Add generic generator modifiers

This means mutiple generic generators and some inference helper
* take(n, generator)
* filter(predicate, generator)
* map(func, generator)
* repeat(generator, repeats)

include/internal/catch_generators.cpp

@@ -16,6 +16,10 @@ namespace Catch {
 
 IGeneratorTracker::~IGeneratorTracker() {}
 
+const char* GeneratorException::what() const noexcept {
+    return m_msg;
+}
+
 namespace Generators {
 
     GeneratorUntypedBase::~GeneratorUntypedBase() {}

include/internal/catch_generators.hpp

@@ -16,8 +16,21 @@
 #include <cassert>
 
 #include <utility>
+#include <exception>
 
 namespace Catch {
+
+class GeneratorException : public std::exception {
+    const char* const m_msg = "";
+
+public:
+    GeneratorException(const char* msg):
+        m_msg(msg)
+    {}
+
+    const char* what() const noexcept override final;
+};
+
 namespace Generators {
 
     // !TBD move this into its own location?
@@ -166,6 +179,175 @@ namespace Generators {
         return makeGenerators( value( T( std::forward<U>( val ) ) ), std::forward<Gs>( moreGenerators )... );
     }
 
+    template <typename T>
+    class TakeGenerator : public IGenerator<T> {
+        GeneratorWrapper<T> m_generator;
+        size_t m_returned = 0;
+        size_t m_target;
+    public:
+        TakeGenerator(size_t target, GeneratorWrapper<T>&& generator):
+            m_generator(std::move(generator)),
+            m_target(target)
+        {
+            assert(target != 0 && "Empty generators are not allowed");
+        }
+        T const& get() const override {
+            return m_generator.get();
+        }
+        bool next() override {
+            ++m_returned;
+            if (m_returned >= m_target) {
+                return false;
+            }
+
+            const auto success = m_generator.next();
+            // If the underlying generator does not contain enough values
+            // then we cut short as well
+            if (!success) {
+                m_returned = m_target;
+            }
+            return success;
+        }
+    };
+
+    template <typename T>
+    GeneratorWrapper<T> take(size_t target, GeneratorWrapper<T>&& generator) {
+        return GeneratorWrapper<T>(pf::make_unique<TakeGenerator<T>>(target, std::move(generator)));
+    }
+
+
+    template <typename T, typename Predicate>
+    class FilterGenerator : public IGenerator<T> {
+        GeneratorWrapper<T> m_generator;
+        Predicate m_predicate;
+    public:
+        template <typename P = Predicate>
+        FilterGenerator(P&& pred, GeneratorWrapper<T>&& generator):
+            m_generator(std::move(generator)),
+            m_predicate(std::forward<P>(pred))
+        {
+            if (!m_predicate(m_generator.get())) {
+                // It might happen that there are no values that pass the
+                // filter. In that case we throw an exception.
+                auto has_initial_value = next();
+                if (!has_initial_value) {
+                    Catch::throw_exception(GeneratorException("No valid value found in filtered generator"));
+                }
+            }
+        }
+
+        T const& get() const override {
+            return m_generator.get();
+        }
+
+        bool next() override {
+            bool success = m_generator.next();
+            if (!success) {
+                return false;
+            }
+            while (!m_predicate(m_generator.get()) && (success = m_generator.next()) == true);
+            return success;
+        }
+    };
+
+
+    template <typename T, typename Predicate>
+    GeneratorWrapper<T> filter(Predicate&& pred, GeneratorWrapper<T>&& generator) {
+        return GeneratorWrapper<T>(std::unique_ptr<IGenerator<T>>(pf::make_unique<FilterGenerator<T, Predicate>>(std::forward<Predicate>(pred), std::move(generator))));
+    }
+
+    template <typename T>
+    class RepeatGenerator : public IGenerator<T> {
+        GeneratorWrapper<T> m_generator;
+        mutable std::vector<T> m_returned;
+        size_t m_target_repeats;
+        size_t m_current_repeat = 0;
+        size_t m_repeat_index = 0;
+    public:
+        RepeatGenerator(size_t repeats, GeneratorWrapper<T>&& generator):
+            m_generator(std::move(generator)),
+            m_target_repeats(repeats)
+        {
+            assert(m_target_repeats > 0 && "Repeat generator must repeat at least once");
+        }
+
+        T const& get() const override {
+            if (m_current_repeat == 0) {
+                m_returned.push_back(m_generator.get());
+                return m_returned.back();
+            }
+            return m_returned[m_repeat_index];
+        }
+
+        bool next() override {
+            // There are 2 basic cases:
+            // 1) We are still reading the generator
+            // 2) We are reading our own cache
+
+            // In the first case, we need to poke the underlying generator.
+            // If it happily moves, we are left in that state, otherwise it is time to start reading from our cache
+            if (m_current_repeat == 0) {
+                const auto success = m_generator.next();
+                if (!success) {
+                    ++m_current_repeat;
+                }
+                return m_current_repeat < m_target_repeats;
+            }
+
+            // In the second case, we need to move indices forward and check that we haven't run up against the end
+            ++m_repeat_index;
+            if (m_repeat_index == m_returned.size()) {
+                m_repeat_index = 0;
+                ++m_current_repeat;
+            }
+            return m_current_repeat < m_target_repeats;
+        }
+    };
+
+    template <typename T>
+    GeneratorWrapper<T> repeat(size_t repeats, GeneratorWrapper<T>&& generator) {
+        return GeneratorWrapper<T>(pf::make_unique<RepeatGenerator<T>>(repeats, std::move(generator)));
+    }
+
+    template <typename T, typename U, typename Func>
+    class MapGenerator : public IGenerator<T> {
+        // TBD: provide static assert for mapping function, for friendly error message
+        GeneratorWrapper<U> m_generator;
+        Func m_function;
+        // To avoid returning dangling reference, we have to save the values
+        T m_cache;
+    public:
+        template <typename F2 = Func>
+        MapGenerator(F2&& function, GeneratorWrapper<U>&& generator) :
+            m_generator(std::move(generator)),
+            m_function(std::forward<F2>(function)),
+            m_cache(m_function(m_generator.get()))
+        {}
+
+        T const& get() const override {
+            return m_cache;
+        }
+        bool next() override {
+            const auto success = m_generator.next();
+            if (success) {
+                m_cache = m_function(m_generator.get());
+            }
+            return success;
+        }
+    };
+
+    template <typename T, typename U, typename Func>
+    GeneratorWrapper<T> map(Func&& function, GeneratorWrapper<U>&& generator) {
+        return GeneratorWrapper<T>(
+            pf::make_unique<MapGenerator<T, U, Func>>(std::forward<Func>(function), std::move(generator))
+        );
+    }
+    template <typename T, typename Func>
+    GeneratorWrapper<T> map(Func&& function, GeneratorWrapper<T>&& generator) {
+        return GeneratorWrapper<T>(
+            pf::make_unique<MapGenerator<T, T, Func>>(std::forward<Func>(function), std::move(generator))
+        );
+    }
 
