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); }
18 public static int getLine() {
19 Interpreter c = Interpreter.current();
20 return c == null || c.f == null || c.pc < 0 || c.pc >= c.f.size ? -1 : c.f.line[c.pc];
23 public static String getSourceName() {
24 Interpreter c = Interpreter.current();
25 return c == null || c.f == null ? null : c.f.sourceName;
28 public static class NotPauseableException extends Exception { NotPauseableException() { } }
30 /** returns a callback which will restart the context; expects a value to be pushed onto the stack when unpaused */
31 public static UnpauseCallback pause() throws NotPauseableException {
32 Interpreter i = Interpreter.current();
33 if (i.pausecount == -1) throw new NotPauseableException();
35 return new JS.UnpauseCallback(i);
38 public static class UnpauseCallback implements Scheduler.Task {
40 UnpauseCallback(Interpreter i) { this.i = i; }
41 public void perform() throws JSExn { unpause(null); }
42 public void unpause(Object o) throws JSExn {
43 // FIXME: if o instanceof JSExn, throw it into the JSworld
51 // Static Helper Methods ///////////////////////////////////////////////////////////////////////////////////
53 /** coerce an object to a Boolean */
54 public static boolean toBoolean(Object o) {
55 if (o == null) return false;
56 if (o instanceof Boolean) return ((Boolean)o).booleanValue();
57 if (o instanceof Long) return ((Long)o).longValue() != 0;
58 if (o instanceof Integer) return ((Integer)o).intValue() != 0;
59 if (o instanceof Number) {
60 double d = ((Number) o).doubleValue();
61 // NOTE: d == d is a test for NaN. It should be faster than Double.isNaN()
62 return d != 0.0 && d == d;
64 if (o instanceof String) return ((String)o).length() != 0;
68 /** coerce an object to a Long */
69 public static long toLong(Object o) { return toNumber(o).longValue(); }
71 /** coerce an object to an Int */
72 public static int toInt(Object o) { return toNumber(o).intValue(); }
74 /** coerce an object to a Double */
75 public static double toDouble(Object o) { return toNumber(o).doubleValue(); }
77 /** coerce an object to a Number */
78 public static Number toNumber(Object o) {
79 if (o == null) return ZERO;
80 if (o instanceof Number) return ((Number)o);
82 // NOTE: There are about 3 pages of rules in ecma262 about string to number conversions
83 // We aren't even close to following all those rules. We probably never will be.
84 if (o instanceof String)
85 try { return N((String)o); } catch (NumberFormatException e) { return N(Double.NaN); }
86 if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? N(1) : ZERO;
87 if (o instanceof JS) return ((JS)o).coerceToNumber();
88 throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
91 /** coerce an object to a String */
92 public static String toString(Object o) {
93 if(o == null) return "null";
94 if(o instanceof String) return (String) o;
95 if(o instanceof Integer || o instanceof Long || o instanceof Boolean) return o.toString();
96 if(o instanceof JS) return ((JS)o).coerceToString();
97 if(o instanceof Double || o instanceof Float) {
98 double d = ((Number)o).doubleValue();
99 if((int)d == d) return Integer.toString((int)d);
106 // Instance Methods ////////////////////////////////////////////////////////////////////
108 public static final Integer ZERO = new Integer(0);
110 // this gets around a wierd fluke in the Java type checking rules for ?..:
111 public static final Object T = Boolean.TRUE;
112 public static final Object F = Boolean.FALSE;
114 public static final Boolean B(boolean b) { return b ? Boolean.TRUE : Boolean.FALSE; }
115 public static final Boolean B(int i) { return i==0 ? Boolean.FALSE : Boolean.TRUE; }
116 public static final Number N(String s) { return s.indexOf('.') == -1 ? N(Integer.parseInt(s)) : new Double(s); }
117 public static final Number N(double d) { return (int)d == d ? N((int)d) : new Double(d); }
118 public static final Number N(long l) { return N((int)l); }
120 private static final Integer[] smallIntCache = new Integer[65535 / 4];
121 private static final Integer[] largeIntCache = new Integer[65535 / 4];
122 public static final Number N(int i) {
