From 754bbf7a25a8dda49b5d08ef0d0443bbf5af0e36 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Sun, 7 Apr 2024 13:41:34 -0500 Subject: new repository --- devdocs/elisp/bool_002dvectors.html | 45 +++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 devdocs/elisp/bool_002dvectors.html (limited to 'devdocs/elisp/bool_002dvectors.html') diff --git a/devdocs/elisp/bool_002dvectors.html b/devdocs/elisp/bool_002dvectors.html new file mode 100644 index 00000000..c91cd969 --- /dev/null +++ b/devdocs/elisp/bool_002dvectors.html @@ -0,0 +1,45 @@ +

Bool-vectors

A bool-vector is much like a vector, except that it stores only the values t and nil. If you try to store any non-nil value into an element of the bool-vector, the effect is to store t there. As with all arrays, bool-vector indices start from 0, and the length cannot be changed once the bool-vector is created. Bool-vectors are constants when evaluated.

Several functions work specifically with bool-vectors; aside from that, you manipulate them with same functions used for other kinds of arrays.

Function: make-bool-vector length initial +

Return a new bool-vector of length elements, each one initialized to initial.

+
Function: bool-vector &rest objects +

This function creates and returns a bool-vector whose elements are the arguments, objects.

+
Function: bool-vector-p object +

This returns t if object is a bool-vector, and nil otherwise.

+

There are also some bool-vector set operation functions, described below:

Function: bool-vector-exclusive-or a b &optional c +

Return bitwise exclusive or of bool vectors a and b. If optional argument c is given, the result of this operation is stored into c. All arguments should be bool vectors of the same length.

+
Function: bool-vector-union a b &optional c +

Return bitwise or of bool vectors a and b. If optional argument c is given, the result of this operation is stored into c. All arguments should be bool vectors of the same length.

+
Function: bool-vector-intersection a b &optional c +

Return bitwise and of bool vectors a and b. If optional argument c is given, the result of this operation is stored into c. All arguments should be bool vectors of the same length.

+
Function: bool-vector-set-difference a b &optional c +

Return set difference of bool vectors a and b. If optional argument c is given, the result of this operation is stored into c. All arguments should be bool vectors of the same length.

+
Function: bool-vector-not a &optional b +

Return set complement of bool vector a. If optional argument b is given, the result of this operation is stored into b. All arguments should be bool vectors of the same length.

+
Function: bool-vector-subsetp a b +

Return t if every t value in a is also t in b, nil otherwise. All arguments should be bool vectors of the same length.

+
Function: bool-vector-count-consecutive a b i +

Return the number of consecutive elements in a equal b starting at i. a is a bool vector, b is t or nil, and i is an index into a.

+
Function: bool-vector-count-population a +

Return the number of elements that are t in bool vector a.

+

The printed form represents up to 8 boolean values as a single character: 

(bool-vector t nil t nil)
+     ⇒ #&4"^E"
+(bool-vector)
+     ⇒ #&0""
+
+

You can use vconcat to print a bool-vector like other vectors: 

(vconcat (bool-vector nil t nil t))
+     ⇒ [nil t nil t]
+
+

Here is another example of creating, examining, and updating a bool-vector: 

(setq bv (make-bool-vector 5 t))
+     ⇒ #&5"^_"
+(aref bv 1)
+     ⇒ t
+(aset bv 3 nil)
+     ⇒ nil
+bv
+     ⇒ #&5"^W"
+
+

These results make sense because the binary codes for control-_ and control-W are 11111 and 10111, respectively.

+

+ Copyright © 1990-1996, 1998-2022 Free Software Foundation, Inc.
Licensed under the GNU GPL license.
+ https://www.gnu.org/software/emacs/manual/html_node/elisp/Bool_002dVectors.html +

+
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