     auto acquireGeneratorTracker( SourceLineInfo const& lineInfo ) -> IGeneratorTracker&;
 

projects/SelfTest/Baselines/compact.sw.approved.txt

@@ -399,6 +399,24 @@ Matchers.tests.cpp:<line number>: passed: WithinAbs(1.f, 0.f)
 Matchers.tests.cpp:<line number>: passed: WithinAbs(1.f, -1.f), std::domain_error
 Matchers.tests.cpp:<line number>: passed: WithinULP(1.f, 0)
 Matchers.tests.cpp:<line number>: passed: WithinULP(1.f, -1), std::domain_error
+Generators.tests.cpp:<line number>: passed: i % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: i % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: i % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: i < 4 for: 1 < 4
+Generators.tests.cpp:<line number>: passed: i < 4 for: 2 < 4
+Generators.tests.cpp:<line number>: passed: i < 4 for: 3 < 4
+Generators.tests.cpp:<line number>: passed: i % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: i % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: i % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: i.size() == 1 for: 1 == 1
+Generators.tests.cpp:<line number>: passed: i.size() == 1 for: 1 == 1
+Generators.tests.cpp:<line number>: passed: i.size() == 1 for: 1 == 1
+Generators.tests.cpp:<line number>: passed: j > 0 for: 1 > 0
+Generators.tests.cpp:<line number>: passed: j > 0 for: 2 > 0
+Generators.tests.cpp:<line number>: passed: j > 0 for: 3 > 0
+Generators.tests.cpp:<line number>: passed: j > 0 for: 1 > 0
+Generators.tests.cpp:<line number>: passed: j > 0 for: 2 > 0
+Generators.tests.cpp:<line number>: passed: j > 0 for: 3 > 0
 Generators.tests.cpp:<line number>: passed: j < i for: -3 < 1
 Generators.tests.cpp:<line number>: passed: j < i for: -2 < 1
 Generators.tests.cpp:<line number>: passed: j < i for: -1 < 1
@@ -442,6 +460,37 @@ GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == "bb" for: "bb" == "
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
 GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == "cc" for: "cc" == "cc"
 GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: filter([] (int) { return false; }, value(1)), Catch::GeneratorException
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 2 for: 2 == 2
+GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 2.0 for: 2.0 == 2.0
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 4.0 for: 4.0 == 4.0
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 6.0 for: 6.0 == 6.0
+GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 2 for: 2 == 2
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 2 for: 2 == 2
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: gen.get() == 3 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: !(gen.next()) for: !false
 Approx.tests.cpp:<line number>: passed: d >= Approx( 1.22 ) for: 1.23 >= Approx( 1.22 )
 Approx.tests.cpp:<line number>: passed: d >= Approx( 1.23 ) for: 1.23 >= Approx( 1.23 )
 Approx.tests.cpp:<line number>: passed: !(d >= Approx( 1.24 )) for: !(1.23 >= Approx( 1.24 ))

