j2s/src/java/me/topchetoeu/jscript/runtime/values/Value.java

734 lines
29 KiB
Java

package me.topchetoeu.jscript.runtime.values;
import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import me.topchetoeu.jscript.common.Operation;
// import me.topchetoeu.jscript.lib.PromiseLib;
import me.topchetoeu.jscript.runtime.debug.DebugContext;
import me.topchetoeu.jscript.runtime.environment.Environment;
import me.topchetoeu.jscript.runtime.exceptions.ConvertException;
import me.topchetoeu.jscript.runtime.exceptions.EngineException;
import me.topchetoeu.jscript.runtime.exceptions.SyntaxException;
import me.topchetoeu.jscript.utils.interop.NativeWrapperProvider;
public interface Value {
public static enum CompareResult {
NOT_EQUAL,
EQUAL,
LESS,
GREATER;
public boolean less() { return this == LESS; }
public boolean greater() { return this == GREATER; }
public boolean lessOrEqual() { return this == LESS || this == EQUAL; }
public boolean greaterOrEqual() { return this == GREATER || this == EQUAL; }
public static CompareResult from(int cmp) {
if (cmp < 0) return LESS;
if (cmp > 0) return GREATER;
return EQUAL;
}
}
public static final Object NULL = new Object();
public static final Object NO_RETURN = new Object();
public static double number(Object val) {
if (val instanceof Number) return ((Number)val).doubleValue();
else return Double.NaN;
}
@SuppressWarnings("unchecked")
public static <T> T wrapper(Object val, Class<T> clazz) {
if (isWrapper(val)) val = ((NativeWrapper)val).wrapped;
if (val != null && clazz.isInstance(val)) return (T)val;
else return null;
}
public static String type(Object val) {
if (val == null) return "undefined";
if (val instanceof String) return "string";
if (val instanceof Number) return "number";
if (val instanceof Boolean) return "boolean";
if (val instanceof Symbol) return "symbol";
if (val instanceof FunctionValue) return "function";
return "object";
}
public boolean isPrimitive();
public BooleanValue toBoolean();
public default Value call(Environment env, Value self, Value ...args) {
throw EngineException.ofType("Tried to call a non-function value.");
}
public default Value callNew(Environment env, Value ...args) {
var res = new ObjectValue();
try {
var proto = Values.getMember(env, this, "prototype");
setPrototype(env, res, proto);
var ret = this.call(env, res, args);
if (!ret.isPrimitive()) return ret;
return res;
}
catch (IllegalArgumentException e) {
throw EngineException.ofType("Tried to call new on an invalid constructor.");
}
}
public default Value toPrimitive(Environment env, Value val) {
if (val.isPrimitive()) return val;
if (env != null) {
var valueOf = getMember(env, val, "valueOf");
if (valueOf instanceof FunctionValue) {
var res = valueOf.call(env, val);
if (res.isPrimitive()) return res;
}
var toString = getMember(env, val, "toString");
if (toString instanceof FunctionValue) {
var res = toString.call(env, val);
if (res.isPrimitive()) return res;
}
}
throw EngineException.ofType("Value couldn't be converted to a primitive.");
}
public default NumberValue toNumber(Environment ext, Object obj) {
var val = this.toPrimitive(ext, obj, ConvertHint.VALUEOF);
if (val instanceof NumberValue) return number(val);
if (val instanceof Boolean) return ((Boolean)val) ? 1 : 0;
if (val instanceof String) {
try { return Double.parseDouble((String)val); }
catch (NumberFormatException e) { return Double.NaN; }
}
return Double.NaN;
}
public default StringValue toString(Environment ext, Object obj) {
var val = toPrimitive(ext, obj, ConvertHint.VALUEOF);
if (val == null) return "undefined";
if (val == NULL) return "null";
if (val instanceof Number) {
var d = number(val);
if (d == Double.NEGATIVE_INFINITY) return "-Infinity";
if (d == Double.POSITIVE_INFINITY) return "Infinity";
if (Double.isNaN(d)) return "NaN";
return BigDecimal.valueOf(d).stripTrailingZeros().toPlainString();
