xinz / sax_map

A fast and efficient tool for converting XML to Elixir Map

SAXMap

Converts an XML String or an XML file stream to a Map.

Benefit from Saxy's SAX mode, this library has a good conversion efficiency.

Installation

def deps do
  [
    {:sax_map, "~> 1.2"}
  ]
end

Example

iex(1)> xml = """
...(1)> <?xml version="1.0" encoding="UTF-8"?>
...(1)> <thread>
...(1)>   <title>Hello</title>
...(1)>   <items>
...(1)>     <item>item1</item>
...(1)>     <item>item2</item>
...(1)>   </items>
...(1)> </thread>
...(1)> """
iex(2)> SAXMap.from_string(xml)
{:ok,
 %{
   "thread" => %{"items" => %{"item" => ["item1", "item2"]}, "title" => "Hello"}
 }}

By default SAXMap.from_string will ignore all attributes of elements in the result, if you want to merge the attributes as the child elements, please use ignore_attribute option to achieve this:

xml = """
  <thread version="1">
    <title color="red" font="16">Hello</title>
    <items size="3">
      <item font="12">item1</item>
      <item font="12">item2</item>
      <item font="12">item3</item>
    </items>
  </thread>
"""

SAXMap.from_string(xml, ignore_attribute: false)

{:ok,
  %{
    "thread" => %{
      "content" => %{
        "items" => %{
          "content" => %{
            "item" => [
              %{"content" => "item1", "font" => "12"},
              %{"content" => "item2", "font" => "12"},
              %{"content" => "item3", "font" => "12"}
            ]
          },
          "size" => "3"
        },
        "title" => %{"color" => "red", "content" => "Hello", "font" => "16"}
      },
      "version" => "1"
    }
  }}

SAXMap.from_string(xml, ignore_attribute: {false, "@"})
{:ok,
  %{
    "thread" => %{
      "@version" => "1",
      "content" => %{
        "items" => %{
          "@size" => "3",
          "content" => %{
            "item" => [
              %{"@font" => "12", "content" => "item1"},
              %{"@font" => "12", "content" => "item2"},
              %{"@font" => "12", "content" => "item3"}
            ]
          }
        },
        "title" => %{"@color" => "red", "@font" => "16", "content" => "Hello"}
      }
    }
  }}

Notice: The ignore_attribute: false equals ignore_attribute: {false, ""}, in this case, the child elements will be automatically naming with "content" as the key of the key-value pair to distinct this key-value pair is from content or attribute.

Benchmark

Only for your reference, all credit goes to Saxy, the details of benchmark can be found in the bench directory of the repository.

Run:

mix run xml_to_map.exs

Output:

Operating System: macOS
CPU Information: Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
Number of Available Cores: 16
Available memory: 32 GB
Elixir 1.12.2
Erlang 24.0.4

Benchmark suite executing with the following configuration:
warmup: 2 s
time: 10 s
memory time: 2 s
parallel: 1
inputs: none specified
Estimated total run time: 42 s

Benchmarking SAXMap.from_string ignore attribute...
Benchmarking SAXMap.from_string with attribute...
Benchmarking XmlToMap.naive_map...

Name                                          ips        average  deviation         median         99th %
SAXMap.from_string ignore attribute      105.03 K        9.52 μs   ±129.42%           9 μs          33 μs
SAXMap.from_string with attribute         96.74 K       10.34 μs   ±110.08%           9 μs          35 μs
XmlToMap.naive_map                        26.31 K       38.01 μs    ±46.21%          33 μs         105 μs

Comparison:
SAXMap.from_string ignore attribute      105.03 K
SAXMap.from_string with attribute         96.74 K - 1.09x slower +0.82 μs
XmlToMap.naive_map                        26.31 K - 3.99x slower +28.49 μs

Memory usage statistics:

Name                                   Memory usage
SAXMap.from_string ignore attribute        14.61 KB
SAXMap.from_string with attribute          16.69 KB - 1.14x memory usage +2.08 KB
XmlToMap.naive_map                         40.90 KB - 2.80x memory usage +26.29 KB

**All measurements for memory usage were the same**