class RBS::Substitution

Substitution from type variables to types.

The substitution construction is in destructive manner.

sub = Substitution.new sub.add(from: :A, to: type1) sub.add(from: :B, to: type2) sub.instance_type = type3

Attributes

instance_type [RW] Types::t?

The result of applying this substitution to instance type. nil maps to instance type itself.

mapping [R] Hash[Symbol, Types::t]

A hash containing mapping from type variable name to type.

Public Class Methods

build (variables, types, instance_type: nil) { |t| ... }

(Array[Symbol] variables, Array[Types::t] types, ?instance_type: Types::t?) ?{ (Types::t) → Types::t } → instance

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 20
def self.build(variables, types, instance_type: nil, &block)
  unless variables.size == types.size
    raise "Broken substitution: variables=#{variables}, types=#{types}"
  end

  mapping = variables.zip(types).to_h

  self.new.tap do |subst|
    mapping.each do |v, t|
      type = block_given? ? yield(t) : t
      subst.add(from: v, to: type)
    end

    subst.instance_type = instance_type
  end
end

Utility method to construct a substitution. Raises an error when variables.size != types.size. instance_type defaults to nil.

Yields types in types and the block value is used if block is given.

new ()

() → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 12
def initialize()
  @mapping = {}
end

Public Instance Methods

+ (other)

(Substitution) → Substitution

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 66
def +(other)
  return self if other.empty?
  return other if self.empty?

  Substitution.new.tap do |subst|
    subst.mapping.merge!(mapping)

    other.mapping.each do |var, type|
      if mapping.key?(var)
        subst.add(from: var, to: self[type])
      else
        subst.add(from: var, to: type)
      end
    end
  end
end

(s1 + s2)[t] == s2[s1]

[] (ty)

(Types::t) → Types::t

Alias for: apply

add (from:, to:)

(from: Symbol, to: Types::t) → void

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 16
def add(from:, to:)
  mapping[from] = to
end

Add mapping to this substitution. Overwrites the previous mapping if same from is given.

apply (ty)

(Types::t) → Types::t

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 37
def apply(ty)
  case ty
  when Types::Variable
    # @type var ty: Types::Variable
    mapping[ty.name] || ty
  when Types::Bases::Instance
    if t = instance_type
      t
    else
      ty
    end
  else
    ty
  end
end

Applies the substitution to given type.

Also aliased as: [], []

empty? ()

() → bool

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 8
def empty?
  mapping.empty? && instance_type.nil?
end

Returns true if given substitution is identity.

without (*vars)

(*Symbol vars) → Substitution

Source

# File vendor/bundle/ruby/4.0.0/gems/rbs-4.0.3/lib/rbs/substitution.rb, line 55
def without(*vars)
  Substitution.new.tap do |subst|
    subst.mapping.merge!(mapping)
    vars.each do |var|
      subst.mapping.delete(var)
    end

    subst.instance_type = self.instance_type
  end
end

Returns a substitution without variables given in vars.