projects/SelfTest/Baselines/console.std.approved.txt

@@ -1170,6 +1170,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  244 |  184 passed |  56 failed |  4 failed as expected
+test cases:  245 |  185 passed |  56 failed |  4 failed as expected
-assertions: 1248 | 1112 passed | 115 failed | 21 failed as expected
+assertions: 1297 | 1161 passed | 115 failed | 21 failed as expected
 

projects/SelfTest/Baselines/console.sw.approved.txt

@@ -2850,6 +2850,228 @@ Matchers.tests.cpp:<line number>: PASSED:
 Matchers.tests.cpp:<line number>: PASSED:
   REQUIRE_THROWS_AS( WithinULP(1.f, -1), std::domain_error )
 
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Filtering by predicate
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Filtering by predicate
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Filtering by predicate
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Shortening a range
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i < 4 )
+with expansion:
+  1 < 4
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Shortening a range
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i < 4 )
+with expansion:
+  2 < 4
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Shortening a range
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i < 4 )
+with expansion:
+  3 < 4
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Transforming elements
+  Same type
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Transforming elements
+  Same type
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Transforming elements
+  Same type
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Transforming elements
+  Different type
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i.size() == 1 )
+with expansion:
+  1 == 1
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Transforming elements
+  Different type
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i.size() == 1 )
+with expansion:
+  1 == 1
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Transforming elements
+  Different type
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( i.size() == 1 )
+with expansion:
+  1 == 1
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Repeating a generator
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( j > 0 )
+with expansion:
+  1 > 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Repeating a generator
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( j > 0 )
+with expansion:
+  2 > 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Repeating a generator
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( j > 0 )
+with expansion:
+  3 > 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Repeating a generator
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( j > 0 )
+with expansion:
+  1 > 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Repeating a generator
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( j > 0 )
+with expansion:
+  2 > 0
+
+-------------------------------------------------------------------------------
+Generators -- adapters
+  Repeating a generator
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( j > 0 )
+with expansion:
+  3 > 0
+
 -------------------------------------------------------------------------------
 Generators -- simple
   one
@@ -3219,6 +3441,205 @@ GeneratorsImpl.tests.cpp:<line number>: PASSED:
 with expansion:
   !false
 
+-------------------------------------------------------------------------------
+Generators internals
+  Filter generator
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( gen.next() )
+with expansion:
+  !false
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_THROWS_AS( filter([] (int) { return false; }, value(1)), Catch::GeneratorException )
+
+-------------------------------------------------------------------------------
+Generators internals
+  Take generator
+  Take less
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 2 )
+with expansion:
+  2 == 2
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( gen.next() )
+with expansion:
+  !false
+
+-------------------------------------------------------------------------------
+Generators internals
+  Take generator
+  Take more
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( gen.next() )
+with expansion:
+  !false
+
+-------------------------------------------------------------------------------
+Generators internals
+  Map
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 2.0 )
+with expansion:
+  2.0 == 2.0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 4.0 )
+with expansion:
+  4.0 == 4.0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 6.0 )
+with expansion:
+  6.0 == 6.0
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( gen.next() )
+with expansion:
+  !false
+
+-------------------------------------------------------------------------------
+Generators internals
+  Repeat
+  Singular repeat
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( gen.next() )
+with expansion:
+  !false
+
+-------------------------------------------------------------------------------
+Generators internals
+  Repeat
+  Actual repeat
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 2 )
+with expansion:
+  2 == 2
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 2 )
+with expansion:
+  2 == 2
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( gen.get() == 3 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( gen.next() )
+with expansion:
+  !false
+
 -------------------------------------------------------------------------------
 Greater-than inequalities with different epsilons
 -------------------------------------------------------------------------------
@@ -9726,6 +10147,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  244 |  171 passed |  69 failed |  4 failed as expected
+test cases:  245 |  172 passed |  69 failed |  4 failed as expected
-assertions: 1262 | 1112 passed | 129 failed | 21 failed as expected
+assertions: 1311 | 1161 passed | 129 failed | 21 failed as expected
 

