Arrays: isolate axis code in a new class

Remove the axis numbering code from ARRAY_OPTIONS
and place in a new class, ARRAY_AXIS. This keeps
the logic for the array item numbering separate from
the logic for the array item geometry.

This simplifies the logic in the ARRAY_OPTIONS class, which
no longer has to deal with the numbering of each axis.

common/array_axis.cpp

@@ -0,0 +1,153 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2019 KiCad Developers, see AUTHORS.txt for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include <array_axis.h>
+
+
+/**
+ * @return False for schemes like 0,1...9,10
+ *         True for schemes like A,B..Z,AA (where the tens column starts with char 0)
+ */
+static bool schemeNonUnitColsStartAt0( ARRAY_AXIS::NUMBERING_TYPE type )
+{
+    return type == ARRAY_AXIS::NUMBERING_TYPE::NUMBERING_ALPHA_FULL
+           || type == ARRAY_AXIS::NUMBERING_TYPE::NUMBERING_ALPHA_NO_IOSQXZ;
+}
+
+
+ARRAY_AXIS::ARRAY_AXIS() : m_type( NUMBERING_TYPE::NUMBERING_NUMERIC ), m_offset( 0 )
+{
+}
+
+
+const wxString& ARRAY_AXIS::GetAlphabet() const
+{
+    static const wxString alphaNumeric = "0123456789";
+    static const wxString alphaHex = "0123456789ABCDEF";
+    static const wxString alphaFull = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    static const wxString alphaNoIOSQXZ = "ABCDEFGHJKLMNPRTUVWY";
+
+    switch( m_type )
+    {
+    default:
+    case NUMBERING_NUMERIC:
+        return alphaNumeric;
+    case NUMBERING_HEX:
+        return alphaHex;
+    case NUMBERING_ALPHA_NO_IOSQXZ:
+        return alphaNoIOSQXZ;
+    case NUMBERING_ALPHA_FULL:
+        return alphaFull;
+    }
+}
+
+
+OPT<int> ARRAY_AXIS::getNumberingOffset( const wxString& str ) const
+{
+    if( str.length() == 0 )
+        return OPT<int>{};
+
+    const wxString& alphabet = GetAlphabet();
+
+    int       offset = 0;
+    const int radix = alphabet.length();
+
+    for( unsigned i = 0; i < str.length(); i++ )
+    {
+        int chIndex = alphabet.Find( str[i], false );
+
+        if( chIndex == wxNOT_FOUND )
+            return OPT<int>{};
+
+        const bool start0 = schemeNonUnitColsStartAt0( m_type );
+
+        // eg "AA" is actually index 27, not 26
+        if( start0 && i < str.length() - 1 )
+            chIndex++;
+
+        offset *= radix;
+        offset += chIndex;
+    }
+
+    return OPT<int>{ offset };
+}
+
+
+void ARRAY_AXIS::SetAxisType( NUMBERING_TYPE aType )
+{
+    m_type = aType;
+}
+
+
+bool ARRAY_AXIS::SetOffset( const wxString& aOffsetName )
+{
+    OPT<int> offset = getNumberingOffset( aOffsetName );
+
+    // The string does not decode to a valid offset
+    if( !offset )
+        return false;
+
+    SetOffset( *offset );
+    return true;
+}
+
+
+void ARRAY_AXIS::SetOffset( int aOffset )
+{
+    m_offset = aOffset;
+}
+
+
+int ARRAY_AXIS::GetOffset() const
+{
+    return m_offset;
+}
+
+
+wxString ARRAY_AXIS::GetItemNumber( int n ) const
+{
+    wxString        itemNum;
+    const wxString& alphabet = GetAlphabet();
+
+    const bool nonUnitColsStartAt0 = schemeNonUnitColsStartAt0( m_type );
+
+    bool firstRound = true;
+    int  radix = alphabet.Length();
+
+    n += m_offset;
+
+    do
+    {
+        int modN = n % radix;
+
+        if( nonUnitColsStartAt0 && !firstRound )
+            modN--; // Start the "tens/hundreds/etc column" at "Ax", not "Bx"
+
+        itemNum.insert( 0, 1, alphabet[modN] );
+
+        n /= radix;
+        firstRound = false;
+    } while( n );
+
+    return itemNum;
+}