1 // Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
9 /** The minimum set of functionality required for objects which are manipulated by JavaScript */
10 public class JS extends org.xwt.util.BalancedTree {
12 // Static Interpreter Control Methods ///////////////////////////////////////////////////////////////
14 /** log a message with the current JavaScript sourceName/line */
15 public static void log(Object o, Object message) { log(message); }
16 public static void log(Object message) { Log.echo(JS.getSourceName() + ":" + JS.getLine(), message); }
17 public static void log(JSExn e) {
18 Log.echo(e,"JS Exception: " + e.getObject() + "\n" + e.backtrace());
22 public static int getLine() {
23 Interpreter c = Interpreter.current();
24 return c == null || c.f == null || c.pc < 0 || c.pc >= c.f.size ? -1 : c.f.line[c.pc];
27 public static String getSourceName() {
28 Interpreter c = Interpreter.current();
29 return c == null || c.f == null ? null : c.f.sourceName;
32 public static class NotPauseableException extends Exception { NotPauseableException() { } }
34 /** returns a callback which will restart the context; expects a value to be pushed onto the stack when unpaused */
35 public static UnpauseCallback pause() throws NotPauseableException {
36 Interpreter i = Interpreter.current();
37 if (i.pausecount == -1) throw new NotPauseableException();
39 return new JS.UnpauseCallback(i);
42 public static class UnpauseCallback implements Scheduler.Task {
44 UnpauseCallback(Interpreter i) { this.i = i; }
45 public void perform() throws JSExn { unpause(null); }
46 public void unpause(Object o) throws JSExn {
47 // FIXME: if o instanceof JSExn, throw it into the JSworld
55 // Static Helper Methods ///////////////////////////////////////////////////////////////////////////////////
57 /** coerce an object to a Boolean */
58 public static boolean toBoolean(Object o) {
59 if (o == null) return false;
60 if (o instanceof Boolean) return ((Boolean)o).booleanValue();
61 if (o instanceof Long) return ((Long)o).longValue() != 0;
62 if (o instanceof Integer) return ((Integer)o).intValue() != 0;
63 if (o instanceof Number) {
64 double d = ((Number) o).doubleValue();
65 // NOTE: d == d is a test for NaN. It should be faster than Double.isNaN()
66 return d != 0.0 && d == d;
68 if (o instanceof String) return ((String)o).length() != 0;
72 /** coerce an object to a Long */
73 public static long toLong(Object o) { return toNumber(o).longValue(); }
75 /** coerce an object to an Int */
76 public static int toInt(Object o) { return toNumber(o).intValue(); }
78 /** coerce an object to a Double */
79 public static double toDouble(Object o) { return toNumber(o).doubleValue(); }
81 /** coerce an object to a Number */
82 public static Number toNumber(Object o) {
83 if (o == null) return ZERO;
84 if (o instanceof Number) return ((Number)o);
86 // NOTE: There are about 3 pages of rules in ecma262 about string to number conversions
87 // We aren't even close to following all those rules. We probably never will be.
88 if (o instanceof String)
89 try { return N((String)o); } catch (NumberFormatException e) { return N(Double.NaN); }
90 if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? N(1) : ZERO;
91 if (o instanceof JS) return ((JS)o).coerceToNumber();
92 throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
95 /** coerce an object to a String */
96 public static String toString(Object o) {
97 if(o == null) return "null";
98 if(o instanceof String) return (String) o;
99 if(o instanceof Integer || o instanceof Long || o instanceof Boolean) return o.toString();
100 if(o instanceof JS) return ((JS)o).coerceToString();
101 if(o instanceof Double || o instanceof Float) {
102 double d = ((Number)o).doubleValue();
103 if((int)d == d) return Integer.toString((int)d);
110 // Instance Methods ////////////////////////////////////////////////////////////////////
112 public static final Integer ZERO = new Integer(0);
114 // this gets around a wierd fluke in the Java type checking rules for ?..:
115 public static final Object T = Boolean.TRUE;
116 public static final Object F = Boolean.FALSE;
118 public static final Boolean B(boolean b) { return b ? Boolean.TRUE : Boolean.FALSE; }
119 public static final Boolean B(int i) { return i==0 ? Boolean.FALSE : Boolean.TRUE; }
120 public static final Number N(String s) { return s.indexOf('.') == -1 ? N(Integer.parseInt(s)) : new Double(s); }
