Class: TAlgebra::Monad::Parser

Inherits:
Either
  • Object
show all
Includes:
SingleValued
Defined in:
lib/t_algebra/monad/parser.rb

Direct Known Subclasses

Optional

Defined Under Namespace

Classes: Optional

Constant Summary

Constants inherited from Either

Either::LEFT, Either::RIGHT

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from SingleValued

included

Methods inherited from Either

#==, #from_either, #from_either!, left, #left?, pure, #right?, #to_obj

Constructor Details

#initialize(is:, value:, name: nil) ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/t_algebra/monad/parser.rb', line 6

def initialize(is:, value:, name: nil)
  super(is: is, value: value)
  @name = name
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/t_algebra/monad/parser.rb', line 38

def name
  @name
end

Class Method Details

.chain_bind(ma, &block) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 28

def chain_bind(ma, &block)
  raise "Yield blocks must return instances of #{self}. Got #{ma.class}" unless [Parser, Parser::Optional].include?(ma.class)

  ma.as_parser.bind(&block)
end

.failure(msg, name = nil) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 12

def failure(msg, name = nil)
  new(is: Either::LEFT, value: msg, name: name)
end

.fetch(o, key) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 20

def fetch(o, key)
  parse(o).fetch(key)
end

.fetch!(o, key) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 24

def fetch!(o, key)
  parse(o).fetch!(key)
end

.parse(val, name = nil) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 16

def parse(val, name = nil)
  new(is: Either::RIGHT, value: val, name: name)
end

Instance Method Details

#as_parser ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 110

def as_parser
  instance_of?(Parser::Optional) ? Parser.new(is: is, value: value, name: name) : self
end

#bind ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 58

def bind
  super
rescue => e
  self.class.failure("Unable to bind: #{e}", name)
end

#extract_parsed(&block) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 75

def extract_parsed(&block)
  return yield("#{name}: #{value}") if left? && !name.nil?
  from_either(&block)
end

#extract_parsed! ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 80

def extract_parsed!
  extract_parsed { |e| raise UnsafeError.new("#extract_parsed! exception. #{e}") }
end

#fetch(key) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 44

def fetch(key)
  with_name(key).fmap { |o| o.respond_to?(:[]) ? o[key] : o.send(key) }.optional
end

#fetch!(key) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 48

def fetch!(key)
  with_name(key).fmap { |o| o.respond_to?(:[]) ? o[key] : o.send(key) }.required
end

#fmap ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 52

def fmap
  super.with_name(name)
rescue => e
  self.class.failure("Unable to fmap: #{e}", name)
end

#is_a?(*klasses) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/t_algebra/monad/parser.rb', line 64

def is_a?(*klasses)
  validate("Must be type #{klasses.join(", ")}") do |v|
    klasses.any? { |k| v.is_a?(k) }
  end
end

#optional ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 88

def optional
  Optional.new(is: is, value: value, name: name)
end

#required ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 84

def required
  validate("Is required") { |v| !v.nil? }
end

#validate(msg = "Invalid") ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 70

def validate(msg = "Invalid")
  n = name
  bind { |val| yield(val) ? Parser.parse(val, n) : Parser.failure(msg, n) }
end

#with_name(name) ⇒ Object 



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# File 'lib/t_algebra/monad/parser.rb', line 39

def with_name(name)
  @name = name
  self
end