Elixir Exercism Acronym
I am working to understand xianrusso’s solution to Exercism’s Acronym solution.
defmodule Acronym do
def abbreviate(string) do
The portion that I am working to digest is the Regex.
I believe this link contains the answer I just want to confirm that what I am thinking is happening is indeed what is happening. Advanced Regex Tutorial—Regex Syntax
I believe that in this ~r/(?<![A-Z])[A-Z]/ - that the (?<![A-Z]) is saying that as long as where we are at in the string does not have a capital letter that immediately precedes it then we can continue to keep matching it to [A-Z].
I believe that in this ~r/(?<!’)\b[a-z]/ it is saying that as long as where we are at in the string there is not a ’ that precedes it then we can keep matching it to \b[a-z]
quiet, but note that
\b is s zero-width (same as lookbehinds) assertion, which is a word boundary. A limit between \w (a word) and a non-word (\W), or the beginning or end of a word.
So the second part of the regex is telling you [a-z] preceeded by any non-word that is not a single quote, and it can match a [a-z] at the beginning of the string.
The regex commented out in plain English:
regex = ~r/
(?<![A-Z])[A-Z] # Match ONE uppercase letter from A to Z,
# that is not preceded by another uppercase letter from A to Z.
| # OR
(?<!\') # no need to escape the single quote
[a-z] # Match ONE lowercase letter from a to z,
# that is preceded by a word boundary (\b)
# and that is not preceded by a single quote.
# Note: the beginning of a string is considered a word boundary.
/x # "x" modifier to to allow comments
Note the regex is valid, feel free to use it in your code, if you want.