1 // Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
10 * The public API for the JS engine. JS itself is actually a class
11 * implementing the absolute minimal amount of functionality for an
12 * Object which can be manipulated by JavaScript code.
14 public abstract class JS {
16 // Public Helper Methods //////////////////////////////////////////////////////////////////////
18 /** parse and compile a function */
19 public static JSFunction parse(String sourceName, int firstLine, Reader sourceCode) throws IOException {
20 return new JSFunction(sourceName, firstLine, sourceCode, null);
23 /** coerce an object to a Boolean */
24 public static boolean toBoolean(Object o) {
25 if (o == null) return false;
26 if (o instanceof Boolean) return ((Boolean)o).booleanValue();
27 if (o instanceof Long) return ((Long)o).longValue() != 0;
28 if (o instanceof Integer) return ((Integer)o).intValue() != 0;
29 if (o instanceof Number) {
30 double d = ((Number) o).doubleValue();
31 // NOTE: d == d is a test for NaN. It should be faster than Double.isNaN()
32 return d != 0.0 && d == d;
34 if (o instanceof String) return ((String)o).length() != 0;
38 /** coerce an object to a Long */
39 public static long toLong(Object o) { return toNumber(o).longValue(); }
41 /** coerce an object to an Int */
42 public static int toInt(Object o) { return toNumber(o).intValue(); }
44 /** coerce an object to a Double */
45 public static double toDouble(Object o) { return toNumber(o).doubleValue(); }
47 /** coerce an object to a Number */
48 public static Number toNumber(Object o) {
49 if (o == null) return new Long(0);
50 if (o instanceof Number) return ((Number)o);
52 // NOTE: There are about 3 pages of rules in ecma262 about string to number conversions
53 // We aren't even close to following all those rules. We probably never will be.
54 if (o instanceof String)
55 try { return new Double((String)o); } catch (NumberFormatException e) { return new Double(Double.NaN); }
56 if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? new Long(1) : new Long(0);
57 if (o instanceof JS) return ((JS)o).coerceToNumber();
58 throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
61 /** coerce an object to a String */
62 public static String toString(Object o) {
63 if(o == null) return "null";
64 if(o instanceof String) return (String) o;
65 if(o instanceof Integer || o instanceof Long || o instanceof Boolean) return o.toString();
66 if(o instanceof JS) return ((JS)o).coerceToString();
67 if(o instanceof Double || o instanceof Float) {
68 double d = ((Number)o).doubleValue();
69 if((int)d == d) return Integer.toString((int)d);
75 // Instance Methods ////////////////////////////////////////////////////////////////////
77 public abstract Object get(Object key) throws JS.Exn;
78 public void put(Object key, Object val) throws JS.Exn { throw new JS.Exn("you cannot put to this object"); }
80 public Enumeration keys() { throw new Error("you cannot apply for..in to a " + this.getClass().getName()); }
82 public Number coerceToNumber() { throw new JS.Exn("tried to coerce a JavaScript object to a Number"); }
83 public String coerceToString() { throw new JS.Exn("tried to coerce a JavaScript object to a String"); }
84 public boolean coerceToBoolean() { throw new JS.Exn("tried to coerce a JavaScript object to a Boolean"); }
86 public String typeName() { return "object"; }
89 // Inner Classes /////////////////////////////////////////////////////////////////////////
91 /** An exception which can be thrown and caught by JavaScript code */
92 public static class Exn extends RuntimeException {
93 private Object js = null;
94 public Exn(Object js) { this.js = js; }
95 public String toString() { return "JS.Exn: " + js; }
96 public String getMessage() { return toString(); }
97 public Object getObject() { return js; }
100 /** the result of a graft */
101 public static class Graft extends JSCallable {
103 private Object replaced_key;
104 private Object replaced_val;
105 public Graft(Object graftee, Object key, Object val) {
106 if (graftee instanceof JSArray) throw new JS.Exn("can't graft onto JSArrays (yet)");
107 if (graftee instanceof JSCallable) throw new JS.Exn("can't graft onto JSCallables (yet)");
108 if (graftee instanceof JSScope) throw new JS.Exn("can't graft onto JSScopes (yet)");
109 this.graftee = (JS)graftee;
113 public boolean equals(Object o) { return (this == o || graftee.equals(o)); }
114 public int hashCode() { return graftee.hashCode(); }
115 public Object get(Object key) { return replaced_key.equals(key) ? replaced_val : graftee.get(key); }
116 public void put(Object key, Object val) { graftee.put(key, val); }
117 public Object call(Object method, JSArray args) {
118 if (replaced_key.equals(method)) return ((JSCallable)replaced_val).call(null, args);
119 else if (graftee instanceof JSCallable) return ((JSCallable)graftee).call(method, args);
120 else throw new JS.Exn("cannot call this value");
122 public Number coerceToNumber() { return graftee.coerceToNumber(); }
123 public String coerceToString() { return graftee.coerceToString(); }
124 public boolean coerceToBoolean() { return graftee.coerceToBoolean(); }
125 public String typeName() { return graftee.typeName(); }
126 public Enumeration keys() {
127 return new Enumeration() {
128 Enumeration graftee_enumeration = graftee.keys();
129 boolean returned_replaced = false;
130 public boolean hasMoreElements() {
131 if (graftee_enumeration.hasMoreElements()) return true;
132 return !returned_replaced;
134 public Object nextElement() {
135 if (!graftee_enumeration.hasMoreElements()) {
136 if (returned_replaced) throw new NoSuchElementException();
137 returned_replaced = true;
140 Object ret = graftee_enumeration.nextElement();
141 if (!returned_replaced && ret.equals(replaced_key)) returned_replaced = true;