Add get_header() to answer_type.

include/answer.hpp

@@ -99,6 +99,15 @@ struct answer_type
      */
     friend std::ostream &operator <<(std::ostream &out,
                                      const answer_type &answer);
+
+    /*!
+     *  @brief  Returns the value of a header field.
+     *
+     *  Case insensitive, only ASCII.
+     *
+     *  @since  0.1.0
+     */
+    string_view get_header(string_view field) const;
 };
 
 } // namespace mastodonpp

src/answer.cpp

@@ -16,9 +16,15 @@
 
 #include "answer.hpp"
 
+#include <algorithm>
+#include <cctype>
+
 namespace mastodonpp
 {
 
+using std::search;
+using std::tolower;
+
 answer_type::operator bool() const
 {
     return (curl_error_code == 0 && http_status == 200);
@@ -35,4 +41,23 @@ std::ostream &operator <<(std::ostream &out, const answer_type &answer)
     return out;
 }
 
+string_view answer_type::get_header(const string_view field) const
+{
+    const string_view searchstring{string(field) += ':'};
+    auto it{search(headers.begin(), headers.end(),
+                   searchstring.begin(), searchstring.end(),
+                   [](unsigned char a, unsigned char b)
+                   { return tolower(a) == tolower(b); })};
+
+    if (it != headers.end())
+    {
+        auto pos{static_cast<size_t>(it - headers.begin())};
+        pos = headers.find(':', pos) + 2;
+        const auto endpos{headers.find('\n', pos)};
+        return headers.substr(pos, endpos - pos);
+    }
+
+    return {};
+}
+
 } // namespace mastodonpp