feat: greatly improve Context API

src/me/topchetoeu/jscript/engine/Context.java

@@ -2,9 +2,8 @@ package me.topchetoeu.jscript.engine;
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
+import java.util.Iterator;
 import java.util.List;
-import java.util.Stack;
 import java.util.TreeSet;
 import java.util.stream.Collectors;
 
@@ -14,35 +13,44 @@ import me.topchetoeu.jscript.engine.debug.DebugContext;
 import me.topchetoeu.jscript.engine.frame.CodeFrame;
 import me.topchetoeu.jscript.engine.values.ArrayValue;
 import me.topchetoeu.jscript.engine.values.FunctionValue;
+import me.topchetoeu.jscript.engine.values.Symbol;
 import me.topchetoeu.jscript.engine.values.Values;
 import me.topchetoeu.jscript.exceptions.EngineException;
 import me.topchetoeu.jscript.lib.EnvironmentLib;
 import me.topchetoeu.jscript.mapping.SourceMap;
 
-public class Context extends ExtensionStack {
+public class Context implements Extensions {
-    private final Stack<Environment> env = new Stack<>();
+    public final Context parent;
-    private final ArrayList<CodeFrame> frames = new ArrayList<>();
+    public final Environment environment;
+    public final CodeFrame frame;
     public final Engine engine;
+    public final int stackSize;
 
-    @Override
+    @Override public <T> void add(Symbol key, T obj) {
-    protected Extensions[] extensionStack() {
+        if (environment != null) environment.add(key, obj);
-        return new Extensions[] { environment(), engine.globalEnvironment };
+        else if (engine != null) engine.globalEnvironment.add(key, obj);
     }
+    @Override public <T> T get(Symbol key) {
+        if (environment != null && environment.has(key)) return environment.get(key);
+        else if (engine != null && engine.globalEnvironment.has(key)) return engine.globalEnvironment.get(key);
+        return null;
+    }
+    @Override public boolean has(Symbol key) {
+        return
+            environment != null && environment.has(key) ||
+            engine != null && engine.globalEnvironment.has(key);
+    }
+    @Override public boolean remove(Symbol key) {
+        var res = false;
 
-    public Environment environment() {
+        if (environment != null) res |= environment.remove(key);
-        return env.empty() ? null : env.peek();
+        else if (engine != null) res |= engine.globalEnvironment.remove(key);
-    }
 
-    private Context pushEnv(Environment env) {
+        return res;
-        this.env.push(env);
-        return this;
-    }
-    private void popEnv() {
-        if (!env.empty()) this.env.pop();
     }
 
     public FunctionValue compile(Filename filename, String raw) {
-        var env = environment();
+        var env = environment;
         var result = Environment.compileFunc(this).call(this, null, raw, filename.toString(), new EnvironmentLib(env));
 
         var function = (FunctionValue)Values.getMember(this, result, "function");
@@ -74,33 +82,37 @@ public class Context extends ExtensionStack {
         return function;
     }
 
-    public void pushFrame(CodeFrame frame) {
+    public Context pushFrame(CodeFrame frame) {
-        frames.add(frame);
+        var res = new Context(this, frame.function.environment, frame, engine, stackSize + 1);
-        if (frames.size() > engine.maxStackFrames) throw EngineException.ofRange("Stack overflow!");
+        DebugContext.get(res).onFramePush(res, frame);
-        pushEnv(frame.function.environment);
+        return res;
-        DebugContext.get(this).onFramePush(this, frame);
-    }
-    public boolean popFrame(CodeFrame frame) {
-        if (frames.size() == 0) return false;
-        if (frames.get(frames.size() - 1) != frame) return false;
-        frames.remove(frames.size() - 1);
-        popEnv();
-        DebugContext.get(this).onFramePop(this, frame);
-        return true;
-    }
-    public CodeFrame peekFrame() {
-        if (frames.size() == 0) return null;
-        return frames.get(frames.size() - 1);
     }
 
-    public List<CodeFrame> frames() {
+    public Iterable<CodeFrame> frames() {
-        return Collections.unmodifiableList(frames);
+        var self = this;
+        return () -> new Iterator<CodeFrame>() {
+            private Context curr = self;
+
+            private void update() {
+                while (curr.frame == null && curr != null) curr = curr.parent;
+            }
+
+            @Override public boolean hasNext() {
+                update();
+                return curr != null;
+            }
+            @Override public CodeFrame next() {
+                update();
+                var res = curr.frame;
+                curr = curr.parent;
+                return res;
+            }
+        };
     }
     public List<String> stackTrace() {
         var res = new ArrayList<String>();
 
-        for (var i = frames.size() - 1; i >= 0; i--) {
+        for (var el : frames()) {
-            var el = frames.get(i);
             var name = el.function.name;
             Location loc = null;
 
