Class: MilkTea::CompileTime::BlockContext

Inherits:
Object
  • Object
show all
Defined in:
lib/milk_tea/core/compile_time.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(checker, initial_variables: nil, variable_types: nil) ⇒ BlockContext

Returns a new instance of BlockContext.



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# File 'lib/milk_tea/core/compile_time.rb', line 352

def initialize(checker, initial_variables: nil, variable_types: nil)
  @checker = checker
  @variables = initial_variables || {}
  @variable_types = variable_types || {}
end

Instance Attribute Details

#checker ⇒ Object (readonly)

Returns the value of attribute checker.



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# File 'lib/milk_tea/core/compile_time.rb', line 350

def checker
  @checker
end

Instance Method Details

#apply_compile_time_binary(operator, left, right) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 586

def apply_compile_time_binary(operator, left, right)
  case operator
  when "+"
    if left.is_a?(String) && right.is_a?(String)
      left + right
    elsif left.is_a?(Numeric) && right.is_a?(Numeric)
      left + right
    else
      nil
    end
  when "-" then left.is_a?(Numeric) && right.is_a?(Numeric) ? left - right : nil
  when "*" then left.is_a?(Numeric) && right.is_a?(Numeric) ? left * right : nil
  when "/" then left.is_a?(Numeric) && right.is_a?(Numeric) && !zero_numeric?(right) ? left / right : nil
  when "%" then left.is_a?(Integer) && right.is_a?(Integer) && !right.zero? ? left % right : nil
  when "&" then left.is_a?(Integer) && right.is_a?(Integer) ? left & right : nil
  when "|" then left.is_a?(Integer) && right.is_a?(Integer) ? left | right : nil
  when "^" then left.is_a?(Integer) && right.is_a?(Integer) ? left ^ right : nil
  when "<<" then left.is_a?(Integer) && right.is_a?(Integer) ? left << right : nil
  when ">>" then left.is_a?(Integer) && right.is_a?(Integer) ? left >> right : nil
  end
end

#compile_time_decl_type(expression, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 516

def compile_time_decl_type(expression, scopes:)
  return nil unless @checker.respond_to?(:comptime_expression_type)

  @checker.comptime_expression_type(expression, scopes:)
rescue StandardError
  nil
end

#control_outcome?(outcome) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/compile_time.rb', line 371

def control_outcome?(outcome)
  outcome.is_a?(ReturnOutcome) || outcome.is_a?(BreakOutcome) || outcome.is_a?(ContinueOutcome)
end

#destructure_field_names(type_name) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 507

def destructure_field_names(type_name)
  return nil unless type_name
  return nil unless @checker.respond_to?(:comptime_struct_field_names)

  @checker.comptime_struct_field_names(type_name)
rescue StandardError
  nil
end

#evaluate_assignment(assignment, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 524

def evaluate_assignment(assignment, scopes:)
  value = evaluate_expression(assignment.value, scopes:)
  return nil unless value

  case assignment.target
  when AST::Identifier
    return nil unless @variables.key?(assignment.target.name)

    if assignment.operator != "="
      current = @variables[assignment.target.name]
      value = apply_compile_time_binary(assignment.operator.chomp("="), current, value)
    end
    @variables[assignment.target.name] = value
  when AST::MemberAccess
    return nil unless evaluate_member_assignment(assignment, value, scopes:)
  when AST::IndexAccess
    return nil unless evaluate_index_assignment(assignment, value, scopes:)
  end
  value
end

#evaluate_block(statements, scopes: nil) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 358

def evaluate_block(statements, scopes: nil)
  result = nil

  statements.each do |statement|
    outcome = evaluate_statement(statement, scopes:)
    return outcome if control_outcome?(outcome)

    result = outcome
  end

  result
end

#evaluate_destructure_local_decl(decl, value) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 483

def evaluate_destructure_local_decl(decl, value)
  if value.is_a?(Array)
    decl.destructure_bindings.each_with_index do |name, idx|
      next if name == "_"

