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linux/Documentation/sphinx/automarkup.py
Jonathan Corbet 3e893e16af docs: Raise the minimum Sphinx requirement to 2.4.4 
Commit 31abfdda65 (docs: Deprecate use of Sphinx < 2.4.x) in 6.2 added a
warning that support for older versions of Sphinx would be going away.
There have been no complaints, so the time has come.  Raise the minimum
Sphinx version to 2.4.4 and clean out some compatibility code that we no
longer need.

Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/874jgs47fq.fsf@meer.lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-12-15 08:36:33 -07:00

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# SPDX-License-Identifier: GPL-2.0
# Copyright 2019 Jonathan Corbet <corbet@lwn.net>
#
# Apply kernel-specific tweaks after the initial document processing
# has been done.
#
from docutils import nodes
import sphinx
from sphinx import addnodes
from sphinx.errors import NoUri
import re
from itertools import chain
#
# Python 2 lacks re.ASCII...
#
try:
ascii_p3 = re.ASCII
except AttributeError:
ascii_p3 = 0
#
# Regex nastiness. Of course.
# Try to identify "function()" that's not already marked up some
# other way. Sphinx doesn't like a lot of stuff right after a
# :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last
# bit tries to restrict matches to things that won't create trouble.
#
RE_function = re.compile(r'\b(([a-zA-Z_]\w+)\(\))', flags=ascii_p3)
#
# Sphinx 2 uses the same :c:type role for struct, union, enum and typedef
#
RE_generic_type = re.compile(r'\b(struct|union|enum|typedef)\s+([a-zA-Z_]\w+)',
flags=ascii_p3)
#
# Sphinx 3 uses a different C role for each one of struct, union, enum and
# typedef
#
RE_struct = re.compile(r'\b(struct)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
RE_union = re.compile(r'\b(union)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
RE_enum = re.compile(r'\b(enum)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
RE_typedef = re.compile(r'\b(typedef)\s+([a-zA-Z_]\w+)', flags=ascii_p3)
#
# Detects a reference to a documentation page of the form Documentation/... with
# an optional extension
#
RE_doc = re.compile(r'(\bDocumentation/)?((\.\./)*[\w\-/]+)\.(rst|txt)')
RE_namespace = re.compile(r'^\s*..\s*c:namespace::\s*(\S+)\s*$')
#
# Reserved C words that we should skip when cross-referencing
#
Skipnames = [ 'for', 'if', 'register', 'sizeof', 'struct', 'unsigned' ]
#
# Many places in the docs refer to common system calls. It is
# pointless to try to cross-reference them and, as has been known
# to happen, somebody defining a function by these names can lead
# to the creation of incorrect and confusing cross references. So
# just don't even try with these names.
#
Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap',
'select', 'poll', 'fork', 'execve', 'clone', 'ioctl',
'socket' ]
c_namespace = ''
#
# Detect references to commits.
#
RE_git = re.compile(r'commit\s+(?P<rev>[0-9a-f]{12,40})(?:\s+\(".*?"\))?',
flags=re.IGNORECASE | re.DOTALL)
def markup_refs(docname, app, node):
t = node.astext()
done = 0
repl = [ ]
#
# Associate each regex with the function that will markup its matches
#
markup_func_sphinx2 = {RE_doc: markup_doc_ref,
RE_function: markup_c_ref,
RE_generic_type: markup_c_ref}
markup_func_sphinx3 = {RE_doc: markup_doc_ref,
RE_function: markup_func_ref_sphinx3,
RE_struct: markup_c_ref,
RE_union: markup_c_ref,
RE_enum: markup_c_ref,
RE_typedef: markup_c_ref,
RE_git: markup_git}
if sphinx.version_info[0] >= 3:
markup_func = markup_func_sphinx3
else:
markup_func = markup_func_sphinx2
match_iterators = [regex.finditer(t) for regex in markup_func]
#
# Sort all references by the starting position in text
#
sorted_matches = sorted(chain(*match_iterators), key=lambda m: m.start())
for m in sorted_matches:
#
# Include any text prior to match as a normal text node.
#
if m.start() > done:
repl.append(nodes.Text(t[done:m.start()]))
#
# Call the function associated with the regex that matched this text and
# append its return to the text
#
repl.append(markup_func[m.re](docname, app, m))
done = m.end()
if done < len(t):
repl.append(nodes.Text(t[done:]))
return repl
#
# Keep track of cross-reference lookups that failed so we don't have to
# do them again.
#
failed_lookups = { }
def failure_seen(target):
return (target) in failed_lookups
def note_failure(target):
