// Copyright 2003 Adam Megacz, see the COPYING file for licensing [GPL]
-
package org.xwt.js;
+
import org.xwt.util.*;
import org.xwt.*;
import java.io.*;
import java.util.*;
-/**
- * The public API for the JS engine. JS itself is actually a class
- * implementing the absolute minimal amount of functionality for an
- * Object which can be manipulated by JavaScript code. The static
- * methods, fields, and inner classes of JS define the publicly
- * visible API for the XWT JavaScript engine; code outside this
- * package should never depend on anything not defined in this file.
- */
-public abstract class JS {
-
- // Public Helper Methods //////////////////////////////////////////////////////////////////////
-
- /** parse and compile a function */
- public static Function parse(String sourceName, int firstLine, Reader sourceCode) throws IOException {
- return new Function(sourceName, firstLine, sourceCode, null);
+/** The minimum set of functionality required for objects which are manipulated by JavaScript */
+public class JS {
+
+ // Static Interpreter Control Methods ///////////////////////////////////////////////////////////////
+
+ public static int getLine() {
+ Interpreter c = Interpreter.current();
+ return c.f == null || c.pc < 0 || c.pc >= c.f.size ? -1 : c.f.line[c.pc];
}
+ public static String getSourceName() {
+ Interpreter c = Interpreter.current();
+ return c.f == null ? null : c.f.sourceName;
+ }
+
+ public static class PausedException extends Exception { PausedException() { } }
+
+ public static void invokePauseable(JSFunction function) throws JS.PausedException {
+ Interpreter i = new Interpreter(function, true, new JSArray());
+ int oldpausecount = i.pausecount;
+ i.resume();
+ if (i.pausecount > oldpausecount) throw new PausedException();
+ }
+
+ public static class NotPauseableException extends Exception { NotPauseableException() { } }
+
+ /** returns a callback which will restart the context; expects a value to be pushed onto the stack when unpaused */
+ public static UnpauseCallback pause() throws NotPauseableException {
+ Interpreter i = Interpreter.current();
+ if (i.pausecount == -1) throw new NotPauseableException();
+ i.pausecount++;
+ return new JS.UnpauseCallback(i);
+ }
+
+ public static class UnpauseCallback {
+ Interpreter i;
+ UnpauseCallback(Interpreter i) { this.i = i; }
+ public void unpause(Object o) throws PausedException {
+ i.stack.push(o);
+ i.resume();
+ }
+ }
+
+
+
+ // Static Helper Methods ///////////////////////////////////////////////////////////////////////////////////
+
/** coerce an object to a Boolean */
public static boolean toBoolean(Object o) {
if (o == null) return false;
/** coerce an object to a Number */
public static Number toNumber(Object o) {
- if (o == null) return new Long(0);
+ if (o == null) return ZERO;
if (o instanceof Number) return ((Number)o);
// NOTE: There are about 3 pages of rules in ecma262 about string to number conversions
// We aren't even close to following all those rules. We probably never will be.