      @variables[name] = value[idx]
    end
    return value
  end

  if value.is_a?(Hash)
    field_names = destructure_field_names(decl.destructure_type_name)
    decl.destructure_bindings.each_with_index do |name, idx|
      next if name == "_"

      field_name = field_names&.[](idx) || name
      @variables[name] = value[field_name]
    end
    return value
  end

  nil
end

#evaluate_expression(expression, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 409

def evaluate_expression(expression, scopes:)
  case expression
  when AST::Identifier
    return @variables[expression.name] if @variables.key?(expression.name)
    @checker.evaluate_compile_time_const_value(expression, scopes:)
  else
    CompileTime.evaluate(
      expression,
      resolve_identifier: ->(id_expr) {
        return @variables[id_expr.name] if @variables.key?(id_expr.name)
        @checker.evaluate_compile_time_const_value(id_expr, scopes:)
      },
      resolve_member_access: ->(ma_expr) {
        if ma_expr.receiver.is_a?(AST::Identifier) && @variables.key?(ma_expr.receiver.name)
          value = @variables[ma_expr.receiver.name]
          case value
          when Hash
            return value[ma_expr.member] if value.key?(ma_expr.member)
          when Array
            if ma_expr.member =~ /\A_(\d+)\z/
              return value[Regexp.last_match(1).to_i]
            end
            return value.length if ma_expr.member == "len"
          when String
            return value.length if ma_expr.member == "len"
          end
        end

        @checker.evaluate_compile_time_const_value(ma_expr, scopes:)
      },
      resolve_call: ->(call_expr) { resolve_compile_time_call(call_expr, scopes:) },
      resolve_type_ref: ->(type_ref) { @checker.resolve_type_ref(type_ref) },
    )
  end
end

#evaluate_for(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 638

def evaluate_for(statement, scopes:)
  iterable = evaluate_expression(statement.iterable, scopes:)
  return nil unless iterable.is_a?(Array)

  result = nil
  loop_var_name = statement.binding.name

  iterable.each do |element|
    @variables[loop_var_name] = element
    statement.body.each do |body_stmt|
      outcome = evaluate_statement(body_stmt, scopes:)
      case outcome
      when ReturnOutcome then return outcome
      when BreakOutcome then return result
      when ContinueOutcome then break
      end
    end
  end

  result
end

#evaluate_guard_local_decl(decl, value, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 464

def evaluate_guard_local_decl(decl, value, scopes:)
  if value.is_a?(CompileTime::VariantValue)
    case value.arm
    when "some", "success"
      @variables[decl.name] = value.fields["value"]
      @variable_types[decl.name] = compile_time_decl_type(decl.value, scopes:) unless @variable_types.key?(decl.name)
      return value
    when "none", "failure"
      @variables[decl.else_binding.name] = value.fields["error"] if decl.else_binding
      return evaluate_block(decl.else_body, scopes:)
    end
    return nil
  end

  @variables[decl.name] = value
  @variable_types[decl.name] = compile_time_decl_type(decl.value, scopes:) unless @variable_types.key?(decl.name)
  value
end

#evaluate_if(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 668

def evaluate_if(statement, scopes:)
  statement.branches.each do |branch|
    condition = evaluate_expression(branch.condition, scopes:)
    next unless CompileTime.boolean_value?(condition) && condition

    return run_body(branch.body, scopes:, fallback: condition)
  end

  return run_body(statement.else_body, scopes:) if statement.else_body

  nil
end

#evaluate_index_assignment(assignment, value, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 564

def evaluate_index_assignment(assignment, value, scopes:)
  target = assignment.target
  return nil unless target.receiver.is_a?(AST::Identifier)
  return nil unless @variables.key?(target.receiver.name)

  receiver = @variables[target.receiver.name]
  return nil unless receiver.is_a?(Array)

  index = evaluate_expression(target.index, scopes:)
  return nil unless index.is_a?(Integer)

  if assignment.operator != "="
    current = receiver[index]
    value = apply_compile_time_binary(assignment.operator.chomp("="), current, value)
    return nil unless value
  end

  updated = receiver.dup
  updated[index] = value
  @variables[target.receiver.name] = updated
end

#evaluate_local_decl(decl, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 445

def evaluate_local_decl(decl, scopes:)
  return nil unless decl.value

  value = evaluate_expression(decl.value, scopes:)
  return value unless value

  if decl.else_body
    return evaluate_guard_local_decl(decl, value, scopes:)
  end

  if decl.destructure_bindings&.any?
    return evaluate_destructure_local_decl(decl, value)
  end

