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| -rw-r--r-- | doc/lispref/text.texi | 77 |
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diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi index 4c3a1a01e7d..6b93e51fc60 100644 --- a/doc/lispref/text.texi +++ b/doc/lispref/text.texi @@ -2365,83 +2365,6 @@ already indented, it calls @code{completion-at-point} to complete the text at point (@pxref{Completion in Buffers}). @end defopt -@cindex literate programming -@cindex multi-mode indentation - Some major modes need to support embedded regions of text whose -syntax belongs to a different major mode. Examples include -@dfn{literate programming} source files that combine documentation and -snippets of source code, Yacc/Bison programs that include snippets of -plain C code, etc. To correctly indent the embedded chunks, the major -mode needs to delegate the indentation to another mode's indentation -engine (e.g., call @code{c-indent-defun} for C code or -@code{python-indent-line} for Python), while providing it with some -context to guide the indentation. The following facilities support -such multi-mode indentation. - -@defvar prog-indentation-context -This variable, when non-@code{nil}, holds the indentation context for -the sub-mode's indentation engine provided by the superior major mode. -The value should be a list of the form @code{(@var{first-column} -@w{(@var{start} . @var{end})} @code{prev-chunk})}. The members of the -list have the following meaning: - -@table @var -@item first-column -The column to be used for top-level constructs. This replaces the -default value of the top-level column used by the sub-mode, usually -zero. -@item start -@itemx end -The region of the code chunk to be indented by the sub-mode. The -value of @var{end} can be @code{nil}, which stands for the value of -@code{point-max}. -@item prev-chunk -If this is non-@code{nil}, it should provide the sub-mode's -indentation engine with a virtual context of the code chunk. Valid -values include: - -@itemize @minus -@item -A string whose contents is the text the sub-mode's indentation engine -should consider to precede the code chunk. The sub-mode's indentation -engine can add text properties to that string, to be reused in -repeated calls with the same string, thus using it as a cache. An -example where this is useful is code chunks that need to be indented -as function bodies, but lack the function's preamble---the string -could then include that missing preamble. -@item -A function. It is expected to be called with the start position of -the current chunk, and should return a cons cell -@w{@code{(@var{prev-start} . @var{prev-end})}} that specifies the -region of the previous code chunk, or @code{nil} if there is no previous -chunk. This is useful in literate-programming sources, where code is -split into chunks, and correct indentation needs to access previous -chunks. -@end itemize -@end table -@end defvar - -The following convenience functions should be used by major mode's -indentation engine in support of invocations as sub-modes of another -major mode. - -@defun prog-first-column -Call this function instead of using a literal value (usually, zero) of -the column number for indenting top-level program constructs. The -function's value is the column number to use for top-level constructs. -When no superior mode is in effect, this function returns zero. -@end defun - -@defun prog-widen -Call this function instead of @code{widen} to remove any restrictions -imposed by the mode's indentation engine and restore the restrictions -recorded in @code{prog-indentation-context}. This prevents the -indentation engine of a sub-mode from inadvertently operating on text -outside of the chunk it was supposed to indent, and preserves the -restriction imposed by the superior mode. When no superior mode is in -effect, this function just calls @code{widen}. -@end defun - @node Region Indent @subsection Indenting an Entire Region |