projects/SelfTest/Baselines/junit.sw.approved.txt

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="113" tests="1263" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="113" tests="1312" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <testcase classname="<exe-name>.global" name="# A test name that starts with a #" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="#1005: Comparing pointer to int and long (NULL can be either on various systems)" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="#1027" time="{duration}"/>
@@ -339,12 +339,23 @@ Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Floating point matchers: float/ULPs" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Floating point matchers: float/Composed" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Floating point matchers: float/Constructor validation" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators -- adapters/Filtering by predicate" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators -- adapters/Shortening a range" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators -- adapters/Transforming elements/Same type" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators -- adapters/Transforming elements/Different type" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators -- adapters/Repeating a generator" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/one" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators -- simple/two" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Single value" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Preset values" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Generator combinator" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Generators internals/Explicitly typed generator sequence" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators internals/Filter generator" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators internals/Take generator/Take less" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators internals/Take generator/Take more" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators internals/Map" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators internals/Repeat/Singular repeat" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="Generators internals/Repeat/Actual repeat" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="Greater-than inequalities with different epsilons" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="INFO and WARN do not abort tests" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="INFO gets logged on failure" time="{duration}">

projects/SelfTest/Baselines/xml.sw.approved.txt

@@ -3538,6 +3538,225 @@
       </Section>
       <OverallResult success="true"/>
     </TestCase>
+    <TestCase name="Generators -- adapters" tags="[generators]" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Section name="Filtering by predicate" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            i % 2 == 0
+          </Original>
+          <Expanded>
+            0 == 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Filtering by predicate" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            i % 2 == 0
+          </Original>
+          <Expanded>
+            0 == 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Filtering by predicate" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            i % 2 == 0
+          </Original>
+          <Expanded>
+            0 == 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Shortening a range" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            i &lt; 4
+          </Original>
+          <Expanded>
+            1 &lt; 4
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Shortening a range" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            i &lt; 4
+          </Original>
+          <Expanded>
+            2 &lt; 4
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Shortening a range" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            i &lt; 4
+          </Original>
+          <Expanded>
+            3 &lt; 4
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Transforming elements" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Same type" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              i % 2 == 0
+            </Original>
+            <Expanded>
+              0 == 0
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Transforming elements" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Same type" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              i % 2 == 0
+            </Original>
+            <Expanded>
+              0 == 0
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Transforming elements" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Same type" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              i % 2 == 0
+            </Original>
+            <Expanded>
+              0 == 0
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Transforming elements" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Different type" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              i.size() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Transforming elements" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Different type" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              i.size() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Transforming elements" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Section name="Different type" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+            <Original>
+              i.size() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeating a generator" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            j > 0
+          </Original>
+          <Expanded>
+            1 > 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeating a generator" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            j > 0
+          </Original>
+          <Expanded>
+            2 > 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeating a generator" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            j > 0
+          </Original>
+          <Expanded>
+            3 > 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeating a generator" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            j > 0
+          </Original>
+          <Expanded>
+            1 > 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeating a generator" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            j > 0
+          </Original>
+          <Expanded>
+            2 > 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeating a generator" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
+          <Original>
