80 lines
2.6 KiB
Java
80 lines
2.6 KiB
Java
package function;
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import java.util.ArrayList;
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import function.builtin.*;
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import sexpression.*;
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import table.SymbolTable;
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public class UserDefinedFunction extends LispFunction {
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private String name;
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private Cons body;
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private Cons lambdaExpression;
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private SymbolTable environment;
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private ArrayList<String> formalParameters;
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private ArgumentValidator argumentValidator;
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public UserDefinedFunction(String name, Cons lambdaList, Cons body) {
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this.name = name;
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this.body = body;
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this.lambdaExpression = new Cons(new Symbol(name), new Cons(lambdaList, body));
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this.environment = SETF.getEnvironment();
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for (this.formalParameters = new ArrayList<>(); lambdaList.consp(); lambdaList = (Cons) lambdaList.getCdr())
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this.formalParameters.add(lambdaList.getCar().toString());
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this.argumentValidator = new ArgumentValidator(this.name);
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this.argumentValidator.setExactNumberOfArguments(this.formalParameters.size());
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}
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public SExpression call(Cons argList) {
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argumentValidator.validate(argList);
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// push a new symbol table onto this function's environment (for its
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// parameters)
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environment = new SymbolTable(environment);
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// bind the values of the arguments to the formal parameter names
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for (String param : formalParameters) {
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SExpression currentArg = argList.getCar();
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environment.put(param, currentArg);
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argList = (Cons) argList.getCdr();
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}
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// store the environment of the S-expression that called this function
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// (the current environment)
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SymbolTable currentEnvironment = SETF.getEnvironment();
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// replace the current environment with the environment of this
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// function
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SETF.setEnvironment(environment);
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Cons currentSExpression = body;
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SExpression retval = null;
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// evaluate all the S-expressions making up this function's body
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while (currentSExpression.consp()) {
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retval = EVAL.eval(currentSExpression.getCar());
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currentSExpression = (Cons) currentSExpression.getCdr();
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}
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// replace the environment of the S-expression that called this
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// function
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SETF.setEnvironment(currentEnvironment);
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// remove the bindings of the arguments to the formal parameter names
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// in the environment of this function
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environment = new SymbolTable(environment.getParent());
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return retval;
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}
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public Cons getLambdaExpression() {
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return lambdaExpression;
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}
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}
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