Path: Add CreateFileURL()

src/common/file_system.cpp

@@ -745,6 +745,114 @@ std::string Path::Combine(const std::string_view& base, const std::string_view&
   return ret;
 }
 
+std::string Path::URLEncode(std::string_view str)
+{
+  std::string ret;
+  ret.reserve(str.length() + ((str.length() + 3) / 4) * 3);
+
+  for (size_t i = 0, l = str.size(); i < l; i++)
+  {
+    const char c = str[i];
+    if ((c >= '0' && c <= '9') || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '-' || c == '_' ||
+        c == '.' || c == '!' || c == '~' || c == '*' || c == '\'' || c == '(' || c == ')')
+    {
+      ret.push_back(c);
+    }
+    else
+    {
+      ret.push_back('%');
+
+      const unsigned char n1 = static_cast<unsigned char>(c) >> 4;
+      const unsigned char n2 = static_cast<unsigned char>(c) & 0x0F;
+      ret.push_back((n1 >= 10) ? ('a' + (n1 - 10)) : ('0' + n1));
+      ret.push_back((n2 >= 10) ? ('a' + (n2 - 10)) : ('0' + n2));
+    }
+  }
+
+  return ret;
+}
+
+std::string Path::URLDecode(std::string_view str)
+{
+  std::string ret;
+  ret.reserve(str.length());
+
+  for (size_t i = 0, l = str.size(); i < l; i++)
+  {
+    const char c = str[i];
+    if (c == '+')
+    {
+      ret.push_back(c);
+    }
+    else if (c == '%')
+    {
+      if ((i + 2) >= str.length())
+        break;
+
+      const char clower = str[i + 1];
+      const char cupper = str[i + 2];
+      const unsigned char lower =
+        (clower >= '0' && clower <= '9') ?
+          static_cast<unsigned char>(clower - '0') :
+          ((clower >= 'a' && clower <= 'f') ?
+             static_cast<unsigned char>(clower - 'a') :
+             ((clower >= 'A' && clower <= 'F') ? static_cast<unsigned char>(clower - 'A') : 0));
+      const unsigned char upper =
+        (cupper >= '0' && cupper <= '9') ?
+          static_cast<unsigned char>(cupper - '0') :
+          ((cupper >= 'a' && cupper <= 'f') ?
+             static_cast<unsigned char>(cupper - 'a') :
+             ((cupper >= 'A' && cupper <= 'F') ? static_cast<unsigned char>(cupper - 'A') : 0));
+      const char dch = static_cast<char>(lower | (upper << 4));
+      ret.push_back(dch);
+    }
+    else
+    {
+      ret.push_back(c);
+    }
+  }
+
+  return std::string(str);
+}
+
+std::string Path::CreateFileURL(std::string_view path)
+{
+  DebugAssert(IsAbsolute(path));
+
+  std::string ret;
+  ret.reserve(path.length() + 10);
+  ret.append("file://");
+
+  const std::vector<std::string_view> components = SplitNativePath(path);
+  Assert(!components.empty());
+
+  const std::string_view& first = components.front();
+#ifdef _WIN32
+  // Windows doesn't urlencode the drive letter.
+  // UNC paths should be omit the leading slash.
+  if (first.starts_with("\\\\"))
+  {
+    // file://hostname/...
+    ret.append(first.substr(2));
+  }
+  else
+  {
+    // file:///c:/...
+    fmt::format_to(std::back_inserter(ret), "/{}", first);
+  }
+#else
+  // Don't append a leading slash for the first component.
+  ret.append(first);
+#endif
+
+  for (size_t comp = 1; comp < components.size(); comp++)
+  {
+    fmt::format_to(std::back_inserter(ret), "/{}", URLEncode(components[comp]));
+  }
+
+  return ret;
+}
+
 std::FILE* FileSystem::OpenCFile(const char* filename, const char* mode, Error* error)
 {
 #ifdef _WIN32

src/common/path.h

@@ -71,4 +71,13 @@ std::string JoinWindowsPath(const std::vector<std::string_view>& components);
 /// Splits a path into its components, only handling native separators.
 std::vector<std::string_view> SplitNativePath(const std::string_view& path);
 std::string JoinNativePath(const std::vector<std::string_view>& components);
+
+/// URL encodes the specified string.
+std::string URLEncode(std::string_view str);
+
+/// Decodes the specified escaped string.
+std::string URLDecode(std::string_view str);
+
+/// Returns a URL for a given path. The path should be absolute.
+std::string CreateFileURL(std::string_view path);
 } // namespace Path