New

Author: d-frey

include/tao/json/internal/value_builder.hh

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+// Copyright (c) 2016 Dr. Colin Hirsch and Daniel Frey
+// Please see LICENSE for license or visit https://github.com/taocpp/json/
+
+#ifndef TAOCPP_JSON_INCLUDE_INTERNAL_VALUE_BUILDER_HH
+#define TAOCPP_JSON_INCLUDE_INTERNAL_VALUE_BUILDER_HH
+
+#include "../value.hh"
+
+namespace tao
+{
+   namespace json
+   {
+      namespace internal
+      {
+         // General interface for a SAX handler:
+         //
+         // template< template< typename ... > class Traits >
+         // class value_handler
+         // {
+         //    void null() {}
+         //    void bool_( const bool v ) {}
+         //    void number( const std::int64_t v ) {}
+         //    void number( const std::uint64_t v ) {}
+         //    void number( const double v ) {}
+         //    void string( std::string && v ) {}
+         //    void begin_array() {}
+         //    void commit_element() {}
+         //    void end_array() {}
+         //    void begin_object() {}
+         //    void commit_key( std::string && key ) {}
+         //    void commit_member() {}
+         //    void end_object() {}
+         // };
+
+         template< template< typename ... > class Traits >
+         struct value_builder
+         {
+            basic_value< Traits > value;
+
+            basic_value< Traits > * current;
+            std::vector< basic_value< Traits > * > stack;
+
+            value_builder() : current( & value ) {}
+
+            void null() { current->unsafe_assign_null(); }
+            void bool_( const bool v ) { current->unsafe_assign_bool( v ); }
+            void number( const std::int64_t v ) { current->unsafe_assign_signed( v ); }
+            void number( const std::uint64_t v ) { current->unsafe_assign_unsigned( v ); }
+            void number( const double v ) { current->unsafe_assign_double( v ); }
+            void string( std::string && v ) { current->unsafe_emplace_string( std::move( v ) ); }
+
+            // array
+            void begin_array()
+            {
+               current->unsafe_emplace_array();
+               current->unsafe_emplace_back( json::null );
+               stack.push_back( current );
+               current = & current->unsafe_get_array().back();
+            }
+
+            void commit_element()
+            {
+               stack.back()->unsafe_emplace_back( json::null );
+               current = & stack.back()->unsafe_get_array().back();
+            }
+
+            void end_array()
+            {
+               current = stack.back();
+               current->unsafe_get_array().pop_back();
+               stack.pop_back();
+            }
+
+            // object
+            void begin_object()
+            {
+               current->unsafe_emplace_object();
+            }
+
+            void commit_key( std::string && key )
+            {
+               const auto r = current->unsafe_emplace( std::move( key ), json::null );
+               if ( ! r.second ) {
+                  // TODO: throw on duplicate key? offer a choice?
+                  r.first->second = json::null;
+               }
+               stack.push_back( current );
+               current = & r.first->second;
+            }
+
+            void commit_member()
+            {
+               current = stack.back();
+               stack.pop_back();
+            }
+
+            void end_object() {}
+         };
+
+      } // internal
+
+   } // json
+
+} // tao
+
+#endif