if (o instanceof String)
- try { return new Double((String)o); } catch (NumberFormatException e) { return new Double(Double.NaN); }
- if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? new Long(1) : new Long(0);
+ try { return N((String)o); } catch (NumberFormatException e) { return N(Double.NaN); }
+ if (o instanceof Boolean) return ((Boolean)o).booleanValue() ? N(1) : ZERO;
if (o instanceof JS) return ((JS)o).coerceToNumber();
throw new Error("toNumber() got object of type " + o.getClass().getName() + " which we don't know how to handle");
}
-
+
/** coerce an object to a String */
public static String toString(Object o) {
if(o == null) return "null";
}
return o.toString();
}
+
// Instance Methods ////////////////////////////////////////////////////////////////////
+
+ public static final Integer ZERO = new Integer(0);
- public abstract Object get(Object key) throws JS.Exn;
- public abstract Object put(Object key, Object val) throws JS.Exn;
- public abstract Object[] keys();
- public Object callMethod(Object method, Array args, boolean checkOnly) throws JS.Exn {
- if (checkOnly) return Boolean.FALSE;
- Object o = get(method);
- if (o instanceof JS.Callable) return ((JS.Callable)o).call(args);
- else if (o == null) throw new JS.Exn("Attempted to call non-existent method: " + method);
- else throw new JS.Exn("Attempted to call a non-function: " +method);
- }
+ // this gets around a wierd fluke in the Java type checking rules for ?..:
+ public static final Object T = Boolean.TRUE;
+ public static final Object F = Boolean.FALSE;
+
+ public static final Number N(int i) { return new Integer(i); }
+ public static final Number N(long l) { return new Long(l); }
+ public static final Number N(double d) { return new Double(d); }
+ public static final Number N(String s) { return new Double(s); }
+ public static final Boolean B(boolean b) { return b ? Boolean.TRUE : Boolean.FALSE; }
+ public static final Boolean B(int i) { return i==0 ? Boolean.FALSE : Boolean.TRUE; }
- public Number coerceToNumber() { throw new JS.Exn("tried to coerce a JavaScript object to a Number"); }
- public String coerceToString() { throw new JS.Exn("tried to coerce a JavaScript object to a String"); }
- public boolean coerceToBoolean() { throw new JS.Exn("tried to coerce a JavaScript object to a Boolean"); }
- public String typeName() { return "object"; }
+ private static Enumeration emptyEnumeration = new Enumeration() {
+ public boolean hasMoreElements() { return false; }
+ public Object nextElement() { throw new NoSuchElementException(); }
+ };
+
+ private Hash entries = null;
+ public Enumeration keys() { return entries == null ? emptyEnumeration : entries.keys(); }
+ public Object get(Object key) { return entries == null ? null : entries.get(key, null); }
+ public void put(Object key, Object val) { if (entries == null) entries = new Hash(); entries.put(key, null, val); }
- // Inner Classes /////////////////////////////////////////////////////////////////////////
-
- /** A sensible implementation of the abstract methods in the JS class */
- public static class Obj extends JS {
- private Hash entries = null;
- private boolean sealed = false;
- public Obj() { this(false); }
- public Obj(boolean sealed) { this.sealed = sealed; }
- public void setSeal(boolean sealed) { this.sealed = sealed; } ///< a sealed object cannot have its properties modified
- public Object put(Object key, Object val) { put2(key, null, val); return null; }
- protected void put2(Object key, Object key2, Object val) {
- if (sealed) return;
- if (entries == null) entries = new Hash();
- entries.put(key, key2, val); }
- public Object[] keys() { return entries == null ? new Object[0] : entries.keys(); }
- public Object get(Object key) { return get(key, null); }
- protected Object get(Object key, Object key2) {
- if (entries == null) return null;
- if(key2 == null && callMethod((String)key, null, true) == Boolean.TRUE)
- return new Internal.CallableStub(this, key);
- return entries.get(key, key2);
- }
- }
+ // Trap support //////////////////////////////////////////////////////////////////////////////
- /** An exception which can be thrown and caught by JavaScript code */
- public static class Exn extends RuntimeException {
- private Object js = null;
- public Exn(Object js) { this.js = js; }
- public String toString() { return "JS.Exn: " + js; }
- public String getMessage() { return toString(); }
- public Object getObject() { return js; }
- }
+ /** override and return true to allow placing traps on this object */
+ protected boolean isTrappable() { return false; }
- /** The publicly-visible face of JavaScript Array objects */
- public static class Array extends ArrayImpl {
- public Array() { }
- public Array(int size) { super(size); }
- public void setSize(int i) { super.setSize(i); }
- public int length() { return super.length(); }
- public Object elementAt(int i) { return super.elementAt(i); }
- public void addElement(Object o) { super.addElement(o); }
