Class: Steep::TypeInference::CaseWhen

Inherits:
Object
  • Object
show all
Extended by:
NodeHelper
Includes:
NodeHelper
Defined in:
lib/steep/type_inference/case_when.rb

Defined Under Namespace

Classes: WhenPatterns

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from NodeHelper

clone_node, deconstruct_case_node, deconstruct_case_node!, deconstruct_if_node, deconstruct_if_node!, deconstruct_resbody_node, deconstruct_resbody_node!, deconstruct_rescue_node, deconstruct_rescue_node!, deconstruct_send_node, deconstruct_send_node!, deconstruct_sendish_and_block_nodes, deconstruct_when_node, deconstruct_when_node!, deconstruct_whileish_node, deconstruct_whileish_node!, each_child_node, each_descendant_node, private_send?, test_case_node, test_if_node, test_resbody_node, test_rescue_node, test_send_node, test_when_node, test_whileish_node, value_node?

Constructor Details

#initialize(node, logic) ⇒ CaseWhen

Returns a new instance of CaseWhen.



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# File 'lib/steep/type_inference/case_when.rb', line 119

def initialize(node, logic)
  @node = node

  condition_node, when_nodes, else_node, location = deconstruct_case_node!(node)
  condition_node or raise "CaseWhen works for case-when syntax with condition node"

  @condition_node = condition_node
  @when_nodes = when_nodes
  @else_node = else_node
  @location = location
  @logic = logic
  @clause_results = []

  type, constr = yield(condition_node)

  @var_name = "__case_when:#{SecureRandom.alphanumeric(5)}__".to_sym
  @value_node, @assignment_node = rewrite_condition_node(var_name, condition_node)

  @initial_constr = constr.update_type_env do |env|
    env.merge(local_variable_types: { var_name => [type, nil] })
  end
end

Instance Attribute Details

#assignment_node ⇒ Object (readonly)

Returns the value of attribute assignment_node.



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# File 'lib/steep/type_inference/case_when.rb', line 117

def assignment_node
  @assignment_node
end

#clause_results ⇒ Object (readonly)

Returns the value of attribute clause_results.



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# File 'lib/steep/type_inference/case_when.rb', line 116

def clause_results
  @clause_results
end

#condition_node ⇒ Object (readonly)

Returns the value of attribute condition_node.



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# File 'lib/steep/type_inference/case_when.rb', line 115

def condition_node
  @condition_node
end

#else_node ⇒ Object (readonly)

Returns the value of attribute else_node.



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# File 'lib/steep/type_inference/case_when.rb', line 115

def else_node
  @else_node
end

#else_result ⇒ Object (readonly)

Returns the value of attribute else_result.



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# File 'lib/steep/type_inference/case_when.rb', line 116

def else_result
  @else_result
end

#initial_constr ⇒ Object (readonly)

Returns the value of attribute initial_constr.



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# File 'lib/steep/type_inference/case_when.rb', line 116

def initial_constr
  @initial_constr
end

#location ⇒ Object (readonly)

Returns the value of attribute location.



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# File 'lib/steep/type_inference/case_when.rb', line 115

def location
  @location
end

#logic ⇒ Object (readonly)

Returns the value of attribute logic.



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# File 'lib/steep/type_inference/case_when.rb', line 116

def logic
  @logic
end

#node ⇒ Object (readonly)

Returns the value of attribute node.



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# File 'lib/steep/type_inference/case_when.rb', line 115

def node
  @node
end

#value_node ⇒ Object (readonly)

Returns the value of attribute value_node.



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# File 'lib/steep/type_inference/case_when.rb', line 117

def value_node
  @value_node
end

#var_name ⇒ Object (readonly)

Returns the value of attribute var_name.



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# File 'lib/steep/type_inference/case_when.rb', line 117

def var_name
  @var_name
end

#when_nodes ⇒ Object (readonly)

Returns the value of attribute when_nodes.



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# File 'lib/steep/type_inference/case_when.rb', line 115

def when_nodes
  @when_nodes
end

Class Method Details

.type_check(constr, node, logic, hint:, condition:) ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 71

def self.type_check(constr, node, logic, hint:, condition:)
  case_when = new(node, logic) do |condition_node|
    constr.synthesize(condition_node)
  end

  case_when.when_clauses() do |when_pats, patterns, body_node, loc|
    patterns.each do |pat|
      when_pats.add_pattern(pat) {|test, constr| constr.synthesize(test) }
    end

    body_constr, body_unreachable = when_pats.body_result() do |env|
      case_when.propagate_value_node_type(env)
    end

    if body_node
      body_constr = body_constr.for_branch(body_node)
      type, body_constr = body_constr.synthesize(body_node, hint: hint, condition: condition)
    else
      type = AST::Builtin.nil_type
    end

    body_result = LogicTypeInterpreter::Result.new(
      type: type,
      env: body_constr.context.type_env,
      unreachable: body_unreachable
    )

    falsy_constr, falsy_unreachable = when_pats.falsy_result
    next_result = LogicTypeInterpreter::Result.new(
      type: AST::Builtin.any_type,    # Unused for falsy pattern
      env: falsy_constr.context.type_env,
      unreachable: falsy_unreachable
    )

