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 23

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 21

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 157

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 28

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 61

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) {
        if call_expr.callee.is_a?(AST::Identifier)
          func = @checker.top_level_function(call_expr.callee.name)
          if 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 = CompileTime::BlockContext.new(@checker, initial_variables: initial_vars)
              next ctx.evaluate_block(func.ast.body, scopes:)
            rescue CompileTime::ReturnValue => e
              next e.value
            end
          end
        end

        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
        if callee_name && (type = types[callee_name]) && 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
          next fields
        end

        if call_expr.callee.is_a?(AST::Specialization) && @checker.respond_to?(:resolve_type_expression)
          resolved = @checker.resolve_type_expression(call_expr.callee)
          if 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
            next values
          end
        end

        @checker.evaluate_compile_time_const_value(call_expr, scopes:)
      },
    )
  end
end

#evaluate_for(statement, scopes:) ⇒ Object 



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# File 'lib/milk_tea/core/compile_time.rb', line 195

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 224

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 149

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 166

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