+            j > 0
+          </Original>
+          <Expanded>
+            3 > 0
+          </Expanded>
+        </Expression>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
+      <OverallResult success="true"/>
+    </TestCase>
     <TestCase name="Generators -- simple" tags="[generators]" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
       <Section name="one" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
         <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Generators.tests.cpp" >
@@ -3952,6 +4171,284 @@
         </Expression>
         <OverallResults successes="7" failures="0" expectedFailures="0"/>
       </Section>
+      <Section name="Filter generator" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.get() == 1
+          </Original>
+          <Expanded>
+            1 == 1
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.next()
+          </Original>
+          <Expanded>
+            true
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.get() == 3
+          </Original>
+          <Expanded>
+            3 == 3
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE_FALSE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            !(gen.next())
+          </Original>
+          <Expanded>
+            !false
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE_THROWS_AS" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            filter([] (int) { return false; }, value(1)), Catch::GeneratorException
+          </Original>
+          <Expanded>
+            filter([] (int) { return false; }, value(1)), Catch::GeneratorException
+          </Expanded>
+        </Expression>
+        <OverallResults successes="5" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Take generator" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Section name="Take less" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.next()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 2
+            </Original>
+            <Expanded>
+              2 == 2
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE_FALSE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              !(gen.next())
+            </Original>
+            <Expanded>
+              !false
+            </Expanded>
+          </Expression>
+          <OverallResults successes="4" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="4" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Take generator" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Section name="Take more" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE_FALSE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              !(gen.next())
+            </Original>
+            <Expanded>
+              !false
+            </Expanded>
+          </Expression>
+          <OverallResults successes="2" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="2" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Map" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.get() == 2.0
+          </Original>
+          <Expanded>
+            2.0 == 2.0
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.next()
+          </Original>
+          <Expanded>
+            true
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.get() == 4.0
+          </Original>
+          <Expanded>
+            4.0 == 4.0
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.next()
+          </Original>
+          <Expanded>
+            true
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            gen.get() == 6.0
+          </Original>
+          <Expanded>
+            6.0 == 6.0
+          </Expanded>
+        </Expression>
+        <Expression success="true" type="REQUIRE_FALSE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Original>
+            !(gen.next())
+          </Original>
+          <Expanded>
+            !false
+          </Expanded>
+        </Expression>
+        <OverallResults successes="6" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeat" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Section name="Singular repeat" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 3
+            </Original>
+            <Expanded>
+              3 == 3
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE_FALSE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              !(gen.next())
+            </Original>
+            <Expanded>
+              !false
+            </Expanded>
+          </Expression>
+          <OverallResults successes="2" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="2" failures="0" expectedFailures="0"/>
+      </Section>
+      <Section name="Repeat" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Section name="Actual repeat" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.next()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 2
+            </Original>
+            <Expanded>
+              2 == 2
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.next()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 3
+            </Original>
+            <Expanded>
+              3 == 3
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.next()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 1
+            </Original>
+            <Expanded>
+              1 == 1
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.next()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 2
+            </Original>
+            <Expanded>
+              2 == 2
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.next()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              gen.get() == 3
+            </Original>
+            <Expanded>
+              3 == 3
+            </Expanded>
+          </Expression>
+          <Expression success="true" type="REQUIRE_FALSE" filename="projects/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+            <Original>
+              !(gen.next())
+            </Original>
+            <Expanded>
+              !false
+            </Expanded>
+          </Expression>
+          <OverallResults successes="12" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="12" failures="0" expectedFailures="0"/>
+      </Section>
       <OverallResult success="true"/>
     </TestCase>
     <TestCase name="Greater-than inequalities with different epsilons" tags="[Approx]" filename="projects/<exe-name>/UsageTests/Approx.tests.cpp" >
@@ -11654,7 +12151,7 @@ loose text artifact
       </Section>
       <OverallResult success="true"/>
     </TestCase>
-    <OverallResults successes="1112" failures="130" expectedFailures="21"/>
+    <OverallResults successes="1161" failures="130" expectedFailures="21"/>
   </Group>
-  <OverallResults successes="1112" failures="129" expectedFailures="21"/>
+  <OverallResults successes="1161" failures="129" expectedFailures="21"/>
 </Catch>

