feat: add char type (#449)

add a test for char options

add support for char types to the lexical cast, to allow single character types that make sense, add a integral_conversion operations to simplify the conversions from string to integers and allow discrimination in a few cases with enumerations.

Author: phlptp

README.md

@@ -224,7 +224,7 @@ While all options internally are the same type, there are several ways to add an
 app.add_option(option_name, help_str="")
 
 app.add_option(option_name,
-               variable_to_bind_to, // bool, int, float, vector, enum, or string-like, or anything with a defined conversion from a string or that takes an int 🆕, double 🆕, or string in a constructor. Also allowed are tuples 🆕, std::array 🆕 or std::pair 🆕. Also supported are complex numbers🚧, wrapper types🚧, and containers besides vector🚧 of any other supported type.
+               variable_to_bind_to, // bool, char(see note)🚧, int, float, vector, enum, or string-like, or anything with a defined conversion from a string or that takes an int 🆕, double 🆕, or string in a constructor. Also allowed are tuples 🆕, std::array 🆕 or std::pair 🆕. Also supported are complex numbers🚧, wrapper types🚧, and containers besides vector🚧 of any other supported type.
                help_string="")
 
 app.add_option_function<type>(option_name,
@@ -233,6 +233,8 @@ app.add_option_function<type>(option_name,
 
 app.add_complex(... // Special case: support for complex numbers ⚠️. Complex numbers are now fully supported in the add_option so this function is redundant.
 
+// char as an option type is supported before 2.0 but in 2.0 it defaulted to allowing single non numerical characters in addition to the numeric values.
+
 // 🆕 There is a template overload which takes two template parameters the first is the type of object to assign the value to, the second is the conversion type.  The conversion type should have a known way to convert from a string, such as any of the types that work in the non-template version.  If XC is a std::pair and T is some non pair type.  Then a two argument constructor for T is called to assign the value.  For tuples or other multi element types, XC must be a single type or a tuple like object of the same size as the assignment type
 app.add_option<typename T, typename XC>(option_name,
                T &output, // output must be assignable or constructible from a value of type XC

book/chapters/options.md

@@ -22,6 +22,7 @@ You can use any C++ int-like type, not just `int`. CLI11 understands the followi
 |-------------|-------|
 | number like    | Integers, floats, bools, or any type that can be constructed from an integer or floating point number |
 | string-like | std\::string, or anything that can be constructed from or assigned a std\::string |
+| char | For a single char, single string values are accepted, otherwise longer strings are treated as integral values and a conversion is attempted |
 | complex-number | std::complex or any type which has a real(), and imag() operations available, will allow 1 or 2 string definitions like "1+2j" or two arguments "1","2" |
 | enumeration | any enum or enum class type is supported through conversion from the underlying type(typically int, though it can be specified otherwise) |
 | container-like | a container(like vector) of any available types including other containers |

include/CLI/TypeTools.hpp

@@ -505,6 +505,7 @@ struct expected_count<T, typename std::enable_if<!is_mutable_container<T>::value
 
 // Enumeration of the different supported categorizations of objects
 enum class object_category : int {
+    char_value = 1,
     integral_value = 2,
     unsigned_integral = 4,
     enumeration = 6,
@@ -525,27 +526,36 @@ enum class object_category : int {
 
 };
 
+/// Set of overloads to classify an object according to type
+
 /// some type that is not otherwise recognized
 template <typename T, typename Enable = void> struct classify_object {
     static constexpr object_category value{object_category::other};
 };
 
-/// Set of overloads to classify an object according to type
+/// Signed integers
 template <typename T>
-struct classify_object<T,
-                       typename std::enable_if<std::is_integral<T>::value && std::is_signed<T>::value &&
-                                               !is_bool<T>::value && !std::is_enum<T>::value>::type> {
+struct classify_object<
+    T,
+    typename std::enable_if<std::is_integral<T>::value && !std::is_same<T, char>::value && std::is_signed<T>::value &&
+                            !is_bool<T>::value && !std::is_enum<T>::value>::type> {
     static constexpr object_category value{object_category::integral_value};
 };
 
