parse: add throwing native type parsers

CMakeLists.txt

@@ -334,6 +334,8 @@ list (
     memory/deleter.cpp
     memory/deleter.hpp
     nocopy.hpp
+    parse.cpp
+    parse.hpp
     pascal.cpp
     pascal.hpp
     platform.hpp
@@ -491,6 +493,7 @@ if (TESTS)
         maths
         matrix
         memory/deleter
+        parse
         point
         polynomial
         pool

parse.cpp

@@ -0,0 +1,86 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2017 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "./parse.hpp"
+
+#include <cstdlib>
+#include <stdexcept>
+
+using util::parse;
+
+///////////////////////////////////////////////////////////////////////////////
+template <typename T> struct c_traits;
+template <> struct c_traits<long> { static constexpr auto func = strtol; };
+template <> struct c_traits<long long> { static constexpr auto func = strtoll; };
+template <> struct c_traits<unsigned long> { static constexpr auto func = strtoul; };
+template <> struct c_traits<unsigned long long> { static constexpr auto func = strtoull; };
+
+template <> struct c_traits<float> { static constexpr auto func = strtof; };
+template <> struct c_traits<double> { static constexpr auto func = strtod; };
+template <> struct c_traits<long double> { static constexpr auto func = strtold; };
+
+
+//-----------------------------------------------------------------------------
+template <typename T>
+T
+c_iparse (const char *first, const char *last)
+{
+    auto tail = const_cast<char *> (last);
+    auto val = c_traits<T>::func (first, &tail, 0);
+
+    if (tail != last)
+        throw std::invalid_argument ("unable to parse");
+
+    return val;
+}
+
+
+//-----------------------------------------------------------------------------
+template <typename T>
+T
+c_fparse (const char *first, const char *last)
+{
+    auto tail = const_cast<char *> (last);
+    auto val = c_traits<T>::func (first, &tail);
+
+    if (tail != last)
+        throw std::invalid_argument ("unable to parse");
+
+    return val;
+}
+
+
+
+
+///////////////////////////////////////////////////////////////////////////////
+#define C_PARSE(T, KLASS) \
+template <> \
+T \
+util::parse<T> (const char *first, const char *last) \
+{ \
+    return c_ ## KLASS ## parse<T> (first, last); \
+}
+
+
+//-----------------------------------------------------------------------------
+C_PARSE(long, i)
+C_PARSE(long long, i)
+C_PARSE(unsigned long, i)
+C_PARSE(unsigned long long, i)
+
+C_PARSE(float, f)
+C_PARSE(double, f)
+C_PARSE(long double, f)

parse.hpp

@@ -0,0 +1,53 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2017 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef CRUFT_UTIL_PARSE_HPP
+#define CRUFT_UTIL_PARSE_HPP
+
+#include <cstring>
+#include <string>
+#include <iterator>
+
+
+namespace util {
+    ///////////////////////////////////////////////////////////////////////////
+    /// extracts an instance of a native type T from the string [first, last).
+    ///
+    /// throws std::invalid_argument when the type cannot be parsed.
+    template <typename T>
+    T
+    parse (const char *first, const char *last);
+
+
+    //-------------------------------------------------------------------------
+    template <typename T>
+    T
+    parse (const char *str)
+    {
+        return parse<T> (str, str + strlen (str));
+    }
+
+
+    //-------------------------------------------------------------------------
+    template <typename T>
+    T
+    parse (const std::string &str)
+    {
+        return parse<T> (std::cbegin (str), std::cend (str));
+    }
+}
+
+#endif

test/parse.cpp

@@ -0,0 +1,18 @@
+#include "parse.hpp"
+#include "tap.hpp"
+
+
+///////////////////////////////////////////////////////////////////////////////
+int
+main (void)
+{
+    util::TAP::logger tap;
+
+    tap.expect_eq (util::parse<long> ("1"), 1L, "parsing long '1'");
+    tap.expect_throw<std::invalid_argument> ([] () { util::parse<long> ("a"); }, "parsing long 'a'");
+
+    tap.expect_eq (util::parse<float> ("1"), 1.f, "parsing float '1'");
+    tap.expect_throw<std::invalid_argument> ([] () { util::parse<float> ("a"); }, "parsing float 'a'");
+
+    return tap.status ();
+}