Improved unary minus

charon25 · Apr 21, 2023 · f6bf043 · f6bf043
1 parent 3ca506d
commit f6bf043
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Showing 6 changed files with 38 additions and 27 deletions.
diff --git a/README.md b/README.md
@@ -114,3 +114,7 @@ print(list(sy.tokenize('1+(2 * 3) - 4 * (2 / 3)')))
 # ['1', '+', '(', '2', '*', '3', ')', '-', '4', '*', '(', '2', '/', '3', ')']
 
 ```
+
+## Note
+
+Unary minus (e.g. `-1` or `-(x+1)`) will be converted to `(0-1)*` before computing the RPN of the expression. Unary plus will be removed.
diff --git a/setup.py b/setup.py
@@ -5,7 +5,7 @@
 
 setuptools.setup(
 	name="shunting-yard",
-	version="1.0.10",
+	version="1.0.11",
 	author="Paul 'charon25' Kern",
 	description="Compute any math expression",
 	long_description=long_description,
@@ -14,5 +14,5 @@
 	url="https://www.github.com/charon25/ShuntingYard",
 	license="MIT",
 	packages=['shunting_yard'],
-	download_url="https://github.com/charon25/ShuntingYard/archive/refs/tags/v1.0.10.tar.gz"
+	download_url="https://github.com/charon25/ShuntingYard/archive/refs/tags/v1.0.11.tar.gz"
 )
diff --git a/shunting_yard/shunting_yard.py b/shunting_yard/shunting_yard.py
@@ -17,8 +17,6 @@ class MismatchedBracketsError(Exception):
     '*': 20,
     '/': 20,
     '^': 30,
-    '-u': 40,
-    '+u': 40,
 }
 
 # Returns the precendence if the operator is one of +-*/^, or infinity if it is a function
@@ -105,11 +103,13 @@ def shunting_yard(expression: str, case_sensitive: bool = True, variable: Option
                 output.append(operator_stack.pop())
 
         elif first_char in BASE_OPERATORS:
-            while (len(operator_stack) > 0 and
-                  (operator := operator_stack[-1]) not in SEPARATORS_NO_CLOSING_BRACKET and
-                  (get_precedence(operator) > get_precedence(token) or
-                        (get_precedence(operator) == get_precedence(token) and
-                        OPERATORS_ASSOCIATIVITY[token] == Associativity.LEFT))):
+            while   (len(operator_stack) > 0 and
+                    (prev_operator := operator_stack[-1]) not in SEPARATORS_NO_CLOSING_BRACKET and (
+                        get_precedence(prev_operator) > get_precedence(token) or (
+                            get_precedence(prev_operator) == get_precedence(token) and
+                            OPERATORS_ASSOCIATIVITY[token] == Associativity.LEFT
+                        )
+                    )):
 
                 output.append(operator_stack.pop())
 

diff --git a/shunting_yard/tokenize.py b/shunting_yard/tokenize.py
@@ -56,7 +56,8 @@ def tokenize(string: str, convert_scientific_notation: bool = True) -> Iterator[
         char = string[cursor]
 
         if not is_infix and char in UNARY_OPERATORS:
-            yield f'{char}u'
+            if char == '-':
+                yield from '(0-1)*'
             cursor += 1
 
         elif char in BASE_OPERATORS or char in SEPARATORS:

diff --git a/tests/test_shunting_yard.py b/tests/test_shunting_yard.py
@@ -48,11 +48,17 @@ def test_case_sensitive(self):
         self.assertEqual(shunting_yard('min(1, 2)', case_sensitive=False), shunting_yard('MIN(1, 2)', case_sensitive=False))
 
     def test_unary_in_function(self):
-        self.assertEqual(shunting_yard('min(-1, 2)'), '1 -u 2 min')
-        self.assertEqual(shunting_yard('min(-(1+3), 2)'), '1 3 + -u 2 min')
-        self.assertEqual(shunting_yard('min(1, -2)'), '1 2 -u min')
-        self.assertEqual(shunting_yard('min(1, -(2+3))'), '1 2 3 + -u min')
-        self.assertEqual(shunting_yard('min(1, -min(3, 4))'), '1 3 4 min -u min')
+        self.assertEqual(shunting_yard('min(-1, 2)'), '0 1 - 1 * 2 min')
+        self.assertEqual(shunting_yard('min(-(1+3), 2)'), '0 1 - 1 3 + * 2 min')
+        self.assertEqual(shunting_yard('min(1, -2)'), '1 0 1 - 2 * min')
