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comparison src/fns.c @ 209:41ff10fd062f r20-4b3

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Import from CVS: tag r20-4b3
author cvs
date Mon, 13 Aug 2007 10:04:58 +0200
parents e45d5e7c476e
children 78478c60bfcd
comparison
equal deleted inserted replaced
208:f427b8ec4379 209:41ff10fd062f
3349 DEFUN ("featurep", Ffeaturep, 1, 1, 0, /* 3349 DEFUN ("featurep", Ffeaturep, 1, 1, 0, /*
3350 Return non-nil if feature FEXP is present in this Emacs. 3350 Return non-nil if feature FEXP is present in this Emacs.
3351 Use this to conditionalize execution of lisp code based on the 3351 Use this to conditionalize execution of lisp code based on the
3352 presence or absence of emacs or environment extensions. 3352 presence or absence of emacs or environment extensions.
3353 FEXP can be a symbol, a number, or a list. 3353 FEXP can be a symbol, a number, or a list.
3354 If a symbol, it will be looked up in the `features' variable, and 3354 If it is a symbol, that symbol is looked up in the `features' variable,
3355 non-nil will be returned if it is found. 3355 and non-nil will be returned if found.
3356 If FEXP is a number, the function will return non-nil if this Emacs 3356 If it is a number, the function will return non-nil if this Emacs
3357 has an equal or greater version number than FEXP. 3357 has an equal or greater version number than FEXP.
3358 If FEXP is a list whose car is the symbol `and', it will return 3358 If it is a list whose car is the symbol `and', it will return
3359 non-nil if all the features in its cdr are non-nil. 3359 non-nil if all the features in its cdr are non-nil.
3360 If FEXP is a list whose car is the symbol `or', it will return non-nil 3360 If it is a list whose car is the symbol `or', it will return non-nil
3361 if any of the features in its cdr are non-nil. 3361 if any of the features in its cdr are non-nil.
3362 If FEXP is a list whose car is the symbol `not', it will return 3362 If it is a list whose car is the symbol `not', it will return
3363 non-nil if the feature is not present. 3363 non-nil if the feature is not present.
3364
3365 Examples:
3366
3367 (featurep 'xemacs)
3368 => ; Non-nil on XEmacs.
3369
3370 (featurep '(and xemacs gnus))
3371 => ; Non-nil on XEmacs with Gnus loaded.
3372
3373 (featurep '(or tty-frames (and emacs 19.30)))
3374 => ; Non-nil if this Emacs supports TTY frames.
3375
3376 (featurep '(or (and xemacs 19.15) (and emacs 19.34)))
3377 => ; Non-nil on XEmacs 19.15 and later, or FSF Emacs 19.34 and later.
3378
3379 NOTE: The advanced arguments of this function (anything other than a
3380 symbol) are not yet supported by FSF Emacs. If you feel they are useful
3381 for supporting multiple Emacs variants, lobby Richard Stallman at
3382 <bug-gnu-emacs@prep.ai.mit.edu>.
3364 */ 3383 */
3365 (fexp)) 3384 (fexp))
3366 { 3385 {
3367 #ifndef FEATUREP_SYNTAX 3386 #ifndef FEATUREP_SYNTAX
3368 CHECK_SYMBOL (fexp); 3387 CHECK_SYMBOL (fexp);
3369 return NILP (Fmemq (fexp, Vfeatures)) ? Qnil : Qt; 3388 return NILP (Fmemq (fexp, Vfeatures)) ? Qnil : Qt;
3370 #else /* FEATUREP_SYNTAX */ 3389 #else /* FEATUREP_SYNTAX */
3371 extern Lisp_Object Vemacs_major_version, Vemacs_minor_version; 3390 extern Lisp_Object Vemacs_major_version, Vemacs_minor_version;
3391 extern Lisp_Object Qfeaturep;
3372 static double featurep_emacs_version; 3392 static double featurep_emacs_version;
3373 3393
3374 /* Brute force translation from Erik Naggum's lisp function. */ 3394 /* Brute force translation from Erik Naggum's lisp function. */
3375 if (SYMBOLP(fexp)) 3395 if (SYMBOLP(fexp))
3376 { 3396 {
3398 Lisp_Object negate; 3418 Lisp_Object negate;
3399 3419
3400 tem = XCDR (fexp); 3420 tem = XCDR (fexp);
3401 negate = Fcar (tem); 3421 negate = Fcar (tem);
3402 if (!NILP (tem)) 3422 if (!NILP (tem))
3403 return NILP (Ffeaturep (negate)) ? Qt : Qnil; 3423 return NILP (call1 (Qfeaturep, negate)) ? Qt : Qnil;
3404 else 3424 else
3405 return Fsignal (Qinvalid_read_syntax, list1 (tem)); 3425 return Fsignal (Qinvalid_read_syntax, list1 (tem));
3406 } 3426 }
3407 else if (EQ(tem, Qand)) 3427 else if (EQ(tem, Qand))
3408 { 3428 {
3409 tem = XCDR(fexp); 3429 tem = XCDR(fexp);
3410 /* Use Fcar/Fcdr for error-checking. */ 3430 /* Use Fcar/Fcdr for error-checking. */
3411 while (!NILP (tem) && !NILP (Ffeaturep (Fcar (tem)))) 3431 while (!NILP (tem) && !NILP (call1 (Qfeaturep, Fcar (tem))))
3412 { 3432 {
3413 tem = Fcdr (tem); 3433 tem = Fcdr (tem);
3414 } 3434 }
3415 return NILP(tem) ? Qt : Qnil; 3435 return NILP(tem) ? Qt : Qnil;
3416 } 3436 }
3417 else if (EQ(tem, Qor)) 3437 else if (EQ(tem, Qor))
3418 { 3438 {
3419 tem = XCDR (fexp); 3439 tem = XCDR (fexp);
3420 /* Use Fcar/Fcdr for error-checking. */ 3440 /* Use Fcar/Fcdr for error-checking. */
3421 while (!NILP (tem) && NILP (Ffeaturep (Fcar (tem)))) 3441 while (!NILP (tem) && NILP (call1 (Qfeaturep, Fcar (tem))))
3422 { 3442 {
3423 tem = Fcdr (tem); 3443 tem = Fcdr (tem);
3424 } 3444 }
3425 return NILP(tem) ? Qnil : Qt; 3445 return NILP(tem) ? Qnil : Qt;
3426 } 3446 }