Re: cc-mode error in switch in awk

[Alan M. <ac...@mu...>]

Hello, Eric.

On Thu, Nov 17, 2011 at 10:03:44AM -0600, Eric Pement wrote:
> I am using GNU Emacs version 23.3.1 for Windows, executed with
> "--no-init-file", and cc-mode version 5.32.2.

> GNU awk version 4.0 offers the switch statement as a gawk extension.
> However, when cc-mode v5.32.2 is active while editing an awk script,
> the switch statement is not properly managed in AWK mode, for both
> syntax highlighting and for line indentation.

Ah.  AWK now has switch statements.  ;-)

> In syntax highlighting, the statement "switch (somename) { ...}"
> improperly changes font color and highlighting for "h (' in the
> statement name and left parenthesis.

AWK Mode was interpreting "switch" as a user defined function name.  This
triggered the feature which warns about a space between the function name
and the opening parenthesis.

> In line indentation, following a "case /pattern/:" directive, the
> first line is properly indented, but second, third, and successive
> lines are out-dented without recognition that the "case" directive is
> still active and thus these additional lines should continue
> indentation.

This should be fixed in the patch below.

> To demonstrate the problem, I have attached a JPG image,
> "cc-mode_error_on_switch.jpg" to show this.

> If images are not supported in bug reports, name the following block
> "switch-statement-error.awk" and load it into Emacs.

> BEGIN {
>     var = "foo"
>     switch (var) {
> 	case "food":
> 	    x = 1;
> 	break;

> 	default:
> 	y = 1;
> 	break;
>     }
> }

Thanks for reporting this bug, and even more thanks that your report was
of such high quality.

Please try the following patch.  I hope it implements AWK's switch
properly.  When you compile the files, note that cc-langs.el must be
compiled first, and cc-engine.el and cc-mode.el must also be compiled as
well as cc-awk.el.  Or just compile the whole lot.  :-)

Please let me know how it performs.



*** orig/cc-awk.el	2011-11-20 11:10:37.000000000 +0000
--- cc-awk.el	2011-11-20 12:41:37.000000000 +0000
***************
*** 897,903 ****
  	     (regexp-opt
  	      '("BEGIN" "END" "break" "continue" "delete" "do" "else"
  		"exit" "for" "getline" "if" "in" "next" "nextfile"
! 		"return" "while")
  	      t) "\\>")
  
       ;; Builtins.
--- 897,903 ----
  	     (regexp-opt
  	      '("BEGIN" "END" "break" "continue" "delete" "do" "else"
  		"exit" "for" "getline" "if" "in" "next" "nextfile"
! 		"return" "switch" "while")
  	      t) "\\>")
  
       ;; Builtins.
*** orig/cc-langs.el	2011-11-20 11:10:37.000000000 +0000
--- cc-langs.el	2011-11-20 12:54:35.000000000 +0000
***************
*** 2235,2242 ****
  
  (c-lang-defconst c-label-kwds
    "Keywords introducing colon terminated labels in blocks."
!   t '("case" "default")
!   awk nil)
  
  (c-lang-defconst c-label-kwds-regexp
    ;; Adorned regexp matching any keyword that introduces a label.
--- 2235,2241 ----
  
  (c-lang-defconst c-label-kwds
    "Keywords introducing colon terminated labels in blocks."
!   t '("case" "default"))
  
  (c-lang-defconst c-label-kwds-regexp
    ;; Adorned regexp matching any keyword that introduces a label.
***************
*** 2990,3007 ****
  tested at the beginning of every sexp in a suspected label,
  i.e. before \":\".  Only used if `c-recognize-colon-labels' is set."
    t (concat
-      ;; Don't allow string literals.  Character constants are OK.
-      "\"\\|"
       ;; All keywords except `c-label-kwds' and `c-protection-kwds'.
       (c-make-keywords-re t
         (set-difference (c-lang-const c-keywords)
  		       (append (c-lang-const c-label-kwds)
  			       (c-lang-const c-protection-kwds))
  		       :test 'string-equal)))
    ;; Also check for open parens in C++, to catch member init lists in
    ;; constructors.  We normally allow it so that macros with arguments
    ;; work in labels.
!   c++ (concat "\\s\(\\|" (c-lang-const c-nonlabel-token-key)))
  (c-lang-defvar c-nonlabel-token-key (c-lang-const c-nonlabel-token-key))
  
  (c-lang-defconst c-nonlabel-token-2-key
--- 2989,3007 ----
  tested at the beginning of every sexp in a suspected label,
  i.e. before \":\".  Only used if `c-recognize-colon-labels' is set."
    t (concat
       ;; All keywords except `c-label-kwds' and `c-protection-kwds'.
       (c-make-keywords-re t
         (set-difference (c-lang-const c-keywords)
  		       (append (c-lang-const c-label-kwds)
  			       (c-lang-const c-protection-kwds))
  		       :test 'string-equal)))
+   ;; Don't allow string literals, except in AWK.  Character constants are OK.
+   (c objc java pike idl) (concat "\"\\|"
+ 				 (c-lang-const c-nonlabel-token-key))
    ;; Also check for open parens in C++, to catch member init lists in
    ;; constructors.  We normally allow it so that macros with arguments
    ;; work in labels.
!   c++ (concat "\\s\(\\|\"\\|" (c-lang-const c-nonlabel-token-key)))
  (c-lang-defvar c-nonlabel-token-key (c-lang-const c-nonlabel-token-key))
  
  (c-lang-defconst c-nonlabel-token-2-key

> Kind regards,

> Eric Pement - eri...@gm...

-- 
Alan Mackenzie (Nuremberg, Germany).