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1 ;;; c-mode.el --- C code editing commands for Emacs
2 ;; Copyright (C) 1985, 1986, 1987, 1992, 1994 Free Software Foundation, Inc.
4 ;; Maintainer: FSF
5 ;; Keywords: c
7 ;; This file is part of GNU Emacs.
9 ;; GNU Emacs is free software; you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation; either version 2, or (at your option)
12 ;; any later version.
14 ;; GNU Emacs is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with GNU Emacs; see the file COPYING. If not, write to
21 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
23 ;;; Commentary:
25 ;; A smart editing mode for C code. It knows a lot about C syntax and tries
26 ;; to position the curser according to C layout conventions. You can
27 ;; change the details of the layout style with option variables. Load it
28 ;; and do M-x describe-mode for details.
30 ;;; Code:
84 "Display the result of expanding all C macros occurring in the region.
85 The expansion is entirely correct because it uses the C preprocessor."
86 t)
92 ()
120 "*Extra indent for substatements that start with open-braces.
156 "*Non-nil means automatically newline before and after braces,
157 and after colons and semicolons, inserted in C code.
158 If you do not want a leading newline before braces then use:
162 "*Non-nil means TAB in C mode should always reindent the current line,
165 ;;; Regular expression used internally to recognize labels in switch
166 ;;; statements.
169 \f
171 "Major mode for editing C code.
172 Expression and list commands understand all C brackets.
173 Tab indents for C code.
174 Comments are delimited with /* ... */.
175 Paragraphs are separated by blank lines only.
176 Delete converts tabs to spaces as it moves back.
178 Variables controlling indentation style:
179 c-tab-always-indent
180 Non-nil means TAB in C mode should always reindent the current line,
181 regardless of where in the line point is when the TAB command is used.
182 c-auto-newline
183 Non-nil means automatically newline before and after braces,
184 and after colons and semicolons, inserted in C code.
185 c-indent-level
186 Indentation of C statements within surrounding block.
187 The surrounding block's indentation is the indentation
188 of the line on which the open-brace appears.
189 c-continued-statement-offset
190 Extra indentation given to a substatement, such as the
191 then-clause of an if or body of a while.
192 c-continued-brace-offset
193 Extra indentation given to a brace that starts a substatement.
194 This is in addition to c-continued-statement-offset.
195 c-brace-offset
196 Extra indentation for line if it starts with an open brace.
197 c-brace-imaginary-offset
198 An open brace following other text is treated as if it were
199 this far to the right of the start of its line.
200 c-argdecl-indent
201 Indentation level of declarations of C function arguments.
202 c-label-offset
203 Extra indentation for line that is a label, or case or default.
205 Settings for K&R and BSD indentation styles are
206 c-indent-level 5 8
207 c-continued-statement-offset 5 8
208 c-brace-offset -5 -8
209 c-argdecl-indent 0 8
210 c-label-offset -5 -8
212 Turning on C mode calls the value of the variable c-mode-hook with no args,
213 if that value is non-nil."
255 \f
256 ;; This is used by indent-for-comment
257 ;; to decide how much to indent a comment in C code
258 ;; based on its context.
266 ;; A comment following a solitary close-brace
267 ;; should have only one space.
277 ;; If comment-column is 0, and nothing but space
278 ;; before the comment, align it at 0 rather than 1.
286 If any of the current line is a comment or within a comment,
287 fill the comment or the paragraph of it that point is in,
288 preserving the comment indentation or line-starting decorations."
292 ;; Check for obvious entry to comment.
304 ;; Lines containing just a comment start or just an end
305 ;; should not be filled into paragraphs they are next to.
307 paragraph-start
311 paragraph-separate
315 ;; Move up to first line of this comment.
320 ;; Find the comment start in this line.
322 ;; Set the fill-prefix to be what all lines except the first
323 ;; should start with.
328 "//"
331 ;; Narrow down to just the lines of this comment.
