Added striptags filter

Author: igor-sadchenko

README.md

@@ -96,7 +96,7 @@ More detailed examples and features description can be found in the documentatio
 ## Current Jinja2 support
 Currently, Jinja2C++ supports the limited number of Jinja2 features. By the way, Jinja2C++ is planned to be a full [jinja2 specification](http://jinja.pocoo.org/docs/2.10/templates/)-conformant. The current support is limited to:
 -  expressions. You can use almost every expression style: simple, filtered, conditional, and so on.
--  the big number of filters (**sort, default, first, last, length, max, min, reverse, unique, sum, attr, map, reject, rejectattr, select, selectattr, pprint, dictsort, abs, float, int, list, round, random, trim, title, upper, wordcount, replace, truncate, groupby, urlencode, capitalize, escape, tojson**)
+-  the big number of filters (**sort, default, first, last, length, max, min, reverse, unique, sum, attr, map, reject, rejectattr, select, selectattr, pprint, dictsort, abs, float, int, list, round, random, trim, title, upper, wordcount, replace, truncate, groupby, urlencode, capitalize, escape, tojson, striptags**)
 -  the big number of testers (**eq, defined, ge, gt, iterable, le, lt, mapping, ne, number, sequence, string, undefined, in, even, odd, lower, upper**)
 -  the number of functions (**range**, **loop.cycle**)
 -  'if' statement (with 'elif' and 'else' branches)

src/filters.cpp

@@ -70,6 +70,7 @@ std::unordered_map<std::string, ExpressionFilter::FilterFactoryFn> s_filters = {
     {"selectattr", FilterFactory<filters::Tester>::MakeCreator(filters::Tester::SelectAttrMode)},
     {"slice", FilterFactory<filters::Slice>::MakeCreator(filters::Slice::SliceMode)},
     {"sort", &FilterFactory<filters::Sort>::Create},
+    {"striptags", FilterFactory<filters::StringConverter>::MakeCreator(filters::StringConverter::StriptagsMode) },
     {"sum", FilterFactory<filters::SequenceAccessor>::MakeCreator(filters::SequenceAccessor::SumItemsMode)},
     {"title", FilterFactory<filters::StringConverter>::MakeCreator(filters::StringConverter::TitleMode)},
     {"tojson", FilterFactory<filters::Serialize>::MakeCreator(filters::Serialize::JsonMode)},

src/filters.h

@@ -182,6 +182,7 @@ class StringConverter : public  FilterBase
         EscapeHtmlMode,
         LowerMode,
         ReplaceMode,
+        StriptagsMode,
         TitleMode,
         TrimMode,
         TruncateMode,

src/string_converter_filter.cpp

@@ -5,6 +5,7 @@
 
 #include <algorithm>
 #include <numeric>
+#include <regex>
 #include <sstream>
 
 #include <boost/algorithm/string/trim_all.hpp>
@@ -343,6 +344,30 @@ InternalValue StringConverter::Filter(const InternalValue& baseVal, RenderContex
             }
         });
         break;
+     case StriptagsMode:
+        result = ApplyStringConverter(baseVal, [](auto srcStr) -> TargetString {
+            auto str = sv_to_string(srcStr);
+            using StringT = decltype(str);
+            using CharT = typename StringT::value_type;
+            static const std::basic_regex<CharT> STRIPTAGS_RE(UNIVERSAL_STR("(<!--.*?-->|<[^>]*>)").GetValue<CharT>());
+            str = std::regex_replace(str, STRIPTAGS_RE, UNIVERSAL_STR("").GetValue<CharT>());
+            ba::trim_all(str);
+            static const StringT html_entities [] {
+                UNIVERSAL_STR("&amp;").GetValue<CharT>(), UNIVERSAL_STR("&").GetValue<CharT>(),
+                UNIVERSAL_STR("&apos;").GetValue<CharT>(), UNIVERSAL_STR("\'").GetValue<CharT>(),
+                UNIVERSAL_STR("&gt;").GetValue<CharT>(), UNIVERSAL_STR(">").GetValue<CharT>(),
+                UNIVERSAL_STR("&lt;").GetValue<CharT>(), UNIVERSAL_STR("<").GetValue<CharT>(),
+                UNIVERSAL_STR("&quot;").GetValue<CharT>(), UNIVERSAL_STR("\"").GetValue<CharT>(),
+                UNIVERSAL_STR("&#39;").GetValue<CharT>(), UNIVERSAL_STR("\'").GetValue<CharT>(),
+                UNIVERSAL_STR("&#34;").GetValue<CharT>(), UNIVERSAL_STR("\"").GetValue<CharT>(),
+            };
+            for (auto it = std::begin(html_entities), end = std::end(html_entities); it < end; it += 2)
+            {
+                ba::replace_all(str, *it, *(it + 1));
+            }
+            return str;
+        });
+        break;
     default:
         break;
     }

test/filters_test.cpp

@@ -555,3 +555,12 @@ INSTANTIATE_TEST_CASE_P(ListSlice, ListSliceTest, ::testing::Values(
                             InputOutputPair{"[1, 2, 3, 4, 5, 6, 7] | slice(3) | pprint",             "[[1, 2, 3], [4, 5, 6], [7]]"},
                             InputOutputPair{"[1, 2, 3, 4, 5, 6, 7] | slice(3, 0) | pprint",          "[[1, 2, 3], [4, 5, 6], [7, 0, 0]]"}
                             ));
+
+INSTANTIATE_TEST_CASE_P(Striptags, FilterGenericTest, ::testing::Values(
+                            InputOutputPair{ "' Hello  World ' | striptags | pprint", "'Hello World'" },
+                            InputOutputPair{ "'foo <bar> baz <qux>' | striptags | pprint", "'foo baz'" },
+                            InputOutputPair{"'ab&cd&amp;&gt;&lt;efgh' | striptags | pprint", "'ab&cd&><efgh'"},
+                            InputOutputPair{"'<em>Foo &amp; Bar</em>' | striptags | pprint", "'Foo & Bar'"},
+                            InputOutputPair{"'&amp;&apos;&gt;&lt;&quot;&#39;\"&#34;' | striptags | pprint", "'&\'><\"\'\"\"'"},
+                            InputOutputPair{"'&#34;&#39;' | striptags | pprint", "'\"\''"}));
+