Add cuneiform_python.py example

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+#
+# cuneiform_python.py
+#
+# Example showing how to create a custom Unicode set for parsing
+#
+# Copyright Paul McGuire, 2021
+#
+from typing import List, Tuple
+import pyparsing as pp
+
+
+class Cuneiform(pp.unicode_set):
+    """Unicode set for Cuneiform Character Range"""
+
+    _ranges: List[Tuple[int, ...]] = [
+        (0x12000, 0x123FF),
+    ]
+
+
+# list out all valid identifier characters
+# print(Cuneiform.identchars)
+
+
+"""
+Simple Cuneiform Python language transformer
+
+Define Cuneiform "words"
+    print: 𒄑𒉿𒅔𒋫
+    hello: 𒀄𒂖𒆷𒁎
+    world: 𒍟𒁎𒉿𒆷𒀳
+    def: 𒁴𒈫
+"""
+
+# uncomment to show parse-time debugging
+# pp.enable_diag(pp.Diagnostics.enable_debug_on_named_expressions)
+
+# define a MINIMAL Python parser
+LPAR, RPAR, COLON, EQ = map(pp.Suppress, "():=")
+def_ = pp.Keyword("𒁴𒈫", ident_chars=Cuneiform.identbodychars).set_name("def")
+any_keyword = def_
+ident = (~any_keyword) + pp.Word(
+    Cuneiform.identchars, Cuneiform.identbodychars, asKeyword=True
+)
+str_expr = pp.infix_notation(
+    pp.QuotedString('"') | pp.common.integer,
+    [
+        ("*", 2, pp.OpAssoc.LEFT),
+        ("+", 2, pp.OpAssoc.LEFT),
+    ],
+)
+
+rvalue = pp.Forward()
+fn_call = (ident + pp.Group(LPAR + pp.Optional(rvalue) + RPAR)).set_name("fn_call")
+
+rvalue <<= fn_call | ident | str_expr | pp.common.number
+assignment_stmt = ident + EQ + rvalue
+
+stmt = pp.Group(fn_call | assignment_stmt).set_name("stmt")
+
+fn_def = pp.Group(
+    def_ + ident + pp.Group(LPAR + pp.Optional(rvalue) + RPAR) + COLON
+).set_name("fn_def")
+fn_body = pp.IndentedBlock(stmt).set_name("fn_body")
+fn_expr = pp.Group(fn_def + pp.Group(fn_body))
+
+script = fn_expr[...] + stmt[...]
+
+
+# parse some Python written in Cuneiform
+cuneiform_hello_world = r"""
+𒁴𒈫 𒀄𒂖𒆷𒁎():
+    𒀁 = "𒀄𒂖𒆷𒁎, 𒍟𒁎𒉿𒆷𒀳!\n" * 3
+    𒄑𒉿𒅔𒋫(𒀁)
+
+𒀄𒂖𒆷𒁎()"""
+script.parseString(cuneiform_hello_world).pprint(width=30)
+
+
+# use transform_string to convert keywords and builtins to runnable Python
+names_map = {
+    "𒄑𒉿𒅔𒋫": "print",
+}
+ident.add_parse_action(lambda t: names_map.get(t[0], t[0]))
+def_.add_parse_action(lambda: "def")
+
+print("\nconvert Cuneiform Python to executable Python")
+transformed = (
+    (ident | def_)
+    .ignore(pp.quoted_string)
+    .transform_string(cuneiform_hello_world)
+    .strip()
+)
+print(
+    "=================\n"
+    + cuneiform_hello_world.strip()
+    + "\n=================\n"
+    + transformed
+    + "\n=================\n"
+)
+print("# run transformed Python")
+exec(transformed)