Word delimiters in standard syntax table

Question

I'm trying to configure other programs to emulate Emacs.

I know Emacs' word delimiters are:

1. User configurable
2. Mode dependent

But I'd still like to know what the default word boundary characters are. Because they are configurable and variable, I haven't found any lists.

I would love a list of the default word separators in emacs-lisp-mode. Of course, a description of how the delimiters vary by mode would be awesome too.

Answer 1

As far as I understand, in emacs -- word boundary is when next to a "w" syntax class stands char of some other class. This is in contrast to things like sentence-end which is determined by matching a regexp (sentence-end returns regexp).

Emacs lisp mode inherits standard-syntax-table:

;; from lisp-mode.el:
(defvar emacs-lisp-mode-syntax-table
  (let ((table (make-syntax-table))
  ..

(make-syntax-table is default to standard-syntax-table.)

The easiest way to browse standard-syntax-table is to enter fundamental-mode and call describe-syntax (C-h s).

Emacs lisp mode makes some tweaks to standard-syntax-table, of which I understand the following:

• `',@# are expression prefixes:

  (modify-syntax-entry ?` "'   " table)
  (modify-syntax-entry ?' "'   " table)
  (modify-syntax-entry ?, "'   " table)
  (modify-syntax-entry ?@ "'   " table)
  (modify-syntax-entry ?# "'   " table)
  

• ; starts a comment, \n ends it:

  (modify-syntax-entry ?\; "<   " table)
  (modify-syntax-entry ?\n ">   " table)
  

• \ is an escape char:

  (modify-syntax-entry ?\" "\"    " table)