    [body_result, next_result]
  end

  case_when.else_clause do |else_node, constr|
    constr.synthesize(else_node, hint: hint, condition: condition)
  end

  case_when.result()
end

Instance Method Details

#else_clause ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 178

def else_clause()
  unless else_loc = has_else_clause?
    return
  end

  constr, unreachable = latest_result

  constr = constr.update_type_env do |env|
    propagate_value_node_type(env) || env
  end

  @else_result =
    if else_node
      yield(else_node, constr)
    else
      TypeConstruction::Pair.new(type: AST::Builtin.nil_type, constr: constr)
    end

  else_result or raise

  if unreachable
    if else_result.type.is_a?(AST::Types::Any) || initial_constr.no_subtyping?(sub_type: else_result.type, super_type: AST::Builtin.bottom_type)
      typing.add_error(
        Diagnostic::Ruby::UnreachableValueBranch.new(
          node: else_node || node,
          type: else_result.type,
          location: else_loc
        )
      )
    end
  end
end

#has_else_clause? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/steep/type_inference/case_when.rb', line 257

def has_else_clause?
  location.else
end

#latest_result ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 211

def latest_result
  if (_, falsy_result = clause_results.last)
    [
      initial_constr.update_type_env { falsy_result.env },
      falsy_result.unreachable
    ]
  else
    [initial_constr, false]
  end
end

#propagate_value_node_type(env) ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 292

def propagate_value_node_type(env)
  if value_node
    if (call = initial_constr.typing.method_calls[value_node]).is_a?(MethodCall::Typed)
      if env[value_node]
        env.merge(pure_method_calls: { value_node => [call, env[var_name]] })
      end
    end
  end
end

#result ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 222

def result
  results = clause_results.filter_map do |body, _|
    unless body.unreachable
      body
    end
  end
  next_constr, next_clause_unreachable = latest_result

  unless next_clause_unreachable
    if else_result
      results << LogicTypeInterpreter::Result.new(
        type: else_result.type,
        env: else_result.context.type_env,
        unreachable: false    # Unused
      )
    else
      results << LogicTypeInterpreter::Result.new(
        type: AST::Builtin.nil_type,
        env: next_constr.context.type_env,
        unreachable: false
      )
    end
  end

  results.reject! { _1.type.is_a?(AST::Types::Bot) }

  types = results.map {|result| result.type }
  envs = results.map {|result| result.env }

  [
    types,
    envs
  ]
end

#rewrite_condition_node(var_name, node) ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 265

def rewrite_condition_node(var_name, node)
  case node.type
  when :lvasgn
    name, rhs = node.children
    value, rhs = rewrite_condition_node(var_name, rhs)
    [value, node.updated(nil, [name, rhs])]
  when :lvar
    name, = node.children
    [
      nil,
      node.updated(:lvasgn, [name, node.updated(:lvar, [var_name])])
    ]
  when :begin
    *children, last = node.children
    value_node, last = rewrite_condition_node(var_name, last)
    [
      value_node,
      node.updated(nil, children.push(last))
    ]
  else
    [
      node,
      node.updated(:lvar, [var_name])
    ]
  end
end

#typing ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 261

def typing
  logic.typing
end

#when_clauses ⇒ Object 



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# File 'lib/steep/type_inference/case_when.rb', line 142

def when_clauses()
  when_nodes.each do |when_node|
    clause_constr, unreachable = latest_result

    patterns, body, loc = deconstruct_when_node!(when_node)

    when_pats = WhenPatterns.new(
      logic,
      clause_constr,
      unreachable,
      assignment_node
    )

    body_result, next_result = yield(
      when_pats,
      patterns,
      body,
      loc
    )

    if body_result.unreachable
      if body_result.type.is_a?(AST::Types::Any) || initial_constr.no_subtyping?(sub_type: body_result.type, super_type: AST::Builtin.bottom_type)
        typing.add_error(
          Diagnostic::Ruby::UnreachableValueBranch.new(
            node: when_node,
            type: body_result.type,
            location: loc.keyword
          )
        )
      end
    end

    clause_results << [body_result, next_result]
  end
end