}
if (val instanceof Boolean) return (Boolean)val ? "true" : "false";
if (val instanceof String) return (String)val;
if (val instanceof Symbol) return val.toString();
return "Unknown value";
}
public static Object add(Environment ext, Object a, Object b) {
if (a instanceof String || b instanceof String) return toString(ext, a) + toString(ext, b);
else return toNumber(ext, a) + toNumber(ext, b);
}
public static double subtract(Environment ext, Object a, Object b) {
return toNumber(ext, a) - toNumber(ext, b);
}
public static double multiply(Environment ext, Object a, Object b) {
return toNumber(ext, a) * toNumber(ext, b);
}
public static double divide(Environment ext, Object a, Object b) {
return toNumber(ext, a) / toNumber(ext, b);
}
public static double modulo(Environment ext, Object a, Object b) {
return toNumber(ext, a) % toNumber(ext, b);
}
public static double negative(Environment ext, Object obj) {
return -toNumber(ext, obj);
}
public static int and(Environment ext, Object a, Object b) {
return (int)toNumber(ext, a) & (int)toNumber(ext, b);
}
public static int or(Environment ext, Object a, Object b) {
return (int)toNumber(ext, a) | (int)toNumber(ext, b);
}
public static int xor(Environment ext, Object a, Object b) {
return (int)toNumber(ext, a) ^ (int)toNumber(ext, b);
}
public static int bitwiseNot(Environment ext, Object obj) {
return ~(int)toNumber(ext, obj);
}
public static int shiftLeft(Environment ext, Object a, Object b) {
return (int)toNumber(ext, a) << (int)toNumber(ext, b);
}
public static int shiftRight(Environment ext, Object a, Object b) {
return (int)toNumber(ext, a) >> (int)toNumber(ext, b);
}
public static long unsignedShiftRight(Environment ext, Object a, Object b) {
long _a = (long)toNumber(ext, a);
long _b = (long)toNumber(ext, b);
if (_a < 0) _a += 0x100000000l;
if (_b < 0) _b += 0x100000000l;
return _a >>> _b;
}
public static CompareResult compare(Environment ext, Object a, Object b) {
a = toPrimitive(ext, a, ConvertHint.VALUEOF);
b = toPrimitive(ext, b, ConvertHint.VALUEOF);
if (a instanceof String && b instanceof String) CompareResult.from(((String)a).compareTo((String)b));
var _a = toNumber(ext, a);
var _b = toNumber(ext, b);
if (Double.isNaN(_a) || Double.isNaN(_b)) return CompareResult.NOT_EQUAL;
return CompareResult.from(Double.compare(_a, _b));
}
public static boolean not(Object obj) {
return !toBoolean(obj);
}
public static boolean isInstanceOf(Environment ext, Object obj, Object proto) {
if (obj == null || obj == NULL || proto == null || proto == NULL) return false;
var val = getPrototype(ext, obj);
while (val != null) {
if (val.equals(proto)) return true;
val = val.getPrototype(ext);
}
return false;
}
public static Object operation(Environment ext, Operation op, Object ...args) {
switch (op) {
case ADD: return add(ext, args[0], args[1]);
case SUBTRACT: return subtract(ext, args[0], args[1]);
case DIVIDE: return divide(ext, args[0], args[1]);
case MULTIPLY: return multiply(ext, args[0], args[1]);
case MODULO: return modulo(ext, args[0], args[1]);
case AND: return and(ext, args[0], args[1]);
case OR: return or(ext, args[0], args[1]);
case XOR: return xor(ext, args[0], args[1]);
case EQUALS: return strictEquals(ext, args[0], args[1]);
case NOT_EQUALS: return !strictEquals(ext, args[0], args[1]);
case LOOSE_EQUALS: return looseEqual(ext, args[0], args[1]);
case LOOSE_NOT_EQUALS: return !looseEqual(ext, args[0], args[1]);
case GREATER: return compare(ext, args[0], args[1]).greater();
case GREATER_EQUALS: return compare(ext, args[0], args[1]).greaterOrEqual();
case LESS: return compare(ext, args[0], args[1]).less();
case LESS_EQUALS: return compare(ext, args[0], args[1]).lessOrEqual();
case INVERSE: return bitwiseNot(ext, args[0]);
case NOT: return not(args[0]);
case POS: return toNumber(ext, args[0]);
