Case-insensitive comparator for extMimeTypes.

Author: ThisIsFineTM

src/zimwriterfs/tools.cpp

@@ -26,91 +26,82 @@
 #include <iostream>
 #include <iomanip>
 #include <map>
+#include <string_view>
 
 #include <zlib.h>
 #include <magic.h>
 
-/* Init file extensions hash */
-static std::map<std::string, std::string> _create_extMimeTypes()
-{
-  std::map<std::string, std::string> extMimeTypes;
-  extMimeTypes["HTML"] = "text/html";
-  extMimeTypes["html"] = "text/html";
-  extMimeTypes["HTM"] = "text/html";
-  extMimeTypes["htm"] = "text/html";
-  extMimeTypes["PNG"] = "image/png";
-  extMimeTypes["png"] = "image/png";
-  extMimeTypes["TIFF"] = "image/tiff";
-  extMimeTypes["tiff"] = "image/tiff";
-  extMimeTypes["TIF"] = "image/tiff";
-  extMimeTypes["tif"] = "image/tiff";
-  extMimeTypes["JPEG"] = "image/jpeg";
-  extMimeTypes["jpeg"] = "image/jpeg";
-  extMimeTypes["JPG"] = "image/jpeg";
-  extMimeTypes["jpg"] = "image/jpeg";
-  extMimeTypes["GIF"] = "image/gif";
-  extMimeTypes["gif"] = "image/gif";
-  extMimeTypes["SVG"] = "image/svg+xml";
-  extMimeTypes["svg"] = "image/svg+xml";
-  extMimeTypes["TXT"] = "text/plain";
-  extMimeTypes["txt"] = "text/plain";
-  extMimeTypes["XML"] = "text/xml";
-  extMimeTypes["xml"] = "text/xml";
-  extMimeTypes["EPUB"] = "application/epub+zip";
-  extMimeTypes["epub"] = "application/epub+zip";
-  extMimeTypes["PDF"] = "application/pdf";
-  extMimeTypes["pdf"] = "application/pdf";
-  extMimeTypes["OGG"] = "audio/ogg";
-  extMimeTypes["ogg"] = "audio/ogg";
-  extMimeTypes["OGV"] = "video/ogg";
-  extMimeTypes["ogv"] = "video/ogg";
-  extMimeTypes["JS"] = "application/javascript";
-  extMimeTypes["js"] = "application/javascript";
-  extMimeTypes["JSON"] = "application/json";
-  extMimeTypes["json"] = "application/json";
-  extMimeTypes["CSS"] = "text/css";
-  extMimeTypes["css"] = "text/css";
-  extMimeTypes["otf"] = "font/otf";
-  extMimeTypes["OTF"] = "font/otf";
-  extMimeTypes["sfnt"] = "font/sfnt";
-  extMimeTypes["SFNT"] = "font/sfnt";
-  extMimeTypes["eot"] = "application/vnd.ms-fontobject";
-  extMimeTypes["EOT"] = "application/vnd.ms-fontobject";
-  extMimeTypes["ttf"] = "font/ttf";
-  extMimeTypes["TTF"] = "font/ttf";
-  extMimeTypes["collection"] = "font/collection";
-  extMimeTypes["COLLECTION"] = "font/collection";
-  extMimeTypes["woff"] = "font/woff";
-  extMimeTypes["WOFF"] = "font/woff";
-  extMimeTypes["woff2"] = "font/woff2";
-  extMimeTypes["WOFF2"] = "font/woff2";
-  extMimeTypes["vtt"] = "text/vtt";
-  extMimeTypes["VTT"] = "text/vtt";
-  extMimeTypes["webm"] = "video/webm";
-  extMimeTypes["WEBM"] = "video/webm";
-  extMimeTypes["webp"] = "image/webp";
-  extMimeTypes["WEBP"] = "image/webp";
-  extMimeTypes["mp4"] = "video/mp4";
-  extMimeTypes["MP4"] = "video/mp4";
-  extMimeTypes["doc"] = "application/msword";
-  extMimeTypes["DOC"] = "application/msword";
-  extMimeTypes["docx"] = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
-  extMimeTypes["DOCX"] = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
-  extMimeTypes["ppt"] = "application/vnd.ms-powerpoint";
-  extMimeTypes["PPT"] = "application/vnd.ms-powerpoint";
-  extMimeTypes["odt"] = "application/vnd.oasis.opendocument.text";
-  extMimeTypes["ODT"] = "application/vnd.oasis.opendocument.text";
-  extMimeTypes["odp"] = "application/vnd.oasis.opendocument.text";
-  extMimeTypes["ODP"] = "application/vnd.oasis.opendocument.text";
-  extMimeTypes["zip"] = "application/zip";
-  extMimeTypes["ZIP"] = "application/zip";
-  extMimeTypes["wasm"] = "application/wasm";
-  extMimeTypes["WASM"] = "application/wasm";
-
-  return extMimeTypes;
-}
+// adapted from cppreference example implementation of lexicographical_compare
+struct tolower_str_comparator {
+    using UChar_t = unsigned char;
+
+    static constexpr UChar_t toLower(const UChar_t c) noexcept {
+        constexpr UChar_t offset {'a' - 'A'};
+        return (c <= 'Z' && c >= 'A') ? c + offset : c;
+    }
+
+    static constexpr bool charCompare(const UChar_t lhs, const UChar_t rhs) noexcept {
+        return toLower(lhs) < toLower(rhs);
+    }
 
