Class: Plumb::ValueClass

Inherits:
Object
  • Object
show all
Includes:
Composable
Defined in:
lib/plumb/value_class.rb

Overview

A single literal value, matched by ==.

Unlike the other bare matchers — a Constraint with no base, an AttributeValueMatch — this does NOT report Types::Any as its #input_type. Those opt out of #>>'s subtype check because they narrow arbitrary input and have no declared domain to check against; a literal's domain is a known singleton, so it keeps the default (self) and accepts only its own value. That is what makes Value['a'] >> Value['b'] raise rather than build a chain no value can satisfy. Narrowing a wider type down to a literal is spelled #[] (Types::String['a']), which builds the refinement directly.

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Composable

#&, #/, #>>, #absorb_input, #absorb_output, #accepted_type, #as_node, #build, #check, #defer, #fusable_step?, #fuse_with, #generate, #idempotent?, included, #input_type, #invalid, #invoke, #match, #metadata, #not, #output_type, #pipeline, #policy, resolve_operand, #static, #subtype_identity, #to_json_schema, #to_mermaid, #to_plumb_type, #to_s, #transform, #value, #where, #with, wrap, #|

Methods included from Callable

#parse, #resolve

Constructor Details

#initialize(value = Undefined) ⇒ ValueClass

Returns a new instance of ValueClass.



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# File 'lib/plumb/value_class.rb', line 21

def initialize(value = Undefined)
  @value = value
  # Pre-build the failure message once (the object is frozen and @value is
  # fixed), so a miss on the hot path — eg. every non-matching branch of a
  # `Value[a] | Value[b]` enum union — doesn't allocate a fresh String.
  # Frozen because it's shared across every failing call (and across threads
  # under Types::Array#concurrent) and only ever read, never mutated.
  @error = "Must be equal to #{value}".freeze
  @children = [value].freeze
  freeze
end

Instance Attribute Details

#children ⇒ Object (readonly)

Returns the value of attribute children.



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# File 'lib/plumb/value_class.rb', line 19

def children
  @children
end

Instance Method Details

#[](value) ⇒ Object 



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# File 'lib/plumb/value_class.rb', line 33

def [](value) = self.class.new(value)

#call(result) ⇒ Object 



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# File 'lib/plumb/value_class.rb', line 38

def call(result)
  @value == result.value ? result : result.invalid!(errors: @error)
end

#value_preserving? ⇒ Boolean

Matches a specific value and passes it through unchanged.

Returns:

  • (Boolean) 


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# File 'lib/plumb/value_class.rb', line 36

def value_preserving? = true