1 files changed, 163 insertions, 0 deletions
diff --git a/dev/_task.py b/dev/_task.py
new file mode 100644
index 0000000..5cc257a
--- /dev/null
+++ b/dev/_task.py
@@ -0,0 +1,163 @@
+# coding: utf-8
+from __future__ import unicode_literals, division, absolute_import, print_function
+
+import ast
+import _ast
+import os
+import sys
+
+from . import package_root, task_keyword_args
+from ._import import _import_from
+
+
+if sys.version_info < (3,):
+    byte_cls = str
+else:
+    byte_cls = bytes
+
+
+def _list_tasks():
+    """
+    Fetches a list of all valid tasks that may be run, and the args they
+    accept. Does not actually import the task module to prevent errors if a
+    user does not have the dependencies installed for every task.
+
+    :return:
+        A list of 2-element tuples:
+         0: a unicode string of the task name
+         1: a list of dicts containing the parameter definitions
+    """
+
+    out = []
+    dev_path = os.path.join(package_root, 'dev')
+    for fname in sorted(os.listdir(dev_path)):
+        if fname.startswith('.') or fname.startswith('_'):
+            continue
+        if not fname.endswith('.py'):
+            continue
+        name = fname[:-3]
+        args = ()
+
+        full_path = os.path.join(package_root, 'dev', fname)
+        with open(full_path, 'rb') as f:
+            full_code = f.read()
+            if sys.version_info >= (3,):
+                full_code = full_code.decode('utf-8')
+
+        task_node = ast.parse(full_code, filename=full_path)
+        for node in ast.iter_child_nodes(task_node):
+            if isinstance(node, _ast.Assign):
+                if len(node.targets) == 1 \
+                        and isinstance(node.targets[0], _ast.Name) \
+                        and node.targets[0].id == 'run_args':
+                    args = ast.literal_eval(node.value)
+                    break
+
+        out.append((name, args))
+    return out
+
+
+def show_usage():
+    """
+    Prints to stderr the valid options for invoking tasks
+    """
+
+    valid_tasks = []
+    for task in _list_tasks():
+        usage = task[0]
+        for run_arg in task[1]:
+            usage += ' '
+            name = run_arg.get('name', '')
+            if run_arg.get('required', False):
+                usage += '{%s}' % name
+            else:
+                usage += '[%s]' % name
+        valid_tasks.append(usage)
+
+    out = 'Usage: run.py'
+    for karg in task_keyword_args:
+        out += ' [%s=%s]' % (karg['name'], karg['placeholder'])
+    out += ' (%s)' % ' | '.join(valid_tasks)
+
+    print(out, file=sys.stderr)
+    sys.exit(1)
+
+
+def _get_arg(num):
+    """
+    :return:
+        A unicode string of the requested command line arg
+    """
+
+    if len(sys.argv) < num + 1:
+        return None
+    arg = sys.argv[num]
+    if isinstance(arg, byte_cls):
+        arg = arg.decode('utf-8')
+    return arg
+
+
+def run_task():
+    """
+    Parses the command line args, invoking the requested task
+    """
+
+    arg_num = 1
+    task = None
+    args = []
+    kwargs = {}
+
+    # We look for the task name, processing any global task keyword args
+    # by setting the appropriate env var
+    while True:
+        val = _get_arg(arg_num)
+        if val is None:
+            break
+
+        next_arg = False
+        for karg in task_keyword_args:
+            if val.startswith(karg['name'] + '='):
+                os.environ[karg['env_var']] = val[len(karg['name']) + 1:]
+                next_arg = True
+                break
+
+        if next_arg:
+            arg_num += 1
+            continue
+
+        task = val
+        break
+
+    if task is None:
+        show_usage()
+
+    task_mod = _import_from('dev.%s' % task, package_root, allow_error=True)
+    if task_mod is None:
+        show_usage()
+
+    run_args = task_mod.__dict__.get('run_args', [])
+    max_args = arg_num + 1 + len(run_args)
+
+    if len(sys.argv) > max_args:
+        show_usage()
+
+    for i, run_arg in enumerate(run_args):
+        val = _get_arg(arg_num + 1 + i)
+        if val is None:
+            if run_arg.get('required', False):
+                show_usage()
+            break
+
+        if run_arg.get('cast') == 'int' and val.isdigit():
+            val = int(val)
+
+        kwarg = run_arg.get('kwarg')
+        if kwarg:
+            kwargs[kwarg] = val
+        else:
+            args.append(val)
+
+    run = task_mod.__dict__.get('run')
+
+    result = run(*args, **kwargs)
+    sys.exit(int(not result))