121 public static final Number N(double d) { return (int)d == d ? N((int)d) : new Double(d); }
122 public static final Number N(long l) { return N((int)l); }
124 private static final Integer[] smallIntCache = new Integer[65535 / 4];
125 private static final Integer[] largeIntCache = new Integer[65535 / 4];
126 public static final Number N(int i) {
128 int idx = i + smallIntCache.length / 2;
129 if (idx < smallIntCache.length && idx > 0) {
130 ret = smallIntCache[idx];
131 if (ret != null) return ret;
133 else ret = largeIntCache[Math.abs(idx % largeIntCache.length)];
134 if (ret == null || ret.intValue() != i) {
135 ret = new Integer(i);
136 if (idx < smallIntCache.length && idx > 0) smallIntCache[idx] = ret;
137 else largeIntCache[Math.abs(idx % largeIntCache.length)] = ret;
142 private static Enumeration emptyEnumeration = new Enumeration() {
143 public boolean hasMoreElements() { return false; }
144 public Object nextElement() { throw new NoSuchElementException(); }
147 private Hash entries = null;
148 public Enumeration keys() throws JSExn {
149 return entries == null ? emptyEnumeration : entries.keys();
151 public Object get(Object key) throws JSExn { return entries == null ? null : entries.get(key, null); }
152 public void put(Object key, Object val) throws JSExn {
153 if (entries == null) entries = new Hash();
154 entries.put(key, null, val);
158 // Trap support //////////////////////////////////////////////////////////////////////////////
160 /** override and return true to allow placing traps on this object.
161 * if isRead true, this is a read trap, otherwise write trap
163 protected boolean isTrappable(Object name, boolean isRead) { return true; }
165 /** performs a put, triggering traps if present; traps are run in an unpauseable interpreter */
166 public void putAndTriggerTraps(Object key, Object value) throws JSExn {
167 Trap t = getTrap(key);
168 if (t != null) t.invoke(value);
169 else put(key, value);
172 /** performs a get, triggering traps if present; traps are run in an unpauseable interpreter */
173 public Object getAndTriggerTraps(Object key) throws JSExn {
174 Trap t = getTrap(key);
175 if (t != null) return t.invoke();
176 else return get(key);
179 /** retrieve a trap from the entries hash */
180 protected final Trap getTrap(Object key) {
181 return entries == null ? null : (Trap)entries.get(key, Trap.class);
184 /** retrieve a trap from the entries hash */
185 protected final void putTrap(Object key, Trap value) {
186 if (entries == null) entries = new Hash();
187 entries.put(key, Trap.class, value);
190 /** adds a trap, avoiding duplicates */
191 protected final void addTrap(Object name, JSFunction f) throws JSExn {
192 if (f.numFormalArgs > 1) throw new JSExn("traps must take either one argument (write) or no arguments (read)");
193 boolean isRead = f.numFormalArgs == 0;
194 if (!isTrappable(name, isRead)) throw new JSExn("not allowed "+(isRead?"read":"write")+" trap on property: "+name);
195 for(Trap t = getTrap(name); t != null; t = t.next) if (t.f == f) return;
196 putTrap(name, new Trap(this, name.toString(), f, (Trap)getTrap(name)));
199 /** deletes a trap, if present */
200 protected final void delTrap(Object name, JSFunction f) {
201 Trap t = (Trap)getTrap(name);
202 if (t == null) return;
203 if (t.f == f) { putTrap(t.name, t.next); return; }
204 for(; t.next != null; t = t.next) if (t.next.f == f) { t.next = t.next.next; return; }
208 // Call Support //////////////////////////////////////////////////////////////////////////////
210 // return this from get() if the key was actually a method.
211 public static final Object METHOD = new Object();
212 public Object callMethod(Object method, Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
213 throw new JSExn("attempted to call the null value (method "+method+")");
215 public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
216 throw new JSExn("you cannot call this object (class=" + this.getClass().getName() +")");
220 // Typing Support //////////////////////////////////////////////////////////////////////////////
222 public Number coerceToNumber() { throw new JSRuntimeExn("tried to coerce a JavaScript object to a Number"); }
223 public String coerceToString() { throw new JSRuntimeExn("tried to coerce a JavaScript object to a String"); }
224 public boolean coerceToBoolean() { throw new JSRuntimeExn("tried to coerce a JavaScript object to a Boolean"); }
226 public String typeName() { return "object"; }