343 ;; t if we enter a comment between start of function and this line.
345 ;; t if this line contains a comment starter.
353 t)
355 ;; Inside a comment: fill one comment paragraph.
357 ;; The prefix for each line of this paragraph
358 ;; is the appropriate part of the start of this line,
359 ;; up to the column at which text should be indented.
373 ;; How shall we decide where the end of the
374 ;; fill-prefix is?
375 ;; calculate-c-indent-within-comment bases its value
376 ;; on the indentation of previous lines; if they're
377 ;; indented specially, it could return a column
378 ;; that's well into the current line's text. So
379 ;; we'll take at most that many space, tab, or *
380 ;; characters, and use that as our fill prefix.
385 t)
391 ;; If the comment is only one line followed by a blank
392 ;; line, calling move-to-column above may have added
393 ;; some spaces and tabs to the end of the line; the
394 ;; fill-paragraph function will then delete it and the
395 ;; newline following it, so we'll lose a blank line
396 ;; when we shouldn't. So delete anything
397 ;; move-to-column added to the end of the line. We
398 ;; record the line width instead of the position of the
399 ;; old line end because move-to-column might break a
400 ;; tab into spaces, and the new characters introduced
401 ;; there shouldn't be deleted.
403 ;; If you can see a better way to do this, please make
404 ;; the change. This seems very messy to me.
410 ;; Lines containing just a comment start or just an end
411 ;; should not be filled into paragraphs they are next to.
413 paragraph-start
417 paragraph-separate
421 ;; Don't fill the comment together with the code following it.
422 ;; So temporarily exclude everything before the comment start,
423 ;; and everything after the line where the comment ends.
424 ;; If comment-start-place is non-nil, the comment starter is there.
425 ;; Otherwise, point is inside the comment.
430 ;; Protect text before the comment start
431 ;; by excluding it. Add spaces to bring back
432 ;; proper indentation of that point.
445 ;; Delete the chars we inserted to avoid clobbering
446 ;; the stuff before the comment start.
450 ;; Find the comment ender (should be on last line of buffer,
451 ;; given the narrowing) and don't leave it on its own line.
452 ;; Do this with a fill command, so as to preserve sentence
453 ;; boundaries.
462 ;; Outside of comments: do ordinary filling.
466 "Insert character and correct line's indentation."
481 ;; (newline) may have done auto-fill
494 "Insert character and correct line's indentation."
504 "Insert character and correct line's indentation."
511 "Insert character and correct line's indentation."
519 ;; Colon is special only after a label, or case ....
520 ;; So quickly rule out most other uses of colon
521 ;; and do no indentation for them.
539 ;; (newline) may have done auto-fill
560 \f
562 "Indent current line as C code, or in some cases insert a tab character.
563 If `c-tab-always-indent' is non-nil (the default), always indent current line.
564 Otherwise, indent the current line only if point is at the left margin or
565 in the line's indentation; otherwise insert a tab.
567 A numeric argument, regardless of its value, means indent rigidly all the
568 lines of the expression starting after point so that this line becomes
569 properly indented. The relative indentation among the lines of the
570 expression are preserved."
573 ;; If arg, always indent this line as C
574 ;; and shift remaining lines of expression the same amount.
576 beg end)
580 ;; Find beginning of following line.
583 ;; Find first beginning-of-sexp for sexp extending past this line.
598 "Indent current line as C code.
599 Return the amount the indentation changed by."
601 beg shift-amt
635 ;; This is a `while' that ends a do-while.
650 ;; If initial point was within line's indentation,
651 ;; position after the indentation. Else stay at same point in text.
654 shift-amt))
657 "Return appropriate indentation for current line as C code.
658 In usual case returns an integer: the column to indent to.
659 Returns nil if line starts inside a string, t if in a comment."
664 state
665 containing-sexp)
674 ;; return nil or t if should not change this line
677 ;; Line is at top level. May be data or function definition,
678 ;; or may be function argument declaration.
