Class: RedShift::Flow

Inherits:
Object show all
Defined in:
lib/redshift/component.rb,
lib/redshift/target/c/flow-gen.rb

Overview

rename to equation? formula? put in meta?

Constant Summary collapse

CT_STRUCT_NAME = 
"Context"

Class Attribute Summary collapse

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(v, f) ⇒ Flow

Returns a new instance of Flow.



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# File 'lib/redshift/component.rb', line 93

def initialize v, f
  @var, @formula = v, f
  @strict = true
  self.class.needed = true
end

Class Attribute Details

.needed ⇒ Object

Returns the value of attribute needed.



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# File 'lib/redshift/component.rb', line 99

def needed
  @needed
end

Instance Attribute Details

#formula ⇒ Object (readonly)

Returns the value of attribute formula.



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# File 'lib/redshift/component.rb', line 85

def formula
  @formula
end

#strict ⇒ Object (readonly)

Strict flows change value only over continuous time, and not within the steps of the discrete update. This can be false only for an AlgebraicFlow which depends on non-strict variables. In the algebraic case, a flow is strict iff the RHS of the eqn. has only strictly continuous variables.



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# File 'lib/redshift/component.rb', line 91

def strict
  @strict
end

#var ⇒ Object (readonly)

Returns the value of attribute var.



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# File 'lib/redshift/component.rb', line 85

def var
  @var
end

Instance Method Details

#external_constant?(var) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/redshift/target/c/flow-gen.rb', line 143

def external_constant? var
  RedShift.library.external_constant? var
end

#make_ct_struct(flow_fn, cl) ⇒ Object

Since MSVC doesn’t support nested functions…



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# File 'lib/redshift/target/c/flow-gen.rb', line 150

def make_ct_struct(flow_fn, cl)
  sf = flow_fn.parent
  ct_struct = sf.declare![CT_STRUCT_NAME]

  if ct_struct
    ct_struct = ct_struct[1] ## hacky

  else
    ct_struct = sf.declare_struct(CT_STRUCT_NAME)

    ct_struct.declare :shadow => "#{cl.shadow_struct.name} *shadow"

    flow_fn.declare :ct => "#{CT_STRUCT_NAME} ct"
    flow_fn.setup   :ct_shadow => "ct.shadow = shadow"
  end

  ct_struct
end

#translate(flow_fn, result_var, rk_level, cl, orig_formula = nil) ⇒ Object 



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# File 'lib/redshift/target/c/flow-gen.rb', line 11

def translate flow_fn, result_var, rk_level, cl, orig_formula = nil
  translation = {}
  setup = []    ## should use accumulator
  
  orig_formula ||= @formula
  c_formula = orig_formula.dup
  strict = true
  
  re = /(?:([A-Za-z_]\w*)\.)?([A-Za-z_]\w*)(?!\w*\s*[(])/
  
  c_formula.gsub! re do |expr|

    unless translation[expr]
      link, var = $1, $2
      if link
        result =
          translate_link(link, var, translation, flow_fn, cl, expr, rk_level)
        strict &&= result # Don't combine with method call!!!
                  
      else # expr == 'var'
        varsym = var.intern
        
        link_type, link_strictness = cl.link_variables[varsym]
        
        if link_type
          # l ==> link_l
          strict &&= (link_strictness == :strict)

          link = var
          link_cname = "link_#{link}"
          unless translation[link]
            translation[link] = "ct.#{link_cname}"

            ct_struct = make_ct_struct(flow_fn, cl)

            link_type_ssn = link_type.shadow_struct.name
            ct_struct.declare link_cname => "#{link_type_ssn} *#{link_cname}"
            flow_fn.setup  link_cname => "ct.#{link_cname} = shadow->#{link}"
          end
          
        elsif (kind = cl.constant_variables[varsym])
          strict &&= (kind == :strict)
          translation[var] = "shadow->#{var}"
        
        elsif (kind = cl.continuous_variables[varsym])
          # x ==> var_x
          strict &&= (kind == :strict)

          var_cname = "var_#{var}"
          sh_cname = "shadow"
          cs_cname = "cont_state"
          cont_var = "#{cs_cname}->#{var}"
          translation[var] = var_cname

