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) ⇒ BlockContext

Returns a new instance of BlockContext.



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# File 'lib/milk_tea/core/compile_time.rb', line 202

def initialize(checker, initial_variables: nil)
  @checker = checker
  @variables = initial_variables || {}
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 200

def checker
  @checker
end

Instance Method Details

#evaluate_assignment(assignment, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 268

def evaluate_assignment(assignment, scopes:)
  value = evaluate_expression(assignment.value, scopes:)
  case assignment.target
  when AST::Identifier
    @variables[assignment.target.name] = value
  end
  value
end

#evaluate_block(statements, scopes: nil) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 207

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

  statements.each do |statement|
    case statement
    when AST::LocalDecl
      result = evaluate_local_decl(statement, scopes:)
    when AST::ReturnStmt
      value = statement.value ? evaluate_expression(statement.value, scopes:) : nil
      raise ReturnValue.new(value)
    when AST::WhileStmt
      result = evaluate_while(statement, scopes:)
    when AST::ForStmt
      result = evaluate_for(statement, scopes:)
    when AST::Assignment
      result = evaluate_assignment(statement, scopes:)
    when AST::IfStmt
      result = evaluate_if(statement, scopes:)
    when AST::ExpressionStmt
      evaluate_expression(statement.expression, scopes:)
    when AST::PassStmt, AST::BreakStmt, AST::ContinueStmt
      # no-op at compile time
    when AST::EmitStmt
      # evaluated during lowering
      result = nil
    else
      result = nil
    end
  end

  result
end

#evaluate_expression(expression, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 240

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

#evaluate_for(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 306

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|
      case body_stmt
      when AST::ReturnStmt
        value = body_stmt.value ? evaluate_expression(body_stmt.value, scopes:) : nil
        raise ReturnValue.new(value)
      when AST::Assignment
        evaluate_assignment(body_stmt, scopes:)
      when AST::ExpressionStmt
        evaluate_expression(body_stmt.expression, scopes:)
      when AST::IfStmt
        result = evaluate_if(body_stmt, scopes:)
      when AST::WhileStmt
        result = evaluate_while(body_stmt, scopes:)
      end
    end
  end

  result
end

#evaluate_if(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 335

def evaluate_if(statement, scopes:)
  statement.branches.each do |branch|
    condition = evaluate_expression(branch.condition, scopes:)
    if CompileTime.boolean_value?(condition) && condition
      branch.body.each do |body_stmt|
        case body_stmt
        when AST::ReturnStmt
          value = body_stmt.value ? evaluate_expression(body_stmt.value, scopes:) : nil
          raise ReturnValue.new(value)
        when AST::Assignment
          evaluate_assignment(body_stmt, scopes:)
        when AST::ExpressionStmt
          evaluate_expression(body_stmt.expression, scopes:)
        end
      end
      return condition
    end
  end

  if statement.else_body
    statement.else_body.each do |body_stmt|
      case body_stmt
      when AST::ReturnStmt
        value = body_stmt.value ? evaluate_expression(body_stmt.value, scopes:) : nil
        raise ReturnValue.new(value)
      when AST::Assignment
        evaluate_assignment(body_stmt, scopes:)
      when AST::ExpressionStmt
        evaluate_expression(body_stmt.expression, scopes:)
      end
    end
  end

  nil
end

#evaluate_local_decl(decl, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 260

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

  value = evaluate_expression(decl.value, scopes:)
  @variables[decl.name] = value
  value
end

#evaluate_while(statement, scopes:) ⇒ Object

Raises:



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# File 'lib/milk_tea/core/compile_time.rb', line 277

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|
      case body_stmt
      when AST::ReturnStmt
        value = body_stmt.value ? evaluate_expression(body_stmt.value, scopes:) : nil
        raise ReturnValue.new(value)
      when AST::Assignment
        evaluate_assignment(body_stmt, scopes:)
      when AST::ExpressionStmt
        evaluate_expression(body_stmt.expression, scopes:)
      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 371

def resolve_compile_time_call(call_expr, scopes:)
  result = try_const_function_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

#try_array_constructor_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 444

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 384

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: nil,
        )
      end
      return nil unless arg_value

      initial_vars[param.name] = arg_value
    end
    ctx = BlockContext.new(@checker, initial_variables: initial_vars)
    ctx.evaluate_block(func.ast.body, scopes:)
  rescue ReturnValue => e
    e.value
  end
end

#try_struct_constructor_call(call_expr, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 419

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
  return unless callee_name

  type = types[callee_name]
  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