 /// Unsigned integers
 template <typename T>
-struct classify_object<
-    T,
-    typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value && !is_bool<T>::value>::type> {
+struct classify_object<T,
+                       typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value &&
+                                               !std::is_same<T, char>::value && !is_bool<T>::value>::type> {
     static constexpr object_category value{object_category::unsigned_integral};
 };
 
+/// single character values
+template <typename T>
+struct classify_object<T, typename std::enable_if<std::is_same<T, char>::value && !std::is_enum<T>::value>::type> {
+    static constexpr object_category value{object_category::char_value};
+};
+
 /// Boolean values
 template <typename T> struct classify_object<T, typename std::enable_if<is_bool<T>::value>::type> {
     static constexpr object_category value{object_category::boolean_value};
@@ -657,6 +667,12 @@ template <typename T> struct classify_object<T, typename std::enable_if<is_mutab
 ///  http://stackoverflow.com/questions/1055452/c-get-name-of-type-in-template
 /// But this is cleaner and works better in this case
 
+template <typename T,
+          enable_if_t<classify_object<T>::value == object_category::char_value, detail::enabler> = detail::dummy>
+constexpr const char *type_name() {
+    return "CHAR";
+}
+
 template <typename T,
           enable_if_t<classify_object<T>::value == object_category::integral_value ||
                           classify_object<T>::value == object_category::integer_constructible,
@@ -767,6 +783,30 @@ inline std::string type_name() {
 
 // Lexical cast
 
+/// Convert to an unsigned integral
+template <typename T, enable_if_t<std::is_unsigned<T>::value, detail::enabler> = detail::dummy>
+bool integral_conversion(const std::string &input, T &output) noexcept {
+    if(input.empty()) {
+        return false;
+    }
+    char *val = nullptr;
+    std::uint64_t output_ll = std::strtoull(input.c_str(), &val, 0);
+    output = static_cast<T>(output_ll);
+    return val == (input.c_str() + input.size()) && static_cast<std::uint64_t>(output) == output_ll;
+}
+
+/// Convert to a signed integral
+template <typename T, enable_if_t<std::is_signed<T>::value, detail::enabler> = detail::dummy>
+bool integral_conversion(const std::string &input, T &output) noexcept {
+    if(input.empty()) {
+        return false;
+    }
+    char *val = nullptr;
+    std::int64_t output_ll = std::strtoll(input.c_str(), &val, 0);
+    output = static_cast<T>(output_ll);
+    return val == (input.c_str() + input.size()) && static_cast<std::int64_t>(output) == output_ll;
+}
+
 /// Convert a flag into an integer value  typically binary flags
 inline std::int64_t to_flag_value(std::string val) {
     static const std::string trueString("true");
@@ -810,39 +850,24 @@ inline std::int64_t to_flag_value(std::string val) {
     return ret;
 }
 
-/// Signed integers
+/// Integer conversion
 template <typename T,
-          enable_if_t<classify_object<T>::value == object_category::integral_value, detail::enabler> = detail::dummy>
+          enable_if_t<classify_object<T>::value == object_category::integral_value ||
+                          classify_object<T>::value == object_category::unsigned_integral,
+                      detail::enabler> = detail::dummy>
 bool lexical_cast(const std::string &input, T &output) {
-    try {
-        std::size_t n = 0;
-        std::int64_t output_ll = std::stoll(input, &n, 0);
-        output = static_cast<T>(output_ll);
-        return n == input.size() && static_cast<std::int64_t>(output) == output_ll;
-    } catch(const std::invalid_argument &) {
-        return false;
-    } catch(const std::out_of_range &) {
-        return false;
-    }
+    return integral_conversion(input, output);
 }
 
