Roadmap

• Basic Match Handling: Provides functionality to match regular expressions against test strings.
• Match Positions: Supports the extraction and display of match start and end positions.
• Capture Groups: Extracts and displays capture groups from regex matches.
• Named Captures: Supports capturing named groups from regex matches.
• Regex Quick Reference: Provides a concise list of commonly used regex syntax for quick reference.
• Regex Examples: Interactive examples to test and visualize regex patterns in real-time.
• Execution Time Measurement: Measures and reports the execution time of regex operations.
• Regex Diagram Generation: Generates and visualizes regex patterns using SVG diagrams.
• Regex Substitution Function: Supports regex-based string substitution.
• Ruby Code Snippet Generation: Automatically generates Ruby code snippets for testing regex patterns.
• Web Interface for Regex Testing: Interactive web UI to test and visualize regular expressions in real-time.
• Permalink / Shareable URL generation: Create shareable URLs that encode the editor state (regex, sample text, and options) for easy reproduction.
• ReDoS Check Integration: Check regular expressions for ReDoS vulnerabilities via embedded recheck Playground with one-click pattern copying. (#306)

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Supported Scope of Regexp::Parser Used for SVG Output in Railroad Diagrams

• Alternation: a\|b\|c

• Anchors: \A, ^, \b

• Character Classes: [abc], [^\\], [a-d&&aeiou]

• Character Types: \d, \H, \s

• Cluster Types: \R, \X

• Conditional Expressions: (?(cond)yes-subexp), (?(cond)yes-subexp\|no-subexp)

• Escape Sequences: \t, \\+, \?

• Free Space: whitespace and # Comments (x modifier)

• Grouped Expressions:

  • Assertions:
    • Lookahead: (?=abc)
    • Negative Lookahead: (?!abc)
    • Lookbehind: (?<=abc)
    • Negative Lookbehind: (?<!abc)
  • Atomic: (?>abc)
  • Absence: (?~abc)

• Back-references:

  • Named: \k<name>
  • Nest Level: \k<n-1>
  • Numbered: \k<1>
  • Relative: \k<-2>
  • Traditional: \1 through \9

• Capturing: (abc)

• Comments: (?# comment text)

• Named Captures: (?<name>abc), (?'name'abc)

• Options: (?mi-x:abc), (?a:\s\w+), (?i)

• Passive Captures: (?:abc)

• Subexpression Calls: \g<name>, \g<1>

• Keep: \K, (ab\Kc\|d\Ke)f

• Literals (utf-8):

  • Ruby, ルビー, روبي

• POSIX Classes:

  • [:alpha:], [:^digit:]

• Quantifiers:

  • Greedy: ?, *, +, {m,M}
  • Reluctant (Lazy) [1]: ??, *?, +?
  • Possessive [1]: ?+, *+, ++

• String Escapes:

  • Control: \C-C, \cD
  • Hex: \x20, \xE2\x82\xAC
  • Meta [2]: \M-c, \M-\C-C, \M-\cC, \C-\M-C, \c\M-C
  • Octal: \0, \01, \012
  • Unicode: \uHHHH, \u{H+ H+}

• Unicode Properties (Unicode 15.0.0):

  • Age: \p{Age=5.2}, \P{age=7.0}, \p{^age=8.0}
  • Blocks: \p{InArmenian}, \P{InKhmer}, \p{^InThai}
  • Classes: \p{Alpha}, \P{Space}, \p{^Alnum}
  • Derived: \p{Math}, \P{Lowercase}, \p{^Cased}
  • General Categories: \p{Lu}, \P{Cs}, \p{^sc}
  • Scripts: \p{Arabic}, \P{Hiragana}, \p{^Greek}
  • Simple: \p{Dash}, \p{Extender}, \p{^Hyphen}

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[1]: Simple forms (*?, +?, ??, *+, ++, ?+) are accepted and rendered with a "(lazy)" or "(possessive)" comment label in the diagram. Range forms ({m,M}?, {m,M}+) raise an error — the railroad_diagrams gem does not support the range + lazy/possessive combination.

[2]: As of Ruby 3.1, meta and control sequences are pre-processed to hex escapes when used in Regexp literals, so they only appear as Meta/Control nodes when a String or a Regexp built with ::new is parsed. In Rubree, entering \M-c in UTF-8 mode raises a RegexpError before diagram generation — support requires Regexp::NOENCODING handling.

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For more detailed information about supported syntax, refer to the official documentation: Supported Syntax - Regexp::Parser GitHub README