Fix #23 optimized Statement::getColumn() by name

- fix Statement::getColumn(apName) provided by #45 but was not working
  instead of using #46 that conflicts with current master
- rework it by using a map of columns name as
  a cache populated the first time the method is called
- add corresponding Unit Test

include/SQLiteCpp/Statement.h

@@ -12,6 +12,7 @@
 
 #include <sqlite3.h>
 #include <string>
+#include <map>
 
 #include <SQLiteCpp/Exception.h>
 
@@ -274,7 +275,8 @@ public:
      *  Can be used to access the data of the current row of result when applicable,
      * while the executeStep() method returns true.
      *
-     *  Throw an exception if there is no row to return a Column from :
+     *  Throw an exception if there is no row to return a Column from:
+     * - if provided index is out of bound
      * - before any executeStep() call
      * - after the last executeStep() returned false
      * - after a reset() call
@@ -283,8 +285,7 @@ public:
      *
      * @param[in] aIndex    Index of the column, starting at 0
      *
-     * @note    This method is no more const, starting in v0.5,
-     *          which reflects the fact that the returned Column object will
+     * @note    This method is not const, reflecting the fact that the returned Column object will
      *          share the ownership of the underlying sqlite3_stmt.
      *
      * @warning The resulting Column object must not be memorized "as-is".
@@ -302,16 +303,16 @@ public:
      * while the executeStep() method returns true.
      *
      *  Throw an exception if there is no row to return a Column from :
+     * - if provided name is not one of the aliased column names
      * - before any executeStep() call
      * - after the last executeStep() returned false
      * - after a reset() call
      *
      *  Throw an exception if the specified index is out of the [0, getColumnCount()) range.
      *
-     * @param[in] aName    Name of the column, starting at index 0
+     * @param[in] apName   Name of the column, starting at index 0
      *
-     * @note    This method is no more const, starting in v0.5,
-     *          which reflects the fact that the returned Column object will
+     * @note    This method is not const, reflecting the fact that the returned Column object will
      *          share the ownership of the underlying sqlite3_stmt.
      *
      * @warning The resulting Column object must not be memorized "as-is".
@@ -320,8 +321,8 @@ public:
      *          Thus, you should instead extract immediately its data (getInt(), getText()...)
      *          and use or copy this data for any later usage.
      */
-    Column  getColumn(const char* aName);
-    
+    Column  getColumn(const char* apName);
+
     /**
      * @brief Test if the column value is NULL
      *
@@ -424,10 +425,14 @@ private:
      */
     void check(const int aRet);
 
+private:
+    typedef std::map<std::string, int> TColumnNames;
+
 private:
     std::string     mQuery;         //!< UTF-8 SQL Query
     Ptr             mStmtPtr;       //!< Shared Pointer to the prepared SQLite Statement Object
     int             mColumnCount;   //!< Number of columns in the result of the prepared statement
+    TColumnNames    mColumnNames;   //!< Map of columns index by name
     bool            mbOk;           //!< true when a row has been fetched with executeStep()
     bool            mbDone;         //!< true when the last executeStep() had no more row to fetch
 };

src/Statement.cpp

@@ -258,9 +258,9 @@ Column Statement::getColumn(const int aIndex)
 
 // Return a copy of the column data specified by its column name starting at 0
 // (use the Column copy-constructor)
-Column  Statement::getColumn(const char* aName)
+Column  Statement::getColumn(const char* apName)
 {
-    int aIndex = -1;
+    int Index = -1;
 
     if (false == mbOk)
     {
@@ -268,18 +268,28 @@ Column  Statement::getColumn(const char* aName)
     }
     else
     {
-        for (int i = 0; i < mColumnCount; ++i) {
-            if (sqlite3_column_name(mStmtPtr, i) == aName)
-                break;
+        if (mColumnNames.empty())
+        {
+            for (int i = 0; i < mColumnCount; ++i)
+            {
+                const char* pName = sqlite3_column_name(mStmtPtr, i);
+                mColumnNames[pName] = i;
+            }
         }
 
-        if ((aIndex < 0) || (aIndex >= mColumnCount)) {
+        const TColumnNames::const_iterator iIndex = mColumnNames.find(apName);
+        if (iIndex != mColumnNames.end())
+        {
+            Index = (*iIndex).second;
+        }
+        else
+        {
             throw SQLite::Exception("Column index out of range");
         }
     }
 
     // Share the Statement Object handle with the new Column created
-    return Column(mStmtPtr, aIndex);
+    return Column(mStmtPtr, Index);
 }
 
 // Test if the column is NULL

tests/Statement_test.cpp

@@ -77,3 +77,45 @@ TEST(Statement, invalid) {
     } // Close DB test.db3
     remove("test.db3");
 }
+
+
+TEST(Statement, getColumnByName) {
+    remove("test.db3");
+    {
+        // Create a new database
+        SQLite::Database db("test.db3", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);
+        EXPECT_EQ(SQLITE_OK, db.getErrorCode());
+        EXPECT_EQ(SQLITE_OK, db.getExtendedErrorCode());
+
+        // Create a new table
+        EXPECT_EQ(0, db.exec("CREATE TABLE test (id INTEGER PRIMARY KEY, msg TEXT, int INTEGER, double REAL)"));
+        EXPECT_EQ(SQLITE_OK, db.getErrorCode());
+        EXPECT_EQ(SQLITE_OK, db.getExtendedErrorCode());
+
+        // Create a first row
+        EXPECT_EQ(1, db.exec("INSERT INTO test VALUES (NULL, \"first\", 123, 0.123)"));
+        EXPECT_EQ(1, db.getLastInsertRowid());
+        EXPECT_EQ(1, db.getTotalChanges());
+
+        // Compile a SQL query
+        SQLite::Statement   query(db, "SELECT * FROM test");
+        EXPECT_STREQ("SELECT * FROM test", query.getQuery().c_str());
+        EXPECT_EQ(4, query.getColumnCount());
+        query.executeStep();
+        EXPECT_TRUE (query.isOk());
+        EXPECT_FALSE(query.isDone());
+
+        // Look for unexisting columns
+        EXPECT_THROW(query.getColumn("unknown"), SQLite::Exception);
+        EXPECT_THROW(query.getColumn(""), SQLite::Exception);
+
+		const std::string   msg     = query.getColumn("msg");
+		const int           integer = query.getColumn("int");
+		const double        real    = query.getColumn("double");
+        EXPECT_EQ("first",  msg);
+        EXPECT_EQ(123,      integer);
+        EXPECT_EQ(0.123,    real);
+
+    } // Close DB test.db3
+    remove("test.db3");
+}