679 ;; Indent like the previous top level line
680 ;; unless that ends in a closeparen without semicolon,
681 ;; in which case this line is the first argument decl.
687 ;; Look at previous line that's at column 0
688 ;; to determine whether we are in top-level decls
689 ;; or function's arg decls. Set basic-indent accordingly.
694 ;; Recognize the DEFUN macro in Emacs.
696 ;; Move down to the (putative) argnames line.
700 ;; Go back to the DEFUN, if it is one.
706 c-argdecl-indent
708 ;; This is careful to stop at the first
709 ;; paren if we have
710 ;; int foo Proto ((int, int));
722 ;; Make sure the "function decl" we found
723 ;; is not inside a comment.
725 ;; Move back to the `(' starting arglist
734 basic-indent)))
736 ;; ;; Now add a little if this is a continuation line.
737 ;; (+ basic-indent (if (or (bobp)
738 ;; (memq (preceding-char) '(?\) ?\; ?\}))
739 ;; ;; Line with zero indentation
740 ;; ;; is probably the return-type
741 ;; ;; of a function definition,
742 ;; ;; so following line is function name.
743 ;; (= (current-indentation) 0))
744 ;; 0 c-continued-statement-offset))
747 ;; line is expression, not statement:
748 ;; indent to just after the surrounding open.
752 ;; Statement level. Is it a continuation or a new statement?
753 ;; Find previous non-comment character.
756 ;; Back up over label lines, since they don't
757 ;; affect whether our line is a continuation.
768 ;; Check for a preprocessor statement or its continuation lines.
769 ;; Move back to end of previous non-preprocessor line,
770 ;; or possibly beginning of buffer.
776 stop t))
780 ;; This line is not preceded by a backslash.
781 ;; So either it starts a preprocessor command
782 ;; or any following continuation lines
783 ;; should not be skipped.
789 ;; Now we get the answer.
791 ;; But don't treat a line with a close-brace
792 ;; as a continuation. It is probably the
793 ;; end of an enum type declaration.
798 ;; This line is continuation of preceding line's statement;
799 ;; indent c-continued-statement-offset more than the
800 ;; previous line of the statement.
808 ;; This line starts a new statement.
809 ;; Position following last unclosed open.
811 ;; Is line first statement after an open-brace?
813 ;; If no, find that first statement and indent like it.
819 ;; Skip over comments and labels following openbrace.
825 ;; case or label:
830 ;; The first following code counts
831 ;; if it is before the line we want to indent.
837 ;; If prev stmt starts with open-brace, that
838 ;; open brace was offset by c-brace-offset.
839 ;; Compensate to get the column where
840 ;; an ordinary statement would start.
842 ;; If no previous statement,
843 ;; indent it relative to line brace is on.
844 ;; For open brace in column zero, don't let statement
845 ;; start there too. If c-indent-level is zero,
846 ;; use c-brace-offset + c-continued-statement-offset instead.
847 ;; For open-braces not the first thing in a line,
848 ;; add in c-brace-imaginary-offset.
851 c-indent-level)
852 ;; Move back over whitespace before the openbrace.
853 ;; If openbrace is not first nonwhite thing on the line,
854 ;; add the c-brace-imaginary-offset.
857 ;; If the openbrace is preceded by a parenthesized exp,
858 ;; move to the beginning of that;
859 ;; possibly a different line
863 ;; Get initial indentation of the line we are on.
867 "Return the indentation amount for line inside a block comment.
868 Optional arg AFTER-STAR means, if lines in the comment have a leading star,
869 return the indentation of the text that would follow this star."
883 star-start
932 "If point follows a `do' statement, move to beginning of it and return t.
933 Otherwise return nil and don't move point."
941 ;; Move back one token or one brace or paren group.
943 ;; If we find an open-brace, we lose.
946 nil
947 ;; If we reached a `do', we win.
