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Repl.java
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Repl.java
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package com.stuffwithstuff.magpie;
import java.io.IOException;
import com.stuffwithstuff.magpie.ast.Expr;
import com.stuffwithstuff.magpie.interpreter.ErrorException;
import com.stuffwithstuff.magpie.interpreter.Interpreter;
import com.stuffwithstuff.magpie.interpreter.InterpreterHost;
import com.stuffwithstuff.magpie.interpreter.QuitException;
import com.stuffwithstuff.magpie.parser.CharacterReader;
import com.stuffwithstuff.magpie.parser.Lexer;
import com.stuffwithstuff.magpie.parser.MagpieParser;
import com.stuffwithstuff.magpie.parser.ParseException;
public class Repl implements InterpreterHost {
public void run() {
System.out.println();
System.out.println(" _/Oo>");
System.out.println(" /__/ magpie v0.0.0");
System.out.println("____//hh___________________");
System.out.println(" //");
System.out.println();
System.out.println("Type 'quit()' and press <Enter> to exit.");
Interpreter interpreter = new Interpreter(this);
// The REPL runs and imports relative to the current directory.
interpreter.pushScriptPath(".");
try {
Script.loadBase(interpreter);
while (true) {
Lexer lexer = new Lexer("REPL", createReader());
MagpieParser parser = interpreter.createParser(lexer);
try {
Expr expr = parser.parseExpression();
String result = interpreter.evaluateToString(expr);
if (result != null) printResult(result);
} catch(ParseException ex) {
printError("Parse error: " + ex.getMessage());
} catch(ErrorException ex) {
printError(String.format("Uncaught %s: %s",
ex.getError().getClassObj().getName(), ex.getError().getValue()));
}
}
} catch (QuitException e) {
// Do nothing.
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public boolean allowTopLevelRedefinition() {
return true;
}
@Override
public void print(String text) {
System.out.print(text);
}
protected CharacterReader createReader() {
return new ReplCharacterReader();
}
protected void printResult(String result) {
System.out.print("= ");
System.out.println(result);
}
protected void printError(String message) {
System.out.println("! " + message);
}
}