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 {
18 // Public Helper Methods //////////////////////////////////////////////////////////////////////
20 /** parse and compile a function */
21 public static CompiledFunction parse(String sourceName, int firstLine, Reader sourceCode) throws IOException {
22 return new CompiledFunction(sourceName, firstLine, sourceCode, null);
25 /** coerce an object to a Boolean */
26 public static boolean toBoolean(Object o) {
27 if (o == null) return false;
28 if (o instanceof Boolean) return ((Boolean)o).booleanValue();
29 if (o instanceof Number) return o.equals(new Integer(0));
33 /** coerce an object to a Long */
34 public static long toLong(Object o) { return toNumber(o).longValue(); }
36 /** coerce an object to a Double */
37 public static double toDouble(Object o) { return toNumber(o).doubleValue(); }
39 /** coerce an object to a Number */
40 public static Number toNumber(Object o) {
41 if (o == null) return new Long(0);
42 if (o instanceof Number) return ((Number)o);
43 if (o instanceof String) try { return new Double((String)o); } catch (NumberFormatException e) { return new Double(0); }
44 if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? new Long(1) : new Long(0);
45 if (o instanceof JS) return ((JS)o).coerceToNumber();
46 throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
50 // Instance Methods ////////////////////////////////////////////////////////////////////
52 public abstract Object get(Object key) throws JS.Exn;
53 public abstract void put(Object key, Object val) throws JS.Exn;
54 public abstract Object[] keys();
56 public Number coerceToNumber() { throw new Error("you cannot coerce a " + this.getClass().getName() + " into a Number"); }
57 public String coerceToString() { throw new Error("you cannot coerce a " + this.getClass().getName() + " into a String"); }
58 public boolean coerceToBoolean() { throw new Error("you cannot coerce a " + this.getClass().getName() + " into a Boolean"); }
61 // Inner Classes /////////////////////////////////////////////////////////////////////////
63 /** A sensible implementation of the abstract methods in the JS class */
64 public static class Obj extends JS {
65 private Hash entries = new Hash();
66 private boolean sealed = false;
67 public Obj() { this(false); }
68 public Obj(boolean sealed) { this.sealed = sealed; }
69 public void setSeal(boolean sealed) { this.sealed = sealed; }
70 public Object get(Object key) { return entries.get(key); }
71 public void put(Object key, Object val) { if (!sealed) entries.put(key, val); }
72 public Object[] keys() { return(entries.keys()); }
75 /** An exception which can be thrown and caught by JavaScript code */
76 public static class Exn extends RuntimeException {
77 private Object js = null;
78 public Exn(Object js) { this.js = js; }
79 public String toString() { return "JS.Exn: " + js; }
80 public String getMessage() { return toString(); }
81 public Object getObject() { return js; }
84 /** The publicly-visible face of JavaScript Array objects */
85 public static class Array extends ArrayImpl {
87 public Array(int size) { super(size); }
88 public void setSize(int i) { super.setSize(i); }
89 public int length() { return super.length(); }
90 public Object elementAt(int i) { return super.elementAt(i); }
91 public void addElement(Object o) { super.addElement(o); }
92 public void setElementAt(Object o, int i) { super.setElementAt(o, i); }
95 /** Any object which becomes part of the scope chain must support this interface */
96 public static class Scope extends ScopeImpl {
97 public Scope(Scope parentScope) { this(parentScope, false); }
98 public Scope(Scope parentScope, boolean sealed) { super(parentScope, sealed); }
99 public Scope getParentScope() { return super.getParentScope(); }
100 public boolean isTransparent() { return super.isTransparent(); }
101 public boolean has(Object key) { return super.has(key); }
102 public void declare(String s) { super.declare(s); }
105 /** anything that is callable with the () operator */
106 public static abstract class Callable extends JS.Obj {
107 public abstract Object call(JS.Array args) throws JS.Exn;
110 /** a Callable which was compiled from JavaScript code */
111 public static class CompiledFunction extends CompiledFunctionImpl {
112 public Object call(JS.Array args, JS.Scope scope) throws JS.Exn { return super.call(args, scope); }
113 CompiledFunction(String sourceName, int firstLine, Reader sourceCode, Scope scope) throws IOException {
114 super(sourceName, firstLine, sourceCode, scope);