regular expression

Reminders

• \zs, ze, modify the start or end of regex match, can make replacing or searching easier
  • e.g. \zs can replace positive look behind@<=
  • e.g. \ze can replace positive look ahead @=
• \_. matches all characters and end of line, useful for multiline matching
  • . matches all characters but not end of line
• \w matches word characters, same as [0-9A-Za-z_]
• \s matches space or tab
• \{-} non-greedy match, match as little as possible, this is a multi
  • basically the non-greedy version of *

Intresting Examples

• \(def\s\)\@<!foo_function(\_.\{-}) matches function usage and params single line or multi lines, but not the function definition
• def\s\w*(\zs\_.\{-}\ze) matches only params in function definitions, single line or multi lines

Definition of a pattern in vim

• atom: a an ordinary character, \i a character class, \(foo\) putting pattern in parenthesis making it an atom
• piece: atom + multi, *, \{n,m}, {-}
  • special multi, look ahead \@=, \@!, look behind \@<=,\@<!,
• concat: piece + piece, a*b*
• branch: concat \& concat, \& means matching both regex patterns, like AND
• pattern: branch \| branch, \| means either patterns, like OR