case NEG: return negative(ext, args[0]);
case SHIFT_LEFT: return shiftLeft(ext, args[0], args[1]);
case SHIFT_RIGHT: return shiftRight(ext, args[0], args[1]);
case USHIFT_RIGHT: return unsignedShiftRight(ext, args[0], args[1]);
case IN: return hasMember(ext, args[1], args[0], false);
case INSTANCEOF: {
var proto = getMember(ext, args[1], "prototype");
return isInstanceOf(ext, args[0], proto);
}
default: return null;
}
}
public static Object getMember(Environment ctx, Object obj, Object key) {
obj = normalize(ctx, obj); key = normalize(ctx, key);
if (obj == null) throw new IllegalArgumentException("Tried to access member of undefined.");
if (obj == NULL) throw new IllegalArgumentException("Tried to access member of null.");
if (obj instanceof ObjectValue) return ((ObjectValue)obj).getMember(ctx, key, obj);
if (obj instanceof String && key instanceof Number) {
var i = number(key);
var s = (String)obj;
if (i >= 0 && i < s.length() && i - Math.floor(i) == 0) {
return s.charAt((int)i) + "";
}
}
var proto = getPrototype(ctx, obj);
if (proto == null) return "__proto__".equals(key) ? NULL : null;
else if (key != null && "__proto__".equals(key)) return proto;
else return proto.getMember(ctx, key, obj);
}
public static Object getMemberPath(Environment ctx, Object obj, Object ...path) {
var res = obj;
for (var key : path) res = getMember(ctx, res, key);
return res;
}
public static boolean setMember(Environment ctx, Object obj, Object key, Object val) {
obj = normalize(ctx, obj); key = normalize(ctx, key); val = normalize(ctx, val);
if (obj == null) throw EngineException.ofType("Tried to access member of undefined.");
if (obj == NULL) throw EngineException.ofType("Tried to access member of null.");
if (key != null && "__proto__".equals(key)) return setPrototype(ctx, obj, val);
if (obj instanceof ObjectValue) return ((ObjectValue)obj).setMember(ctx, key, val, obj, false);
var proto = getPrototype(ctx, obj);
return proto.setMember(ctx, key, val, obj, true);
}
public static boolean hasMember(Environment ctx, Object obj, Object key, boolean own) {
if (obj == null || obj == NULL) return false;
obj = normalize(ctx, obj); key = normalize(ctx, key);
if ("__proto__".equals(key)) return true;
if (obj instanceof ObjectValue) return ((ObjectValue)obj).hasMember(ctx, key, own);
if (obj instanceof String && key instanceof Number) {
var i = number(key);
var s = (String)obj;
if (i >= 0 && i < s.length() && i - Math.floor(i) == 0) return true;
}
if (own) return false;
var proto = getPrototype(ctx, obj);
return proto != null && proto.hasMember(ctx, key, own);
}
public static boolean deleteMember(Environment ext, Object obj, Object key) {
if (obj == null || obj == NULL) return false;
obj = normalize(ext, obj); key = normalize(ext, key);
if (obj instanceof ObjectValue) return ((ObjectValue)obj).deleteMember(ext, key);
else return false;
}
public static ObjectValue getPrototype(Environment ext, Object obj) {
if (obj == null || obj == NULL) return null;
obj = normalize(ext, obj);
if (obj instanceof ObjectValue) return ((ObjectValue)obj).getPrototype(ext);
if (ext == null) return null;
if (obj instanceof String) return ext.get(Environment.STRING_PROTO);
else if (obj instanceof Number) return ext.get(Environment.NUMBER_PROTO);
else if (obj instanceof Boolean) return ext.get(Environment.BOOL_PROTO);
else if (obj instanceof Symbol) return ext.get(Environment.SYMBOL_PROTO);
return null;
}
public static boolean setPrototype(Environment ext, Object obj, Object proto) {
obj = normalize(ext, obj);
return obj instanceof ObjectValue && ((ObjectValue)obj).setPrototype(ext, proto);
}
public static void makePrototypeChain(Environment ext, Object... chain) {
for(var i = 1; i < chain.length; i++) {
setPrototype(ext, chain[i], chain[i - 1]);
}
}
public static List<Object> getMembers(Environment ext, Object obj, boolean own, boolean includeNonEnumerable) {
