Use a single ArgumentParser for all subcommands

This has the adventage that "meson --help" shows a list of all commands,
making them discoverable. This also reduce the manual parsing of
arguments to the strict minimum needed for backward compatibility.

11 files changed, 116 insertions, 134 deletions

diff --git a/mesonbuild/mconf.py b/mesonbuild/mconf.py
index 2fd69b0..576c574 100644
--- a/mesonbuild/mconf.py
+++ b/mesonbuild/mconf.py
@@ -13,17 +13,13 @@
 # limitations under the License.
 
 import os
-import argparse
 from . import (coredata, mesonlib, build)
 
-def buildparser():
-    parser = argparse.ArgumentParser(prog='meson configure')
+def add_arguments(parser):
     coredata.register_builtin_arguments(parser)
-
     parser.add_argument('builddir', nargs='?', default='.')
     parser.add_argument('--clearcache', action='store_true', default=False,
                         help='Clear cached state (e.g. found dependencies)')
-    return parser
 
 
 class ConfException(mesonlib.MesonException):
@@ -149,9 +145,7 @@ class Conf:
         self.print_options('Testing options', test_options)
 
 
-def run(args):
-    args = mesonlib.expand_arguments(args)
-    options = buildparser().parse_args(args)
+def run(options):
     coredata.parse_cmd_line_options(options)
     builddir = os.path.abspath(os.path.realpath(options.builddir))
     try:
diff --git a/mesonbuild/mesonmain.py b/mesonbuild/mesonmain.py
index 2174e14..684926c 100644
--- a/mesonbuild/mesonmain.py
+++ b/mesonbuild/mesonmain.py
@@ -15,11 +15,97 @@
 import sys
 import os.path
 import importlib
+import traceback
+import argparse
 
 from . import mesonlib
 from . import mlog
+from . import mconf, minit, minstall, mintro, msetup, mtest, rewriter
 from .mesonlib import MesonException
 from .environment import detect_msys2_arch
+from .wrap import wraptool
+
+
+class CommandLineParser:
+    def __init__(self):
+        self.commands = {}
+        self.parser = argparse.ArgumentParser(prog='meson')
+        self.subparsers = self.parser.add_subparsers(title='Commands',
+                                                     description='If no command is specified it defaults to setup command.')
+        self.add_command('setup', msetup.add_arguments, msetup.run,
+                         help='Configure the project')
+        self.add_command('configure', mconf.add_arguments, mconf.run,
+                         help='Change project options',)
+        self.add_command('install', minstall.add_arguments, minstall.run,
+                         help='Install the project')
+        self.add_command('introspect', mintro.add_arguments, mintro.run,
+                         help='Introspect project')
+        self.add_command('init', minit.add_arguments, minit.run,
+                         help='Create a new project')
+        self.add_command('test', mtest.add_arguments, mtest.run,
+                         help='Run tests')
+        self.add_command('rewrite', rewriter.add_arguments, rewriter.run,
+                         help='Edit project files')
+        self.add_command('wrap', wraptool.add_arguments, wraptool.run,
+                         help='Wrap tools')
+        self.add_command('runpython', self.add_runpython_arguments, self.run_runpython_command,
+                         help='Run a python script')
+        self.add_command('help', self.add_help_arguments, self.run_help_command,
+                         help='Print help of a subcommand')
+
+    def add_command(self, name, add_arguments_func, run_func, help):
+        p = self.subparsers.add_parser(name, help=help)
+        add_arguments_func(p)
+        p.set_defaults(run_func=run_func)
+        self.commands[name] = p
+
+    def add_runpython_arguments(self, parser):
+        parser.add_argument('script_file')
+        parser.add_argument('script_args', nargs=argparse.REMAINDER)
+
+    def run_runpython_command(self, options):
+        import runpy
+        sys.argv[1:] = options.script_args
+        runpy.run_path(options.script_file, run_name='__main__')
+        return 0
+
+    def add_help_arguments(self, parser):
+        parser.add_argument('command', nargs='?')
+
+    def run_help_command(self, options):
+        if options.command:
+            self.commands[options.command].print_help()
+        else:
+            self.parser.print_help()
+        return 0
+
+    def run(self, args):
+        # If first arg is not a known command, assume user wants to run the setup
+        # command.
+        known_commands = list(self.commands.keys()) + ['-h', '--help']
+        if len(args) == 0 or args[0] not in known_commands:
+            args = ['setup'] + args
+
+        args = mesonlib.expand_arguments(args)
+        options = self.parser.parse_args(args)
+
+        try:
+            return options.run_func(options)
+        except MesonException as e:
+            mlog.exception(e)
+            logfile = mlog.shutdown()
+            if logfile is not None:
+                mlog.log("\nA full log can be found at", mlog.bold(logfile))
+            if os.environ.get('MESON_FORCE_BACKTRACE'):
+                raise
+            return 1
+        except Exception as e:
+            if os.environ.get('MESON_FORCE_BACKTRACE'):
+                raise
+            traceback.print_exc()
+            return 2
+        finally:
+            mlog.shutdown()
 