@@ -120,11 +132,20 @@ public class Context extends ExtensionStack {
         return res;
     }
 
-    public Context(Engine engine) {
+    private Context(Context parent, Environment environment, CodeFrame frame, Engine engine, int stackSize) {
+        this.parent = parent;
+        this.environment = environment;
+        this.frame = frame;
         this.engine = engine;
+        this.stackSize = stackSize;
+
+        if (engine != null && stackSize > engine.maxStackFrames) throw EngineException.ofRange("Stack overflow!");
+    }
+
+    public Context(Engine engine) {
+        this(null, null, null, engine, 0);
     }
     public Context(Engine engine, Environment env) {
-        this(engine);
+        this(null, env, null, engine, 0);
-        if (env != null) this.pushEnv(env);
     }
 }

src/me/topchetoeu/jscript/engine/Environment.java

@@ -88,7 +88,7 @@ public class Environment implements Extensions {
     }
     public static FunctionValue regexConstructor(Extensions ext) {
         return ext.init(COMPILE_FUNC, new NativeFunction("RegExp", (ctx, thisArg, args) -> {
-            throw EngineException.ofError("Regular expressions not supported.").setCtx(ctx.environment(), ctx.engine);
+            throw EngineException.ofError("Regular expressions not supported.").setCtx(ctx.environment, ctx.engine);
         }));
     }
 

src/me/topchetoeu/jscript/engine/debug/SimpleDebugger.java

@@ -234,7 +234,7 @@ public class SimpleDebugger implements Debugger {
     }
 
     private synchronized void updateFrames(Context ctx) {
-        var frame = ctx.peekFrame();
+        var frame = ctx.frame;
         if (frame == null) return;
 
         if (!codeFrameToFrame.containsKey(frame)) {
@@ -249,10 +249,9 @@ public class SimpleDebugger implements Debugger {
     }
     private JSONList serializeFrames(Context ctx) {
         var res = new JSONList();
-        var frames = ctx.frames();
 
-        for (var i = frames.size() - 1; i >= 0; i--) {
+        for (var el : ctx.frames()) {
-            var frame = codeFrameToFrame.get(frames.get(i));
+            var frame = codeFrameToFrame.get(el);
             if (frame.location == null) continue;
             frame.serialized.set("location", serializeLocation(frame.location));
             if (frame.location != null) res.add(frame.serialized);
@@ -484,7 +483,7 @@ public class SimpleDebugger implements Debugger {
         env.global = new GlobalScope(codeFrame.local);
 
         var ctx = new Context(engine, env);
-        var awaiter = engine.pushMsg(false, ctx.environment(), new Filename("jscript", "eval"), code, codeFrame.frame.thisArg, codeFrame.frame.args);
+        var awaiter = engine.pushMsg(false, ctx.environment, new Filename("jscript", "eval"), code, codeFrame.frame.thisArg, codeFrame.frame.args);
 
         engine.run(true);
 
@@ -496,7 +495,7 @@ public class SimpleDebugger implements Debugger {
         var res = new ArrayValue();
         var passed = new HashSet<String>();
         var tildas = "~";
-        if (target == null) target = ctx.environment().global;
+        if (target == null) target = ctx.environment.global;
 
         for (var proto = target; proto != null && proto != Values.NULL; proto = Values.getPrototype(ctx, proto)) {
             for (var el : Values.getMembers(ctx, proto, true, true)) {
@@ -944,7 +943,7 @@ public class SimpleDebugger implements Debugger {
         try { idToFrame.remove(codeFrameToFrame.remove(frame).id); }
         catch (NullPointerException e) { }
 
-        if (ctx.frames().size() == 0) {
+        if (ctx.stackSize == 0) {
             if (state == State.PAUSED_EXCEPTION || state == State.PAUSED_NORMAL) resume(State.RESUMED);
         }
         else if (stepOutFrame != null && stepOutFrame.frame == frame && state == State.STEPPING_OUT) {

src/me/topchetoeu/jscript/engine/frame/CodeFrame.java

@@ -94,6 +94,7 @@ public class CodeFrame {
     public final Object[] args;
     public final Stack<TryCtx> tryStack = new Stack<>();
     public final CodeFunction function;
+    public final Context ctx;
     public Object[] stack = new Object[32];
     public int stackPtr = 0;
     public int codePtr = 0;
@@ -187,7 +188,7 @@ public class CodeFrame {
         stack[stackPtr++] = Values.normalize(ctx, val);
     }
 
-    public Object next(Context ctx, Object value, Object returnValue, EngineException error) {
+    public Object next(Object value, Object returnValue, EngineException error) {
         if (value != Runners.NO_RETURN) push(ctx, value);
 
