Longest

Longest[p]

is a pattern object that matches the longest sequence consistent with the pattern p.

Details

  • Longest works for both ordinary expression patterns and string patterns.
  • If several Longest objects occur in the same expression, those that appear first are given higher priority to match longest sequences.
  • Longest[p,pri] is given priority pri to be the longest sequence. Matches for longest sequences are tried first for Longest objects with higher priorities.
  • Priorities can be any expression, and are ordered in standard Wolfram Language Sort order. Longest[p] specifies the highest possible priority.
  • Longest objects with equal priorities are tried in the order they appear in the expression.
  • If no explicit Longest or Shortest is given, ordinary expression patterns are normally effectively assumed to be Shortest[p], while string patterns are assumed to be Longest[p].
  • For ordinary expressions, Longest[p] specifies that not just p itself, but also all parts of p should match the longest sequences.
  • Longest[p] corresponds to a "greedy pattern".
  • Longest[p] may not correspond to the absolutely longest expression matching p if there are additional constraints elsewhere in the pattern.

Examples

open allclose all

Basic Examples  (1)

Require that y__ matches the longest sequence it can:

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The default is to have earlier patterns match shortest sequences:

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Scope  (1)

Applications  (2)

Properties & Relations  (1)

Possible Issues  (1)

See Also

Shortest  BlankSequence  Repeated  StringExpression  LongestCommonSubsequence

Tutorials

Introduced in 2007
(6.0)