sphinx: import docs

The Yocto Project docs was migrated from Docbook to Sphinx in YP
 3.2. This 3.1 is an LTS release, and since 3.1 docs are 'close to'
 the docs in 3.2, we agreed to backport sphinx docs onto 3.1.

This first patch brings all changes done in 3.2 until:
7f64574f7 README: include detailed information about sphinx

There are other changes after this commit, but they will be
 selectively backported in individual patches.

This patch was generated with the following command:

git cherry-pick -n \
 $(git log --reverse --oneline \
 ac352ad7f95db7eeacb53c2778caa31800bd7c26..7f64574f7 \
| cut -f1 -d' ')

The following commits were applies in the dunfell docs, but not in
master, so they were first reverted (and squashed into this change). A
commit will reintroduce the content from these patches in the Sphinx
files in a followup patch.

069c27574 Documenation: Prepared for the 3.1.1 release
bd140f0f9 Documentation: Add 3.1.1 version updates missing from previous commit
17cc71a8f Documenation: Prepared for the 3.1.2 release
1a69e2c02 Documenation: Prepared for the 3.1.3 release
8910ac1c7 Documenation: Prepared for the 3.1.4 release

(From yocto-docs rev: c25fe058b88b893b0d146f3ed27320b47cdec236)

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/documentation/sphinx/yocto-vars.py b/documentation/sphinx/yocto-vars.py
new file mode 100644
index 0000000000..8083d7da19
--- /dev/null
+++ b/documentation/sphinx/yocto-vars.py
@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+import re
+import sys
+
+import sphinx
+from sphinx.application import Sphinx
+
+# This extension uses pyyaml, report an explicit
+# error message if it's not installed
+try:
+    import yaml
+except ImportError:
+    sys.stderr.write("The Yocto Project Sphinx documentation requires PyYAML.\
+    \nPlease make sure to install pyyaml python package.\n")
+    sys.exit(1)
+
+__version__  = '1.0'
+
+# Variables substitutions. Uses {VAR} subst using variables defined in poky.yaml
+# Each .rst file is processed after source-read event (subst_vars_replace runs once per file)
+subst_vars = {}
+
+def subst_vars_replace(app: Sphinx, docname, source):
+    result = source[0]
+    for k in subst_vars:
+        result = result.replace("&"+k+";", subst_vars[k])
+    source[0] = result
+
+PATTERN = re.compile(r'&(.*?);')
+def expand(val, src):
+    return PATTERN.sub(lambda m: expand(src.get(m.group(1), ''), src), val)
+
+def setup(app: Sphinx):
+    #FIXME: if poky.yaml changes, files are not reprocessed.
+    with open("poky.yaml") as file:
+        subst_vars.update(yaml.load(file, Loader=yaml.FullLoader))
+
+    for k in subst_vars:
+        subst_vars[k] = expand(subst_vars[k], subst_vars)
+
+    app.connect('source-read', subst_vars_replace)
+
+    return dict(
+        version = __version__,
+        parallel_read_safe = True,
+        parallel_write_safe = True
+    )