A regular expression is a miniature pattern language for specifying text to search for or match. In Julia, it is useful when literal replacement is too broad—for example, changing the type name Rocket without also changing RocketEngine. section 11.0 section 11.4.3
Prefix a pattern with r to create a Regex object, such as r"Rocket[^A-Za-z]". Character classes describe allowed characters: . matches any character, \d a digit, \w an alphanumeric character or underscore, and \s whitespace. Quantifiers control repetition: * means zero or more, + one or more, and ? zero or one. section 11.4.3
Capture parts of a match
rx = r"\\w+ (\\d+) (\\w+) \\d+"; m = match(rx, "foo 123 bar 42") returns captures "123" and "bar", accessible as m[1] and m[2]. Named groups such as (?<hour>\\d+) can instead be retrieved with m["hour"]. section 11.4.3
Listing 11.14 Text substitution using regular expressions
julia> result = replace(s, r"Rocket[^A-Za-z]"=>"SpaceCraft"); julia> println(result) struct RocketEngine thrust::Float64 Isp::Float64 end mutable struct SpaceCraft tank::Tank engine::RocketEngine end
See the replacement example that preserves RocketEngine while renaming the standalone Rocket type. section 11.4.3
