85 lines
2.7 KiB
Java
85 lines
2.7 KiB
Java
package function;
|
|
|
|
import java.util.ArrayList;
|
|
|
|
import function.builtin.EVAL;
|
|
import function.builtin.special.SETF;
|
|
import sexpression.*;
|
|
import table.SymbolTable;
|
|
|
|
public class UserDefinedFunction extends LispFunction {
|
|
|
|
private String name;
|
|
private Cons body;
|
|
private Cons lambdaExpression;
|
|
private SymbolTable scope;
|
|
private ArrayList<String> formalParameters;
|
|
private ArgumentValidator argumentValidator;
|
|
|
|
public UserDefinedFunction(String name, Cons lambdaList, Cons body) {
|
|
this.name = name;
|
|
this.body = body;
|
|
this.lambdaExpression = new Cons(new Symbol(name), new Cons(lambdaList, body));
|
|
this.scope = SETF.getSymbolTable();
|
|
|
|
for (this.formalParameters = new ArrayList<>(); lambdaList.consp(); lambdaList = (Cons) lambdaList.getCdr())
|
|
this.formalParameters.add(lambdaList.getCar().toString());
|
|
|
|
this.argumentValidator = new ArgumentValidator(this.name);
|
|
this.argumentValidator.setExactNumberOfArguments(this.formalParameters.size());
|
|
}
|
|
|
|
public SExpression call(Cons argumentList) {
|
|
argumentValidator.validate(argumentList);
|
|
|
|
// bind the values of the arguments to the formal parameter names
|
|
bindParameterValues(argumentList);
|
|
|
|
// store the environment of the S-expression that called this function
|
|
// (the current environment)
|
|
SymbolTable callingScope = SETF.getSymbolTable();
|
|
|
|
// replace the current environment with the environment of this
|
|
// function
|
|
SETF.setSymbolTable(scope);
|
|
|
|
Cons currentSExpression = body;
|
|
SExpression lastValue = null;
|
|
|
|
// evaluate all the S-expressions making up this function's body
|
|
while (currentSExpression.consp()) {
|
|
lastValue = EVAL.eval(currentSExpression.getCar());
|
|
currentSExpression = (Cons) currentSExpression.getCdr();
|
|
}
|
|
|
|
// replace the environment of the S-expression that called this
|
|
// function
|
|
SETF.setSymbolTable(callingScope);
|
|
|
|
// remove the bindings of the arguments to the formal parameter names
|
|
// in the environment of this function
|
|
releaseParameterValues();
|
|
|
|
return lastValue;
|
|
}
|
|
|
|
private void bindParameterValues(Cons argumentList) {
|
|
scope = new SymbolTable(scope);
|
|
|
|
for (String parameter : formalParameters) {
|
|
SExpression currentArg = argumentList.getCar();
|
|
scope.put(parameter, currentArg);
|
|
argumentList = (Cons) argumentList.getCdr();
|
|
}
|
|
}
|
|
|
|
private void releaseParameterValues() {
|
|
scope = new SymbolTable(scope.getParent());
|
|
}
|
|
|
|
public Cons getLambdaExpression() {
|
|
return lambdaExpression;
|
|
}
|
|
|
|
}
|