Code generation with Textrude

[andbrs]

I'm working on a project in which I'm trying to make a code generator for Arduino, I was trying Telosys and Acceleo, but these tools don't convince me completely. I would like to know if you consider that Textrude and scriban have enough capabilities to be able to make this code generator.
The idea that occurs to me is that for example a person places in the model section something like "servo" and by means of the template, a code like this is generated:

#include <Servo.h>
Servo servoMotor;
servoMotor.attach(9);
 // We move to the 0º position
  servoMotor.write(0);
  // We wait 1 second
  delay(1000);
  
  // Move to the 90º position
  servoMotor.write(90);
  // We wait 1 second
  delay(1000);
  
  // We move to position 180º.
  servoMotor.write(180);
  // We wait 1 second
  delay(1000);

or something very similar.

[NeilMacMullen]

The thing to consider is how much variation you want in the output vs how much is constant. For example, in your code above, maybe you want the delay time to be variable or perhaps step by 45 degrees rather than 90? Generally you want to use the Scriban template as the place to put the "constant" bits of the code as well as the logic to insert parameterised parts and then use the model to supply parameters.

If you are intending that the user should be able to generate different kinds of things (perhaps you have an "accelerometer" module as well as a "servo" module) then one way to do it is to create a library so that you can write a template that looks something like

#include the library
include "modules.sbn"

#generate servo code using parameters from yaml model..
servo model.servo_delay model.servo_step

#generate accelerometer code...
accelerometer model.accelerometer_sensitivity model.accelerometer_sample_rate

# and so on

Having said, that Scriban is flexible enough that you can "reflect" over the model so it might be possible to model that defines the structure of the output as well as supplying parameters.

For example, you could have a yaml model something like

modules
 - type: servo
    parameters:
      rate : 100
     step : 45

then a template like this...

for m in model.modules
 if (m.type == "server")
    rate = m.parameters.rate
    step = m.parameters.step
    ... output template code for servo module

[andbrs]

Neil, I was working on the code generator and with the structure, you provided I was able to create several sensors and actuators. Now, I have a question. To save me several lines of code in the void loop I thought about making a class for each of the devices, for example, the servo. I already made a class for the servo in Arduino, which works perfectly. But I could not make a template in Textrude, which generates these classes and their instances. Could I do something in Textrude like the code below?

The main idea is to create a class for each device and be able to instance from the Yaml model, what the user wants. Is this possible?

#include <Servo.h>

class servomotor :
  public  Servo {

  public:
    MyClass() {}

    void pin(uint8_t servoPin) {
      attach(servoPin);
    }

    void servoBackward() {
      for (int val=140;val<=160;val+= 1)
      {write(val); delay (15);}
      for (int val = 160; val >= 140; val -= 1) {
      write(val);
      delay(15);
      }
    }
    void servoBack() {
      for (int val=140;val<=160;val+= 1)
      {write(val); delay (100);}
      for (int val = 160; val >= 140; val -= 1) {
      write(val);
      delay(100);
      }
    }   
};
 
servomotor servo1;
servomotor servo2;

void setup() {
  servo1.pin(9);
  servo2.pin(8);
}

void loop() {

    servo1.servoBackward();
     delay(15);  
    servo2.servoBack();
      delay(15); 
}

I worked on this file
cpp_ex.zip

[NeilMacMullen]

It's exactly the same principle as my previous example used to insert the #include headers.. You just need to use an array to keep track of which classes are needed and then insert them via a variable. The variable is updated via a function. Here's some skeleton code...

{{
#track which classes have been inserted
classList =[]
#variable containing text for classes
classText=""

#use a function to insert the class
func addServoClass
#only do it once
if (array.contains classList "servo") ;ret ;end;
classList = array.add classList "servo"
#body of  servo class
classText = classText +"
class myServo{
... class body
}
"
end

func addServo(s)
#ensure the class  body is added
addServoClass
..do more things
end

#now interate over the users yaml model and insert the code we want
for m in model.modules
if (m.type == "servo")
addServo m
end
end

# insert the acculated classes into the output
classText

}}

[andbrs]

Thank you very much for your help, I made some modifications, but I can't manage to do as with the previous examples that I can modify the skeleton of the class (I want to add a def.nameClass). This is my code so far.

cpp_ex.zip

Another question, for the instances of each class how do you recommend me to do it, would it be a new function or in the existing ones?

Thank you very much for your possible help....

[NeilMacMullen]

Sorry for the delay - have been a bit busy with "real" life.. I think you are quite close. Firstly you need to modify the addServoClass function to accept an argument...

func addServoClass(def)

Then you need to ensure that def.nameClass is interpreted as code. As it stands it is just treated as text because it's inside a multiline string. So change the line to

class " + def.nameClass +":

so that def.nameClass is treated as a variable and added to the strings to the left and right of itself.

Finally, you need to ensure that the the part of the model that includes the nameClass declaration is passed in to the function so change the call to addServoClass in func AddServo to

addServoClass s

I've attached a working version.
cpp_ex.zip

Another question, for the instances of each class how do you recommend me to do it, would it be a new function or in the existing ones?

There are lots of ways to arrange this. I used a function per class because it makes for a more obvious grouping but another alternatively would be to use the include directive to include text from library scripts. See the 02_include... example. You could also use separate models to configure the classes - see the 04_multiple... example for this.

[andbrs]

Neil, thank you very much for your response. I will check the example you attached. On another note, I hope you have been able to resolve your busyness with the difficult "real" life. Regards