950 ;; Otherwise, if we skipped a semicolon, we lose.
951 ;; (Exception: we can skip one semicolon before getting
952 ;; to a the last token of the statement, unless that token
953 ;; is a close brace.)
963 ;; If we go too far back in the buffer, we lose.
967 t
969 nil)))
970 \f
972 "Go to the beginning of the innermost C statement.
973 With prefix arg, go back N - 1 statements. If already at the beginning of a
974 statement then go to the beginning of the preceding one.
975 If within a string or comment, or next to a comment (only whitespace between),
976 move by sentences instead of statements."
996 "Go to the end of the innermost C statement.
997 With prefix arg, go forward N - 1 statements.
998 Move forward to end of the next statement if already at end.
999 If within a string or comment, move by sentences instead of statements."
1035 \f
1037 "Put mark at end of C function, point at beginning."
1044 \f
1045 ;; Idea of ENDPOS is, indent each line, stopping when
1046 ;; ENDPOS is encountered. But it's too much of a pain to make that work.
1048 "Indent each line of the C grouping following point."
1055 ;; Find previous fcn-start.
1060 ;; Try to find containing open,
1061 ;; but don't scan past that fcn-start.
1068 ;; We gave up: must be between fcns.
1069 ;; Set opoint to beg of prev fcn
1070 ;; since otherwise calculate-c-indent
1071 ;; will get wrong answers.
1076 restart outer-loop-done inner-loop-done state ostate
1077 this-indent last-sexp
1078 at-else at-brace at-while
1079 last-depth this-point
1081 ;; If the braces don't match, get an error right away.
1084 ;; Realign the comment on the first line, even though we don't reindent it.
1088 comment-start-skip
1090 ;; Make sure this isn't a comment alone on a line
1091 ;; (which should be indented like code instead).
1096 ;; Make sure the comment starter we found
1097 ;; is not actually in a string or quoted.
1100 nil nil state)))
1109 ;; Compute how depth changes over this line
1110 ;; plus enough other lines to get to one that
1111 ;; does not end inside a comment or string.
1112 ;; Meanwhile, do appropriate indentation on comment lines.
1118 nil nil state))
1123 ;; If this line started within a comment, indent it as such.
1126 ;; If it ends outside of comments or strings, exit the inner loop.
1127 ;; Otherwise move on to next line.
1140 nil
1141 ;; If this line had ..))) (((.. in it, pop out of the levels
1142 ;; that ended anywhere in this line, even if the final depth
1143 ;; doesn't indicate that they ended.
1150 ;; Add levels for any parens that were started in this line.
1161 ;; Don't really reindent if the line is just whitespace,
1162 ;; or if it is past the endpos.
1163 ;; (The exit test in the outer while
1164 ;; does not exit until we have passed the first line
1165 ;; past the region.)
1167 nil
1170 ;; Line is on an existing nesting level.
1171 ;; Lines inside parens are handled specially.
1174 ;; Line is at statement level.
1175 ;; Is it a new statement? Is it an else?
1176 ;; Find last non-comment character before this line
1186 ;; Preceding line did not end in comma or semi;
1187 ;; indent this line c-continued-statement-offset
1188 ;; more than previous.
1194 ;; Preceding line ended in comma or semi;
1195 ;; use the standard indent for this level.
1205 ;; Just started a new nesting level.
1206 ;; Compute the standard indent for this level.
1210 opoint))))
1211 ;; t means we are in a block comment and should
1212 ;; calculate accordingly.
1217 ;; Adjust line indentation according to its contents
1227 ;; Don't move an open-brace in column 0.
1228 ;; This is good when constructs such as
1229 ;; `extern "C" {' surround a function definition
1230 ;; that should be indented as usual.
1231 ;; It is also good for nested functions.
1232 ;; It is bad when an open-brace is indented at column 0
1233 ;; and you want to fix that, but we can't win 'em all.