+        self.assertEqual(shunting_yard('min(1, -(2+3))'), '1 0 1 - 2 3 + * min')
+        self.assertEqual(shunting_yard('min(1, -min(3, 4))'), '1 0 1 - 3 4 min * min')
+
+        self.assertEqual(shunting_yard('min(+1, 2)'), '1 2 min')
+        self.assertEqual(shunting_yard('min(+(1+3), 2)'), '1 3 + 2 min')
+        self.assertEqual(shunting_yard('min(1, +2)'), '1 2 min')
+        self.assertEqual(shunting_yard('min(1, +(2+3))'), '1 2 3 + min')
+        self.assertEqual(shunting_yard('min(1, +min(3, 4))'), '1 3 4 min min')
 
     def test_variable(self):
         self.assertEqual(shunting_yard('min(x, 1)'), 'x 1 min')

diff --git a/tests/test_tokenize.py b/tests/test_tokenize.py
@@ -38,7 +38,7 @@ def test_function_one_argument(self):
         self.assertListEqual(list(tokenize('sin(1 + 4)')), ['sin', '(', '1', '+', '4', ')'])
 
     def test_function_no_argument(self):
-        self.assertListEqual(list(tokenize('-3/2*pi')), ['-u', '3', '/', '2', '*', 'pi'])
+        self.assertListEqual(list(tokenize('-3/2*pi')), ['(', '0', '-', '1', ')', '*', '3', '/', '2', '*', 'pi'])
 
     def test_function_2_arguments(self):
         self.assertListEqual(list(tokenize('max(1, 4)')), ['max', '(', '1', ',', '4', ')'])
@@ -54,21 +54,21 @@ def test_function_underscore(self):
         self.assertListEqual(list(tokenize('arc_cos(0)')), ['arc_cos', '(', '0', ')'])
 
     def test_function_unary_minus(self):
-        self.assertListEqual(list(tokenize('-1')), ['-u', '1'])
-        self.assertListEqual(list(tokenize('-(1+2)')), ['-u', '(', '1', '+', '2', ')'])
-        self.assertListEqual(list(tokenize('2*-1')), ['2', '*', '-u', '1'])
-        self.assertListEqual(list(tokenize('-(-1)')), ['-u', '(', '-u', '1', ')'])
+        self.assertListEqual(list(tokenize('-1')), ['(', '0', '-', '1', ')', '*', '1'])
+        self.assertListEqual(list(tokenize('-(1+2)')), ['(', '0', '-', '1', ')', '*',  '(', '1', '+', '2', ')'])
+        self.assertListEqual(list(tokenize('2*-1')), ['2', '*', '(', '0', '-', '1', ')', '*',  '1'])
+        self.assertListEqual(list(tokenize('-(-1)')), ['(', '0', '-', '1', ')', '*',  '(', '(', '0', '-', '1', ')', '*',  '1', ')'])
 
     def test_function_unary_plus(self):
-        self.assertListEqual(list(tokenize('+1')), ['+u', '1'])
-        self.assertListEqual(list(tokenize('+(1+2)')), ['+u', '(', '1', '+', '2', ')'])
-        self.assertListEqual(list(tokenize('2*+1')), ['2', '*', '+u', '1'])
-        self.assertListEqual(list(tokenize('+(+1)')), ['+u', '(', '+u', '1', ')'])
+        self.assertListEqual(list(tokenize('+1')), ['1'])
+        self.assertListEqual(list(tokenize('+(1+2)')), ['(', '1', '+', '2', ')'])
+        self.assertListEqual(list(tokenize('2*+1')), ['2', '*', '1'])
+        self.assertListEqual(list(tokenize('+(+1)')), ['(', '1', ')'])
 
     def test_function_unary_in_function(self):
-        self.assertListEqual(list(tokenize('min(-1, 2)')), ['min', '(', '-u', '1', ',', '2', ')'])
-        self.assertListEqual(list(tokenize('min(1, -2)')), ['min', '(', '1', ',', '-u', '2', ')'])
-        self.assertListEqual(list(tokenize('min(1, -(2+sin(3)))')), ['min', '(', '1', ',', '-u', '(', '2', '+', 'sin', '(', '3', ')', ')', ')'])
+        self.assertListEqual(list(tokenize('min(-1, 2)')), ['min', '(', '(', '0', '-', '1', ')', '*',  '1', ',', '2', ')'])
+        self.assertListEqual(list(tokenize('min(1, -2)')), ['min', '(', '1', ',', '(', '0', '-', '1', ')', '*',  '2', ')'])
+        self.assertListEqual(list(tokenize('min(1, -(2+sin(3)))')), ['min', '(', '1', ',', '(', '0', '-', '1', ')', '*',  '(', '2', '+', 'sin', '(', '3', ')', ')', ')'])
 
     def test_digits_in_function_name(self):
         self.assertListEqual(list(tokenize('min3(1, 2)')), ['min3', '(', '1', ',', '2', ')'])