Comparison of Vim and Emacs for a substitution operation using regular expressions
Preface
This article is a summary of two previous posts that you can read at these pages:
- “Vim: Study on constructing Regular Expressions to delete or reduce blank lines with Global Command”
- “Emacs: Study on constructing Regular Expressions to delete or reduce blank lines”
The topic of “regular expressions” in Vim and Emacs is well suited for a functional comparison across the four different scenarios covered in the above articles to which I refer for a description of the syntax.
Comparation Table
| Target | Vim | Emacs |
|---|---|---|
| Delete “pure” blank lines | :g/^$/d | M-x flush-lines <RET> ^$ <RET> |
| Delete blank lines with whitespace | :g/^\s*$/d | M-x flush-lines <RET> ^\s-*$ <RET> |
| Reduce “pure” blank lines | :g/^$\n^$/d | M-x query-replace-regexp <RET> ^C-qC-j\{2,\} <RET> C-qC-j <RET> |
| Reduce blank lines with whitespace | g/^\s*$\n^\s*$/d | ^\(^C-q<SPC>*C-qC-j\)\{2,\} <RET> C-qC-j <RET> |
Emacs: what you type is not what you see
As explained in the article on Emacs, what you type is not what you see.
Below is a brief summary table for the operation of “reducing” blank lines, the third and fourth formulas in the above table, by distinguishing the keys pressed from the characters displayed.
| Type | Visualize |
|---|---|
^C-qC-j\{2,\} <RET> C-qC-j <RET> | ^^J\{2,\} → ^J |
^\(^C-q<SPC>*C-qC-j\)\{2,\}<RET> C-qC-j <RET> | ^\(^ *^J\)\{2,\} → ^J |
Short summary
The subject of regular expressions in Vim and Emacs shows several differences between the two editors.
I am unable to determine which implementation is the best one.
It is necessary, in any case, to consider that Emacs has a very good emulator of Vim, called Evil, that allows one to use the same regular expression language as the source editor.
Thank you for your attention.