List<Object> res = new ArrayList<>();
if (obj instanceof ObjectValue) res = ((ObjectValue)obj).keys(includeNonEnumerable);
if (obj instanceof String) {
for (var i = 0; i < ((String)obj).length(); i++) res.add((double)i);
}
if (!own) {
var proto = getPrototype(ext, obj);
while (proto != null) {
res.addAll(proto.keys(includeNonEnumerable));
proto = getPrototype(ext, proto);
}
}
return res;
}
public static ObjectValue getMemberDescriptor(Environment ext, Object obj, Object key) {
if (obj instanceof ObjectValue) return ((ObjectValue)obj).getMemberDescriptor(ext, key);
else if (obj instanceof String && key instanceof Number) {
var i = ((Number)key).intValue();
var _i = ((Number)key).doubleValue();
if (i - _i != 0) return null;
if (i < 0 || i >= ((String)obj).length()) return null;
return new ObjectValue(ext, Map.of(
"value", ((String)obj).charAt(i) + "",
"writable", false,
"enumerable", true,
"configurable", false
));
}
else return null;
}
public static boolean strictEquals(Environment ext, Object a, Object b) {
a = normalize(ext, a);
b = normalize(ext, b);
if (a == null || b == null) return a == null && b == null;
if (isNan(a) || isNan(b)) return false;
if (a instanceof Number && number(a) == -0.) a = 0.;
if (b instanceof Number && number(b) == -0.) b = 0.;
return a == b || a.equals(b);
}
public static boolean looseEqual(Environment ext, Object a, Object b) {
a = normalize(ext, a); b = normalize(ext, b);
// In loose equality, null is equivalent to undefined
if (a == NULL) a = null;
if (b == NULL) b = null;
if (a == null || b == null) return a == null && b == null;
// If both are objects, just compare their references
if (!isPrimitive(a) && !isPrimitive(b)) return a == b;
// Convert values to primitives
a = toPrimitive(ext, a, ConvertHint.VALUEOF);
b = toPrimitive(ext, b, ConvertHint.VALUEOF);
// Compare symbols by reference
if (a instanceof Symbol || b instanceof Symbol) return a == b;
if (a instanceof Boolean || b instanceof Boolean) return toBoolean(a) == toBoolean(b);
if (a instanceof Number || b instanceof Number) return strictEquals(ext, toNumber(ext, a), toNumber(ext, b));
// Default to strings
return toString(ext, a).equals(toString(ext, b));
}
public static Object normalize(Environment ext, Object val) {
if (val instanceof Number) return number(val);
if (isPrimitive(val) || val instanceof ObjectValue) return val;
if (val instanceof Character) return val + "";
if (val instanceof Map) {
var res = new ObjectValue();
for (var entry : ((Map<?, ?>)val).entrySet()) {
res.defineProperty(ext, entry.getKey(), entry.getValue());
}
return res;
}
if (val instanceof Iterable) {
var res = new ArrayValue();
for (var entry : ((Iterable<?>)val)) {
res.set(ext, res.size(), entry);
}
return res;
}
if (val instanceof Class) {
if (ext == null) return null;
else return NativeWrapperProvider.get(ext).getConstr((Class<?>)val);
}
return NativeWrapper.of(ext, val);
}
@SuppressWarnings("unchecked")
public static <T> T convert(Environment ext, Object obj, Class<T> clazz) {
if (clazz == Void.class) return null;
if (obj instanceof NativeWrapper) {
var res = ((NativeWrapper)obj).wrapped;
if (clazz.isInstance(res)) return (T)res;
}
if (clazz == null || clazz == Object.class) return (T)obj;
if (obj instanceof ArrayValue) {
if (clazz.isAssignableFrom(ArrayList.class)) {
var raw = ((ArrayValue)obj).toArray();
var res = new ArrayList<>();
for (var i = 0; i < raw.length; i++) res.add(convert(ext, raw[i], Object.class));
return (T)new ArrayList<>(res);
}
if (clazz.isAssignableFrom(HashSet.class)) {
var raw = ((ArrayValue)obj).toArray();
var res = new HashSet<>();
for (var i = 0; i < raw.length; i++) res.add(convert(ext, raw[i], Object.class));
return (T)new HashSet<>(res);
}
if (clazz.isArray()) {
var raw = ((ArrayValue)obj).toArray();
