#include <x/yaml/mappingnode.H> switch (n->nodetype) { // ... case YAML_MAPPING_NODE: handle_mapping(x::yaml::mappingnode(n)); break; // ... }; // ... void handle_mapping(const x::yaml::mappingnode &n) { size_t n=map->size(); std::cout << n << " elements" << std::endl; for (size_t i=0; i<n; ++i) { std::pair<x::yaml::scalarnode, x::yaml::scalarnode> value=map->get(i); std::cout << value.first << "=" << value.second << std::endl; } }
x::yaml::mappingnode
refers to a
subclass of
x::yaml::nodeObj that
represents a mapping in a YAML document. Its
size() method gives the number of values
in the mapping.
get() returns a
std::pair<x::yaml::node,x::yaml::node>
giving the key and the value of a single mapping.
Individually, the key or the value can be converted to
another
x::yaml::scalarnode,
x::yaml::sequencenode, or an
x::yaml::mappingnode,
according to their nodetypes.
void dump(const x::yaml::mappingnode &map) { for (std::pair<x::yaml::scalarnode, x::yaml::scalarnode> value: *map) { std::cout << value.first << "=" << value.second << std::endl; } }
The referenced mapping object implements a
begin() and an
end() that return
x::yaml::mappingnode::base::iterators over
std::pair<x::yaml::node,x::yaml::node>s
in the mapping.
This example iterates over a mapping whose keys and values are expected
to consist
entirely of
x::yaml::scalarnodes,
so the range iteration value gets coerced accordingly.
An exception gets thrown in the event
of a type conversion failure if the mapping contains a different node
for a key or a value.
void dump(const INSERT_LIBX_NAMESPACE::yaml::mappingnode &map) { seq->for_each([] (x::yaml::scalarnode &&key, x::yaml::scalarnode &&value) { std::cout << value.first << "=" << value.second << std::endl; }); }
The for_each() method produces slightly
more efficient code that iterates over the mapping, and invokes the
functor or the lambda argument passing the key and the value of
each individual mapping by rvalue.
Mappings do not have to be mono-typed. The same mapping may contain
a mixture of
x::yaml::scalarnodes
and
x::yaml::sequencenodes,
for example, for its keys and values.
In this case, the range iteration or the
for_each() should take a
x::yaml::node rvalue,
then proceed based on its
nodetype.