1237 ;; Don't leave indentation in empty lines.
1239 ;; Put chosen indentation into effect.
1245 ;; Indent any comment following the text.
1249 comment-start-skip
1251 ;; Make sure the comment starter we found
1252 ;; is not actually in a string or quoted.
1255 nil nil state)))
1259 ;; Look at all comment-start strings in the current line after point.
1260 ;; Return t if one of them starts a real comment.
1261 ;; This is not used yet, because indent-for-comment
1262 ;; isn't smart enough to handle the cases this can find.
1268 t))
1269 ;; Make sure the comment start is not quoted.
1275 win))
1277 ;; Indent every line whose first char is between START and END inclusive.
1281 ;; Advance to first nonblank line.
1287 ;; Indent one line as with TAB.
1289 nextline sexpbeg sexpend)
1293 ;; Find beginning of following line.
1296 ;; Find first beginning-of-sexp for sexp extending past this line.
1308 ;; Make sure the sexp we found really starts on the
1309 ;; current line and extends past it.
1313 ;; If that sexp ends within the region,
1314 ;; indent it all at once, fast.
1320 ;; Move to following line and try again.
1324 \f
1326 "Set C-mode variables to use one of several different indentation styles.
1327 The arguments are a string representing the desired style
1328 and a flag which, if non-nil, means to set the style globally.
1329 \(Interactively, the flag comes from the prefix argument.)
1330 Available styles are GNU, K&R, BSD and Whitesmith."
1332 c-style-alist nil t)
1333 current-prefix-arg))
1342 \f
1343 ;;; This page handles insertion and removal of backslashes for C macros.
1349 "Insert, align, or delete end-of-line backslashes on the lines in the region.
1350 With no argument, inserts backslashes and aligns existing backslashes.
1351 With an argument, deletes the backslashes.
1353 This function does not modify the last line of the region if the region ends
1354 right at the start of the following line; it does not modify blank lines
1355 at the start of the region. So you can put the region around an entire macro
1356 definition and conveniently use this command."
1363 ;; Compute the smallest column number past the ends of all the lines.
1372 ;; Adjust upward to a tab column, if that doesn't push past the margin.
1377 ;; Don't modify blank lines at start of region.
1381 ;; Add or remove backslashes on all the lines.
1383 ;; Don't backslashify the last line
1384 ;; if the region ends right at the start of the next line.
1396 ;; Note that "\\\\" is needed to get one backslash.
1412 \f
1414 "Move back to the containing preprocessor conditional, leaving mark behind.
1415 A prefix argument acts as a repeat count. With a negative argument,
1416 move forward to the end of the containing preprocessor conditional.
1417 When going backwards, `#elif' is treated like `#else' followed by `#if'.
1418 When going forwards, `#elif' is ignored."
1423 "Move back across a preprocessor conditional, leaving mark behind.
1424 A prefix argument acts as a repeat count. With a negative argument,
1425 move forward across a preprocessor conditional."
1430 "Move forward across a preprocessor conditional, leaving mark behind.
1431 A prefix argument acts as a repeat count. With a negative argument,
1432 move backward across a preprocessor conditional."
1443 ;; Find the "next" significant line in the proper direction.
1445 ;; Rather than searching for a # sign that comes
1446 ;; at the beginning of a line aside from whitespace,
1447 ;; search first for a string starting with # sign.
1448 ;; Then verify what precedes it.
1449 ;; This is faster on account of the fastmap feature of
1450 ;; the regexp matcher.
1453 nil t))
1455 ;; Now verify it is really a preproc line.
1458 ;; Update depth according to what we found.
1466 ;; If we are trying to move across, and we find
1467 ;; an end before we find a beginning, get an error.
1470 "No following conditional at this level"
1472 ;; When searching forward, start from next line
1473 ;; so that we don't find the same line again.
1475 ;; If this line exits a level of conditional, exit inner loop.
1485 ;;; c-mode.el ends here