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package jason.stdlib;

import jason.asSemantics.DefaultInternalAction;
import jason.asSemantics.InternalAction;
import jason.asSemantics.TransitionSystem;
import jason.asSemantics.Unifier;
import jason.asSyntax.Term;

/**
  Internal action: .structure.

  
Description: checks whether the argument is a structure, e.g.: "p", "p(1)",
  "[a,b]".  Numbers, strings and free variables are not structures.

  
Parameter:

  + argument (any term): the term to be checked.

  

  Examples:

   .structure(b(10)): true.
  
 .structure(b): true.
  
 .structure(10): false.
  
 .structure("home page"): false.
  
 .structure(X): false if X is free, true if X is bound to a structure.
  
 .structure(a(X)): true.
  
 .structure([a,b,c]): true.
  
 .structure([a,b,c(X)]): true.
  

  @see jason.stdlib.atom
  @see jason.stdlib.list
  @see jason.stdlib.literal
  @see jason.stdlib.number
  @see jason.stdlib.string
  @see jason.stdlib.ground

*/
@Manual(
        literal=".structure(argument)",
        hint="checks whether the argument is a structure",
        argsHint= {
                "the term to be checked"
        },
        argsType= {
                "term"
        },
        examples= {
                ".structure(b(10)): true",
                ".structure(b): true",
                ".structure(10): false",
                ".structure(\"home page\"): false",
                ".structure(X): false if X is free, true if X is bound to a structure",
                ".structure(a(X)): true",
                ".structure(~c(f)): true",
                ".structure([a,b,c]): true",
                ".structure([a,b,c(X)]): true"
        },
        seeAlso= {
                "jason.stdlib.atom",
                "jason.stdlib.list",
                "jason.stdlib.literal",
                "jason.stdlib.number",
                "jason.stdlib.string",
                "jason.stdlib.ground"
        }
    )
@SuppressWarnings("serial")
public class structure extends DefaultInternalAction {

    private static InternalAction singleton = null;
    public static InternalAction create() {
        if (singleton == null)
            singleton = new structure();
        return singleton;
    }

    @Override public int getMinArgs() {
        return 1;
    }
    @Override public int getMaxArgs() {
        return 1;
    }

    @Override
    public Object execute(TransitionSystem ts, Unifier un, Term[] args) throws Exception {
        checkArguments(args);
        return args[0].isStructure();
    }
}