Julia: Regular expression using match function

In previous post, I explained regular expressions using ismatch function, ismatch function return true if the given regex matches the string, else false. Some times you require more information like how the regex matched. You can capture how the regex matched using match function.

match(r::Regex, s::AbstractString[, idx::Integer[, addopts]])

Search for the first match of the regular expression r in s, match() returns 'nothing' regex is not matched, else it returns RegexMatch object.

Argument	Description
Regex	Reguar expression
s	String to match against regular expression
idx	It is optional, specifies an index at which to start the search.

regEx.jl

m = match(r"llo", "Hello, How are you, stello")
if m == nothing
  println("not a comment")
else
  println(m)
end

$ julia regEx.jl

RegexMatch("llo")

You can specify optional argument idx, which specifies an index at which to start the search.

julia> m = match(r"[0-9]", "Hello 1, i met 2 asked about 3 and 4", 1)
RegexMatch("1")

julia> m = match(r"[0-9]", "Hello 1, i met 2 asked about 3 and 4", 10)
RegexMatch("2")

julia> m = match(r"[0-9]", "Hello 1, i met 2 asked about 3 and 4", 15)
RegexMatch("2")

julia> m = match(r"[0-9]", "Hello 1, i met 2 asked about 3 and 4", 25)
RegexMatch("3")

julia> m = match(r"[0-9]", "Hello 1, i met 2 asked about 3 and 4", 32)
RegexMatch("4")

As I said match() function return RegexMatch object. RegExMatch object contain following fields.

  match    :: SubString{UTF8String}

  captures :: Array{Union{SubString{UTF8String},Void},1}

  offset   :: Int64

  offsets  :: Array{Int64,1}

  regex    :: Regex

Field	Description
match	Return the entire substring matched
captures	Return the captured substrings as an array of strings
offset	Return the offset at which the whole match begins
offsets	Return the offsets of the captured substrings as a vector.
regex	Return the regular expression

julia> m = match(r"(w|x|y)(z[a-z])(a)", "wzbawza")
RegexMatch("wzba", 1="w", 2="zb", 3="a")

julia> m.match
"wzba"

julia> m.captures
3-element Array{Union{SubString{UTF8String},Void},1}:
 "w" 
 "zb"
 "a" 

julia> m.offset
1

julia> m.offsets
3-element Array{Int64,1}:
 1
 2
 4

julia> m.regex
r"(w|x|y)(z[a-z])(a)"

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