Aliases in the YAML are processed and replaced with the aliased anchor when the document gets parsed.
maps:
seq1: &alias1
- scalar1
- scalar2
seq2: *alias1
Parsing this document results in a
x::yaml::document
whose root() returns a
x::yaml::mappingnode
with one mapping. Its key is a
x::yaml::scalarnode
“maps”, and its value is another
x::yaml::mappingnode
with two mappings.
The first of the two mappings has a
x::yaml::scalarnode key of “seq1”,
and the value of a
x::yaml::sequencenode
containing two
x::yaml::scalarnodes of
“scalar1”
and
“scalar2”.
The second mapping's
x::yaml::scalarnode key is “seq2”,
and the value is the same
x::yaml::sequencenode.
Each alias, in the YAML document gets replaced by
its anchor node. The resulting document should be processed without
making any particular considerations for aliases.
It's possible to create circular references using aliases, like this:
yaml:
name1: &alias1
key1: value1
key2: *alias1
Retrieving the value of the “key2” mapping comes back with the value of the “name1” mapping, the same mapping with the alias reference.
This gets handled by the underlying LibYAML parser, and due to the nature of LibYAML's internal structures this does not create an internal circular reference or a memory leak. Provided, of course, that a circular reference or a memory leak does not get created indirectly as a result of processing the recursive alias.