- public void setElementAt(Object o, int i) { super.setElementAt(o, i); }
- public Object get(Object key) { return super._get(key); }
- public Object put(Object key, Object val) { super._put(key, val); return null; }
+ /** performs a put, triggering traps if present; traps are run in an unpauseable interpreter */
+ public final void putAndTriggerTraps(Object key, Object value) {
+ Trap t = getTrap(key);
+ if (t != null) t.invoke(key, value);
+ else put(key, value);
}
- /** Any object which becomes part of the scope chain must support this interface */
- public static class Scope extends ScopeImpl {
- public Scope(Scope parentScope) { this(parentScope, false); }
- public Scope(Scope parentScope, boolean sealed) { super(parentScope, sealed); }
- public boolean isTransparent() { return super.isTransparent(); } //< transparent scopes are not returned by THIS
- public boolean has(Object key) { return super.has(key); }
- public Object get(Object key) { return super._get(key); }
- public Object put(Object key, Object val) { super._put(key, val); return null; }
- public void declare(String s) { super.declare(s); }
- }
-
- /** the result of a graft */
- public static class Graft extends JS {
- private JS graftee;
- private Object replaced_key;
- private Object replaced_val;
- public Graft(JS graftee, Object key, Object val) {
- if (graftee instanceof Array) throw new JS.Exn("can't graft onto Arrays (yet)");
- if (graftee instanceof Callable) throw new JS.Exn("can't graft onto Callables (yet)");
- if (graftee instanceof Scope) throw new JS.Exn("can't graft onto Scopes (yet)");
- this.graftee = graftee;
- replaced_key = key;
- replaced_val = val;
- }
- public boolean equals(Object o) { return (this == o || graftee.equals(o)); }
- public int hashCode() { return graftee.hashCode(); }
- public Object get(Object key) { return replaced_key.equals(key) ? replaced_val : graftee.get(key); }
- public Object put(Object key, Object val) { graftee.put(key, val); return null; }
- public Object callMethod(Object method, Array args, boolean checkOnly) throws JS.Exn {
- if (!replaced_key.equals(method)) return graftee.callMethod(method, args, checkOnly);
- if (replaced_val instanceof Callable) return checkOnly ? Boolean.TRUE : ((Callable)replaced_val).call(args);
- if (checkOnly) return Boolean.FALSE;
- throw new JS.Exn("attempt to call non-function");
- }
- public Number coerceToNumber() { return graftee.coerceToNumber(); }
- public String coerceToString() { return graftee.coerceToString(); }
- public boolean coerceToBoolean() { return graftee.coerceToBoolean(); }
- public String typeName() { return graftee.typeName(); }
- public Object[] keys() {
- Object[] ret = graftee.keys();
- for(int i=0; i<ret.length; i++) if (replaced_key.equals(ret[i])) return ret;
- Object[] ret2 = new Object[ret.length + 1];
- System.arraycopy(ret, 0, ret2, 0, ret.length);
- ret2[ret2.length - 1] = replaced_key;
- return ret2;
- }
+ /** performs a get, triggering traps if present; traps are run in an unpauseable interpreter */
+ public final Object getAndTriggerTraps(Object key) {
+ Trap t = getTrap(key);
+ if (t != null) return t.invoke(key);
+ else return get(key);
}
- /** anything that is callable with the () operator and wasn't compiled from JS code */
- public static abstract class Callable extends JS.Obj {
- public abstract Object call(JS.Array args) throws JS.Exn;
+ /** retrieve a trap from the entries hash */
+ protected final Trap getTrap(Object key) {
+ return !isTrappable() || entries == null ? null : (Trap)entries.get(key, Trap.class);
}
- /** a scope that is populated with js objects and functions normally found in the global scope */
- public static class GlobalScope extends GlobalScopeImpl {
- public GlobalScope() { this(null); }
- public GlobalScope(JS.Scope parent) { super(parent); }
+ /** retrieve a trap from the entries hash */
+ protected final void putTrap(Object key, Trap value) {
+ if (!isTrappable()) return;
+ if (entries == null) entries = new Hash();
+ entries.put(key, Trap.class, value);
}
- public static class TailCall {
- Function func = null;
- JS.Array args = null;
- public TailCall() { }
- public TailCall set(Function func) { this.func = func; this.args = new JS.Array(); return this; }
- public TailCall set(Function func, JS.Array args) { this.func = func; this.args = args; return this; }
+ /** adds a trap, avoiding duplicates */
+ protected final void addTrap(Object name, JSFunction f) {
+ for(Trap t = getTrap(name); t != null; t = t.next) if (t.f == f) return;
+ putTrap(name, new Trap(this, name.toString(), f, (Trap)getTrap(name)));
}
-
- /** encapsulates the state of a JavaScript "thread" (ie stack) */
- public static class Context {
-
-
- // Statics //////////////////////////////////////////////////////////////////////
-
- /**
- * Return this from call/get/put in order to make the interpreter pause. The interpreter will expect a value
- * (the return from the call or the get) to be pushed onto the stack when it is resumed.