projects/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp

@@ -43,4 +43,61 @@ TEST_CASE("Generators internals", "[generators][internals]") {
         REQUIRE(gen.get() == "cc");
         REQUIRE_FALSE(gen.next());
     }
+    SECTION("Filter generator") {
+        // Normal usage
+        auto gen = filter([] (int i) { return i != 2; }, values({ 2, 1, 2, 3, 2, 2 }));
+        REQUIRE(gen.get() == 1);
+        REQUIRE(gen.next());
+        REQUIRE(gen.get() == 3);
+        REQUIRE_FALSE(gen.next());
+
+        // Completely filtered-out generator should throw on construction
+        REQUIRE_THROWS_AS(filter([] (int) { return false; }, value(1)), Catch::GeneratorException);
+    }
+    SECTION("Take generator") {
+        SECTION("Take less") {
+            auto gen = take(2, values({ 1, 2, 3 }));
+            REQUIRE(gen.get() == 1);
+            REQUIRE(gen.next());
+            REQUIRE(gen.get() == 2);
+            REQUIRE_FALSE(gen.next());
+        }
+        SECTION("Take more") {
+            auto gen = take(2, value(1));
+            REQUIRE(gen.get() == 1);
+            REQUIRE_FALSE(gen.next());
+        }
+    }
+    SECTION("Map") {
+        auto gen = map<double>([] (int i) {return 2.0 * i; }, values({ 1, 2, 3 }));
+        REQUIRE(gen.get() == 2.0);
+        REQUIRE(gen.next());
+        REQUIRE(gen.get() == 4.0);
+        REQUIRE(gen.next());
+        REQUIRE(gen.get() == 6.0);
+        REQUIRE_FALSE(gen.next());
+    }
+    SECTION("Repeat") {
+        SECTION("Singular repeat") {
+            auto gen = repeat(1, value(3));
+            REQUIRE(gen.get() == 3);
+            REQUIRE_FALSE(gen.next());
+        }
+        SECTION("Actual repeat") {
+            auto gen = repeat(2, values({ 1, 2, 3 }));
+            REQUIRE(gen.get() == 1);
+            REQUIRE(gen.next());
+            REQUIRE(gen.get() == 2);
+            REQUIRE(gen.next());
+            REQUIRE(gen.get() == 3);
+            REQUIRE(gen.next());
+            REQUIRE(gen.get() == 1);
+            REQUIRE(gen.next());
+            REQUIRE(gen.get() == 2);
+            REQUIRE(gen.next());
+            REQUIRE(gen.get() == 3);
+            REQUIRE_FALSE(gen.next());
+        }
+    }
+
 }

projects/SelfTest/UsageTests/Generators.tests.cpp

@@ -56,24 +56,7 @@ TEST_CASE("tables", "[generators]") {
 
 #ifdef __cpp_structured_bindings
 
-// One way to do pairs of values (actual/ expected?)
+// Structured bindings make the table utility much nicer to use
-// For a simple case like this I'd recommend writing out a series of REQUIREs
-// but it demonstrates a possible usage.
-// Spelling out the pair like this is a bit verbose, so read on for better examples
-// - the use of structured bindings here is an optional convenience
-TEST_CASE( "strlen", "[approvals][generators]" ) {
-    auto [test_input, expected] = GENERATE( values<std::pair<std::string_view, size_t>>({
-            {"one", 3},
-            {"two", 3},
-            {"three", 5},
-            {"four", 4}
-        }));
-
-    REQUIRE( test_input.size() == expected );
-}
-
-// A nicer way to do pairs (or more) of values - using the table generator.
-// Note, you must specify the types up-front.
 TEST_CASE( "strlen2", "[approvals][generators]" ) {
     auto [test_input, expected] = GENERATE( table<std::string, size_t>({
             {"one", 3},
@@ -129,3 +112,36 @@ SCENARIO("Eating cucumbers", "[generators][approvals]") {
     }
 }
 #endif
+
+// There are also some generic generator manipulators
+TEST_CASE("Generators -- adapters", "[generators]") {
+    // TODO: This won't work yet, introduce GENERATE_VAR?
+    //auto numbers = Catch::Generators::values({ 1, 2, 3, 4, 5, 6 });
+    SECTION("Filtering by predicate") {
+        // This filters out all odd (false) numbers, giving [2, 4, 6]
+        auto i = GENERATE(filter([] (int val) { return val % 2 == 0; }, values({ 1, 2, 3, 4, 5, 6 })));
+        REQUIRE(i % 2 == 0);
+    }
+    SECTION("Shortening a range") {
+        // This takes the first 3 elements from the values, giving back [1, 2, 3]
+        auto i = GENERATE(take(3, values({ 1, 2, 3, 4, 5, 6 })));
+        REQUIRE(i < 4);
+    }
+    SECTION("Transforming elements") {
+        SECTION("Same type") {
+            // This doubles values [1, 2, 3] into [2, 4, 6]
+            auto i = GENERATE(map([] (int val) { return val * 2; }, values({ 1, 2, 3 })));
+            REQUIRE(i % 2 == 0);
+        }
+        SECTION("Different type") {
+            // This takes a generator that returns ints and maps them into strings
+            auto i = GENERATE(map<std::string>([] (int val) { return std::to_string(val); }, values({ 1, 2, 3 })));
+            REQUIRE(i.size() == 1);
+        }
+    }
+    SECTION("Repeating a generator") {
+        // This will return values [1, 2, 3, 1, 2, 3]
+        auto j = GENERATE(repeat(2, values({ 1, 2, 3 })));
+        REQUIRE(j > 0);
+    }
+}