Function: calculate-lisp-indent
calculate-lisp-indent is a byte-compiled function defined in
lisp-mode.el.gz.
Signature
(calculate-lisp-indent &optional PARSE-START)
Documentation
Return appropriate indentation for current line as Lisp code.
In usual case returns an integer: the column to indent to. If the value is nil, that means don't change the indentation because the line starts inside a string.
PARSE-START may be a buffer position to start parsing from, or a
parse state as returned by calling parse-partial-sexp up to the
beginning of the current line.
The value can also be a list of the form (COLUMN CONTAINING-SEXP-START). This means that following lines at the same level of indentation should not necessarily be indented the same as this line. Then COLUMN is the column to indent to, and CONTAINING-SEXP-START is the buffer position of the start of the containing expression.
Source Code
;; Defined in /usr/src/emacs/lisp/emacs-lisp/lisp-mode.el.gz
(defun calculate-lisp-indent (&optional parse-start)
"Return appropriate indentation for current line as Lisp code.
In usual case returns an integer: the column to indent to.
If the value is nil, that means don't change the indentation
because the line starts inside a string.
PARSE-START may be a buffer position to start parsing from, or a
parse state as returned by calling `parse-partial-sexp' up to the
beginning of the current line.
The value can also be a list of the form (COLUMN CONTAINING-SEXP-START).
This means that following lines at the same level of indentation
should not necessarily be indented the same as this line.
Then COLUMN is the column to indent to, and CONTAINING-SEXP-START
is the buffer position of the start of the containing expression."
(save-excursion
(beginning-of-line)
(let ((indent-point (point))
state
;; setting this to a number inhibits calling hook
(desired-indent nil)
(retry t)
whitespace-after-open-paren
calculate-lisp-indent-last-sexp containing-sexp)
(cond ((or (markerp parse-start) (integerp parse-start))
(goto-char parse-start))
((null parse-start) (beginning-of-defun))
(t (setq state parse-start)))
(unless state
;; Find outermost containing sexp
(while (< (point) indent-point)
(setq state (parse-partial-sexp (point) indent-point 0))))
;; Find innermost containing sexp
(while (and retry
state
(> (elt state 0) 0))
(setq retry nil)
(setq calculate-lisp-indent-last-sexp (elt state 2))
(setq containing-sexp (elt state 1))
;; Position following last unclosed open.
(goto-char (1+ containing-sexp))
;; Is there a complete sexp since then?
(if (and calculate-lisp-indent-last-sexp
(> calculate-lisp-indent-last-sexp (point)))
;; Yes, but is there a containing sexp after that?
(let ((peek (parse-partial-sexp calculate-lisp-indent-last-sexp
indent-point 0)))
(if (setq retry (car (cdr peek))) (setq state peek)))))
(if retry
nil
;; Innermost containing sexp found
(goto-char (1+ containing-sexp))
(setq whitespace-after-open-paren (looking-at (rx whitespace)))
(if (not calculate-lisp-indent-last-sexp)
;; indent-point immediately follows open paren.
;; Don't call hook.
(setq desired-indent (current-column))
;; Find the start of first element of containing sexp.
(parse-partial-sexp (point) calculate-lisp-indent-last-sexp 0 t)
(cond ((looking-at "\\s(")
;; First element of containing sexp is a list.
;; Indent under that list.
)
((> (save-excursion (forward-line 1) (point))
calculate-lisp-indent-last-sexp)
;; This is the first line to start within the containing sexp.
;; It's almost certainly a function call.
(if (or (= (point) calculate-lisp-indent-last-sexp)
whitespace-after-open-paren)
;; Containing sexp has nothing before this line
;; except the first element, or the first element is
;; preceded by whitespace. Indent under that element.
nil
;; Skip the first element, find start of second (the first
;; argument of the function call) and indent under.
(progn (forward-sexp 1)
(parse-partial-sexp (point)
calculate-lisp-indent-last-sexp
0 t)))
(backward-prefix-chars))
(t
;; Indent beneath first sexp on same line as
;; `calculate-lisp-indent-last-sexp'. Again, it's
;; almost certainly a function call.
(goto-char calculate-lisp-indent-last-sexp)
(beginning-of-line)
(parse-partial-sexp (point) calculate-lisp-indent-last-sexp
0 t)
(backward-prefix-chars)))))
;; Point is at the point to indent under unless we are inside a string.
;; Call indentation hook except when overridden by lisp-indent-offset
;; or if the desired indentation has already been computed.
(let ((normal-indent (current-column)))
(cond ((elt state 3)
;; Inside a string, don't change indentation.
nil)
((and (integerp lisp-indent-offset) containing-sexp)
;; Indent by constant offset
(goto-char containing-sexp)
(+ (current-column) lisp-indent-offset))
;; in this case calculate-lisp-indent-last-sexp is not nil
(calculate-lisp-indent-last-sexp
(or
;; try to align the parameters of a known function
(and lisp-indent-function
(not retry)
(funcall lisp-indent-function indent-point state))
;; If the function has no special alignment
;; or it does not apply to this argument,
;; try to align a constant-symbol under the last
;; preceding constant symbol, if there is such one of
;; the last 2 preceding symbols, in the previous
;; uncommented line.
(and (save-excursion
(goto-char indent-point)
(skip-chars-forward " \t")
(looking-at ":"))
;; The last sexp may not be at the indentation
;; where it begins, so find that one, instead.
(save-excursion
(goto-char calculate-lisp-indent-last-sexp)
;; Handle prefix characters and whitespace
;; following an open paren. (Bug#1012)
(backward-prefix-chars)
(while (not (save-excursion
(skip-chars-backward " \t")
(or (= (point) (line-beginning-position))
(and containing-sexp
(= (point) (1+ containing-sexp))))))
(forward-sexp -1)
(backward-prefix-chars))
(setq calculate-lisp-indent-last-sexp (point)))
(> calculate-lisp-indent-last-sexp
(save-excursion
(goto-char (1+ containing-sexp))
(parse-partial-sexp (point) calculate-lisp-indent-last-sexp 0 t)
(point)))
(let ((parse-sexp-ignore-comments t)
indent)
(goto-char calculate-lisp-indent-last-sexp)
(or (and (looking-at ":")
(setq indent (current-column)))
(and (< (line-beginning-position)
(prog2 (backward-sexp) (point)))
(looking-at ":")
(setq indent (current-column))))
indent))
;; another symbols or constants not preceded by a constant
;; as defined above.
normal-indent))
;; in this case calculate-lisp-indent-last-sexp is nil
(desired-indent)
(t
normal-indent))))))