[1205a] Rebased trac1205 into trac1205a (more things to add anyway)

src/lib/dhcpsrv/Makefile.am

@@ -85,6 +85,7 @@ libkea_dhcpsrv_la_SOURCES += alloc_engine.cc alloc_engine.h
 libkea_dhcpsrv_la_SOURCES += alloc_engine_log.cc alloc_engine_log.h
 libkea_dhcpsrv_la_SOURCES += base_host_data_source.h
 libkea_dhcpsrv_la_SOURCES += callout_handle_store.h
+libkea_dhcpsrv_la_SOURCES += cfg_to_element.h
 libkea_dhcpsrv_la_SOURCES += cfg_4o6.h
 libkea_dhcpsrv_la_SOURCES += cfg_db_access.cc cfg_db_access.h
 libkea_dhcpsrv_la_SOURCES += cfg_duid.cc cfg_duid.h
@@ -222,6 +223,7 @@ EXTRA_DIST += logging.spec
 # following headers are anticipated to be useful for the user libraries.
 libkea_dhcpsrv_includedir = $(pkgincludedir)/dhcpsrv
 libkea_dhcpsrv_include_HEADERS = \
+    cfg_to_element.h \
     cfg_option.h \
     cfg_4o6.h \
     d2_client_cfg.h \

src/lib/dhcpsrv/cfg_to_element.h

+// Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef CFG_TO_ELEMENT_H
+#define CFG_TO_ELEMENT_H
+
+#include <exceptions/exceptions.h>
+#include <cc/data.h>
+#include <stdint.h>
+
+namespace isc {
+
+/// @brief Cannot unparse error
+///
+/// This exception is expected to be thrown when toElement fails
+/// and to skip flawed elements is not wanted.
+class ToElementError : public isc::Exception {
+public:
+    ToElementError(const char* file, size_t line, const char* what) :
+        isc::Exception(file, line, what) { };
+};
+
+namespace dhcp {
+
+/// @name Constants for unparsing styles
+///
+//@{
+/// Default
+static const uint32_t TO_ELEMENT_DEFAULT        = 0x00000000;
+/// Add default values
+static const uint32_t TO_ELEMENT_ADD_DEFAULTS   = 0x00000001;
+/// Ignore disables
+static const uint32_t TO_ELEMENT_IGNORE_DISABLE = 0x00000002;
+/// Don't copy
+static const uint32_t TO_ELEMENT_DO_NOT_COPY    = 0x00000004;
+
+/// Get option names
+static const uint32_t TO_ELEMENT_OPTION_NAMES   = 0x00000100;
+/// Get ranges as prefixs
+static const uint32_t TO_ELEMENT_TRY_PREFIXES   = 0x00000200;
+
+/// Skip (vs throw) on errors
+static const uint32_t TO_ELEMENT_SKIP_ERRORS    = 0x80000000;
+//@}
+
+
+/// @brief Abstract class for configuration Cfg_* classes
+///
+template<typename ... Args>
+struct CfgToElement {
+    /// Destructor
+    virtual ~CfgToElement() { }
+
+    /// @brief Unparse a configuration objet
+    ///
+    /// Returns an element which must parse into the same objet, i.e.
+    /// @code
+    /// for all valid config C parse(toElement(parse(C)) == parse(C)
+    /// @endcode
+    ///
+    /// @param extras extra arguments
+    /// @param flags a bitfield which can be used to modify the result
+    /// @return a pointer to a configuration which can be parsed into
+    /// the initial configuration object
+    virtual isc::data::ElementPtr toElement(Args... extras,
+                                            const uint32_t flags) const = 0;
+};
+
+}; // namespace isc::dhcp
+}; // namespace isc
+
+#endif // CFG_TO_ELEMENT_H

src/lib/dhcpsrv/libdhcpsrv.dox

-// Copyright (C) 2012-2016 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2012-2017 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -79,6 +79,15 @@ configuration. For example: the value of 1 identifies an immediate
 predecessor of the current configuration, the value of 2 identifies the
 one that occurred before it etc.
 
+All configuration classes are derived from the abstract base class
+\ref isc::dhcp::CfgBase and define the unparse virtual method
+which returns a \ref isc::data::ConstElementPtr which must be
+parsed into the same object, i.e. fullfil this property:
+@code
+for all valid C: parse(unparse(parse(C))) == parse(C)
+@endcode
+
+
 @section hostmgr Host Manager
 
 Host Manager implemented by the \ref isc::dhcp::HostMgr is a singleton object