New Syntax Table Features

• You can use two new functions to move across characters in certain syntax classes. skip-syntax-forward moves point forward across characters whose syntax classes are mentioned in its first argument, a string. It stops when it encounters the end of the buffer, or position lim (the optional second argument), or a character it is not supposed to skip. The function skip-syntax-backward is similar but moves backward.
• The new function forward-comment moves point by comments. It takes one argument, count; it moves point forward across count comments (backward, if count is negative). If it finds anything other than a comment or whitespace, it stops, leaving point at the far side of the last comment found. It also stops after satisfying count.
• The new variable words-include-escapes affects the behavior of forward-word and everything that uses it. If it is non-nil, then characters in the "escape" and "character quote" syntax classes count as part of words.
• There are two new syntax flags for use in syntax tables.
  • The prefix flag. The `p' flag identifies additional "prefix characters" in Lisp syntax. You can set this flag with modify-syntax-entry by including the letter `p' in the syntax specification. These characters are treated as whitespace when they appear between expressions. When they appear withing an expression, they are handled according to their usual syntax codes. The function backward-prefix-chars moves back over these characters, as well as over characters whose primary syntax class is prefix (`'').
  • The `b' comment style flag. Emacs can now supports two comment styles simultaneously. (This is for the sake of C++.) More specifically, it can recognize two different comment-start sequences. Both must share the same first character; only the second character may differ. Mark the second character of the `b'-style comment start sequence with the `b' flag. You can set this flag with modify-syntax-entry by including the letter `b' in the syntax specification. The two styles of comment can have different comment-end sequences. A comment-end sequence (one or two characters) applies to the `b' style if its first character has the `b' flag set; otherwise, it applies to the `a' style. The appropriate comment syntax settings for C++ are as follows:

    `/'

    `124b'

    `*'

    `23'

    newline

    `>b'

    Thus `/*' is a comment-start sequence for `a' style, `//' is a comment-start sequence for `b' style, `*/' is a comment-end sequence for `a' style, and newline is a comment-end sequence for `b' style.