Yaml (Camel YAML)

A yet another Crystal library for parsing and writing YAML documents.

Yaml does/is:

• parses comments to write them back
• integrates your own document schema to easily access typed contents
• a pure Crystal implementation not requiring libyaml or another library.

Also, Yaml is not fully compatible with the standard YAML for simplicity.

This project is experimental.

Installation

Add this to your application's shard.yml:

dependencies:
  camel_yaml:
    github: mosop/camel_yaml

Code Examples

Basic

yaml = Yaml.parse(<<-EOS
smilies:
  :): hello
  :(: bye
EOS
)

yaml.raw
# => {":)" => "hello", ":(" => "bye"}

Multiple Documents

yaml = Yaml.parse(<<-EOS
smiley:
  face: :)
  greeting: hello
---
smiley:
  face: :(
  greeting: bye
EOS
)

yaml.documents[0].raw
# => {"smiley" => {"face" => ":)", "greeting" => "hello"}}
yaml.documents[1].raw
# => {"smiley" => {"face" => ":(", "greeting" => "bye"}}

Accessor

yaml = Yaml.parse(<<-EOS
ducks:
- name: huey
- name: dewey
- name: louie
EOS
)

yaml["ducks"].a
# => [{"name" => "huey"}, {"name" => "dewey"}, {"name" => "louie"}]
yaml["ducks"][0].h
# => {"name" => "huey"}
yaml["ducks"][0]["name"].s
# => "huey"

Numeral Access

yaml = Yaml.parse(<<-EOS
Yoshimi: Battles
the: Pink Robots
EOS
)

yaml[0].s # => "Battles"
yaml[1].s # => "Pink Robots"

Accessing Keys

yaml = Yaml.parse(<<-EOS
Yoshimi: Battles
the: Pink Robots
EOS
)

yaml[0].key # => "Yoshimi"
yaml[1].key # => "the"

Nilable Access

yaml = Yaml.parse(<<-EOS
foo:
EOS
)

yaml["bar"].s? # => nil

yaml = Yaml.parse(<<-EOS
cakes:
- name: strawberry
- name: cheese
- name: chocolat
EOS
)

yaml["cakes"][999]["name"].s? # => nil

Building

doc = Yaml.map do |map|
  map["faces"].seq do |seq|
    seq.comment = <<-EOS
     add smiley icons below
     one face a row
    EOS
    seq.s ":)"
    seq.s ":("
    seq.s ":P"
  end
end

puts doc.pretty

doc["faces"][0].build do |s|
  s.value = ";)"
  s.trailing_comment = " wink!"
end

puts doc.pretty

Output:

---
faces:
# add smiley icons below
# one face a row
- :)
- :(
- :P
---
faces:
# add smiley icons below
# one face a row
- ;) # wink!
- :(
- :P

Custom Accessor

class Site < Yaml::Accessor
  def name
    s
  end

  def url
    "http://mosop.#{s}"
  end
end

class Sites < Yaml::Accessor
  custom_seq Site
end

yaml = Yaml.parse(<<-EOS
- rocks
- yoga
- ninja
EOS
)

yaml[Sites][0].name # => "rocks"
yaml[Sites][0].url # => "http://mosop.rocks"

Layering

layer = Yaml.parse(<<-EOS
:): hello
EOS
).new_layer

layer.next_layer = Yaml.parse(<<-EOS
:(: bye
EOS
).new_layer

layer[":)"].s => # hello
layer[":("].s => # bye

Usage

require "camel_yaml"

and see Code Examples and Wiki.