          flow_fn.declare var_cname => "double    #{var_cname}"
          flow_fn.setup var_cname => %{
            if (#{cont_var}.algebraic) {
              if (#{cont_var}.rk_level < shadow->world->rk_level ||
                 (shadow->world->rk_level == 0 &&
                  (#{cont_var}.strict ? !#{cont_var}.d_tick :
                   #{cont_var}.d_tick != shadow->world->d_tick)
                  ))
                (*#{cont_var}.flow)((ComponentShadow *)#{sh_cname});
            }
            else {
              #{cont_var}.d_tick = shadow->world->d_tick;
            }
          }
          # The d_tick assignment is explained in component-gen.rb.
          setup << "#{var_cname} = #{cont_var}.value_#{rk_level};"
        
        elsif (kind = cl.input_variables[varsym])
          # x ==> var_x
          strict &&= (kind == :strict)
            # note that we check in Component#connect that the
            # source var is strict

          var_cname = "var_#{var}"
          translation[var] = var_cname
          src_comp    = cl.src_comp(varsym)

          flow_fn.declare var_cname => "double    #{var_cname}"
          flow_fn.setup var_cname => %{\
            #{var_cname} = rs_eval_input_var(shadow, &shadow->#{src_comp});
          }
        
        elsif (event_idx = cl.exported_events[varsym])
          unless self.kind_of? ResetExpr
            raise NoValueError,
              "Event #{varsym.inspect} has no value in this context."
          end
          
          strict = false # strict doesn't matter

          var_cname = "event_#{var}"
          translation[var] = var_cname
          flow_fn.declare var_cname => "double    #{var_cname}"
          flow_fn.setup var_cname => %{\
            VALUE event_values, event_val;
            event_values = shadow->event_values;
            assert(event_values != Qnil);
            event_val = RARRAY(event_values)->ptr[#{event_idx}];
            #{var_cname} = NUM2DBL(event_val);
          }
        
        elsif /\A[eE]\z/ =~ var
          translation[expr] = expr # scientific notation
        
        elsif cl.const_defined?(var)
          translation[expr] = cl.const_get(var)
        
        elsif external_constant?(var)
          translation[expr] = expr
          
        else
          raise NameError, "Unknown variable: #{var}"
        end
        
      end
    end
    translation[expr]
  end
  
  yield strict if block_given?  ## funky way to return another value
  
  setup << "#{result_var} = (#{c_formula})"
  
rescue NameError, ArgumentError => ex
  ex.message << "\nclass: #{cl.name}\nformula:\n#{orig_formula}\n\n"
  raise ex
end

#translate_link(link, var, translation, flow_fn, cl, expr, rk_level) ⇒ Object

l.x ==> get_l__x()->value_n

Raises:

  • (NameError) 


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# File 'lib/redshift/target/c/flow-gen.rb', line 170

def translate_link(link, var, translation, flow_fn, cl, expr, rk_level)
  link_type, link_strictness = cl.link_variables[link.intern]
  raise(NameError, "No such link, #{link}") unless link_type
  strict = (link_strictness == :strict)
  
  flow_fn.include link_type.shadow_library_include_file
  
  link_cname = "link_#{link}"
  get_var_cname = "get_#{link}__#{var}"

  ct_struct = make_ct_struct(flow_fn, cl)

  varsym = var.intern
  if (kind = link_type.constant_variables[varsym])
    var_type = :constant
  elsif (kind = link_type.continuous_variables[varsym])
    var_type = :continuous
  elsif (kind = link_type.input_variables[varsym])
    var_type = :input
  elsif (a = link_type.link_variables[varsym])
    var_type = :link
    link_link_type, kind = a
  elsif (event_idx = link_type.exported_events[varsym])
    unless self.kind_of? ResetExpr
      raise NoValueError, "Event #{varsym.inspect} has no value in this context."
    end
    var_type = :event
    kind = false # strict doesn't matter
  else
    raise NameError, "Unknown variable: #{var} in #{link_type}"
  end

  strict &&= (kind == :strict)
  
  if var_type == :continuous or var_type == :input
    checked_var_cname = "checked_#{link}__#{var}" ## not quite unambig.
    ct_struct.declare checked_var_cname => "int #{checked_var_cname}"
    flow_fn.setup     checked_var_cname => "ct.#{checked_var_cname} = 0"
  end

  if var_type == :continuous
    link_cs_ssn = link_type.cont_state_class.shadow_struct.name
    link_cs_cname = "link_cs_#{link}"
    ct_struct.declare link_cs_cname => "#{link_cs_ssn} *#{link_cs_cname}"
  end

  unless translation[link + "."]
    translation[link + "."] = true # just so we know we've handled it

    unless translation[link]
      translation[link] = link_cname
      link_type_ssn = link_type.shadow_struct.name
      ct_struct.declare link_cname => "#{link_type_ssn} *#{link_cname}"
      flow_fn.setup     link_cname => "ct.#{link_cname} = shadow->#{link}"
    end ## same as below
  end

  sf = flow_fn.parent

  exc_nil = flow_fn.declare_class(NilLinkError) ## class var
  msg_nil = "Link #{link} is nil."