-/// Unsigned integers
+/// char values
 template <typename T,
-          enable_if_t<classify_object<T>::value == object_category::unsigned_integral, detail::enabler> = detail::dummy>
+          enable_if_t<classify_object<T>::value == object_category::char_value, detail::enabler> = detail::dummy>
 bool lexical_cast(const std::string &input, T &output) {
-    if(!input.empty() && input.front() == '-')
-        return false;  // std::stoull happily converts negative values to junk without any errors.
-
-    try {
-        std::size_t n = 0;
-        std::uint64_t output_ll = std::stoull(input, &n, 0);
-        output = static_cast<T>(output_ll);
-        return n == input.size() && static_cast<std::uint64_t>(output) == output_ll;
-    } catch(const std::invalid_argument &) {
-        return false;
-    } catch(const std::out_of_range &) {
-        return false;
+    if(input.size() == 1) {
+        output = static_cast<T>(input[0]);
+        return true;
     }
+    return integral_conversion(input, output);
 }
 
 /// Boolean values
@@ -867,15 +892,13 @@ bool lexical_cast(const std::string &input, T &output) {
 template <typename T,
           enable_if_t<classify_object<T>::value == object_category::floating_point, detail::enabler> = detail::dummy>
 bool lexical_cast(const std::string &input, T &output) {
-    try {
-        std::size_t n = 0;
-        output = static_cast<T>(std::stold(input, &n));
-        return n == input.size();
-    } catch(const std::invalid_argument &) {
-        return false;
-    } catch(const std::out_of_range &) {
+    if(input.empty()) {
         return false;
     }
+    char *val = nullptr;
+    auto output_ld = std::strtold(input.c_str(), &val);
+    output = static_cast<T>(output_ld);
+    return val == (input.c_str() + input.size());
 }
 
 /// complex
@@ -932,8 +955,7 @@ template <typename T,
           enable_if_t<classify_object<T>::value == object_category::enumeration, detail::enabler> = detail::dummy>
 bool lexical_cast(const std::string &input, T &output) {
     typename std::underlying_type<T>::type val;
-    bool retval = detail::lexical_cast(input, val);
-    if(!retval) {
+    if(!integral_conversion(input, val)) {
         return false;
     }
     output = static_cast<T>(val);
@@ -958,7 +980,7 @@ template <
     enable_if_t<classify_object<T>::value == object_category::number_constructible, detail::enabler> = detail::dummy>
 bool lexical_cast(const std::string &input, T &output) {
     int val;
-    if(lexical_cast(input, val)) {
+    if(integral_conversion(input, val)) {
         output = T(val);
         return true;
     } else {
@@ -977,7 +999,7 @@ template <
     enable_if_t<classify_object<T>::value == object_category::integer_constructible, detail::enabler> = detail::dummy>
 bool lexical_cast(const std::string &input, T &output) {
     int val;
-    if(lexical_cast(input, val)) {
+    if(integral_conversion(input, val)) {
         output = T(val);
         return true;
     }

include/CLI/Validators.hpp

@@ -966,14 +966,11 @@ class AsNumberWithUnit : public Validator {
             if(opts & CASE_INSENSITIVE) {
                 unit = detail::to_lower(unit);
             }
-
-            bool converted = detail::lexical_cast(input, num);
-            if(!converted) {
-                throw ValidationError(std::string("Value ") + input + " could not be converted to " +
-                                      detail::type_name<Number>());
-            }
-
             if(unit.empty()) {
+                if(!detail::lexical_cast(input, num)) {
+                    throw ValidationError(std::string("Value ") + input + " could not be converted to " +
+                                          detail::type_name<Number>());
+                }
                 // No need to modify input if no unit passed
                 return {};
             }
@@ -987,12 +984,22 @@ class AsNumberWithUnit : public Validator {
                                       detail::generate_map(mapping, true));
             }
 
-            // perform safe multiplication
-            bool ok = detail::checked_multiply(num, it->second);
-            if(!ok) {
-                throw ValidationError(detail::to_string(num) + " multiplied by " + unit +
-                                      " factor would cause number overflow. Use smaller value.");
+            if(!input.empty()) {
+                bool converted = detail::lexical_cast(input, num);
+                if(!converted) {
+                    throw ValidationError(std::string("Value ") + input + " could not be converted to " +
+                                          detail::type_name<Number>());
+                }
+                // perform safe multiplication
+                bool ok = detail::checked_multiply(num, it->second);
+                if(!ok) {
+                    throw ValidationError(detail::to_string(num) + " multiplied by " + unit +
+                                          " factor would cause number overflow. Use smaller value.");
+                }
+            } else {
+                num = static_cast<Number>(it->second);
             }
+
             input = detail::to_string(num);
 
             return {};

tests/HelpersTest.cpp

@@ -911,6 +911,9 @@ TEST(Types, TypeName) {
     std::string float_name = CLI::detail::type_name<double>();
     EXPECT_EQ("FLOAT", float_name);
 