-static std::map<std::string, std::string> extMimeTypes = _create_extMimeTypes();
+    constexpr bool operator() (const std::string_view lhs, const std::string_view rhs) const noexcept {
+        auto first1 = lhs.cbegin();
+        const auto last1 = lhs.cend();
+        auto first2 = rhs.cbegin();
+        const auto last2 = rhs.cend();
+
+        for (; (first1 != last1) && (first2 != last2); ++first1, ++first2) {
+            if (charCompare(*first1, *first2)) {
+                return true;
+            }
+            if (charCompare(*first2, *first1)) {
+                return false;
+            }
+        }
+        return (first1 == last1) && (first2 != last2);
+    }
+};
+
+using MimeMap_t = std::map<std::string, const std::string, tolower_str_comparator>;
+
+static const MimeMap_t extMimeTypes {
+      {"html", "text/html"},
+      {"htm", "text/html"},
+      {"png", "image/png"},
+      {"tiff", "image/tiff"},
+      {"tif", "image/tiff"},
+      {"jpeg", "image/jpeg"},
+      {"jpg", "image/jpeg"},
+      {"gif", "image/gif"},
+      {"svg", "image/svg+xml"},
+      {"txt", "text/plain"},
+      {"xml", "text/xml"},
+      {"epub", "application/epub+zip"},
+      {"pdf", "application/pdf"},
+      {"ogg", "audio/ogg"},
+      {"ogv", "video/ogg"},
+      {"js", "application/javascript"},
+      {"json", "application/json"},
+      {"css", "text/css"},
+      {"otf", "font/otf"},
+      {"sfnt", "font/sfnt"},
+      {"eot", "application/vnd.ms-fontobject"},
+      {"ttf", "font/ttf"},
+      {"collection", "font/collection"},
+      {"woff", "font/woff"},
+      {"woff2", "font/woff2"},
+      {"vtt", "text/vtt"},
+      {"webm", "video/webm"},
+      {"webp", "image/webp"},
+      {"mp4", "video/mp4"},
+      {"doc", "application/msword"},
+      {"docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"},
+      {"ppt", "application/vnd.ms-powerpoint"},
+      {"odt", "application/vnd.oasis.opendocument.text"},
+      {"odp", "application/vnd.oasis.opendocument.text"},
+      {"zip", "application/zip"},
+      {"wasm", "application/wasm"},
+};
 
 static std::map<std::string, std::string> fileMimeTypes;
 
@@ -162,7 +153,7 @@ inline bool seemsToBeHtml(const std::string& path)
   if (path.find_last_of(".") != std::string::npos) {
     std::string mimeType = path.substr(path.find_last_of(".") + 1);
     if (extMimeTypes.find(mimeType) != extMimeTypes.end()) {
-      return "text/html" == extMimeTypes[mimeType];
+      return "text/html" == extMimeTypes.at(mimeType);
     }
   }