  case var_type
  when :continuous
    cs_cname = "ct->#{link_cs_cname}"
    cont_var = "#{cs_cname}->#{var}"
    sf.declare get_var_cname => %{
      inline static ContVar *#{get_var_cname}(#{CT_STRUCT_NAME} *ct) {
        if (!ct->#{checked_var_cname}) {
          ct->#{checked_var_cname} = 1;
          if (!ct->#{link_cname})
            rs_raise(#{exc_nil}, ct->shadow->self, #{msg_nil.inspect});
          #{cs_cname} = (#{link_cs_ssn} *)ct->#{link_cname}->cont_state;
          if (#{cont_var}.algebraic) {
            if (#{cont_var}.rk_level < ct->shadow->world->rk_level ||
               (ct->shadow->world->rk_level == 0 &&
                (#{cont_var}.strict ? !#{cont_var}.d_tick :
                 #{cont_var}.d_tick != ct->shadow->world->d_tick)
               ))
              (*#{cont_var}.flow)((ComponentShadow *)ct->#{link_cname});
          }
          else {
            #{cont_var}.d_tick = ct->shadow->world->d_tick;
          }
        }
        return &(#{cont_var});
      }
    } ## algebraic test is same as above

    translation[expr] = "#{get_var_cname}(&ct)->value_#{rk_level}"
  
  when :constant
    sf.declare get_var_cname => %{
      inline static double #{get_var_cname}(#{CT_STRUCT_NAME} *ct) {
        if (!ct->#{link_cname})
          rs_raise(#{exc_nil}, ct->shadow->self, #{msg_nil.inspect});
        return ct->#{link_cname}->#{var};
      }
    }

    translation[expr] = "#{get_var_cname}(&ct)"
  
  when :link
    link_link_type_ssn = link_link_type.shadow_struct.name
    sf.declare get_var_cname => %{
      inline static #{link_link_type_ssn} *#{get_var_cname}(#{CT_STRUCT_NAME} *ct) {
        if (!ct->#{link_cname})
          rs_raise(#{exc_nil}, ct->shadow->self, #{msg_nil.inspect});
        return ct->#{link_cname}->#{var};
      }
    }

    translation[expr] = "#{get_var_cname}(&ct)"

  when :input
    src_comp    = link_type.src_comp(var.intern)
    result_name = "value_#{link}__#{var}"
    ct_struct.declare result_name => "double #{result_name}"

    sf.declare get_var_cname => %{
      inline static double #{get_var_cname}(#{CT_STRUCT_NAME} *ct) {
        if (!ct->#{checked_var_cname}) {
          ct->#{checked_var_cname} = 1;
          if (!ct->#{link_cname})
            rs_raise(#{exc_nil}, ct->shadow->self, #{msg_nil.inspect});
          ct->#{result_name} = rs_eval_input_var(ct->#{link_cname},
              &ct->#{link_cname}->#{src_comp});
        }
        return ct->#{result_name};
      }
    }
    
    translation[expr] = "#{get_var_cname}(&ct)"
    
  when :event
    sf.declare get_var_cname => %{
      inline static double #{get_var_cname}(#{CT_STRUCT_NAME} *ct) {
        VALUE event_values, event_val;
        if (!ct->#{link_cname})
          rs_raise(#{exc_nil}, ct->shadow->self, #{msg_nil.inspect});
        event_values = ct->#{link_cname}->event_values;
        assert(event_values != Qnil);
        event_val = RARRAY(event_values)->ptr[#{event_idx}];
        return NUM2DBL(event_val);
      }
    }

    translation[expr] = "#{get_var_cname}(&ct)"
  
  else
    raise ArgumentError, "Bad var_type: #{var_type.inspect}"
  end

  return strict
end