 def run_script_command(script_name, script_args):
     # Map script name to module name for those that doesn't match
@@ -50,6 +136,7 @@ def run(original_args, mainfile):
         print('You have python %s.' % sys.version)
         print('Please update your environment')
         return 1
+
     # https://github.com/mesonbuild/meson/issues/3653
     if sys.platform.lower() == 'msys':
         mlog.error('This python3 seems to be msys/python on MSYS2 Windows, which is known to have path semantics incompatible with Meson')
@@ -75,57 +162,7 @@ def run(original_args, mainfile):
         else:
             return run_script_command(args[1], args[2:])
 
-    if len(args) > 0:
-        # First check if we want to run a subcommand.
-        cmd_name = args[0]
-        remaining_args = args[1:]
-        # "help" is a special case: Since printing of the help may be
-        # delegated to a subcommand, we edit cmd_name before executing
-        # the rest of the logic here.
-        if cmd_name == 'help':
-            remaining_args += ['--help']
-            args = remaining_args
-            cmd_name = args[0]
-        if cmd_name == 'test':
-            from . import mtest
-            return mtest.run(remaining_args)
-        elif cmd_name == 'install':
-            from . import minstall
-            return minstall.run(remaining_args)
-        elif cmd_name == 'introspect':
-            from . import mintro
-            return mintro.run(remaining_args)
-        elif cmd_name == 'rewrite':
-            from . import rewriter
-            return rewriter.run(remaining_args)
-        elif cmd_name == 'configure':
-            try:
-                from . import mconf
-                return mconf.run(remaining_args)
-            except MesonException as e:
-                mlog.exception(e)
-                sys.exit(1)
-        elif cmd_name == 'wrap':
-            from .wrap import wraptool
-            return wraptool.run(remaining_args)
-        elif cmd_name == 'init':
-            from . import minit
-            return minit.run(remaining_args)
-        elif cmd_name == 'runpython':
-            import runpy
-            script_file = remaining_args[0]
-            sys.argv[1:] = remaining_args[1:]
-            runpy.run_path(script_file, run_name='__main__')
-            sys.exit(0)
-        else:
-            # If cmd_name is not a known command, assume user wants to run the
-            # setup command.
-            from . import msetup
-            if cmd_name != 'setup':
-                remaining_args = args
-            return msetup.run(remaining_args)
-
-    return 0
+    return CommandLineParser().run(args)
 
 def main():
     # Always resolve the command path so Ninja can find it for regen, tests, etc.
diff --git a/mesonbuild/minit.py b/mesonbuild/minit.py
index a66361f..394fe40 100644
--- a/mesonbuild/minit.py
+++ b/mesonbuild/minit.py
@@ -14,7 +14,7 @@
 
 """Code that creates simple startup projects."""
 
-import os, sys, argparse, re, shutil, subprocess
+import os, sys, re, shutil, subprocess
 from glob import glob
 from mesonbuild import mesonlib
 from mesonbuild.environment import detect_ninja
@@ -425,8 +425,7 @@ def create_meson_build(options):
     open('meson.build', 'w').write(content)
     print('Generated meson.build file:\n\n' + content)
 
-def run(args):
-    parser = argparse.ArgumentParser(prog='meson')
+def add_arguments(parser):
     parser.add_argument("srcfiles", metavar="sourcefile", nargs="*",
                         help="source files. default: all recognized files in current directory")
     parser.add_argument("-n", "--name", help="project name. default: name of current directory")
@@ -441,7 +440,8 @@ def run(args):
     parser.add_argument('--type', default='executable',
                         choices=['executable', 'library'])
     parser.add_argument('--version', default='0.1')
-    options = parser.parse_args(args)
+
+def run(options):
     if len(glob('*')) == 0:
         autodetect_options(options, sample=True)
         if not options.language:
diff --git a/mesonbuild/minstall.py b/mesonbuild/minstall.py
index 1d72179..b65abe0 100644
--- a/mesonbuild/minstall.py
+++ b/mesonbuild/minstall.py
@@ -14,7 +14,6 @@
 
 import sys, pickle, os, shutil, subprocess, gzip, errno
 import shlex
-import argparse
 from glob import glob
 from .scripts import depfixer
 from .scripts import destdir_join
@@ -33,15 +32,13 @@ build definitions so that it will not break when the change happens.'''
 
 selinux_updates = []
 