  @variables[decl.name] = value
  @variable_types[decl.name] = compile_time_decl_type(decl.value, scopes:) unless @variable_types.key?(decl.name)
  value
end

#evaluate_match(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 681

def evaluate_match(statement, scopes:)
  scrutinee = evaluate_expression(statement.expression, scopes:)
  return nil unless scrutinee

  statement.arms.each do |arm|
    wildcard = arm.pattern.is_a?(AST::Identifier) && arm.pattern.name == "_"
    if wildcard || CompileTime.equality_result(scrutinee, evaluate_expression(arm.pattern, scopes:)) == true
      return run_body(arm.body, scopes:, fallback: scrutinee)
    end
  end

  nil
end

#evaluate_member_assignment(assignment, value, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 545

def evaluate_member_assignment(assignment, value, scopes:)
  target = assignment.target
  return nil unless target.receiver.is_a?(AST::Identifier)
  return nil unless @variables.key?(target.receiver.name)

  receiver = @variables[target.receiver.name]
  return nil unless receiver.is_a?(Hash)

  if assignment.operator != "="
    current = receiver[target.member]
    value = apply_compile_time_binary(assignment.operator.chomp("="), current, value)
    return nil unless value
  end

  updated = receiver.dup
  updated[target.member] = value
  @variables[target.receiver.name] = updated
end

#evaluate_statement(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 375

def evaluate_statement(statement, scopes:)
  case statement
  when AST::LocalDecl
    evaluate_local_decl(statement, scopes:)
  when AST::ReturnStmt
    value = statement.value ? evaluate_expression(statement.value, scopes:) : nil
    ReturnOutcome.new(value)
  when AST::WhileStmt
    evaluate_while(statement, scopes:)
  when AST::ForStmt
    evaluate_for(statement, scopes:)
  when AST::MatchStmt
    evaluate_match(statement, scopes:)
  when AST::Assignment
    evaluate_assignment(statement, scopes:)
  when AST::IfStmt
    evaluate_if(statement, scopes:)
  when AST::ExpressionStmt
    evaluate_expression(statement.expression, scopes:)
  when AST::PassStmt
    # no-op at compile time
    nil
  when AST::BreakStmt
    BreakOutcome.new(nil)
  when AST::ContinueStmt
    ContinueOutcome.new(nil)
  when AST::EmitStmt
    # emitted declarations are collected during lowering
    nil
  else
    nil
  end
end

#evaluate_while(statement, scopes:) ⇒ Object

Raises:



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# File 'lib/milk_tea/core/compile_time.rb', line 612

def evaluate_while(statement, scopes:)
  result = nil
  iterations = 0
  max_iterations = 10_000

  while iterations < max_iterations
    condition = evaluate_expression(statement.condition, scopes:)
    break unless condition
    break unless CompileTime.boolean_value?(condition)

    statement.body.each do |body_stmt|
      outcome = evaluate_statement(body_stmt, scopes:)
      case outcome
      when ReturnOutcome then return outcome
      when BreakOutcome then return result
      when ContinueOutcome then break
      end
    end
    iterations += 1
  end

  raise Error, "compile-time while loop exceeded iteration limit" if iterations >= max_iterations

  result
end

#resolve_compile_time_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 695

def resolve_compile_time_call(call_expr, scopes:)
  result = try_const_function_call(call_expr, scopes:)
  return result if result

  result = try_const_method_call(call_expr, scopes:)
  return result if result

  result = try_struct_constructor_call(call_expr, scopes:)
  return result if result

  result = try_array_constructor_call(call_expr, scopes:)
  return result if result

  @checker.evaluate_compile_time_const_value(call_expr, scopes:)
end

#run_body(body, scopes:, fallback: nil) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 660

def run_body(body, scopes:, fallback: nil)
  body.each do |body_stmt|
    outcome = evaluate_statement(body_stmt, scopes:)
    return outcome if control_outcome?(outcome)
  end
  fallback
end

