Documentation/sphinx/automarkup.py

   1 # SPDX-License-Identifier: GPL-2.0
   2 # Copyright 2019 Jonathan Corbet <corbet@lwn.net>
   3 #
   4 # Apply kernel-specific tweaks after the initial document processing
   5 # has been done.
   6 #
   7 from docutils import nodes
   8 import sphinx
   9 from sphinx import addnodes
  10 if sphinx.version_info[0] < 2 or \
  11    sphinx.version_info[0] == 2 and sphinx.version_info[1] < 1:
  12     from sphinx.environment import NoUri
  13 else:
  14     from sphinx.errors import NoUri
  15 import re
  16
  17 #
  18 # Regex nastiness.  Of course.
  19 # Try to identify "function()" that's not already marked up some
  20 # other way.  Sphinx doesn't like a lot of stuff right after a
  21 # :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last
  22 # bit tries to restrict matches to things that won't create trouble.
  23 #
  24 RE_function = re.compile(r'([\w_][\w\d_]+\(\))')
  25
  26 #
  27 # Many places in the docs refer to common system calls.  It is
  28 # pointless to try to cross-reference them and, as has been known
  29 # to happen, somebody defining a function by these names can lead
  30 # to the creation of incorrect and confusing cross references.  So
  31 # just don't even try with these names.
  32 #
  33 Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap',
  34               'select', 'poll', 'fork', 'execve', 'clone', 'ioctl',
  35               'socket' ]
  36
  37 #
  38 # Find all occurrences of function() and try to replace them with
  39 # appropriate cross references.
  40 #
  41 def markup_funcs(docname, app, node):
  42     cdom = app.env.domains['c']
  43     t = node.astext()
  44     done = 0
  45     repl = [ ]
  46     for m in RE_function.finditer(t):
  47         #
  48         # Include any text prior to function() as a normal text node.
  49         #
  50         if m.start() > done:
  51             repl.append(nodes.Text(t[done:m.start()]))
  52         #
  53         # Go through the dance of getting an xref out of the C domain
  54         #
  55         target = m.group(1)[:-2]
  56         target_text = nodes.Text(target + '()')
  57         xref = None
  58         if target not in Skipfuncs:
  59             lit_text = nodes.literal(classes=['xref', 'c', 'c-func'])
  60             lit_text += target_text
  61             pxref = addnodes.pending_xref('', refdomain = 'c',
  62                                           reftype = 'function',
  63                                           reftarget = target, modname = None,
  64                                           classname = None)
  65             #
  66             # XXX The Latex builder will throw NoUri exceptions here,
  67             # work around that by ignoring them.
  68             #
  69             try:
  70                 xref = cdom.resolve_xref(app.env, docname, app.builder,
  71                                          'function', target, pxref, lit_text)
  72             except NoUri:
  73                 xref = None
  74         #
  75         # Toss the xref into the list if we got it; otherwise just put
  76         # the function text.
  77         #
  78         if xref:
  79             repl.append(xref)
  80         else:
  81             repl.append(target_text)
  82         done = m.end()
  83     if done < len(t):
  84         repl.append(nodes.Text(t[done:]))
  85     return repl
  86
  87 def auto_markup(app, doctree, name):
  88     #
  89     # This loop could eventually be improved on.  Someday maybe we
  90     # want a proper tree traversal with a lot of awareness of which
  91     # kinds of nodes to prune.  But this works well for now.
  92     #
  93     # The nodes.literal test catches ``literal text``, its purpose is to
  94     # avoid adding cross-references to functions that have been explicitly
  95     # marked with cc:func:.
  96     #
  97     for para in doctree.traverse(nodes.paragraph):
  98         for node in para.traverse(nodes.Text):
  99             if not isinstance(node.parent, nodes.literal):
 100                 node.parent.replace(node, markup_funcs(name, app, node))
 101
 102 def setup(app):
 103     app.connect('doctree-resolved', auto_markup)
 104     return {
 105         'parallel_read_safe': True,
 106         'parallel_write_safe': True,
 107         }