-def buildparser():
-    parser = argparse.ArgumentParser(prog='meson install')
+def add_arguments(parser):
     parser.add_argument('-C', default='.', dest='wd',
                         help='directory to cd into before running')
     parser.add_argument('--no-rebuild', default=False, action='store_true',
                         help='Do not rebuild before installing.')
     parser.add_argument('--only-changed', default=False, action='store_true',
                         help='Only overwrite files that are older than the copied file.')
-    return parser
 
 class DirMaker:
     def __init__(self, lf):
@@ -501,9 +498,7 @@ class Installer:
                     else:
                         raise
 
-def run(args):
-    parser = buildparser()
-    opts = parser.parse_args(args)
+def run(opts):
     datafilename = 'meson-private/install.dat'
     private_dir = os.path.dirname(datafilename)
     log_dir = os.path.join(private_dir, '../meson-logs')
@@ -520,6 +515,3 @@ def run(args):
         append_to_log(lf, '# Does not contain files installed by custom scripts.')
         installer.do_install(datafilename)
     return 0
-
-if __name__ == '__main__':
-    sys.exit(run(sys.argv[1:]))
diff --git a/mesonbuild/mintro.py b/mesonbuild/mintro.py
index 188459a..b15a608 100644
--- a/mesonbuild/mintro.py
+++ b/mesonbuild/mintro.py
@@ -23,12 +23,10 @@ import json
 from . import build, mtest, coredata as cdata
 from . import mesonlib
 from .backend import ninjabackend
-import argparse
 import sys, os
 import pathlib
 
-def buildparser():
-    parser = argparse.ArgumentParser(prog='meson introspect')
+def add_arguments(parser):
     parser.add_argument('--targets', action='store_true', dest='list_targets', default=False,
                         help='List top level targets.')
     parser.add_argument('--installed', action='store_true', dest='list_installed', default=False,
@@ -48,7 +46,6 @@ def buildparser():
     parser.add_argument('--projectinfo', action='store_true', dest='projectinfo', default=False,
                         help='Information about projects.')
     parser.add_argument('builddir', nargs='?', default='.', help='The build directory')
-    return parser
 
 def determine_installed_path(target, installdata):
     install_target = None
@@ -206,9 +203,8 @@ def list_projinfo(builddata):
     result['subprojects'] = subprojects
     print(json.dumps(result))
 
-def run(args):
+def run(options):
     datadir = 'meson-private'
-    options = buildparser().parse_args(args)
     if options.builddir is not None:
         datadir = os.path.join(options.builddir, datadir)
     if not os.path.isdir(datadir):
diff --git a/mesonbuild/msetup.py b/mesonbuild/msetup.py
index b07e7c4..1576556 100644
--- a/mesonbuild/msetup.py
+++ b/mesonbuild/msetup.py
@@ -19,7 +19,6 @@ import os.path
 import platform
 import cProfile as profile
 import argparse
-import traceback
 
 from . import environment, interpreter, mesonlib
 from . import build
@@ -27,8 +26,7 @@ from . import mlog, coredata
 from .mesonlib import MesonException
 from .wrap import WrapMode
 
-def buildparser():
-    parser = argparse.ArgumentParser(prog='meson')
+def add_arguments(parser):
     coredata.register_builtin_arguments(parser)
     parser.add_argument('--cross-file', default=None,
                         help='File describing cross compilation environment.')
@@ -48,7 +46,6 @@ def buildparser():
                              'is not working.')
     parser.add_argument('builddir', nargs='?', default=None)
     parser.add_argument('sourcedir', nargs='?', default=None)
-    return parser
 
 def wrapmodetype(string):
     try:
@@ -193,35 +190,8 @@ class MesonApp:
                     os.unlink(cdf)
             raise
 
-def run(args):
-    args = mesonlib.expand_arguments(args)
-    options = buildparser().parse_args(args)
+def run(options):
     coredata.parse_cmd_line_options(options)
-    try:
-        app = MesonApp(options)
-    except Exception as e:
-        # Log directory does not exist, so just print
-        # to stdout.
-        print('Error during basic setup:\n')
-        print(e)
-        return 1
-    try:
-        app.generate()
-    except Exception as e:
-        if isinstance(e, MesonException):
-            mlog.exception(e)
-            # Path to log file
-            mlog.shutdown()
-            logfile = os.path.join(app.build_dir, environment.Environment.log_dir, mlog.log_fname)
-            mlog.log("\nA full log can be found at", mlog.bold(logfile))
-            if os.environ.get('MESON_FORCE_BACKTRACE'):
-                raise
-            return 1
-        else:
-            if os.environ.get('MESON_FORCE_BACKTRACE'):
-                raise
-            traceback.print_exc()
-            return 2
-    finally:
-        mlog.shutdown()
+    app = MesonApp(options)
+    app.generate()
     return 0
diff --git a/mesonbuild/mtest.py b/mesonbuild/mtest.py
index 8d9a585..78f2252 100644
--- a/mesonbuild/mtest.py
+++ b/mesonbuild/mtest.py
@@ -60,8 +60,7 @@ def determine_worker_count():
             num_workers = 1
     return num_workers
 
