From fd00805ca76808197758800d9d19ee2d6ac708ae Mon Sep 17 00:00:00 2001
From: CleoQc <cleoqc1124@gmail.com>
Date: Mon, 12 Nov 2018 13:56:41 -0500
Subject: [PATCH] support scientific notation

---
 docs/templates.rst    | 13 ++++++++++---
 jinja2/lexer.py       | 10 ++++++++--
 tests/test_filters.py |  4 +++-
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/docs/templates.rst b/docs/templates.rst
index 6d3bf367..9da05773 100644
--- a/docs/templates.rst
+++ b/docs/templates.rst
@@ -1177,12 +1177,19 @@ for Python objects such as strings and numbers.  The following literals exist:
     arguments to function calls and filters, or just to extend or include a
     template).
 
-42 / 42.23:
-    Integers and floating point numbers are created by just writing the
-    number down.  If a dot is present, the number is a float, otherwise an
+42:
+    Integers numbers are created by just writing the number down. 
+    If a dot is present, the number will be considered a float, otherwise an
     integer.  Keep in mind that, in Python, ``42`` and ``42.0``
     are different (``int`` and ``float``, respectively).
 
+42.23 / 42e2 / 42E2 / 1e0:
+    Floating point numbers are created by just writing the
+    number down. Floating points can be written using the dot as a decimal mark,
+    or they can be written in scientific notation in which
+    case you can use lower case 'e' or upper case 'E' to indicate the exponent
+    part. 
+
 ['list', 'of', 'objects']:
     Everything between two brackets is a list.  Lists are useful for storing
     sequential data to be iterated over.  For example, you can easily
diff --git a/jinja2/lexer.py b/jinja2/lexer.py
index e23a9987..119dc99d 100644
--- a/jinja2/lexer.py
+++ b/jinja2/lexer.py
@@ -22,6 +22,8 @@ from jinja2._compat import implements_iterator, intern, iteritems, text_type
 from jinja2.exceptions import TemplateSyntaxError
 from jinja2.utils import LRUCache
 
+from ast import literal_eval # to support scientific notation
+
 # cache for the lexers. Exists in order to be able to have multiple
 # environments with the same lexer
 _lexer_cache = LRUCache(50)
@@ -52,7 +54,11 @@ else:
     del jinja2._identifier
     del _identifier
 
-float_re = re.compile(r'(?<!\.)\d+\.\d+')
+# Note: Float now supports 0 or 1 dots, and must thus be evaluated in the right 
+# order so that pure integers are caught first. Floats can now be written with 
+# scientific notation.
+float_re = re.compile(r'(?<!\.)\d+\.?\d+(?:e-?\d+)?', re.IGNORECASE)
+
 newline_re = re.compile(r'(\r\n|\r|\n)')
 
 # internal the tokens and keep references to them
@@ -601,7 +607,7 @@ class Lexer(object):
             elif token == 'integer':
                 value = int(value)
             elif token == 'float':
-                value = float(value)
+                value = literal_eval(value)
             elif token == 'operator':
                 token = operators[value]
             yield Token(lineno, token, value)
diff --git a/tests/test_filters.py b/tests/test_filters.py
index fd3a0cf9..28d1f302 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -136,9 +136,11 @@ class TestFilter(object):
     def test_float(self, env):
         tmpl = env.from_string('{{ "42"|float }}|'
                                '{{ "ajsghasjgd"|float }}|'
+                               '{{ "10e1"|float }}|'
+                               '{{ "10.5e-10"|float }}|'
                                '{{ "32.32"|float }}')
         out = tmpl.render()
-        assert out == '42.0|0.0|32.32'
+        assert out == '42.0|0.0|100.0|1.05e-09|32.32'
 
     def test_format(self, env):
         tmpl = env.from_string('''{{ "%s|%s"|format("a", "b") }}''')
-- 
2.47.2