failed_lookups[target] = True
#
# In sphinx3 we can cross-reference to C macro and function, each one with its
# own C role, but both match the same regex, so we try both.
#
def markup_func_ref_sphinx3(docname, app, match):
cdom = app.env.domains['c']
#
# Go through the dance of getting an xref out of the C domain
#
base_target = match.group(2)
target_text = nodes.Text(match.group(0))
xref = None
possible_targets = [base_target]
# Check if this document has a namespace, and if so, try
# cross-referencing inside it first.
if c_namespace:
possible_targets.insert(0, c_namespace + "." + base_target)
if base_target not in Skipnames:
for target in possible_targets:
if (target not in Skipfuncs) and not failure_seen(target):
lit_text = nodes.literal(classes=['xref', 'c', 'c-func'])
lit_text += target_text
pxref = addnodes.pending_xref('', refdomain = 'c',
reftype = 'function',
reftarget = target,
modname = None,
classname = None)
#
# XXX The Latex builder will throw NoUri exceptions here,
# work around that by ignoring them.
#
try:
xref = cdom.resolve_xref(app.env, docname, app.builder,
'function', target, pxref,
lit_text)
except NoUri:
xref = None
if xref:
return xref
note_failure(target)
return target_text
def markup_c_ref(docname, app, match):
class_str = {# Sphinx 2 only
RE_function: 'c-func',
RE_generic_type: 'c-type',
# Sphinx 3+ only
RE_struct: 'c-struct',
RE_union: 'c-union',
RE_enum: 'c-enum',
RE_typedef: 'c-type',
}
reftype_str = {# Sphinx 2 only
RE_function: 'function',
RE_generic_type: 'type',
# Sphinx 3+ only
RE_struct: 'struct',
RE_union: 'union',
RE_enum: 'enum',
RE_typedef: 'type',
}
cdom = app.env.domains['c']
#
# Go through the dance of getting an xref out of the C domain
#
base_target = match.group(2)
target_text = nodes.Text(match.group(0))
xref = None
possible_targets = [base_target]
# Check if this document has a namespace, and if so, try
# cross-referencing inside it first.
if c_namespace:
possible_targets.insert(0, c_namespace + "." + base_target)
if base_target not in Skipnames:
for target in possible_targets:
if not (match.re == RE_function and target in Skipfuncs):
lit_text = nodes.literal(classes=['xref', 'c', class_str[match.re]])
lit_text += target_text
pxref = addnodes.pending_xref('', refdomain = 'c',
reftype = reftype_str[match.re],
reftarget = target, modname = None,
classname = None)
#
# XXX The Latex builder will throw NoUri exceptions here,
# work around that by ignoring them.
#
try:
xref = cdom.resolve_xref(app.env, docname, app.builder,
reftype_str[match.re], target, pxref,
lit_text)
except NoUri:
xref = None
if xref:
return xref
return target_text
#
# Try to replace a documentation reference of the form Documentation/... with a
# cross reference to that page
#
def markup_doc_ref(docname, app, match):
stddom = app.env.domains['std']
#
# Go through the dance of getting an xref out of the std domain
#
absolute = match.group(1)
target = match.group(2)
if absolute:
target = "/" + target
xref = None
pxref = addnodes.pending_xref('', refdomain = 'std', reftype = 'doc',
reftarget = target, modname = None,
classname = None, refexplicit = False)
#
# XXX The Latex builder will throw NoUri exceptions here,
# work around that by ignoring them.
#
try:
xref = stddom.resolve_xref(app.env, docname, app.builder, 'doc',
target, pxref, None)
except NoUri:
xref = None
#
# Return the xref if we got it; otherwise just return the plain text.
#
if xref:
return xref
else:
return nodes.Text(match.group(0))
def get_c_namespace(app, docname):
source = app.env.doc2path(docname)
with open(source) as f:
for l in f:
match = RE_namespace.search(l)
if match:
return match.group(1)
return ''
def markup_git(docname, app, match):
# While we could probably assume that we are running in a git
# repository, we can't know for sure, so let's just mechanically
# turn them into git.kernel.org links without checking their
# validity. (Maybe we can do something in the future to warn about
# these references if this is explicitly requested.)
text = match.group(0)
rev = match.group('rev')
return nodes.reference('', nodes.Text(text),
refuri=f'https://git.kernel.org/torvalds/c/{rev}')
def auto_markup(app, doctree, name):
global c_namespace
c_namespace = get_c_namespace(app, name)
def text_but_not_a_reference(node):
# The nodes.literal test catches ``literal text``, its purpose is to
# avoid adding cross-references to functions that have been explicitly
# marked with cc:func:.
if not isinstance(node, nodes.Text) or isinstance(node.parent, nodes.literal):
return False
child_of_reference = False
parent = node.parent
while parent:
if isinstance(parent, nodes.Referential):
child_of_reference = True
break
parent = parent.parent
return not child_of_reference
#
# This loop could eventually be improved on. Someday maybe we
# want a proper tree traversal with a lot of awareness of which
# kinds of nodes to prune. But this works well for now.
#
for para in doctree.traverse(nodes.paragraph):
for node in para.traverse(condition=text_but_not_a_reference):
node.parent.replace(node, markup_refs(name, app, node))
def setup(app):
app.connect('doctree-resolved', auto_markup)
return {
'parallel_read_safe': True,
'parallel_write_safe': True,
}
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