-def buildparser():
-    parser = argparse.ArgumentParser(prog='meson test')
+def add_arguments(parser):
     parser.add_argument('--repeat', default=1, dest='repeat', type=int,
                         help='Number of times to run the tests.')
     parser.add_argument('--no-rebuild', default=False, action='store_true',
@@ -102,7 +101,6 @@ def buildparser():
                         help='Arguments to pass to the specified test(s) or all tests')
     parser.add_argument('args', nargs='*',
                         help='Optional list of tests to run')
-    return parser
 
 
 def returncode_to_status(retcode):
@@ -737,9 +735,7 @@ def rebuild_all(wd):
 
     return True
 
-def run(args):
-    options = buildparser().parse_args(args)
-
+def run(options):
     if options.benchmark:
         options.num_processes = 1
 
@@ -784,3 +780,9 @@ def run(args):
         else:
             print(e)
         return 1
+
+def run_with_args(args):
+    parser = argparse.ArgumentParser(prog='meson test')
+    add_arguments(parser)
+    options = parser.parse_args(args)
+    return run(options)
diff --git a/mesonbuild/rewriter.py b/mesonbuild/rewriter.py
index 1127288..5da8c89 100644
--- a/mesonbuild/rewriter.py
+++ b/mesonbuild/rewriter.py
@@ -27,11 +27,8 @@ import mesonbuild.astinterpreter
 from mesonbuild.mesonlib import MesonException
 from mesonbuild import mlog
 import sys, traceback
-import argparse
-
-def buildparser():
-    parser = argparse.ArgumentParser(prog='meson rewrite')
 
+def add_arguments(parser):
     parser.add_argument('--sourcedir', default='.',
                         help='Path to source directory.')
     parser.add_argument('--target', default=None,
@@ -39,10 +36,8 @@ def buildparser():
     parser.add_argument('--filename', default=None,
                         help='Name of source file to add or remove to target.')
     parser.add_argument('commands', nargs='+')
-    return parser
 
-def run(args):
-    options = buildparser().parse_args(args)
+def run(options):
     if options.target is None or options.filename is None:
         sys.exit("Must specify both target and filename.")
     print('This tool is highly experimental, use with care.')
diff --git a/mesonbuild/wrap/wraptool.py b/mesonbuild/wrap/wraptool.py
index 364452d..bb64b5b 100644
--- a/mesonbuild/wrap/wraptool.py
+++ b/mesonbuild/wrap/wraptool.py
@@ -16,7 +16,6 @@ import json
 import sys, os
 import configparser
 import shutil
-import argparse
 
 from glob import glob
 
@@ -208,9 +207,6 @@ def status(options):
         else:
             print('', name, 'not up to date. Have %s %d, but %s %d is available.' % (current_branch, current_revision, latest_branch, latest_revision))
 
-def run(args):
-    parser = argparse.ArgumentParser(prog='wraptool')
-    add_arguments(parser)
-    options = parser.parse_args(args)
+def run(options):
     options.wrap_func(options)
     return 0
diff --git a/run_project_tests.py b/run_project_tests.py
index ba7b5e0..876d135 100755
--- a/run_project_tests.py
+++ b/run_project_tests.py
@@ -247,12 +247,12 @@ def run_test_inprocess(testdir):
     os.chdir(testdir)
     test_log_fname = Path('meson-logs', 'testlog.txt')
     try:
-        returncode_test = mtest.run(['--no-rebuild'])
+        returncode_test = mtest.run_with_args(['--no-rebuild'])
         if test_log_fname.exists():
             test_log = test_log_fname.open(errors='ignore').read()
         else:
             test_log = ''
-        returncode_benchmark = mtest.run(['--no-rebuild', '--benchmark', '--logbase', 'benchmarklog'])
+        returncode_benchmark = mtest.run_with_args(['--no-rebuild', '--benchmark', '--logbase', 'benchmarklog'])
     finally:
         sys.stdout = old_stdout
         sys.stderr = old_stderr
diff --git a/run_tests.py b/run_tests.py
index 2a078ef..af926ea 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -181,7 +181,7 @@ def run_mtest_inprocess(commandlist):
     old_stderr = sys.stderr
     sys.stderr = mystderr = StringIO()
     try:
-        returncode = mtest.run(commandlist)
+        returncode = mtest.run_with_args(commandlist)
     finally:
         sys.stdout = old_stdout
         sys.stderr = old_stderr