Object res = Array.newInstance(clazz.getComponentType(), raw.length);
for (var i = 0; i < raw.length; i++) Array.set(res, i, convert(ext, raw[i], Object.class));
return (T)res;
}
}
if (obj instanceof ObjectValue && clazz.isAssignableFrom(HashMap.class)) {
var res = new HashMap<>();
for (var el : ((ObjectValue)obj).values.entrySet()) res.put(
convert(ext, el.getKey(), null),
convert(ext, el.getValue(), null)
);
return (T)res;
}
if (clazz == String.class) return (T)toString(ext, obj);
if (clazz == Boolean.class || clazz == Boolean.TYPE) return (T)(Boolean)toBoolean(obj);
if (clazz == Byte.class || clazz == byte.class) return (T)(Byte)(byte)toNumber(ext, obj);
if (clazz == Integer.class || clazz == int.class) return (T)(Integer)(int)toNumber(ext, obj);
if (clazz == Long.class || clazz == long.class) return (T)(Long)(long)toNumber(ext, obj);
if (clazz == Short.class || clazz == short.class) return (T)(Short)(short)toNumber(ext, obj);
if (clazz == Float.class || clazz == float.class) return (T)(Float)(float)toNumber(ext, obj);
if (clazz == Double.class || clazz == double.class) return (T)(Double)toNumber(ext, obj);
if (clazz == Character.class || clazz == char.class) {
if (obj instanceof Number) return (T)(Character)(char)number(obj);
else {
var res = toString(ext, obj);
if (res.length() == 0) throw new ConvertException("\"\"", "Character");
else return (T)(Character)res.charAt(0);
}
}
if (obj == null) return null;
if (clazz.isInstance(obj)) return (T)obj;
if (clazz.isAssignableFrom(NativeWrapper.class)) {
return (T)NativeWrapper.of(ext, obj);
}
throw new ConvertException(type(obj), clazz.getSimpleName());
}
public static Iterable<Object> fromJSIterator(Environment ext, Object obj) {
return () -> {
try {
var symbol = Symbol.get("Symbol.iterator");
var iteratorFunc = getMember(ext, obj, symbol);
if (!(iteratorFunc instanceof FunctionValue)) return Collections.emptyIterator();
var iterator = iteratorFunc instanceof FunctionValue ?
((FunctionValue)iteratorFunc).call(ext, obj, obj) :
iteratorFunc;
var nextFunc = getMember(ext, call(ext, iteratorFunc, obj), "next");
if (!(nextFunc instanceof FunctionValue)) return Collections.emptyIterator();
return new Iterator<Object>() {
private Object value = null;
public boolean consumed = true;
private FunctionValue next = (FunctionValue)nextFunc;
private void loadNext() {
if (next == null) value = null;
else if (consumed) {
var curr = next.call(ext, iterator);
if (curr == null) { next = null; value = null; }
if (toBoolean(Values.getMember(ext, curr, "done"))) { next = null; value = null; }
else {
this.value = Values.getMember(ext, curr, "value");
consumed = false;
}
}
}
@Override
public boolean hasNext() {
loadNext();
return next != null;
}
@Override
public Object next() {
loadNext();
var res = value;
value = null;
consumed = true;
return res;
}
};
}
catch (IllegalArgumentException | NullPointerException e) {
return Collections.emptyIterator();
}
};
}
public static ObjectValue toJSIterator(Environment ext, Iterator<?> it) {
var res = new ObjectValue();
try {
var key = getMember(ext, getMember(ext, ext.get(Environment.SYMBOL_PROTO), "constructor"), "iterator");
res.defineProperty(ext, key, new NativeFunction("", args -> args.self));
}
catch (IllegalArgumentException | NullPointerException e) { }
res.defineProperty(ext, "next", new NativeFunction("", args -> {
if (!it.hasNext()) return new ObjectValue(ext, Map.of("done", true));
else {
var obj = new ObjectValue();
obj.defineProperty(args.env, "value", it.next());
return obj;
}
}));
return res;
}
public static ObjectValue toJSIterator(Environment ext, Iterable<?> it) {
return toJSIterator(ext, it.iterator());
}
public static ObjectValue toJSAsyncIterator(Environment ext, Iterator<?> it) {
var res = new ObjectValue();
try {
var key = getMemberPath(ext, ext.get(Environment.SYMBOL_PROTO), "constructor", "asyncIterator");
