Learning GNU Emacs, 3rd Edition

Useful Built-in Emacs Functions

Many of the Emacs functions that exist and that you may write involve searching and manipulating the text in a buffer. Such functions are particularly useful in specialized modes, like the programming language modes described in Chapter 9. Many built-in Emacs functions relate to text in strings and buffers; the most interesting ones take advantage of Emacs's regular expression facility, which we introduced in Chapter 3.

We first describe the basic functions relating to buffers and strings that don't use regular expressions. Afterwards, we discuss regular expressions in more depth than was the case in Chapter 3, concentrating on the features that are most useful to Lisp programmers, and we describe the functions that Emacs makes available for dealing with regular expressions.

Buffers, Text, and Regions

Table 11-4 shows some basic Emacs functions relating to buffers, text, and strings that are only useful to Lisp programmers and thus aren't bound to keystrokes. We already saw a couple of them in the count-words-buffer example. Notice that some of these are predicates, and their names reflect this.

Table 11-4. Buffer and text functions

Function	Value or action
point	Character position of point.
mark	Character position of mark.
point-min	Minimum character position (usually 1).
point-max	Maximum character position (usually size of buffer).
bolp	Whether point is at the beginning of the line (t or nil).
eolp	Whether point ...