randstr: Random String Generator🔗ℹ

1 Features🔗ℹ

• Generate random strings from regex-like patterns

• Support for character classes, ranges, and quantifiers

• POSIX character classes ([:alpha:], [:digit:], etc.)

• Unicode property support (\\p{L}, \\p{Script=Han}, etc.)

• Normal distribution quantifiers for realistic length variation

• Named groups and backreferences for pattern reuse

• Command-line interface for quick generation

• Fair distribution: duplicate characters in classes are deduplicated

2 Functions🔗ℹ

3 Pattern Syntax🔗ℹ

The following pattern syntax is supported:

• {n} - Exactly n repetitions

• {n+} - Normal distribution with mean n (2nd order)

• {n++} - Normal distribution with mean n (3rd order, more concentrated)

• {n1+n2} - Normal distribution in range n1..n2 (2nd order)

• {n1++n2} - Normal distribution in range n1..n2 (3rd order)

• {+n} - Shorthand for {0+n} (range 0..n)

• {++n} - Shorthand for {0++n} (range 0..n, 3rd order)

• (?<name>...) - Named group (captures pattern for later reference)

• \\k<name> - Backreference to named group

• [abc] - Choose randomly from characters a, b, or c

• [a-z] - Choose randomly from lowercase letters a through z

• (abc|def) - Choose randomly between "abc" or "def"

• a* - Zero or more of the preceding character

• a+ - One or more of the preceding character

• a? - Zero or one of the preceding character

• . - Any character

• [:alpha:] - Alphabetic characters

• [:digit:] - Numeric characters

• [:alnum:] - Alphanumeric characters (POSIX standard) or [:alphanum:] (alias)

• [:word:] - Word characters (alphanumeric plus underscore)

• [:blank:] - Blank characters (space and tab)

• [:space:] - Whitespace characters

• [:upper:] - Uppercase letters

• [:lower:] - Lowercase letters

• [:ascii:] - ASCII characters

• [:cntrl:] - Control characters

• [:graph:] - Printable characters except space

• [:print:] - Printable characters including space

• [:punct:] - Punctuation characters

• [:xdigit:] - Hexadecimal digits

• \\p{L} - Unicode letters

• \\p{N} - Unicode numbers

• \\p{P} - Unicode punctuation

• \\p{M} - Unicode marks

• \\p{S} - Unicode symbols

• \\p{Z} - Unicode separators

• \\p{C} - Unicode other (control characters)

• \\p{Lu} - Unicode uppercase letters

• \\p{Ll} - Unicode lowercase letters

• \\p{Nd} - Unicode decimal numbers

• \\p{Letter} - Unicode letters (alias for \\p{L})

• \\p{Number} - Unicode numbers (alias for \\p{N})

• \\p{Punctuation} - Unicode punctuation (alias for \\p{P})

• \\p{Script=Han} - Unicode characters from Han script

• \\p{Script=Latin} - Unicode characters from Latin script

• \\p{Block=Basic_Latin} - Unicode characters from Basic Latin block

• \\p{Block=CJK_Unified_Ideographs} - Unicode characters from CJK Unified Ideographs block

• \\p{Alphabetic} - Unicode alphabetic characters

• \\p{Uppercase} - Unicode uppercase characters

• \\p{Lowercase} - Unicode lowercase characters

• \\p{White_Space} - Unicode whitespace characters

• \\p{Cased} - Unicode characters with case distinctions

• \\p{Dash} - Unicode dash characters

• \\p{Emoji} - Unicode emoji characters

• \\p{Emoji_Component} - Unicode emoji component characters

• \\p{Emoji_Modifier} - Unicode emoji modifier characters

• \\p{Emoji_Modifier_Base} - Unicode emoji modifier base characters

• \\p{Emoji_Presentation} - Unicode emoji presentation characters

• \\p{Extended_Pictographic} - Unicode extended pictographic characters

• \\p{Hex_Digit} - Unicode hexadecimal digits

• \\p{ID_Continue} - Unicode identifier continuation characters

• \\p{ID_Start} - Unicode identifier start characters

• \\p{Ideographic} - Unicode ideographic characters

• \\p{Math} - Unicode mathematical symbols

• \\p{Quotation_Mark} - Unicode quotation mark characters

4 Advanced Examples🔗ℹ

In addition to basic pattern matching, the library supports more complex patterns:

(randstr "[[:alpha:]]{5}")

(randstr "[[:digit:]]{3}")

(randstr "[[:alnum:]]{4}")

(randstr "[[:word:]]+")

(randstr "[[:upper:]0-9]+")

(randstr "[[:lower:]_]+")

(randstr "[[:alpha:]0-9]+")

(randstr "\\p{L}{5}")

(randstr "\\p{N}{3}")

(randstr "\\p{P}{2}")

(randstr "\\p{Lu}{3}\\p{Ll}{3}")

(randstr "\\p{Letter}{5}")

(randstr "\\p{Number}{3}")

(randstr "\\p{Script=Han}{2}")

(randstr "\\p{Block=Basic_Latin}{5}")

(randstr "\\p{Alphabetic}{4}")

(randstr "\\p{White_Space}{3}")

5 Normal Distribution Quantifiers🔗ℹ

Generate strings with lengths following a normal distribution for more realistic random data:

(randstr "\\w{10+}")

(randstr "\\w{10++}")

(randstr "\\w{5+15}")

(randstr "\\w{5++15}")

(randstr "\\d{+10}")

(randstr "\\d{++10}")

Higher order (more + signs) means values are more concentrated around the center/mean.

6 Named Groups and Backreferences🔗ℹ

Capture generated content and reuse it later in the pattern:

(randstr "(?<word>\\w{4})-\\k<word>")

(randstr "(?<id>\\d{3}):\\k<id>")

(randstr "(?<a>[A-Z]{2})(?<b>\\d{2})-\\k<a>\\k<b>")

Named groups are defined with (?<name>...) and referenced with \\k<name>. The backreference will produce the exact same string that was generated by the named group.

7 Character Class Duplicate Handling🔗ℹ

When a character class contains duplicate elements, each unique character is treated equally regardless of how many times it appears in the class. For example:

• [aaabbbccc] - Each of a, b, c has equal probability (1/3 each), not a=3/9, b=3/9, c=3/9

• [a-cb-e] - Each of a, b, c, d, e has equal probability (1/5 each)

• [[:digit:]0-2] - Digits 0, 1, 2 appear in both the POSIX class and the range, but each digit still has equal probability

This ensures fair distribution of character selection in all character classes.

8 Changelog🔗ℹ

9 License🔗ℹ

This project is licensed under the MIT License. See the "LICENSE" file for details.