res.defineProperty(ext, key, new NativeFunction("", args -> args.self));
}
catch (IllegalArgumentException | NullPointerException e) { }
res.defineProperty(ext, "next", new NativeFunction("", args -> {
return PromiseLib.await(args.env, () -> {
if (!it.hasNext()) return new ObjectValue(ext, Map.of("done", true));
else {
var obj = new ObjectValue();
obj.defineProperty(args.env, "value", it.next());
return obj;
}
});
}));
return res;
}
private static boolean isEmptyFunc(ObjectValue val) {
if (!(val instanceof FunctionValue)) return false;
if (!val.values.containsKey("prototype") || val.values.size() + val.properties.size() > 1) return false;
var proto = val.values.get("prototype");
if (!(proto instanceof ObjectValue)) return false;
var protoObj = (ObjectValue)proto;
if (protoObj.values.get("constructor") != val) return false;
if (protoObj.values.size() + protoObj.properties.size() != 1) return false;
return true;
}
private static String toReadable(Environment ext, Object val, HashSet<Object> passed, int tab) {
if (tab == 0 && val instanceof String) return (String)val;
if (passed.contains(val)) return "[circular]";
var printed = true;
var res = new StringBuilder();
var dbg = DebugContext.get(ext);
if (val instanceof FunctionValue) {
res.append(val.toString());
var loc = val instanceof CodeFunction ? dbg.getMapOrEmpty((CodeFunction)val).start() : null;
if (loc != null) res.append(" @ " + loc);
}
else if (val instanceof ArrayValue) {
res.append("[");
var obj = ((ArrayValue)val);
for (int i = 0; i < obj.size(); i++) {
if (i != 0) res.append(", ");
else res.append(" ");
if (obj.has(i)) res.append(toReadable(ext, obj.get(i), passed, tab));
else res.append("<empty>");
}
res.append(" ] ");
}
else if (val instanceof NativeWrapper) {
var obj = ((NativeWrapper)val).wrapped;
res.append("Native " + obj.toString() + " ");
}
else printed = false;
if (val instanceof ObjectValue) {
if (tab > 3) {
return "{...}";
}
passed.add(val);
var obj = (ObjectValue)val;
if (obj.values.size() + obj.properties.size() == 0 || isEmptyFunc(obj)) {
if (!printed) res.append("{}\n");
}
else {
res.append("{\n");
for (var el : obj.values.entrySet()) {
for (int i = 0; i < tab + 1; i++) res.append(" ");
res.append(toReadable(ext, el.getKey(), passed, tab + 1));
res.append(": ");
res.append(toReadable(ext, el.getValue(), passed, tab + 1));
res.append(",\n");
}
for (var el : obj.properties.entrySet()) {
for (int i = 0; i < tab + 1; i++) res.append(" ");
res.append(toReadable(ext, el.getKey(), passed, tab + 1));
res.append(": [prop],\n");
}
for (int i = 0; i < tab; i++) res.append(" ");
res.append("}");
}
passed.remove(val);
}
else if (val == null) return "undefined";
else if (val == Values.NULL) return "null";
else if (val instanceof String) return "'" + val + "'";
else return Values.toString(ext, val);
return res.toString();
}
public static String toReadable(Environment ext, Object val) {
return toReadable(ext, val, new HashSet<>(), 0);
}
public static String errorToReadable(RuntimeException err, String prefix) {
prefix = prefix == null ? "Uncaught" : "Uncaught " + prefix;
if (err instanceof EngineException) {
var ee = ((EngineException)err);
try {
return prefix + " " + ee.toString(ee.env);
}
catch (EngineException ex) {
return prefix + " " + toReadable(ee.env, ee.value);
}
}
else if (err instanceof SyntaxException) {
return prefix + " SyntaxError " + ((SyntaxException)err).msg;
}
else if (err.getCause() instanceof InterruptedException) return "";
else {
var str = new ByteArrayOutputStream();
err.printStackTrace(new PrintStream(str));
return prefix + " internal error " + str.toString();
}
}
public static void printValue(Environment ext, Object val) {
System.out.print(toReadable(ext, val));
}
public static void printError(RuntimeException err, String prefix) {
System.out.println(errorToReadable(err, prefix));
}
}