private static SymbolTable readOneImport()

in src/com/amazon/ion/impl/LocalSymbolTable.java [665:770]
85 lines of code
22 McCabe index (conditional complexity)

    private static SymbolTable readOneImport(IonReader ionRep,
                                             IonCatalog catalog)
    {
        assert (ionRep.getType() == IonType.STRUCT);

        String name = null;
        int    version = -1;
        int    maxid = -1;

        ionRep.stepIn();
        IonType t;
        while ((t = ionRep.next()) != null)
        {
            if (ionRep.isNullValue()) continue;

            SymbolToken symTok = ionRep.getFieldNameSymbol();
            int field_id = symTok.getSid();
            if (field_id == UNKNOWN_SYMBOL_ID)
            {
                // this is a user defined reader or a pure DOM
                // we fall back to text here
                final String fieldName = ionRep.getFieldName();
                field_id = getSidForSymbolTableField(fieldName);
            }
            switch(field_id)
            {
                case NAME_SID:
                    if (t == IonType.STRING)
                    {
                        name = ionRep.stringValue();
                    }
                    break;
                case VERSION_SID:
                    if (t == IonType.INT)
                    {
                        version = ionRep.intValue();
                    }
                    break;
                case MAX_ID_SID:
                    if (t == IonType.INT)
                    {
                        maxid = ionRep.intValue();
                    }
                    break;
                default:
                    // we just ignore anything else as "open content"
                    break;
            }
        }
        ionRep.stepOut();

        // Ignore import clauses with malformed name field.
        if (name == null || name.length() == 0 || name.equals(ION))
        {
            return null;
        }

        if (version < 1)
        {
            version = 1;
        }

        SymbolTable itab = null;
        if (catalog != null)
        {
            itab = catalog.getTable(name, version);
        }
        if (maxid < 0)
        {
            if (itab == null || version != itab.getVersion())
            {
                String message =
                    "Import of shared table "
                        + IonTextUtils.printString(name)
                        + " lacks a valid max_id field, but an exact match was not"
                        + " found in the catalog";
                if (itab != null)
                {
                    message += " (found version " + itab.getVersion() + ")";
                }
                // TODO custom exception
                throw new IonException(message);
            }

            // Exact match is found, but max_id is undefined in import
            // declaration, set max_id to largest sid of shared symtab
            maxid = itab.getMaxId();
        }

        if (itab == null)
        {
            assert maxid >= 0;

            // Construct substitute table with max_id undefined symbols
            itab = new SubstituteSymbolTable(name, version, maxid);
        }
        else if (itab.getVersion() != version || itab.getMaxId() != maxid)
        {
            // A match was found BUT specs are not an exact match
            // Construct a substitute with correct specs, containing the
            // original import table that was found
            itab = new SubstituteSymbolTable(itab, version, maxid);
        }

        return itab;
    }