meson: hook up update-constants helper

$ ninja -C build update-constants -v
ninja: Entering directory `build'
[1/1] /home/zbyszek/src/python-systemd/update-constants.py /home/zbyszek/src/python-systemd/src/systemd/id128-constants.h /home/zbyszek/src/python-systemd/docs/id128.rst /home/zbyszek/src/python-systemd/src/systemd/id128-defines.h /usr/include/systemd/sd-messages.h
Writing /home/zbyszek/src/python-systemd/src/systemd/id128-constants.h…
Writing /home/zbyszek/src/python-systemd/src/systemd/id128-defines.h…
Writing /home/zbyszek/src/python-systemd/docs/id128.rst…

The helper is updated to do the everything in the python script. The wrapper in
Makefile is dropped. It wasn't working properly anyway, and I think the version
in meson is enough.

Author: keszybz

Makefile

@@ -11,20 +11,6 @@ BUILD_DIR = build
 
 all: build
 
-.PHONY: update-constants
-update-constants: update-constants.py $(INCLUDE_DIR)/systemd/sd-messages.h
-	$(PYTHON) $+ src/systemd/id128-defines.h | \
-	  sort -u | \
-	  tee src/systemd/id128-defines.h.tmp | \
-	  $(SED) -n -r 's/,//g; s/#define (SD_MESSAGE_[A-Z0-9_]+)\s.*/add_id(m, "\1", \1) JOINER/p' | \
-	  sort -u > src/systemd/id128-constants.h.tmp
-	mv src/systemd/id128-defines.h{.tmp,}
-	mv src/systemd/id128-constants.h{.tmp,}
-	($(SED) 9q <docs/id128.rst && \
-	  sed -n -r 's/#define (SD_MESSAGE_[A-Z0-9_]+) .*/   .. autoattribute:: systemd.id128.\1/p' \
-	  src/systemd/id128-defines.h) >docs/id128.rst.tmp
-	mv docs/id128.rst{.tmp,}
-
 build:
 	$(PYTHON) -m build -Cbuild-dir=$(BUILD_DIR)
 

meson.build

@@ -20,4 +20,8 @@ common_c_args = [
         '-DLIBSYSTEMD_VERSION=@0@'.format(libsystemd_dep.version()),
 ]
 
+update_constants_py = files('update-constants.py')
+
 subdir('src/systemd')
+
+alias_target('update-constants', update_constants)

src/systemd/meson.build

@@ -66,3 +66,15 @@ python.install_sources(
         'test/test_id128.py',
         subdir: 'systemd/test',
 )
+
+include_dir = libsystemd_dep.get_variable(pkgconfig: 'includedir')
+
+update_constants = custom_target(
+        output: 'update-constants-impl',
+        command: [
+                update_constants_py,
+                meson.current_source_dir() / 'id128-constants.h',
+                meson.project_source_root() / 'docs/id128.rst',
+                meson.current_source_dir() / 'id128-defines.h',
+                include_dir / 'systemd/sd-messages.h',
+        ])

update-constants.py

@@ -1,11 +1,51 @@
+#!/usr/bin/env python3
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 import sys
 
-for file in sys.argv[1:]:
+def defines(file):
     lines = iter(open(file).read().splitlines())
     for line in lines:
         if line.startswith('#define SD_MESSAGE') and '_STR ' not in line:
             if line.endswith('\\'):
                 line = line[:-1] + next(lines)
-            print(' '.join(line.split()))
+            _, name, value = line.split()
+            assert 'SD_' in name
+            assert 'SD_ID128_MAKE' in value
+            yield name, value
+
+
+def process(includefile, docfile, *headers):
+    # Collects all messages from all headers and saves the sorted list back to
+    # headers[0]. Writes includefile (C) and docfile (rst).
+
+    # Collect all messages into a single sorted, deduplicated list
+    defs = sum((list(defines(file)) for file in headers), start=[])
+    defs = sorted(set(defs))
+
+    with open(includefile, 'wt') as out:
+        print(f'Writing {out.name}…')
+        for name, value in defs:
+            print(f'add_id(m, "{name}", {name}) JOINER', file=out)
+
+    with open(headers[0], 'wt') as out:
+        print(f'Writing {out.name}…')
+        for name, value in defs:
+            print(f'#define {name} {value}', file=out)
+
+    old = open(docfile).read().splitlines()
+
+    with open(docfile, 'wt') as out:
+        print(f'Writing {out.name}…')
+        for line in old:
+            print(line, file=out)
+            if 'autogenerated' in line:
+                break
+        for name, value in defs:
+            print(f'   .. autoattribute:: systemd.id128.{name}', file=out)
+
+if __name__ == '__main__':
+    includefile = sys.argv[1]
+    docfile = sys.argv[2]
+    headers = sys.argv[3:]
+    process(includefile, docfile, *headers)