From fdf0339e167208b8eb62b59ab45fc73163cd1f32 Mon Sep 17 00:00:00 2001
From: Simon Forman <sforman@hushmail.com>
Date: Mon, 2 Dec 2019 14:26:07 -0800
Subject: [PATCH] Make parser REs into module-level "constants".

---
 joy/parser.py | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/joy/parser.py b/joy/parser.py
index 3307c6b..3d92f7a 100644
--- a/joy/parser.py
+++ b/joy/parser.py
@@ -36,11 +36,20 @@ brackets.   Terms must be separated by blanks, which can be omitted
 around square brackets.
 
 '''
-#TODO: explain the details of float lits and strings.
 from re import Scanner
 from .utils.stack import list_to_stack
 
 
+#TODO: explain the details of float lits and strings.
+FLOAT = r'-?\d+\.\d*'
+INT = r'-?\d+'
+SYMBOL = r'[•\w!@$%^&*()_+<>?|\/;:`~,.=-]+'
+BRACKETS = r'\[|\]'
+STRING_DOUBLE_QUOTED = r'"(?:[^"\\]|\\.)*"'
+STRING_SINGLE_QUOTED = r"'(?:[^'\\]|\\.)*'"
+BLANKS = r'\s+'
+
+
 class Symbol(str):
   '''A string class that represents Joy function names.'''
   __repr__ = str.__str__
@@ -105,11 +114,11 @@ def _parse(tokens):
 
 
 _scanner = Scanner([
-  (r'-?\d+\.\d*', lambda _, token: float(token)),
-  (r'-?\d+', lambda _, token: int(token)),
-  (r'[•\w!@$%^&*()_+<>?|\/;:`~,.=-]+', lambda _, token: Symbol(token)),
-  (r'\[|\]', lambda _, token: token),
-  (r'"(?:[^"\\]|\\.)*"', lambda _, token: token[1:-1].replace('\\"', '"')),
-  (r"'(?:[^'\\]|\\.)*'", lambda _, token: token[1:-1].replace("\\'", "'")),
-  (r'\s+', None),
+  (FLOAT, lambda _, token: float(token)),
+  (INT, lambda _, token: int(token)),
+  (SYMBOL, lambda _, token: Symbol(token)),
+  (BRACKETS, lambda _, token: token),
+  (STRING_DOUBLE_QUOTED, lambda _, token: token[1:-1].replace('\\"', '"')),
+  (STRING_SINGLE_QUOTED, lambda _, token: token[1:-1].replace("\\'", "'")),
+  (BLANKS, None),
   ])