Fix issue #1694

Fixes issue with expressions such as `1 + 2e-7` treating `e` as
the mathematical constant rather than `* 10 ^`.

lib/DDG/Goodie/Calculator.pm

@@ -91,7 +91,7 @@ handle query_nowhitespace => sub {
 
     # Grab expression.
     my $tmp_expr = spacing($query, 1);
-   
+
 
     return if $tmp_expr eq $query;     # If it didn't get spaced out, there are no operations to be done.
 
@@ -102,7 +102,7 @@ handle query_nowhitespace => sub {
     }
 
     $tmp_expr =~ s#log[_]?(\d{1,3})#(1/log($1))*log#xg;                # Arbitrary base logs.
-    $tmp_expr =~ s/ (\d+?)E(-?\d+)([^\d]|\b) /\($1 * 10**$2\)$3/xg;    # E == *10^n
+    $tmp_expr =~ s/ (\d+?)E(-?\d+)([^\d]|\b) /\($1 * 10**$2\)$3/ixg;   # E == *10^n
     $tmp_expr =~ s/\$//g;                                              # Remove $s.
     $tmp_expr =~ s/=$//;                                               # Drop =.
     $tmp_expr =~ s/([0-9])\s*([a-zA-Z])([^0-9])/$1*$2$3/g;             # Support 0.5e or 0.5pi; but don't break 1e8
@@ -179,7 +179,7 @@ sub spacing {
     my ($text, $space_for_parse) = @_;
 
     $text =~ s/\s{2,}/ /g;
-    $text =~ s/(\s*(?<!<)(?:[\+\-\^xX×∙⋅\*\/÷\%]|times|plus|minus|dividedby)+\s*)/ $1 /ig;
+    $text =~ s/(\s*(?<!<)(?:[\+\^xX×∙⋅\*\/÷\%]|(?<!e)\-|times|plus|minus|dividedby)+\s*)/ $1 /ig;
     $text =~ s/\s*dividedby\s*/ divided by /ig;
     $text =~ s/(\d+?)((?:dozen|pi|gross|squared|score))/$1 $2/ig;
     $text =~ s/([\(\)])/ $1 /g if ($space_for_parse);

t/Calculator.t

@@ -705,6 +705,24 @@ ddg_goodie_test(
             result    => qr/>400,001</
         }
     ),
+    '3e-2* 9 ' => test_zci(
+        '(3  *  10 ^- 2) * 9 = 0.27',
+        heading           => 'Calculator',
+        structured_answer => {
+            input     => ['(3  *  10 ^- 2) * 9'],
+            operation => 'Calculate',
+            result    => qr/>0.27</
+        }
+    ),
+    '7e-4 *8' => test_zci(
+        '(7  *  10 ^- 4) * 8 = 0.0056',
+        heading           => 'Calculator',
+        structured_answer => {
+            input     => ['(7  *  10 ^- 4) * 8'],
+            operation => 'Calculate',
+            result    => qr/>0.0056</
+        }
+    ),
     'pi/1e9' => test_zci(
         'pi / (1  *  10 ^ 9) = 3.14159265358979 * 10^-9',
         heading           => 'Calculator',