From b9fe701df27953cb3fd59f8a26075dfeff600837 Mon Sep 17 00:00:00 2001
From: Laurence Hudson <laurence.hudson@mindfoundry.ai>
Date: Thu, 10 Dec 2020 12:38:28 +0000
Subject: [PATCH] Make string literal quote types configurable (i.e. make
 axiacore/py-expression-eval#47 optional)

---
 py_expression_eval/__init__.py |  6 ++++--
 py_expression_eval/tests.py    | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/py_expression_eval/__init__.py b/py_expression_eval/__init__.py
index 849d6a0..4450543 100644
--- a/py_expression_eval/__init__.py
+++ b/py_expression_eval/__init__.py
@@ -329,7 +329,9 @@ def append(self, a, b):
         a.append(b)
         return a
 
-    def __init__(self):
+    def __init__(self, string_literal_quotes = ("'", "\"")):
+        self.string_literal_quotes = string_literal_quotes
+
         self.success = False
         self.errormsg = ''
         self.expression = ''
@@ -662,7 +664,7 @@ def isString(self):
         r = False
         str = ''
         startpos = self.pos
-        if self.pos < len(self.expression) and self.expression[self.pos] in ("'", "\""):
+        if self.pos < len(self.expression) and self.expression[self.pos] in self.string_literal_quotes:
             quote_type = self.expression[self.pos]
             self.pos += 1
             while self.pos < len(self.expression):
diff --git a/py_expression_eval/tests.py b/py_expression_eval/tests.py
index b981286..b296b44 100755
--- a/py_expression_eval/tests.py
+++ b/py_expression_eval/tests.py
@@ -32,6 +32,9 @@ def test_parser(self):
 
         # but '"a b"' can *not* be used as a variable
         self.assertEqual(parser.parse('"a b"*2').evaluate({'"a b"': 2}), "a ba b")
+        # unless parse configured to allow double quoted variables (i.e. allow multi-word vars)
+        parser2 = Parser(string_literal_quotes=("'")) # only single, not double!
+        self.assertEqual(parser2.parse('"a b"*2').evaluate({'"a b"':2}),4)
 
         # evaluate
         self.assertExactEqual(parser.parse('1').evaluate({}), 1)
@@ -215,15 +218,31 @@ def test_custom_functions_with_inline_strings(self):
         expr = parser.parse("func(1, \"func(2, 4)\")")
         self.assertEqual(expr.variables(), ['func'])
 
+        expr = parser.parse("func(1, 'func(2, 4)')")
+        self.assertEqual(expr.variables(), ['func'])
+
+        parser2 = Parser(string_literal_quotes=("'"))
+        expr = parser2.parse("func(1, \"func(2, 4)\")")
+        self.assertEqual(expr.variables(), ['func', "\"func(2, 4)\""])
+
+        expr = parser2.parse("func(1, 'func(2, 4)')")
+        self.assertEqual(expr.variables(), ['func'])
+
     def test_custom_functions_substitute_strings(self):
         def func(var, str):
             if str == "custom text":
                 return 1
+            if str == "foo":
+                return 2
             return 0
 
         parser = Parser()
         expr = parser.parse("func(1, \"custom text\")")
         self.assertEqual(expr.evaluate({"func": func}), 1)
+        
+        parser = Parser(string_literal_quotes=("'"))
+        expr = parser.parse("func(1, \"custom text\")")
+        self.assertEqual(expr.evaluate({"func": func, "\"custom text\"": "foo" }), 2)
 
     def test_decimals(self):
         parser = Parser()