124 int idx = i + smallIntCache.length / 2;
125 if (idx < smallIntCache.length && idx > 0) {
126 ret = smallIntCache[idx];
127 if (ret != null) return ret;
129 else ret = largeIntCache[Math.abs(idx % largeIntCache.length)];
130 if (ret == null || ret.intValue() != i) {
131 ret = new Integer(i);
132 if (idx < smallIntCache.length && idx > 0) smallIntCache[idx] = ret;
133 else largeIntCache[Math.abs(idx % largeIntCache.length)] = ret;
138 private static Enumeration emptyEnumeration = new Enumeration() {
139 public boolean hasMoreElements() { return false; }
140 public Object nextElement() { throw new NoSuchElementException(); }
143 private Hash entries = null;
144 public Enumeration keys() throws JSExn {
145 return entries == null ? emptyEnumeration : entries.keys();
147 public Object get(Object key) throws JSExn { return entries == null ? null : entries.get(key, null); }
148 public void put(Object key, Object val) throws JSExn {
149 if (entries == null) entries = new Hash();
150 entries.put(key, null, val);
154 // Trap support //////////////////////////////////////////////////////////////////////////////
156 /** override and return true to allow placing traps on this object.
157 * if isRead true, this is a read trap, otherwise write trap
159 protected boolean isTrappable(Object name, boolean isRead) { return false; }
161 /** performs a put, triggering traps if present; traps are run in an unpauseable interpreter */
162 public void putAndTriggerTraps(Object key, Object value) throws JSExn {
163 Trap t = getTrap(key);
164 if (t != null) t.invoke(value);
165 else put(key, value);
168 /** performs a get, triggering traps if present; traps are run in an unpauseable interpreter */
169 public Object getAndTriggerTraps(Object key) throws JSExn {
170 Trap t = getTrap(key);
171 if (t != null) return t.invoke();
172 else return get(key);
175 /** retrieve a trap from the entries hash */
176 protected final Trap getTrap(Object key) {
177 return entries == null ? null : (Trap)entries.get(key, Trap.class);
180 /** retrieve a trap from the entries hash */
181 protected final void putTrap(Object key, Trap value) {
182 if (entries == null) entries = new Hash();
183 entries.put(key, Trap.class, value);
186 /** adds a trap, avoiding duplicates */
187 protected final void addTrap(Object name, JSFunction f) throws JSExn {
188 if (f.numFormalArgs > 1) throw new JSExn("traps must take either one argument (write) or no arguments (read)");
189 boolean isRead = f.numFormalArgs == 0;
190 if (!isTrappable(name, isRead)) throw new JSExn("not allowed "+(isRead?"read":"write")+" trap on property: "+name);
191 for(Trap t = getTrap(name); t != null; t = t.next) if (t.f == f) return;
192 putTrap(name, new Trap(this, name.toString(), f, (Trap)getTrap(name)));
195 /** deletes a trap, if present */
196 protected final void delTrap(Object name, JSFunction f) {
197 Trap t = (Trap)getTrap(name);
198 if (t == null) return;
199 if (t.f == f) { putTrap(t.name, t.next); return; }
200 for(; t.next != null; t = t.next) if (t.next.f == f) { t.next = t.next.next; return; }
204 // Call Support //////////////////////////////////////////////////////////////////////////////
206 // return this from get() if the key was actually a method.
207 public static final Object METHOD = new Object();
208 public Object callMethod(Object method, Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
209 throw new JSExn("attempted to call the null value (method "+method+")");
211 public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) throws JSExn {
212 throw new JSExn("you cannot call this object (class=" + this.getClass().getName() +")");
216 // Typing Support //////////////////////////////////////////////////////////////////////////////
218 public Number coerceToNumber() { throw new JSRuntimeExn("tried to coerce a JavaScript object to a Number"); }
219 public String coerceToString() { throw new JSRuntimeExn("tried to coerce a JavaScript object to a String"); }
220 public boolean coerceToBoolean() { throw new JSRuntimeExn("tried to coerce a JavaScript object to a Boolean"); }
222 public String typeName() { return "object"; }