Add MathJax backticks to possibility messages.

src/possibilities.py

@@ -19,8 +19,12 @@ class Possibility(object):
         if self.handler in MESSAGES:
             msg = MESSAGES[self.handler]
 
-            # Surround math notation with backticks
-            msg = re.sub('({[^ ]+)', r'`\1`', msg)
+            # Surround math notation with backticks. If there are any backticks
+            # already, do not add additional backticks. The add_backticks
+            # lambda is necessary otherwise because \1 and \2 are not matched
+            # both at the same time.
+            add_backticks = lambda x: '`%s`' % ''.join(x.groups(''))
+            msg = re.sub('`([^`]*)`|\(?({[^. ]+)', add_backticks, msg)
 
             if callable(msg):
                 msg = msg(self.root, self.args)

src/rules/derivatives.py

@@ -295,7 +295,7 @@ def sinus(root, args):
     return cos(root[0][0])
 
 
-MESSAGES[sinus] = _('Apply standard derivative d/dx sin(x) = cos(x).')
+MESSAGES[sinus] = _('Apply standard derivative `d/dx sin(x)` is `cos(x)`.')
 
 
 def cosinus(root, args):
@@ -305,7 +305,7 @@ def cosinus(root, args):
     return -sin(root[0][0])
 
 
-MESSAGES[cosinus] = _('Apply standard derivative d/dx cos(x) = -sin(x).')
+MESSAGES[cosinus] = _('Apply standard derivative `d/dx cos(x)` is `-sin(x)`.')
 
 
 def tangens(root, args):

src/rules/fractions.py

@@ -46,7 +46,7 @@ def division_by_one(root, args):
     return args[0].negate(root.negated)
 
 
-MESSAGES[division_by_one] = _('Division by 1 yields the nominator.')
+MESSAGES[division_by_one] = _('Division by `1` yields the nominator.')
 
 
 def division_of_zero(root, args):
@@ -56,7 +56,7 @@ def division_of_zero(root, args):
     return L(0, negated=root.negated)
 
 
-MESSAGES[division_of_zero] = _('Division of 0 by {1} reduces to 0.')
+MESSAGES[division_of_zero] = _('Division of `0` by {1} reduces to `0`.')
 
 
 def division_by_self(root, args):
@@ -66,7 +66,7 @@ def division_by_self(root, args):
     return L(1, negated=root.negated)
 
 
-MESSAGES[division_by_self] = _('Division of {1} by itself reduces to 1.')
+MESSAGES[division_by_self] = _('Division of {1} by itself reduces to `1`.')
 
 
 def match_add_fractions(node):
@@ -159,7 +159,7 @@ def equalize_denominators(root, args):
 
 
 MESSAGES[equalize_denominators] = \
-        _('Equalize the denominators of divisions' ' {2} and {3} to {4}.')
+        _('Equalize the denominators of divisions {2} and {3} to {4}.')
 
 
 def constant_to_fraction(root, args):
@@ -271,7 +271,8 @@ def divide_fraction(root, args):
     return negate(a / (b * c), root.negated)
 
 
-MESSAGES[divide_fraction] = _('Move {3} to denominator of fraction {1} / {2}.')
+MESSAGES[divide_fraction] = \
+        _('Move {3} to denominator of fraction `{1} / {2}`.')
 
 
 def divide_by_fraction(root, args):
@@ -285,7 +286,7 @@ def divide_by_fraction(root, args):
 
 
 MESSAGES[divide_by_fraction] = \
-        _('Move {3} to nominator of fraction {1} / {2}.')
+        _('Move {3} to nominator of fraction `{1} / {2}`.')
 
 
 def is_power_combination(a, b):
@@ -398,7 +399,7 @@ def extract_fraction_terms(root, args):
     return negate(div, root.negated)
 
 
-MESSAGES[extract_fraction_terms] = _('Extract {3} / {4} from fraction {0}.')
+MESSAGES[extract_fraction_terms] = _('Extract `{3} / {4}` from fraction {0}.')
 
 
 def divide_fraction_by_term(root, args):

src/rules/goniometry.py

@@ -44,7 +44,7 @@ def add_quadrants(root, args):
     return scope.as_nary_node()
 
 
-MESSAGES[add_quadrants] = _('Add the sinus and cosinus quadrants to 1.')
+MESSAGES[add_quadrants] = _('Add the sinus and cosinus quadrants to `1`.')
 
 
 def factor_out_quadrant_negation(root, args):
@@ -59,7 +59,7 @@ def factor_out_quadrant_negation(root, args):
 
 
 MESSAGES[factor_out_quadrant_negation] = _('Factor out the negations of {2} ' \
-        'and {3} to be able to reduce the quadrant addition to 1.')
+        'and {3} to be able to reduce the quadrant addition to `1`.')
 
