amplrs 0.1.6

Safe Rust API for AMPL optimization modeling system
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use amplrs::Ampl;

fn init() -> Ampl {
  let mut ampl = Ampl::new();
  //ampl.set_bool_option("times", true);
  //ampl.set_bool_option("gentimes", true);
  ampl.set_option("solver", "gurobi");
  ampl
}

pub fn load_diet_model(ampl: &mut Ampl) {
  ampl.eval(
    r#"
    set FOOD;
    set NUTR;
    # Parameters
    param cost { FOOD } > 0;
    param f_min { FOOD } >= 0;
    param f_max {j in FOOD } >= f_min [j];
    param n_min { NUTR } >= 0;
    param n_max {i in NUTR } >= n_min [i];
    param amt {NUTR , FOOD } >= 0;
    # Variables
    var Buy {j in FOOD } >= f_min [j], <= f_max [j];
    # Objective
    minimize total_cost : sum {j in FOOD } cost [j] * Buy[j];
    # Constraints
    subject to diet {i in NUTR }:
      n_min [i] <= sum {j in FOOD } amt[i,j] * Buy[j] <= n_max [i];
    "#
  );
  ampl.eval(
    r#"
    data;
    set NUTR := A C B1 B2 NA CAL;
    set FOOD := BEEF CHK FISH HAM MCH MTL SPG TUR ;
    param : cost f_min f_max :=
      BEEF 3.19 2 10
      CHK 2.59 2 10
      FISH 2.29 2 10
      HAM 2.89 2 10
      MCH 1.89 2 10
      MTL 1.99 2 10
      SPG 1.99 2 10
      TUR 2.49 2 10 ;
    param : n_min n_max :=
      A 700 20000
      C 700 20000
      B1 700 20000
      B2 700 20000
      NA 0 50000
      CAL 16000 24000 ;
    param amt (tr):
      A C B1 B2 NA CAL :=
      BEEF 60 20 10 15 938 295
      CHK 8 0 20 20 2180 770
      FISH 8 10 15 10 945 440
      HAM 40 40 35 10 278 430
      MCH 15 35 15 15 1182 315
      MTL 70 30 15 15 896 400
      SPG 25 50 25 15 1329 370
      TUR 60 20 15 10 1397 450 ;
    "#
  );
}

#[test]
fn objective() {
  let mut ampl = init();
  load_diet_model(&mut ampl);
  
  assert_eq!(1, ampl.get_objectives().len());

  let obj = ampl.get_objective("total_cost");
    
  assert_eq!(ampl.get_current_objective(), "total_cost");
  assert_eq!(1, obj.num_instances()); 
    //assert!(obj.value().is_finite());  // Ensure value is a finite float
    //assert!(obj.astatus().is_string());  // Ensure astatus() returns a string
    //assert!(obj.sstatus().is_string());  // Ensure sstatus() returns a string
    //assert!(obj.exitcode().is_i32());  // Ensure exitcode() returns an integer
    //assert!(obj.message().is_string());  // Ensure message() returns a string
    //assert!(obj.result().is_string());  // Ensure result() returns a string

  obj.drop();
  assert_eq!(obj.astatus(), "drop");

  obj.restore();
  assert_eq!(obj.astatus(), "in");

  assert!(obj.is_minimization());

  ampl.eval(
    r#"
    maximize A: 1;
    minimize B: 1;
    maximize C: 1;
    "#
  );
  assert_eq!(ampl.get_current_objective(), "");

  ampl.eval("objective A;");
  assert_eq!(ampl.get_current_objective(), "A");
  let obj_A = ampl.get_objective("A");
  assert!(!obj_A.is_minimization());

  ampl.eval("objective B;");
  assert_eq!(ampl.get_current_objective(), "B");
  let obj_B = ampl.get_objective("B");
  assert!(obj_B.is_minimization());

  ampl.eval("objective C;");
  assert_eq!(ampl.get_current_objective(), "C");
  let obj_C = ampl.get_objective("C");
  assert!(!obj_C.is_minimization());

  ampl.eval("objective A;");
  assert_eq!(ampl.get_current_objective(), "A");
  let obj_A = ampl.get_objective("A");
  assert!(!obj_A.is_minimization());
}