139 lines
4.1 KiB
Java
139 lines
4.1 KiB
Java
package function.builtin;
|
|
|
|
import java.text.MessageFormat;
|
|
|
|
import error.LispException;
|
|
import function.*;
|
|
import function.builtin.cons.LIST;
|
|
import function.builtin.special.LAMBDA;
|
|
import sexpression.*;
|
|
import table.*;
|
|
|
|
@FunctionNames({ "EVAL" })
|
|
public class EVAL extends LispFunction {
|
|
|
|
public static LispFunction lookupFunctionOrLambda(SExpression functionExpression) {
|
|
LispFunction function = FunctionTable.lookupFunction(functionExpression.toString());
|
|
|
|
if (function == null)
|
|
function = createLambdaFunction(functionExpression);
|
|
|
|
return function;
|
|
}
|
|
|
|
private static LispFunction createLambdaFunction(SExpression lambdaExpression) {
|
|
if (lambdaExpression.isFunction())
|
|
return ((LambdaExpression) lambdaExpression).getFunction();
|
|
else if (LAMBDA.isLambdaExpression(lambdaExpression))
|
|
return LAMBDA.createFunction((Cons) lambdaExpression);
|
|
else
|
|
throw new UndefinedFunctionException(lambdaExpression);
|
|
}
|
|
|
|
public static SExpression lookupSymbol(String symbolName) {
|
|
if (symbolName.equals("NIL"))
|
|
return Nil.getInstance();
|
|
else if (symbolName.equals("T"))
|
|
return Symbol.T;
|
|
else if (symbolName.startsWith(":"))
|
|
return new Symbol(symbolName);
|
|
|
|
return ExecutionContext.getInstance().lookupSymbolValue(symbolName);
|
|
}
|
|
|
|
public static SExpression eval(SExpression sExpression) {
|
|
Cons argumentList = LIST.makeList(sExpression);
|
|
EVAL eval = new EVAL();
|
|
|
|
return eval.call(argumentList);
|
|
}
|
|
|
|
private ArgumentValidator argumentValidator;
|
|
|
|
public EVAL() {
|
|
this.argumentValidator = new ArgumentValidator("EVAL");
|
|
this.argumentValidator.setExactNumberOfArguments(1);
|
|
}
|
|
|
|
public SExpression call(Cons argumentList) {
|
|
argumentValidator.validate(argumentList);
|
|
|
|
SExpression argument = argumentList.getFirst();
|
|
|
|
if (argument.isList()) {
|
|
if (argument.isCons())
|
|
return evaluateList((Cons) argument);
|
|
|
|
return argument; // NIL
|
|
}
|
|
|
|
if (argument.isSymbol()) {
|
|
SExpression symbolValue = lookupSymbol(argument.toString());
|
|
|
|
if (symbolValue != null)
|
|
return symbolValue;
|
|
|
|
throw new UndefinedSymbolException(argument);
|
|
}
|
|
|
|
return argument; // NUMBER or STRING
|
|
}
|
|
|
|
private SExpression evaluateList(Cons list) {
|
|
SExpression functionName = list.getFirst();
|
|
SExpression arguments = list.getRest();
|
|
LispFunction function = lookupFunctionOrLambda(functionName);
|
|
|
|
ArgumentValidator functionListValidator = new ArgumentValidator(functionName.toString());
|
|
functionListValidator.validate(list);
|
|
|
|
Cons argumentList = (Cons) arguments;
|
|
|
|
if (function.evaluateArguments())
|
|
argumentList = evaluateArgList(argumentList);
|
|
|
|
return function.call(argumentList);
|
|
}
|
|
|
|
private Cons evaluateArgList(Cons arguments) {
|
|
if (arguments.isNull())
|
|
return Nil.getInstance();
|
|
|
|
SExpression first = eval(arguments.getFirst());
|
|
SExpression rest = arguments.getRest();
|
|
|
|
return new Cons(first, evaluateArgList((Cons) rest));
|
|
}
|
|
|
|
public static class UndefinedFunctionException extends LispException {
|
|
|
|
private static final long serialVersionUID = 1L;
|
|
private SExpression function;
|
|
|
|
public UndefinedFunctionException(SExpression function) {
|
|
this.function = function;
|
|
}
|
|
|
|
@Override
|
|
public String getMessage() {
|
|
return MessageFormat.format("undefined function: {0}", function);
|
|
}
|
|
}
|
|
|
|
public static class UndefinedSymbolException extends LispException {
|
|
|
|
private static final long serialVersionUID = 1L;
|
|
private SExpression symbol;
|
|
|
|
public UndefinedSymbolException(SExpression symbol) {
|
|
this.symbol = symbol;
|
|
}
|
|
|
|
@Override
|
|
public String getMessage() {
|
|
return MessageFormat.format("symbol {0} has no value", symbol);
|
|
}
|
|
}
|
|
|
|
}
|