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. The static
13 * methods, fields, and inner classes of JS define the publicly
14 * visible API for the XWT JavaScript engine; code outside this
15 * package should never depend on anything not defined in this file.
17 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);
55 // NOTE: There are about 3 pages of rules in ecma262 about string to number conversions
56 // We aren't even close to following all those rules. We probably never will be.
57 if (o instanceof String) try { return new Double((String)o); } catch (NumberFormatException e) { return new Double(Double.NaN); }
58 if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? new Long(1) : new Long(0);
59 if (o instanceof JS) return ((JS)o).coerceToNumber();
60 throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
63 /** coerce an object to a String */
64 public static String toString(Object o) {
65 if(o == null) return "null";
66 if(o instanceof String) return (String) o;
67 if(o instanceof Integer || o instanceof Long || o instanceof Boolean) return o.toString();
68 if(o instanceof JS) return ((JS)o).coerceToString();
69 if(o instanceof Double || o instanceof Float) {
70 double d = ((Number)o).doubleValue();
71 if((int)d == d) return Integer.toString((int)d);
77 // Instance Methods ////////////////////////////////////////////////////////////////////
79 public abstract Object get(Object key) throws JS.Exn;
80 public abstract Object put(Object key, Object val) throws JS.Exn;
81 public abstract Object[] keys();
82 public Object callMethod(Object method, Array args, boolean checkOnly) throws JS.Exn {
83 if (checkOnly) return Boolean.FALSE;
84 Object o = get(method);
85 if(o instanceof JS.Callable) {
86 return ((JS.Callable)o).call(args);
87 } else if(o == null) {
88 throw new JS.Exn("Attempted to call non-existent method: " + method);
90 throw new JS.Exn("Attempted to call a non-method: " +method);
94 public Number coerceToNumber() { return new Integer(0); }
95 public String coerceToString() { throw new JS.Exn("tried to coerce a JavaScript object to a String"); }
96 public boolean coerceToBoolean() { return true; }
98 public String typeName() { return "object"; }
101 // Inner Classes /////////////////////////////////////////////////////////////////////////
103 /** A sensible implementation of the abstract methods in the JS class */
104 public static class Obj extends JS {
105 private Hash entries = null;
106 private boolean sealed = false;
107 public Obj() { this(false); }
108 public Obj(boolean sealed) { this.sealed = sealed; }
109 public void setSeal(boolean sealed) { this.sealed = sealed; } ///< a sealed object cannot have its properties modified
110 public Object put(Object key, Object val) { put2(key, null, val); return null; }
111 protected void put2(Object key, Object key2, Object val) {
113 if (entries == null) entries = new Hash();
114 entries.put(key, key2, val); }
115 public Object[] keys() { return entries == null ? new Object[0] : entries.keys(); }
116 public Object get(Object key) { return get(key, null); }
117 protected Object get(Object key, Object key2) {
118 if (entries == null) return null;
119 if(key2 == null && callMethod((String)key, null, true) == Boolean.TRUE)
120 return new Internal.CallableStub(this, key);
121 return entries.get(key, key2);
125 /** An exception which can be thrown and caught by JavaScript code */
126 public static class Exn extends RuntimeException {
127 private Object js = null;
128 public Exn(Object js) { this.js = js; }
129 public String toString() { return "JS.Exn: " + js; }
130 public String getMessage() { return toString(); }
131 public Object getObject() { return js; }
134 /** The publicly-visible face of JavaScript Array objects */
135 public static class Array extends ArrayImpl {
137 public Array(int size) { super(size); }
138 public void setSize(int i) { super.setSize(i); }
139 public int length() { return super.length(); }
140 public Object elementAt(int i) { return super.elementAt(i); }
141 public void addElement(Object o) { super.addElement(o); }
142 public void setElementAt(Object o, int i) { super.setElementAt(o, i); }
143 public Object get(Object key) { return super._get(key); }
144 public Object put(Object key, Object val) { super._put(key, val); return null; }
147 /** Any object which becomes part of the scope chain must support this interface */
148 public static class Scope extends ScopeImpl {
149 public Scope(Scope parentScope) { this(parentScope, false); }
150 public Scope(Scope parentScope, boolean sealed) { super(parentScope, sealed); }
