[Refactor] Remove reference of Configuration in odbc_connection.cc

cpp/src/arrow/flight/sql/odbc/odbc_api.cc

@@ -752,6 +752,21 @@ SQLRETURN SQLSetConnectAttr(SQLHDBC conn, SQLINTEGER attr, SQLPOINTER valuePtr,
   });
 }
 
+// Load properties from the given DSN. The properties loaded do _not_ overwrite existing
+// entries in the properties.
+void loadPropertiesFromDSN(const std::string& dsn,
+                           Connection::ConnPropertyMap& properties) {
+  driver::flight_sql::config::Configuration config;
+  config.LoadDsn(dsn);
+  Connection::ConnPropertyMap dsnProperties = config.GetProperties();
+  for (auto& [key, value] : dsnProperties) {
+    auto propIter = properties.find(key);
+    if (propIter == properties.end()) {
+      properties.emplace(std::make_pair(std::move(key), std::move(value)));
+    }
+  }
+}
+
 SQLRETURN SQLDriverConnect(SQLHDBC conn, SQLHWND windowHandle,
                            SQLWCHAR* inConnectionString,
                            SQLSMALLINT inConnectionStringLen,
@@ -782,8 +797,11 @@ SQLRETURN SQLDriverConnect(SQLHDBC conn, SQLHWND windowHandle,
     std::string connection_string =
         ODBC::SqlWcharToString(inConnectionString, inConnectionStringLen);
     Connection::ConnPropertyMap properties;
-    std::string dsn =
-        ODBCConnection::getPropertiesFromConnString(connection_string, properties);
+    std::string dsn = ODBCConnection::getDsnIfExists(connection_string);
+    if (!dsn.empty()) {
+      loadPropertiesFromDSN(dsn, properties);
+    }
+    ODBCConnection::getPropertiesFromConnString(connection_string, properties);
 
     std::vector<std::string_view> missing_properties;
 

cpp/src/arrow/flight/sql/odbc/odbcabstraction/include/odbcabstraction/odbc_impl/odbc_connection.h

@@ -84,8 +84,12 @@ class ODBCConnection : public ODBCHandle<ODBCConnection> {
 
   inline bool IsOdbc2Connection() const { return m_is2xConnection; }
 
-  /// @return the DSN or empty string if Driver was used.
-  static std::string getPropertiesFromConnString(
+  /// @return the DSN or an empty string if the DSN is not found or is found after the
+  /// driver
+  static std::string getDsnIfExists(const std::string& connStr);
+
+  /// Read properties from connection string, but does not read values from DSN
+  static void getPropertiesFromConnString(
       const std::string& connStr,
       driver::odbcabstraction::Connection::ConnPropertyMap& properties);
 

cpp/src/arrow/flight/sql/odbc/odbcabstraction/odbc_impl/odbc_connection.cc

@@ -54,22 +54,6 @@ namespace {
 // built statically.
 const boost::xpressive::sregex CONNECTION_STR_REGEX(
     boost::xpressive::sregex::compile("([^=;]+)=({.+}|[^;]+|[^;])"));
-
-// Load properties from the given DSN. The properties loaded do _not_ overwrite existing
-// entries in the properties.
-void loadPropertiesFromDSN(const std::string& dsn,
-                           Connection::ConnPropertyMap& properties) {
-  driver::flight_sql::config::Configuration config;
-  config.LoadDsn(dsn);
-  Connection::ConnPropertyMap dsnProperties = config.GetProperties();
-  for (auto& [key, value] : dsnProperties) {
-    auto propIter = properties.find(key);
-    if (propIter == properties.end()) {
-      properties.emplace(std::make_pair(std::move(key), std::move(value)));
-    }
-  }
-}
-
 }  // namespace
 
 // Public
@@ -696,37 +680,42 @@ void ODBCConnection::dropDescriptor(ODBCDescriptor* desc) {
 
 // Public Static
 // ===================================================================================
-std::string ODBCConnection::getPropertiesFromConnString(
+std::string ODBCConnection::getDsnIfExists(const std::string& connStr) {
+  const int groups[] = {1, 2};  // CONNECTION_STR_REGEX has two groups. key: 1, value: 2
+  boost::xpressive::sregex_token_iterator regex_iter(connStr.begin(), connStr.end(),
+                                                     CONNECTION_STR_REGEX, groups),
+      end;
+
+  // First key in connection string should be either dsn or driver
+  auto it = regex_iter;
+  std::string key = *regex_iter;
+  std::string value = *++regex_iter;
+
+  // Strip wrapping curly braces.
+  if (value.size() >= 2 && value[0] == '{' && value[value.size() - 1] == '}') {
+    value = value.substr(1, value.size() - 2);
+  }
+
+  if (boost::iequals(key, "DSN")) {
+    return value;
+  } else if (boost::iequals(key, "Driver")) {
+    return std::string("");
+  } else {
+    throw DriverException(
+        "Connection string is faulty. The first key should be DSN or Driver.", "HY000");
+  }
+}
+
+void ODBCConnection::getPropertiesFromConnString(
     const std::string& connStr, Connection::ConnPropertyMap& properties) {
   const int groups[] = {1, 2};  // CONNECTION_STR_REGEX has two groups. key: 1, value: 2
-  boost::xpressive::sregex_token_iterator regexIter(connStr.begin(), connStr.end(),
-                                                    CONNECTION_STR_REGEX, groups),
+  boost::xpressive::sregex_token_iterator regex_iter(connStr.begin(), connStr.end(),
+                                                     CONNECTION_STR_REGEX, groups),
       end;
 
-  bool isDsnFirst = false;
-  bool isDriverFirst = false;
-  std::string dsn;
-  for (auto it = regexIter; end != regexIter; ++regexIter) {
-    std::string key = *regexIter;
-    std::string value = *++regexIter;
-
-    // If the DSN shows up before driver key, load settings from the DSN.
-    // Only load values from the DSN once regardless of how many times the DSN
-    // key shows up.
-    if (boost::iequals(key, "DSN")) {
-      if (!isDriverFirst) {
-        if (!isDsnFirst) {
-          isDsnFirst = true;
-          loadPropertiesFromDSN(value, properties);
-          dsn.swap(value);
-        }
-      }
-      continue;
-    } else if (boost::iequals(key, "Driver")) {
-      if (!isDsnFirst) {
-        isDriverFirst = true;
-      }
-    }
+  for (auto it = regex_iter; end != regex_iter; ++regex_iter) {
+    std::string key = *regex_iter;
+    std::string value = *++regex_iter;
 
     // Strip wrapping curly braces.
     if (value.size() >= 2 && value[0] == '{' && value[value.size() - 1] == '}') {
@@ -737,5 +726,4 @@ std::string ODBCConnection::getPropertiesFromConnString(
     // including over entries in the DSN.
     properties[key] = std::move(value);
   }
-  return dsn;
 }