underwriter: start new argument parser

1 files changed, 59 insertions, 0 deletions

diff --git a/natargs.py b/natargs.py
new file mode 100644
index 0000000..8e96d2c
--- /dev/null
+++ b/natargs.py
@@ -0,0 +1,59 @@
+###########################################################################
+#
+###########################################################################
+
+class DuplicateArgumentException:
+	def __str__(self):
+		return f"{self.oldargs} already exists"
+	def __init__(self, oldargs):
+		self.oldargs = oldargs
+
+class TrieElem:
+	def dochk(self, l):
+		return True if self.chk is None \
+		       else self.chk(len(l))
+
+	def __init__(self, chk, f, st):
+		self.chk = chk
+		self.f = f
+		self.st = st
+
+def addargs(dic, oldargs, args, chk, f):
+	if len(args) == 1:
+		if args[0] in dic:
+			raise DuplicateArgumentException(oldargs)
+		else:
+			dic[args[0]] = TrieElem(chk,f,{})
+	else:
+		if args[0] not in dic:
+			dic[args[0]] = TrieElem(None, None, {})
+		dic[args[0]].st = addargs(dic[args[0]].st, \
+		                  oldargs, args[1:], chk, f)
+	return dic
+
+def getarg(dict, l):
+	if len(l) == 0 or l[0] not in dict:
+		return None
+	else:
+		resolved = getarg(dict[l[0]].st, l[1:])
+		if resolved is None:
+			return dict[l[0]].f,l[1:] \
+			       if dict[l[0]].dochk(l[1:]) \
+			       else None
+		else:
+			return resolved
+
+class Arguments:
+	def execarg(self, args):
+		res = getarg(self.trie, args)
+		if res is None:
+			raise Exception
+		return res[0](res[1])
+
+	def addarg(self, args, chk, f):
+		if args == []:
+			raise ValueError
+		self.trie = addargs(self.trie, args, args, chk, f)
+
+	def __init__(self):
+		self.trie = {}