Repo created

libs/search/utm_mgrs_coords_match.cpp

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+#include "search/utm_mgrs_coords_match.hpp"
+
+#include "base/string_utils.hpp"
+
+#include "platform/utm_mgrs_utils.hpp"
+
+#include <string>
+
+#include "base/math.hpp"
+#include "base/string_utils.hpp"
+
+namespace search
+{
+static std::string_view constexpr kSpaceChars = " \t\r\n";
+
+// Matches 2 digits zone code. Returns end position of matched chars or string::npos if no match.
+static size_t MatchZoneCode(std::string const & query, int & zoneCode)
+{
+  auto const pos = query.find_first_not_of(kSpaceChars);
+  if (pos == std::string::npos || query.size() < pos + 2)
+    return std::string::npos;
+
+  char const dig1 = query[pos];
+  char const dig2 = query[pos + 1];
+  if (dig1 > '9' || dig1 < '0' || dig2 > '9' || dig2 < '0')
+    return std::string::npos;
+
+  zoneCode = (dig1 - '0') * 10 + (dig2 - '0');
+  return pos + 2;
+}
+
+// Matches zone letter ignoring spaces. Returns end position of matched chars or string::npos if no match.
+size_t MatchZoneLetter(std::string const & query, char & zoneLetter, size_t startPos)
+{
+  auto const pos = query.find_first_not_of(kSpaceChars, startPos);
+  if (pos == std::string::npos || query.size() == pos)
+    return std::string::npos;
+
+  char const l = query[pos];
+  if (l < 'A' || l > 'Z')
+    return std::string::npos;
+
+  zoneLetter = l;
+  return pos + 1;
+}
+
+// Matches long number ignoring spaces. Returns end position of matched chars or string::npos if no match.
+size_t MatchInt(std::string const & query, int & value, size_t startPos)
+{
+  auto pos = query.find_first_not_of(kSpaceChars, startPos);
+  if (pos == std::string::npos || query.size() == pos)
+    return std::string::npos;
+
+  int n = 0;
+  while (pos < query.size())
+  {
+    char const ch = query[pos];
+    if (ch >= '0' && ch <= '9')  // Found digit
+    {
+      n = n * 10 + (ch - '0');
+      pos++;
+    }
+    else if (kSpaceChars.find(ch) != std::string::npos)  // Found space char matching end of the number
+      break;
+    else  // Found invalid char
+      return std::string::npos;
+  }
+
+  value = n;
+  return pos;
+}
+
+// Parse UTM format "(\d\d)\s?(\W)\s+(\d+)\s+(\d+)" and converts it to lat,lon.
+// Return true if parsed successfully or false otherwise.
+// See utm_mgrs_coords_match_test.cpp for sample UTM strings
+// TODO: Add support of Polar regions. E.g. "A 1492875 2040624"
+// TODO: Support additional formats listed here: https://www.killetsoft.de/t_0901_e.htm
+std::optional<ms::LatLon> MatchUTMCoords(std::string const & query)
+{
+  int easting, northing;
+  int zoneCode;
+  char zoneLetter;
+
+  size_t pos = MatchZoneCode(query, zoneCode);
+  if (pos == std::string::npos)
+    return {};
+
+  pos = MatchZoneLetter(query, zoneLetter, pos);
+  if (pos == std::string::npos)
+    return {};
+
+  pos = MatchInt(query, easting, pos);
+  if (pos == std::string::npos)
+    return {};
+
+  pos = MatchInt(query, northing, pos);
+  if (pos == std::string::npos)
+    return {};
+
+  return utm_mgrs_utils::UTMtoLatLon(easting, northing, zoneCode, zoneLetter);
+}
+
+// Parse MGRS format "(\d\d\W)\s*(\W\W)\s*(\d+)\s*(\d+)" and converts it to lat,lon.
+// Returns true if parsed successfully or false otherwise.
+// See utm_mgrs_coords_match_test.cpp for sample MGRS strings
+// TODO: Add support of Polar regions. E.g. "A SN 92875 40624"
+std::optional<ms::LatLon> MatchMGRSCoords(std::string const & query)
+{
+  int zoneCode;
+  char zoneLetter;
+  char squareCode[2];
+  std::string eastingStr;
+  std::string northingStr;
+  int32_t easting;
+  int32_t northing;
+
+  strings::SimpleTokenizer it(query, " \t\r");
+  if (!it)
+    return {};
+
+  auto token = std::string(*it);
+  // Parse 2 digit zone code and 1 char zone letter
+  if (token.size() >= 3)
+  {
+    char dig1 = token[0];
+    char dig2 = token[1];
+    if (dig1 < '0' || dig1 > '9' || dig2 < '0' || dig2 > '9')
+      return {};
+
+    zoneCode = (dig1 - '0') * 10 + (dig2 - '0');
+    if (zoneCode < 1 || zoneCode > 60)
+      return {};
+
+    zoneLetter = token[2];
+    token = token.substr(3);
+  }
+  else
+    return {};
+
+  // Read next token if needed.
+  if (token.size() == 0)
+  {
+    ++it;
+    if (!it)
+      return {};
+    token = std::string(*it);
+  }
+
+  // Parse 2 chars zone code.
+  if (token.size() >= 2)
+  {
+    squareCode[0] = token[0];
+    squareCode[1] = token[1];
+    token = token.substr(2);
+  }
+
+  // Read next token if needed.
+  if (token.size() == 0)
+  {
+    ++it;
+    if (!it)
+      return {};
+    token = std::string(*it);
+  }
+
+  // Parse easting and norhing.
+  eastingStr = token;
+
+  // Get next token if available.
+  ++it;
+  if (it)
+    northingStr = std::string(*it);
+
+  // Convert eastingStr & northingStr to numbers.
+  if (northingStr.empty())
+  {
+    // eastingStr contains both easting and northing. Let's split
+    if (eastingStr.size() % 2 != 0)
+      return {};
+
+    size_t const eastingSize = eastingStr.size() / 2;
+    northingStr = eastingStr.substr(eastingSize);
+    eastingStr = eastingStr.substr(0, eastingSize);
+  }
+
+  if (eastingStr.size() != northingStr.size() || eastingStr.size() > 5 || northingStr.size() > 5)
+    return {};
+
+  if (!strings::to_int32(eastingStr, easting))
+    return {};
+  if (eastingStr.size() < 5)
+  {
+    uint64_t const decShift = 5 - eastingStr.size();
+    easting *= math::PowUint(10, decShift);
+  }
+
+  if (!strings::to_int32(northingStr, northing))
+    return {};
+  if (northingStr.size() < 5)
+  {
+    uint64_t const decShift = 5 - northingStr.size();
+    northing *= math::PowUint(10, decShift);
+  }
+
+  return utm_mgrs_utils::MGRStoLatLon(easting, northing, zoneCode, zoneLetter, squareCode);
+}
+
+}  // namespace search