1 files changed, 116 insertions, 0 deletions
diff --git a/yapymake/args.py b/yapymake/args.py
new file mode 100644
index 0000000..f13f8e0
--- /dev/null
+++ b/yapymake/args.py
@@ -0,0 +1,116 @@
+import argparse
+from dataclasses import dataclass
+import io
+import os
+import sys
+from typing import List, TextIO
+
+from . import DESCRIPTION, VERSION
+
+__all__ = [
+    'parse',
+    'Args',
+]
+
+parser = argparse.ArgumentParser(
+    description=f'{DESCRIPTION} - version {VERSION}',
+)
+
+parser.add_argument('--environment-overrides', '-e',
+                    action='store_true',
+                    help='Cause environment variables, including those with null values, to override macro assignments '
+                         'within makefiles.')
+parser.add_argument('--makefile', '--file', '-f',
+                    action='append',
+                    type=argparse.FileType('r'),
+                    help="Specify a different makefile (or '-' for standard input).")
+parser.add_argument('--ignore-errors', '-i',
+                    action='store_true',
+                    help='Ignore error codes returned by invoked commands.')
+parser.add_argument('--keep-going', '-k',
+                    action='store_true',
+                    help='Continue to update other targets that do not depend on the current target if a non-ignored '
+                         'error occurs while executing the commands to bring a target up-to-date.')
+parser.add_argument('--dry-run', '--just-print', '--recon', '-n',
+                    action='store_true',
+                    help="Write commands that would be executed on standard output, but do not execute them (but "
+                         "execute lines starting with '+').")
+parser.add_argument('--print-everything', '--print-data-base', '-p',
+                    action='store_true',
+                    help='Write to standard output the complete set of macro definitions and target descriptions.')
+parser.add_argument('--question', '-q',
+                    action='store_true',
+                    help='Return a zero exit value if the target file is up-to-date; otherwise, return an exit value '
+                         'of 1.')
+parser.add_argument('--no-builtin-rules', '-r',
+                    action='store_false',
+                    dest='builtin_rules',
+                    help='Clear the suffix list and do not use the built-in rules.')
+parser.add_argument('--no-keep-going', '--stop', '-S',
+                    action='store_false',
+                    dest='keep_going',
+                    help='Terminate make if an error occurs while executing the commands to bring a target up-to-date '
+                         '(default behavior, required by POSIX to be also a flag for some reason).')
+parser.add_argument('--silent', '--quiet', '-s',
+                    action='store_true',
+                    help='Do not write makefile command lines or touch messages to standard output before executing.')
+parser.add_argument('--touch', '-t',
+                    action='store_true',
+                    help='Update the modification time of each target as though a touch target had been executed.')
+parser.add_argument('targets_or_macros',
+                    nargs='*',
+                    metavar='target_or_macro',
+                    help='Target name or macro definition.')
+
+@dataclass()
+class Args:
+    environment_overrides: bool
+    makefile: List[TextIO]
+    ignore_errors: bool
+    keep_going: bool
+    dry_run: bool
+    print_everything: bool
+    question: bool
+    builtin_rules: bool
+    silent: bool
+    touch: bool
+    targets_or_macros: List[str]
+
+    def __init__(self, parsed_args: argparse.Namespace):
+        self.environment_overrides = parsed_args.environment_overrides
+        if len(parsed_args.makefile) > 0:
+            self.makefile = parsed_args.makefile
+        else:
+            try:
+                self.makefile = [open('./makefile', 'r')]
+            except FileNotFoundError:
+                self.makefile = [open('./Makefile', 'r')]
+        self.ignore_errors = parsed_args.ignore_errors
+        self.keep_going = parsed_args.keep_going
+        self.dry_run = parsed_args.dry_run
+        self.print_everything = parsed_args.print_everything
+        self.question = parsed_args.question
+        self.builtin_rules = parsed_args.builtin_rules
+        self.silent = parsed_args.silent
+        self.touch = parsed_args.touch
+        self.targets_or_macros = parsed_args.targets_or_macros
+
+def parse(cli_args: List[str] = None, env_makeflags: str = None) -> Args:
+    if cli_args is None:
+        cli_args = sys.argv[1:]
+    if env_makeflags is None:
+        env_makeflags = os.environ.get('MAKEFLAGS', '')
+
+    # per POSIX, we accept option letters without a leading -, so to simplify we prepend a - now
+    # TODO allow macro definitions in MAKEFLAGS
+    if len(env_makeflags) > 0 and not env_makeflags.startswith('-'):
+        env_makeflags = '-' + env_makeflags
+
+    if len(env_makeflags) > 0:
+        all_args = [env_makeflags, *cli_args]
+    else:
+        all_args = cli_args
+
+    return Args(parser.parse_args(all_args))
+
+# TODO test any of this