#try_array_constructor_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 805

def try_array_constructor_call(call_expr, scopes:)
  return unless call_expr.callee.is_a?(AST::Specialization)
  return unless @checker.respond_to?(:resolve_type_expression)

  resolved = @checker.resolve_type_expression(call_expr.callee)
  return unless resolved && @checker.respond_to?(:array_type?) && @checker.array_type?(resolved)

  values = []
  call_expr.arguments.each do |argument|
    val = evaluate_expression(argument.value, scopes:)
    return nil unless val
    values << val
  end
  values
end

#try_const_function_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 743

def try_const_function_call(call_expr, scopes:)
  return unless call_expr.callee.is_a?(AST::Identifier)

  func = @checker.top_level_function(call_expr.callee.name)
  return unless func&.ast&.respond_to?(:const) && func.ast.const

  begin
    initial_vars = {}
    func.ast.params.each_with_index do |param, idx|
      return nil if idx >= call_expr.arguments.length

      arg_expr = call_expr.arguments[idx].value
      arg_value = case arg_expr
      when AST::Identifier
        @variables[arg_expr.name] || @checker.evaluate_compile_time_const_value(arg_expr, scopes:)
      else
        CompileTime.evaluate(
          arg_expr,
          resolve_identifier: ->(id) { @variables[id.name] || @checker.evaluate_compile_time_const_value(id, scopes:) },
          resolve_member_access: ->(ma) { @checker.evaluate_compile_time_const_value(ma, scopes:) },
          resolve_type_ref: nil,
          resolve_call: ->(call_expr) { resolve_compile_time_call(call_expr, scopes:) },
        )
      end
      return nil unless arg_value

      initial_vars[param.name] = arg_value
    end
    ctx = BlockContext.new(@checker, initial_variables: initial_vars)
    result = ctx.evaluate_block(func.ast.body, scopes:)
    result.is_a?(ReturnOutcome) ? result.value : result
  end
end

#try_const_method_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 711

def try_const_method_call(call_expr, scopes:)
  return unless call_expr.callee.is_a?(AST::MemberAccess)
  return unless @checker.respond_to?(:comptime_method_binding_for_receiver)
  return unless @checker.respond_to?(:comptime_const_method_body)

  arg_evaluator = ->(expr) { evaluate_expression(expr, scopes:) }

  receiver = call_expr.callee.receiver
  if receiver.is_a?(AST::Identifier) && @variables.key?(receiver.name)
    receiver_value = @variables[receiver.name]
    return nil if receiver_value.nil? || receiver_value.is_a?(Types::Base)

    receiver_type = @variable_types[receiver.name]
    return nil unless receiver_type

    binding = @checker.comptime_method_binding_for_receiver(receiver_type, call_expr.callee.member)
    return nil unless binding

    return @checker.comptime_const_method_body(binding, call_expr.arguments, scopes:, receiver_value:, arg_evaluator:)
  end

  return nil unless @checker.respond_to?(:resolve_type_expression)

  receiver_type = @checker.resolve_type_expression(receiver)
  return nil unless receiver_type

  binding = @checker.comptime_method_binding_for_receiver(receiver_type, call_expr.callee.member)
  return nil unless binding

  @checker.comptime_const_method_body(binding, call_expr.arguments, scopes:, receiver_value: nil, arg_evaluator:)
end

#try_struct_constructor_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 777

def try_struct_constructor_call(call_expr, scopes:)
  types = if @checker.respond_to?(:types)
    @checker.types
  else
    @checker.instance_variable_get(:@ctx).types
  end
  callee_name = if call_expr.callee.is_a?(AST::Specialization) && call_expr.callee.callee.respond_to?(:name)
    call_expr.callee.callee.name
  elsif call_expr.callee.respond_to?(:name)
    call_expr.callee.name
  end

  type = if callee_name
    types[callee_name]
  elsif call_expr.callee.is_a?(AST::MemberAccess) && @checker.respond_to?(:resolve_type_expression)
    @checker.resolve_type_expression(call_expr.callee)
  end
  return unless type.is_a?(Types::Struct)

  fields = {}
  call_expr.arguments.each do |argument|
    val = evaluate_expression(argument.value, scopes:)
    return nil unless val
    fields[argument.name] = val
  end
  fields
end

#zero_numeric?(value) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/compile_time.rb', line 608

def zero_numeric?(value)
  (value.is_a?(Integer) && value.zero?) || (value.is_a?(Float) && value.zero?)
end