Insert continuation of a string to a new line (emacs/spacemacs)

Question

I often have long strings I want to break into new lines in various languages. E.g. in python

x = ("The quick brown fox jumps over the lazy dog")
                         /\ cursor here

becomes

x = ("The quick brown fox "
     "jumps over the lazy dog")

Or in javascript

var x = "The quick brown fox jumps over the lazy dog."
                            /\ cursor here

becomes

var x = "The quick brown fox " + 
        "jumps over the lazy dog."

Is there a way to do this in vanilla Emacs or Spacemacs?

Answer 1

The smartparens package provides the command sp-split-sexp. From the docs (for spacemacs)

sp-split-sexp is an interactive compiled Lisp function in ‘smartparens.el’.

It is bound to SPC j s, M-m j s.

(sp-split-sexp ARG)

Split the list or string the point is on into two.

If ARG is a raw prefix SPC u split all the sexps in current expression
in separate lists enclosed with delimiters of the current
expression.

See also setting ‘sp-split-sexp-always-split-as-string’ which
determines how sexps inside strings are treated and also for a
discussion of how to automatically add concatenation operators to
string splitting.

Examples:

  (foo bar |baz quux)   -> (foo bar) |(baz quux)

  "foo bar |baz quux"   -> "foo bar" |"baz quux"

  ([foo |bar baz] quux) -> ([foo] |[bar baz] quux)

  (foo bar| baz quux) -> (foo) (bar|) (baz) (quux) ;; SPC u