+    std::string char_name = CLI::detail::type_name<char>();
+    EXPECT_EQ("CHAR", char_name);
+
     std::string vector_name = CLI::detail::type_name<std::vector<int>>();
     EXPECT_EQ("INT", vector_name);
 
@@ -1025,6 +1028,11 @@ TEST(Types, LexicalCastInt) {
 
     std::string extra_input = "912i";
     EXPECT_FALSE(CLI::detail::lexical_cast(extra_input, y));
+
+    std::string empty_input{};
+    EXPECT_FALSE(CLI::detail::lexical_cast(empty_input, x_signed));
+    EXPECT_FALSE(CLI::detail::lexical_cast(empty_input, x_unsigned));
+    EXPECT_FALSE(CLI::detail::lexical_cast(empty_input, y_signed));
 }
 
 TEST(Types, LexicalCastDouble) {
@@ -1037,10 +1045,14 @@ TEST(Types, LexicalCastDouble) {
     EXPECT_FALSE(CLI::detail::lexical_cast(bad_input, x));
 
     std::string overflow_input = "1" + std::to_string(LDBL_MAX);
-    EXPECT_FALSE(CLI::detail::lexical_cast(overflow_input, x));
+    EXPECT_TRUE(CLI::detail::lexical_cast(overflow_input, x));
+    EXPECT_FALSE(std::isfinite(x));
 
     std::string extra_input = "9.12i";
     EXPECT_FALSE(CLI::detail::lexical_cast(extra_input, x));
+
+    std::string empty_input{};
+    EXPECT_FALSE(CLI::detail::lexical_cast(empty_input, x));
 }
 
 TEST(Types, LexicalCastBool) {

tests/OptionTypeTest.cpp

@@ -167,6 +167,31 @@ TEST_F(TApp, BoolOption) {
     EXPECT_FALSE(bflag);
 }
 
+TEST_F(TApp, CharOption) {
+    char c1{'t'};
+    app.add_option("-c", c1);
+
+    args = {"-c", "g"};
+    run();
+    EXPECT_EQ(c1, 'g');
+
+    args = {"-c", "1"};
+    run();
+    EXPECT_EQ(c1, '1');
+
+    args = {"-c", "77"};
+    run();
+    EXPECT_EQ(c1, 77);
+
+    // convert hex for digit
+    args = {"-c", "0x44"};
+    run();
+    EXPECT_EQ(c1, 0x44);
+
+    args = {"-c", "751615654161688126132138844896646748852"};
+    EXPECT_THROW(run(), CLI::ConversionError);
+}
+
 TEST_F(TApp, vectorDefaults) {
     std::vector<int> vals{4, 5};
     auto opt = app.add_option("--long", vals, "", true);

tests/OptionalTest.cpp

@@ -218,6 +218,7 @@ TEST_F(TApp, BoostOptionalEnumTest) {
 
     enum class eval : char { val0 = 0, val1 = 1, val2 = 2, val3 = 3, val4 = 4 };
     boost::optional<eval> opt, opt2;
+
     auto optptr = app.add_option<decltype(opt), eval>("-v,--val", opt);
     app.add_option_no_stream("-e,--eval", opt2);
     optptr->capture_default_str();

tests/TransformTest.cpp

@@ -692,7 +692,8 @@ TEST_F(TApp, NumberWithUnitBadInput) {
     args = {"-n", "13 c"};
     EXPECT_THROW(run(), CLI::ValidationError);
     args = {"-n", "a"};
-    EXPECT_THROW(run(), CLI::ValidationError);
+    // Assume 1.0 unit
+    EXPECT_NO_THROW(run());
     args = {"-n", "12.0a"};
     EXPECT_THROW(run(), CLI::ValidationError);
     args = {"-n", "a5"};