151 /** transparent scopes are not returned by THIS */
152 public boolean isTransparent() { return super.isTransparent(); }
153 public boolean has(Object key) { return super.has(key); }
154 public Object get(Object key) { return super._get(key); }
155 public Object put(Object key, Object val) { super._put(key, val); return null; }
156 public void declare(String s) { super.declare(s); }
159 /** the result of a graft */
160 public static class Graft extends JS {
162 private Object replaced_key;
163 private Object replaced_val;
164 public Graft(JS graftee, Object key, Object val) {
165 if (graftee instanceof Array) throw new JS.Exn("can't graft onto Arrays (yet)");
166 if (graftee instanceof Callable) throw new JS.Exn("can't graft onto Callables (yet)");
167 if (graftee instanceof Scope) throw new JS.Exn("can't graft onto Scopes (yet)");
168 this.graftee = graftee;
172 public boolean equals(Object o) { return (this == o || graftee.equals(o)); }
173 public int hashCode() { return graftee.hashCode(); }
174 public Object get(Object key) { return replaced_key.equals(key) ? replaced_val : graftee.get(key); }
175 public Object put(Object key, Object val) { graftee.put(key, val); return null; }
176 public Object callMethod(Object method, Array args, boolean checkOnly) throws JS.Exn {
177 if (!replaced_key.equals(method)) return graftee.callMethod(method, args, checkOnly);
178 if (replaced_val instanceof Callable) return checkOnly ? Boolean.TRUE : ((Callable)replaced_val).call(args);
179 if (checkOnly) return Boolean.FALSE;
180 throw new JS.Exn("attempt to call non-function");
182 public Number coerceToNumber() { return graftee.coerceToNumber(); }
183 public String coerceToString() { return graftee.coerceToString(); }
184 public boolean coerceToBoolean() { return graftee.coerceToBoolean(); }
185 public String typeName() { return graftee.typeName(); }
186 public Object[] keys() {
187 Object[] ret = graftee.keys();
188 for(int i=0; i<ret.length; i++) if (replaced_key.equals(ret[i])) return ret;
189 Object[] ret2 = new Object[ret.length + 1];
190 System.arraycopy(ret, 0, ret2, 0, ret.length);
191 ret2[ret2.length - 1] = replaced_key;
196 /** anything that is callable with the () operator */
197 public static abstract class Callable extends JS.Obj {
198 public abstract Object call(JS.Array args) throws JS.Exn;
201 /** a Callable which was compiled from JavaScript code */
202 public static class CompiledFunction extends CompiledFunctionImpl {
203 public int getNumFormalArgs() { return numFormalArgs; }
204 CompiledFunction(String sourceName, int firstLine, Reader sourceCode, Scope scope) throws IOException {
205 super(sourceName, firstLine, sourceCode, scope);
209 /** a scope that is populated with js objects and functions normally found in the global scope */
210 public static class GlobalScope extends GlobalScopeImpl {
211 public GlobalScope() { this(null); }
212 public GlobalScope(JS.Scope parent) { super(parent); }
215 public static final JS Math = new org.xwt.js.Math();
217 public static class TailCall {
218 CompiledFunction func = null;
219 JS.Array args = null;
220 public TailCall() { }
221 public TailCall set(CompiledFunction func) { this.func = func; this.args = new JS.Array(); return this; }
222 public TailCall set(CompiledFunction func, JS.Array args) { this.func = func; this.args = args; return this; }
225 /** encapsulates a single JavaScript thread; the JS.Context->java.lang.Thread mapping is 1:1 */
226 public static class Context {
228 CompiledFunction f = null;
229 Vec stack = new Vec();
230 public Scope scope = null;
233 /** return this to signal a pause */
234 public static Object pause = new Object();
236 public static int getLine() { return current().f == null ? -1 : current().f.getLine(current()); }
237 public static String getSourceName() { return current().f == null ? null : current().f.getSourceName(); }
239 public Context(CompiledFunction function, Scope scope, JS.Array args) {
240 if (scope == null) scope = new CompiledFunctionImpl.FunctionScope("unknown", function.parentScope);
241 if (args == null) args = new JS.Array();
242 stack.push(new CompiledFunctionImpl.CallMarker(this));
248 public Object resume(Object o) {
250 javaContextToJSContext.put(Thread.currentThread(), this);
251 return CompiledFunctionImpl.eval(this, o);
253 javaContextToJSContext.remove(Thread.currentThread());
257 /** fetches the currently-executing javascript function */
258 public static JS.Context current() { return (JS.Context)javaContextToJSContext.get(Thread.currentThread()); }
259 private static Hashtable javaContextToJSContext = new Hashtable();