Add source tags targets

docs/markdown/snippets/tags.md

@@ -0,0 +1,4 @@
+## Source tags targets
+
+When the respective tools are available, 'ctags', 'TAGS' and 'cscope'
+targets will be generated by Meson, unless you have defined your own.

mesonbuild/backend/ninjabackend.py

@@ -2682,11 +2682,29 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
             return
         self.generate_clangtool('tidy')
 
+    def generate_tags(self, tool, target_name):
+        import shutil
+        if not shutil.which(tool):
+            return
+        if target_name in self.all_outputs:
+            return
+        cmd = self.environment.get_build_command() + \
+            ['--internal', 'tags', tool, self.environment.source_dir]
+        elem = NinjaBuildElement(self.all_outputs, 'meson-' + target_name, 'CUSTOM_COMMAND', 'PHONY')
+        elem.add_item('COMMAND', cmd)
+        elem.add_item('pool', 'console')
+        self.add_build(elem)
+        # Alias that runs the target defined above
+        self.create_target_alias('meson-' + target_name)
+
     # For things like scan-build and other helper tools we might have.
     def generate_utils(self):
         self.generate_scanbuild()
         self.generate_clangformat()
         self.generate_clangtidy()
+        self.generate_tags('etags', 'TAGS')
+        self.generate_tags('ctags', 'ctags')
+        self.generate_tags('cscope', 'cscope')
         cmd = self.environment.get_build_command() + ['--internal', 'uninstall']
         elem = NinjaBuildElement(self.all_outputs, 'meson-uninstall', 'CUSTOM_COMMAND', 'PHONY')
         elem.add_item('COMMAND', cmd)

mesonbuild/scripts/tags.py

@@ -0,0 +1,51 @@
+# Copyright 2019 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import subprocess
+from pathlib import Path
+
+
+def ls_as_bytestream():
+    if os.path.exists('.git'):
+        return subprocess.run(['git', 'ls-tree', '-r', '--name-only', 'HEAD'],
+                              stdout=subprocess.PIPE).stdout
+
+    files = [str(p) for p in Path('.').glob('**/*')
+             if not p.is_dir() and
+             not next((x for x in p.parts if x.startswith('.')), None)]
+    return '\n'.join(files).encode()
+
+
+def cscope():
+    ls = b'\n'.join([b'"%s"' % f for f in ls_as_bytestream().split()])
+    return subprocess.run(['cscope', '-v', '-b', '-i-'], input=ls).returncode
+
+
+def ctags():
+    ls = ls_as_bytestream()
+    return subprocess.run(['ctags', '-L-'], input=ls).returncode
+
+
+def etags():
+    ls = ls_as_bytestream()
+    return subprocess.run(['etags', '-'], input=ls).returncode
+
+
+def run(args):
+    tool_name = args[0]
+    srcdir_name = args[1]
+    os.chdir(srcdir_name)
+    assert tool_name in ['cscope', 'ctags', 'etags']
+    return globals()[tool_name]()