 
 def match_negated_parameter(node):

src/rules/integrals.py

@@ -69,7 +69,7 @@ def solve_indef(root, args):
 
 def solve_indef_msg(root, args):  # pragma: nocover
     return _('Solve indefinite integral {0} using substitution ' \
-             'of %s with {0[2]} and {0[1]}.' % find_variable(root[0]))
+             'of `%s` with {0[2]} and {0[1]}.' % find_variable(root[0]))
 
 
 MESSAGES[solve_indef] = solve_indef_msg
@@ -106,7 +106,7 @@ def integrate_variable_root(root, args):
 
 
 MESSAGES[integrate_variable_root] = _('Apply standard integral ' \
-        'int(x ^ n) = 1 / (n + 1) * x ^ (n + 1) + c.')
+        '`int(x ^ n) = 1 / (n + 1) * x ^ (n + 1) + c`.')
 
 
 def integrate_variable_exponent(root, args):
@@ -119,7 +119,7 @@ def integrate_variable_exponent(root, args):
 
 
 MESSAGES[integrate_variable_exponent] = \
-        _('Apply standard integral int(g ^ x) = g ^ x / ln(g) + c.')
+        _('Apply standard integral `int(g ^ x) = g ^ x / ln(g) + c`.')
 
 
 def match_constant_integral(node):
@@ -147,8 +147,8 @@ def single_variable_integral(root, args):
     return integral(root[0] ** 1, *root[1:])
 
 
-MESSAGES[single_variable_integral] = _('Rewrite {0[0]} to {0[0]} ^ 1 and ' \
-        'apply the standard integral for {0[0]} ^ n.')
+MESSAGES[single_variable_integral] = _('Rewrite {0[0]} to `{0[0]} ^ 1` and ' \
+        'apply the standard integral for `{0[0]} ^ n`.')
 
 
 def constant_integral(root, args):
@@ -197,7 +197,7 @@ def split_negation_to_constant(root, args):
 
 
 MESSAGES[split_negation_to_constant] = _('Write the negation of {0[0]} as an' \
-        ' explicit -1 and bring it outside of the integral.')
+        ' explicit `-1` and bring it outside of the integral.')
 
 
 def factor_out_constant(root, args):
@@ -239,7 +239,7 @@ def division_integral(root, args):
 
 
 MESSAGES[division_integral] = \
-        _('1 / {0[1]} has the standard anti-derivative ln|{0[1]}| + c.')
+        _('`1 / {0[1]}` has the standard anti-derivative `ln|{0[1]}| + c`.')
 
 
 def extend_division_integral(root, args):
@@ -252,7 +252,7 @@ def extend_division_integral(root, args):
 
 
 MESSAGES[extend_division_integral] = _('Bring nominator {0[0][0]} out of the' \
-        ' fraction to obtain a standard 1 / {0[0][1]} integral.')
+        ' fraction to obtain a standard `1 / {0[0][1]}` integral.')
 
 
 def match_function_integral(node):
@@ -289,8 +289,8 @@ def logarithm_integral(root, args):
     return solve_integral(root, (x * ln(x) - x) / ln(g))
 
 
-MESSAGES[logarithm_integral] = _('log_g(x) has the standard anti-derivative ' \
-        '(xln(x) - x) / log_g(x) + c.')
+MESSAGES[logarithm_integral] = _('`log_g(x)` has the standard ' \
+        'anti-derivative `(xln(x) - x) / log_g(x) + c`.')
 
 
 def sinus_integral(root, args):
@@ -301,7 +301,7 @@ def sinus_integral(root, args):
 
 
 MESSAGES[sinus_integral] = \
-        _('{0[0]} has the standard anti-derivative -cos({0[0][0]}) + c.')
+        _('{0[0]} has the standard anti-derivative `-cos({0[0][0]}) + c`.')
 
 
 def cosinus_integral(root, args):
@@ -312,7 +312,7 @@ def cosinus_integral(root, args):
 
 
 MESSAGES[cosinus_integral] = \
-        _('{0[0]} has the standard anti-derivative sin({0[0][0]}) + c.')
+        _('{0[0]} has the standard anti-derivative `sin({0[0][0]}) + c`.')
 
 
 def match_sum_rule_integral(node):

tests/test_possibilities.py

@@ -28,7 +28,7 @@ class TestPossibilities(unittest.TestCase):
     def test___str__(self):
         self.assertEqual(str(self.p0),
                 '<Possibility root="1 + 2" handler=dummy_handler args=(1, 2)>')
-        self.assertEqual(str(self.p1), 'foo 1 + 2 bar')
+        self.assertEqual(str(self.p1), 'foo `1` + `2` bar')
 
     def test___repr__(self):
         self.assertEqual(repr(self.p0),