- */
- public static Object pause = new Object();
-
- private int getLine_() { return current().f == null ? -1 : (pc < 0 || pc >= f.size) ? -1 : f.line[pc]; }
- public static int getLine() { return current().getLine_(); }
- public static String getSourceName() { return current().f == null ? null : current().f.sourceName; }
-
- /** fetches the currently-executing javascript function */
- public static JS.Context current() { return (JS.Context)threadToContext.get(Thread.currentThread()); }
- private static Hashtable threadToContext = new Hashtable();
+ /** deletes a trap, if present */
+ protected final void delTrap(Object name, JSFunction f) {
+ Trap t = (Trap)getTrap(name);
+ if (t == null) return;
+ if (t.f == f) { putTrap(t.name, t.next); return; }
+ for(; t.next != null; t = t.next) if (t.next.f == f) { t.next = t.next.next; return; }
+ }
- // Instance members and methods //////////////////////////////////////////////////////////////////////
- /** the currently-executing Function */
- Function f = null;
+ // Call Support //////////////////////////////////////////////////////////////////////////////
- /** the currently-executing scope */
- public Scope scope = null; // FIXME: do we really need this? the function should contain this info
+ // return this from get() if the key was actually a method.
+ public static final Object METHOD = new Object();
+ public Object callMethod(Object method, Object a0, Object a1, Object a2, Object[] rest, int nargs) {
+ throw new JSExn("attempted to call the null value (method "+method+")");
+ }
+ public Object call(Object a0, Object a1, Object a2, Object[] rest, int nargs) {
+ throw new JSExn("you cannot call this object)");
+ }
- /** the object stack */
- Vec stack = new Vec();
- /** the program counter */
- int pc = 0;
+ // Typing Support //////////////////////////////////////////////////////////////////////////////
- public Context(Function function, Scope scope) {
- if (scope == null) scope = new Scope(function.parentScope);
- stack.push(new Function.CallMarker(this));
- stack.push(new JS.Array());
- this.f = function;
- this.scope = scope;
- }
+ public Number coerceToNumber() { throw new JSExn("tried to coerce a JavaScript object to a Number"); }
+ public String coerceToString() { throw new JSExn("tried to coerce a JavaScript object to a String"); }
+ public boolean coerceToBoolean() { throw new JSExn("tried to coerce a JavaScript object to a Boolean"); }
- public Object resume() { return resume(null); }
- public Object resume(Object o) {
- Thread t = Thread.currentThread();
- Context old = (Context)threadToContext.get(t);
- try {
- threadToContext.put(t, this);
- stack.push(o);
- return Function.eval(this);
- } finally {
- if (old == null) threadToContext.remove(t);
- else threadToContext.put(t, old);
- }
- }
+ public String typeName() { return "object"; }
- }
}
-
-
-
-
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