matches anything other than input, which must be a single string or EZRegex chain, not a list. Also optionally accepts the type parameter, which works like this: "Match any type other than input". For example, "match any word which is not foo". Do note that this function is new, and I'm still working out the kinks.

Conditionals

• ifFollowedBy(input)
  • Matches the pattern if it has input coming after it. Can only be used once in a given pattern, as it only applies to the end
• ifNotFollowedBy(input)
  • Matches the pattern if it does not have input coming after it. Can only be used once in a given pattern, as it only applies to the end
• ifPrecededBy(input)
  • Matches the pattern if it has input coming before it. Can only be used once in a given pattern, as it only applies to the beginning
• ifNotPrecededBy(input)
  • Matches the pattern if it does not have input coming before it. Can only be used once in a given pattern, as it only applies to the beginning
• ifEnclosedWith(open, stuff, close=None)
  • Matches if the string has open, then stuff, then close, but only "matches" stuff. Just a convenience combination of ifProceededBy and ifPreceededBy.

Grouping

• group(input, name: str = None)
  • Causes input to be captured as an unnamed group. Only useful when replacing regexs
• earlierGroup(num_or_name)
  • Matches whatever the group referenced by num_or_name matched earlier. Must be after a group which would match num_or_name.
• ifExists(num_or_name, does, doesnt=None)
  • Matches does if the group num_or_name exists, otherwise it matches doesnt
• passiveGroup(input)
  • As all regexs in EZRegex capture passively, this is entirely useless. But if you really want to, here it is
• namedGroup(name, input)
  • Causes input to be captured as a named group, with the name name. Only useful when replacing regexs

Replacement

In the intrest of "I don't want to think about any syntax at all", I have included replace members. Do note that they are not interoperable with the other EZRegexs, and can only be used with other strings and each other.

• rgroup(num_or_name)
  • Puts in its place the group specified, either by group number (for unnamed groups) or group name (for named groups). Named groups are also counted by number, I'm pretty sure. Groups are numbered starting from 1.
• replaceEntire
  • Puts in its place the entire match

Premade

These are some useful combinations that may be commonly used. They are not as stable, and may be changed and added to in later versions to make them more accurate

• literallyAnything
  • Any character, include newline
• signed
  • a signed number, including 123, -123, and +123
• unsigned
  • Same as number. Will not match +123
• plain_float
  • Will match 123.45 and 123.
• full_float
  • Will match plain_float as well as things like 1.23e-10 and 1.23e+10
• int_or_float
• ow
  • "Optional Whitechunk"
• email
  • Matches an email

Misc

• literal(input)
  • This is a redundant function. You should always be able to use ... + 'stuff' just as easily as ... + literal('stuff')
• isExactly(input)
  • This matches the string if and only if the entire string is exactly equal to input
• raw(regex)
  • If you already have some regular regex written, and you want to incorperate it, this will allow you to include it without sanatizing all the backslaches and such, which all the other EZRegexs do automatically.

Flags

These shadow python regex flags, and can just as easily be specified directly to the re library instead. They're provided here for compatibility with other regex dialects. See https://docs.python.org/3/library/re.html#flags for details

• ASCII
• DOTALL
• IGNORECASE
• LOCALE
• MULTILINE
• UNICODE

Operators

• +, <<, >>
  • These all do the same thing: combine expressions
• *
  • Multiplies an expression a number of times. expr * 3 is equivelent to expr + expr + expr. Can also be used like expr * ... is equivalent to anyAmt(expr)
• +
  • A unary + operator acts exactly as a match_max() does, or, if you're familiar with regex syntax, the + operator
• []
  • expr[2, 3] is equivalent to match_range(2, 3, expr)
  • expr[2, ...] or expr[2,] is equivalent to at_least(2, expr)
  • expr[... , 2] is equivalent to at_most(2, expr)
  • expr[...] or expr[0, ...] is equivelent to at_least_0(expr)
  • expr[1, ...] is equivalent to at_least_1(expr)
• &
  • Coming soon! This will work like the + operator, but they can be out of order. Like an and operation.
• |
  • Coming soon! This will work like an or operation, which will work just like anyOf()

• %
  • This automatically calls re.search() for you and returns the match object (or None). Use like this: (digit * 2) % '99 beers on the wall'
• ~
  • This inverts the expression. This is equivalent to calling the .invert() method

Explanation of How it Works

Everything relies on the EZRegex class. In the __init__ file of the package, I have defined a ton of pre-made EZRegexs which mimic all (or at least as many as I can) fundamental parts of the regex syntax, plus a few others which are common combinations (like chunk or whitechunk). These have operators overloaded so you can combine them in intuitive ways and call them by intuitive names. All EZRegexs take a function parameter (or a string which gets converted to a function for convenience), which gets called with the current regex expression and any parameters passed along when the instance gets called with the () operator. That way you can add things to the front or back of an expression for example, and you can change what exactly gets added to the current expression based on other parameters. You can also chain strings together, and pass them as parameters to other EZRegexs, which auto-compiles them and adds them appropriately.

I also have everything which could capture a group capture it passively, except for actual group operators, and always have the (?m) (multiline) flag automatically asserted whenever lineStart/lineEnd are used so as to differentiate between capturing at the beginning/end of a string and the beginning/end of a line.

Todo

See the todo. Eventually, I would like to move the todo to GitHub issues.

License

EZRegex is distributed under the MIT License