dorgan
YarnParser - A parser for Yarn lockfiles
Someone in the Elixir’s Discord guild needed a parser for yarn lock files, and I wanted to try and learn parser combinators, so I wrote a yarn lock files parser
hex.pm
Documentation
GitHub repo
Example usage:
iex> input =
"""
# Some comment
# yarn lockfile v1
key1, key2:
val1 true
subkey1:
val2 123
"""
iex> {:ok, parsed} = YarnParser.decode(input)
iex> parsed
{:ok,
%{
"comments" => ["# Some comment", "# yarn lockfile v1"],
"key1" => %{
"val1" => true,
"subkey1" => %{
"val2" => 123
}
},
"key2" => %{
"val1" => true,
"subkey1" => %{
"val2" => 123
}
}
}
}
iex> YarnParser.get_version(parsed)
1
It currently doesn’t handle merge conflicts like the original parser and I need to improve error messages(mostly regarding invalid indentation).
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kitplummer
I’m pretty sure I know who it was that was looking to parse a yarn.lock file. 
I’ve been building some tooling to support analysis of dependencies in different language ecosystems as part of a research project. I asked a student to look into it - as both an exercise in understanding the “lock” model, as well as digging into parsers and behaviours in Elixir. We’ve been using the YarnParser, which works great.
axelson
It could also be used to generate a bill of materials like the one used in SBoM - Mix task to generate a Software Bill-of-Materials (SBoM)
dorgan
Version 0.4.0 was published
It turns out Yarn 2 now uses YAML instead of their own format, so now YarnParser uses YamlElixir to parse newer lockfiles. Version detection is automatic.
There was also a change in the API, the decode function returns a YarnLock struct that holds lockfile metadata and dependencies. It should be easier to get the lockfile’s version and other stuff now.
dorgan
I published version 0.3.0, it renames YarnParser.parse to YarnParser.decode and adds encoding functionality:
%{
"prop1" => "val1",
"block1" => %{
"prop2" => true
},
"prop3" => 123
} |> YarnParser.encode()
# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
# yarn lockfile v1
block1:
prop2 true
prop1 val1
prop3 123
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