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.

9 files changed, 113 insertions, 131 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