1 // Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
9 * The public API for the JS engine. JS itself is actually a class
10 * implementing the absolute minimal amount of functionality for an
11 * Object which can be manipulated by JavaScript code. The static
12 * methods, fields, and inner classes of JS define the publicly
13 * visible API for the XWT JavaScript engine; code outside this
14 * package should never depend on anything not defined in this file.
16 public abstract class JS {
19 // Public Helper Methods //////////////////////////////////////////////////////////////////////
21 /** parse and compile a function */
22 public static CompiledFunction parse(String sourceName, int firstLine, Reader sourceCode) throws IOException {
23 return new CompiledFunction(sourceName, firstLine, sourceCode, null);
26 /** coerce an object to a Boolean */
27 public static boolean toBoolean(Object o) {
28 if (o == null) return false;
29 if (o instanceof Boolean) return ((Boolean)o).booleanValue();
30 if (o instanceof Long) return ((Long)o).longValue() != 0;
31 if (o instanceof Integer) return ((Integer)o).intValue() != 0;
32 if (o instanceof Number) {
33 double d = ((Number) o).doubleValue();
34 // NOTE: d == d is a test for NaN. It should be faster than Double.isNaN()
35 return d != 0.0 && d == d;
37 if (o instanceof String) return ((String)o).length() != 0;
41 /** coerce an object to a Long */
42 public static long toLong(Object o) { return toNumber(o).longValue(); }
44 /** coerce an object to an Int */
45 public static int toInt(Object o) { return toNumber(o).intValue(); }
47 /** coerce an object to a Double */
48 public static double toDouble(Object o) { return toNumber(o).doubleValue(); }
50 /** coerce an object to a Number */
51 public static Number toNumber(Object o) {
52 if (o == null) return new Long(0);
53 if (o instanceof Number) return ((Number)o);
54 // FIXME: There are about 3 pages of rules in ecma262 about string to number conversions
55 // We aren't even close to following all those rules
56 if (o instanceof String) try { return new Double((String)o); } catch (NumberFormatException e) { return new Double(Double.NaN); }
57 if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? new Long(1) : new Long(0);
58 if (o instanceof JS) return ((JS)o).coerceToNumber();
59 throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
62 // Instance Methods ////////////////////////////////////////////////////////////////////
64 public abstract Object get(Object key) throws JS.Exn;
65 public abstract void put(Object key, Object val) throws JS.Exn;
66 public abstract Object[] keys();
67 public abstract Object callMethod(Object method, JS.Array args, boolean justChecking);
69 public Number coerceToNumber() { throw new Error("you cannot coerce a " + this.getClass().getName() + " into a Number"); }
70 public String coerceToString() { throw new Error("you cannot coerce a " + this.getClass().getName() + " into a String"); }
71 public boolean coerceToBoolean() { throw new Error("you cannot coerce a " + this.getClass().getName() + " into a Boolean"); }
73 public String typeName() { return "object"; }
76 // Inner Classes /////////////////////////////////////////////////////////////////////////
78 /** A sensible implementation of the abstract methods in the JS class */
79 public static class Obj extends JS {
80 private Hash entries = new Hash();
81 private boolean sealed = false;
82 public Obj() { this(false); }
83 public Obj(boolean sealed) { this.sealed = sealed; }
84 /** a sealed object cannot have its properties modified */
85 public void setSeal(boolean sealed) { this.sealed = sealed; }
86 public void put(Object key, Object val) { if (!sealed) entries.put(key, val); }
87 public Object[] keys() { return(entries.keys()); }
88 public Object get(Object key) {
89 if(callMethod((String)key,null,true) == Boolean.TRUE)
90 return new Internal.CallableStub(this,key);
91 return entries.get(key);
93 public Object callMethod(Object method, JS.Array args, boolean checkOnly) throws JS.Exn {
94 if(checkOnly) return Boolean.FALSE;
95 Object o = get(method);
96 if(o instanceof JS.Callable) {
97 return ((JS.Callable)o).call(args);
98 } else if(o == null) {
99 throw new JS.Exn("Attempted to call non-existent method: " + method);
101 throw new JS.Exn("Attempted to call a non-method: " +method);
106 /** An exception which can be thrown and caught by JavaScript code */
107 public static class Exn extends RuntimeException {
108 private Object js = null;
109 public Exn(Object js) { this.js = js; }
110 public String toString() { return "JS.Exn: " + js; }
111 public String getMessage() { return toString(); }
112 public Object getObject() { return js; }
115 /** The publicly-visible face of JavaScript Array objects */
116 public static class Array extends ArrayImpl {
118 public Array(int size) { super(size); }
119 public void setSize(int i) { super.setSize(i); }
120 public int length() { return super.length(); }
121 public Object elementAt(int i) { return super.elementAt(i); }
122 public void addElement(Object o) { super.addElement(o); }
123 public void setElementAt(Object o, int i) { super.setElementAt(o, i); }
124 public Object get(Object key) { return super._get(key); }
125 public void put(Object key, Object val) { super._put(key, val); }
128 /** Any object which becomes part of the scope chain must support this interface */
129 public static class Scope extends ScopeImpl {
130 public Scope(Scope parentScope) { this(parentScope, false); }
131 public Scope(Scope parentScope, boolean sealed) { super(parentScope, sealed); }
132 /** transparent scopes are not returned by THIS */
133 public boolean isTransparent() { return super.isTransparent(); }
134 public boolean has(Object key) { return super.has(key); }
135 public Object get(Object key) { return super._get(key); }
136 public void put(Object key, Object val) { super._put(key, val); }
137 public void declare(String s) { super.declare(s); }
140 /** anything that is callable with the () operator */
141 public static abstract class Callable extends JS.Obj {
142 public abstract Object call(JS.Array args) throws JS.Exn;
145 /** a Callable which was compiled from JavaScript code */
146 public static class CompiledFunction extends CompiledFunctionImpl {
147 CompiledFunction(String sourceName, int firstLine, Reader sourceCode, Scope scope) throws IOException {
148 super(sourceName, firstLine, sourceCode, scope);
152 public static final JS Math = new org.xwt.js.Math();
154 /** encapsulates a single JavaScript thread; the JS.Thread->java.lang.Thread mapping is 1:1 */
155 public static class Thread {
157 CompiledFunction currentCompiledFunction = null;
158 Vec stack = new Vec();
161 /** binds this thread to the current Java Thread */
162 public void bindToCurrentJavaThread() { javaThreadToJSThread.put(java.lang.Thread.currentThread(), this); }
164 /** returns the line of code that is currently executing */
165 public int getLine() { return currentCompiledFunction == null ? -1 : currentCompiledFunction.getLine(pc); }
167 /** returns the name of the source code file which declared the currently executing function */
168 public String getSourceName() { return currentCompiledFunction == null ? null : currentCompiledFunction.getSourceName(); }
170 /** fetches the currently-executing javascript function */
171 public JS.CompiledFunction getCurrentCompiledFunction() { return currentCompiledFunction; }
174 // Statics ///////////////////////////////////////////////////////////////////////
176 private static Hashtable javaThreadToJSThread = new Hashtable();
178 /** returns the JS thread for a given Java thread, creating one if necessary */
179 public static JS.Thread fromJavaThread(java.lang.Thread t) {
180 JS.Thread ret = (JS.Thread)javaThreadToJSThread.get(t);
182 ret = new JS.Thread();
183 ret.bindToCurrentJavaThread();
188 public static JS.Thread currentJSThread() {
189 return fromJavaThread(java.lang.Thread.currentThread());