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lib/xmax.ex
defmodule XMax do
@moduledoc ~S'''
XML to Map conversion.
XMax transforms an XML string into a `Map` containing a collection of pairs
where the key is the node name and the value is its content.
XMax was originally forked from XMap. There are 2 notable difference between the packages:
1) XMax will also map xml attributes. This does however cause for larger mapped objects.
Attributes are mapped to the `"$"` key, while contents are mapped to the `"_"` key. If you know
you're never going to need xml attributes, XMap may be a better fit.
2) XMax does not support atom keys, it's usually not a good idea to generate atoms on the fly.
So to prevent unexpected memory leaks, this feature has been ommitted
## Examples
Here is an example:
iex> xml = """
...> <?xml version="1.0" encoding="UTF-8"?>
...> <blog>
...> <post>
...> <title>Hello Elixir!</title>
...> </post>
...> <post>
...> <title>Hello World!</title>
...> </post>
...> </blog>
...> """
iex> XMax.from_xml(xml)
%{
"blog" => %{
"$" => %{},
"_" => %{
"post" => [
%{
"$" => %{},
"_" => %{"title" => %{"$" => %{}, "_" => "Hello Elixir!"}}
},
%{
"$" => %{},
"_" => %{"title" => %{"$" => %{}, "_" => "Hello World!"}}
}
]
}
}
}
'''
@doc ~S'''
Returns a `Map` containing a collection of pairs where the key is the node name
and the value is its content.
## Examples
Here is an example:
iex> xml = """
...> <?xml version="1.0" encoding="UTF-8"?>
...> <post id="1">
...> <title>Hello world!</title>
...> <stats>
...> <visits type="integer">1000</visits>
...> <likes type="integer">3</likes>
...> </stats>
...> </post>
...> """
iex> XMax.from_xml(xml)
%{
"post" => %{
"$" => %{"id" => '1'},
"_" => %{
"stats" => %{
"$" => %{},
"_" => %{
"likes" => %{"$" => %{"type" => 'integer'}, "_" => "3"},
"visits" => %{"$" => %{"type" => 'integer'}, "_" => "1000"}
}
},
"title" => %{"$" => %{}, "_" => "Hello world!"}
}
}
}
### XML attributes and comments
Both XML attributes and comments are mapped as well:
iex> xml = """
...> <?xml version="1.0" encoding="UTF-8"?>
...> <post id="1">
...> <title>Hello world!</title>
...> <stats>
...> <visits type="integer">1000</visits>
...> <likes type="integer">3</likes>
...> </stats>
...> </post>
...> """
iex> XMax.from_xml(xml)
%{
"post" => %{
"$" => %{"id" => '1'},
"_" => %{
"stats" => %{
"$" => %{},
"_" => %{
"likes" => %{"$" => %{"type" => 'integer'}, "_" => "3"},
"visits" => %{"$" => %{"type" => 'integer'}, "_" => "1000"}
}
},
"title" => %{"$" => %{}, "_" => "Hello world!"}
}
}
}
### Empty XML nodes
Empty XML nodes are parsed as empty maps:
iex> xml = """
...> <?xml version="1.0" encoding="UTF-8"?>
...> <post>
...> <author/>
...> <body>Hello world!</body>
...> <footer></footer>
...> </post>
...> """
iex> XMax.from_xml(xml)
%{
"post" => %{
"$" => %{},
"_" => %{
"author" => %{"$" => %{}, "_" => %{}},
"body" => %{"$" => %{}, "_" => "Hello world!"},
"footer" => %{"$" => %{}, "_" => %{}}
}
}
}
### Casting
The type casting of the values is delegated to the developer.
'''
@spec from_xml(String.t) :: map
def from_xml(xml) do
xml
|> :erlang.bitstring_to_list()
|> :xmerl_scan.string(space: :normalize, comments: false)
|> elem(0)
|> parse_record()
end
defp parse_record([]), do: %{}
defp parse_record([head]), do: parse_record(head)
defp parse_record([head | tail]),
do: head |> parse_record() |> merge_records(parse_record(tail))
defp parse_record({:xmlText, _, _, _, value, _}), do: value |> to_string() |> String.trim()
defp parse_record({:xmlElement, name, _, _, _, _, _, attributes, value, _, _, _}) do
case length(attributes) do
0 -> %{"#{name}" => %{"$" => %{}, "_" => parse_record(value)}}
_ -> %{"#{name}" => %{"$" => parse_attributes(attributes), "_" => parse_record(value)}}
end
end
defp parse_attributes([head]), do: head |> parse_attribute()
defp parse_attributes([head | tail]),
do: head |> parse_attribute() |> merge_records(parse_attributes(tail))
defp parse_attribute({:xmlAttribute, name, _, _, _, _, _, _, value, _}),
do: %{"#{name}" => value}
defp merge_records(r, ""), do: r # Spaces between tags are normalized but parsed as
defp merge_records("", r), do: r # empty xmlText elements.
defp merge_records(r1, r2) when is_binary(r1) and is_binary(r2), do: r1 <> r2
defp merge_records(r1, r2), do: Map.merge(r1, r2, fn _, v1, v2 -> List.flatten([v1, v2]) end)
end