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diff --git a/content/posts/WIP-emacs-align-columns/index.org b/content/posts/WIP-emacs-align-columns/index.org deleted file mode 100644 index eb140f8..0000000 --- a/content/posts/WIP-emacs-align-columns/index.org +++ /dev/null @@ -1,67 +0,0 @@ -#+TITLE: Aligning columns in Emacs -#+DATE: 2021-03-26T11:27:34-04:00 -#+DRAFT: false -#+DESCRIPTION: How to align text separated by whitespace using Emacs -#+TAGS[]: emacs elisp -#+KEYWORDS[]: emacs elisp -#+SLUG: -#+SUMMARY: - -#+ATTR_HTML: :alt Before and after columns aligned -#+ATTR_HTML: :title Before and after aligned columns -[[file:cover.png]] - -I've been writing a lot of GraphQL resolvers in ruby at work recently, -and frequently run into a situation where I have to align many columns -of text by hand. I figured this isn't a very unique problem, and that -there was probably already some code within Emacs to handle it. - -As it turns out I was correct in my assumption. There's an excellent -built-in package called =align= that takes care of just that. - -Many of the features of the =align= package are mode-specific, but I -just wanted a function that can align columns regardless of which mode -they're used in. There's a function that's part of the package that -can be used for just that fortunately, =align-regexp=, which takes a -regular expression as input and uses it to guide the alignment. - -I was able to use it to make a generic function. - -#+begin_src elisp -(defun align-non-space (BEG END) - "Align non-space columns in region BEG END." - (interactive "r") - (align-regexp BEG END "\\(\\s-*\\)\\S-+" 1 1 t)) -#+end_src - -Let's walk through what's going on here. - -- =BEG= and =END= are the beginning and end positions of the area to be aligned -- =(interactive "r")= tells Emacs that the function is interactive, - meaning that it can be called from the =M-x= menu - - ="r"= tells Emacs that when the function is called interactively, it expects a - region (beginning and end points) as arguments -- =align-regexp= where the work is happening. This function has the - following signature. - #+begin_src elisp - (align-regexp BEG END REGEXP &optional GROUP SPACING REPEAT) - #+end_src - - - =BEG= and =END= is the region that it expects as the first arguments - - ="\\(\\s-*\\)\\S-+"= is an Emacs regular expression. Backslashes - are doubled because they need to be escaped in a string literal - - =\( \)= is a capture group - - =\s-= is a [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Regexp-Backslash.html][regular expression construct]] specific to Emacs which - specifies a type of /syntax/ which is to be matched. - - =-= refers to the [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Syntax-Class-Table.html][whitespace characters]] - - =*= means match zero or more - - =\S-= is similar to the previous construct, but instead means to - match anything /other/ than whitespace - - =+= means one or more - - =1= here refers to the group within the regex that will be - modified to align the fields - - =1= is the number of spaces between fields once aligned - - =t= indicates to repeat the rule multiple times on the same line - -To use this function, simply highlight a region you want to align and -run =M-x align-non-space=. |