         Instruction instr = null;
@@ -314,5 +315,6 @@ public class CodeFrame {
 
         this.thisArg = thisArg;
         this.function = func;
+        this.ctx = ctx.pushFrame(this);
     }
 }

src/me/topchetoeu/jscript/engine/frame/Runners.java

@@ -50,7 +50,7 @@ public class Runners {
 
     public static Object execMakeVar(Context ctx, Instruction instr, CodeFrame frame) {
         var name = (String)instr.get(0);
-        ctx.environment().global.define(name);
+        ctx.environment.global.define(name);
         frame.codePtr++;
         return NO_RETURN;
     }
@@ -142,7 +142,7 @@ public class Runners {
     public static Object execLoadVar(Context ctx, Instruction instr, CodeFrame frame) {
         var i = instr.get(0);
 
-        if (i instanceof String) frame.push(ctx, ctx.environment().global.get(ctx, (String)i));
+        if (i instanceof String) frame.push(ctx, ctx.environment.global.get(ctx, (String)i));
         else frame.push(ctx, frame.scope.get((int)i).get(ctx));
 
         frame.codePtr++;
@@ -154,7 +154,7 @@ public class Runners {
         return NO_RETURN;
     }
     public static Object execLoadGlob(Context ctx, Instruction instr, CodeFrame frame) {
-        frame.push(ctx, ctx.environment().global.obj);
+        frame.push(ctx, ctx.environment.global.obj);
         frame.codePtr++;
         return NO_RETURN;
     }
@@ -173,7 +173,7 @@ public class Runners {
             captures[i - 1] = frame.scope.get(instr.get(i));
         }
 
-        var func = new CodeFunction(ctx.environment(), "", Engine.functions.get(id), captures);
+        var func = new CodeFunction(ctx.environment, "", Engine.functions.get(id), captures);
 
         frame.push(ctx, func);
 
@@ -227,7 +227,7 @@ public class Runners {
         var val = (boolean)instr.get(1) ? frame.peek() : frame.pop();
         var i = instr.get(0);
 
-        if (i instanceof String) ctx.environment().global.set(ctx, (String)i, val);
+        if (i instanceof String) ctx.environment.global.set(ctx, (String)i, val);
         else frame.scope.get((int)i).set(ctx, val);
 
         frame.codePtr++;
@@ -274,8 +274,8 @@ public class Runners {
         Object obj;
 
         if (name != null) {
-            if (ctx.environment().global.has(ctx, name)) {
+            if (ctx.environment.global.has(ctx, name)) {
-                obj = ctx.environment().global.get(ctx, name);
+                obj = ctx.environment.global.get(ctx, name);
             }
             else obj = null;
         }

src/me/topchetoeu/jscript/engine/values/CodeFunction.java

@@ -32,16 +32,10 @@ public class CodeFunction extends FunctionValue {
     @Override
     public Object call(Context ctx, Object thisArg, Object ...args) {
         var frame = new CodeFrame(ctx, thisArg, args, this);
-        try {
-            ctx.pushFrame(frame);
 
-            while (true) {
+        while (true) {
-                var res = frame.next(ctx, Runners.NO_RETURN, Runners.NO_RETURN, null);
+            var res = frame.next(Runners.NO_RETURN, Runners.NO_RETURN, null);
-                if (res != Runners.NO_RETURN) return res;
+            if (res != Runners.NO_RETURN) return res;
-            }
-        }
-        finally {
-            ctx.popFrame(frame);
         }
     }
 

src/me/topchetoeu/jscript/engine/values/NativeWrapper.java

@@ -8,7 +8,7 @@ public class NativeWrapper extends ObjectValue {
 
     @Override
     public ObjectValue getPrototype(Context ctx) {
-        if (prototype == NATIVE_PROTO) return ctx.environment().wrappers.getProto(wrapped.getClass());
+        if (prototype == NATIVE_PROTO) return ctx.environment.wrappers.getProto(wrapped.getClass());
         else return super.getPrototype(ctx);
     }
 

src/me/topchetoeu/jscript/engine/values/Values.java

@@ -477,7 +477,7 @@ public class Values {
 
         if (val instanceof Class) {
             if (ctx == null) return null;
-            else return ctx.environment().wrappers.getConstr((Class<?>)val);
+            else return ctx.environment.wrappers.getConstr((Class<?>)val);
         }
 
         return new NativeWrapper(val);

src/me/topchetoeu/jscript/exceptions/EngineException.java

@@ -38,7 +38,7 @@ public class EngineException extends RuntimeException {
             if (function.equals("")) function = null;
 
             if (ctx == null) this.ctx = null;
-            else this.ctx = new Context(ctx.engine, ctx.environment());
+            else this.ctx = new Context(ctx.engine, ctx.environment);
             this.location = location;
             this.function = function;
         }
@@ -53,7 +53,7 @@ public class EngineException extends RuntimeException {
     public EngineException add(Context ctx, String name, Location location) {
         var el = new StackElement(ctx, location, name);
         if (el.function == null && el.location == null) return this;
-        setCtx(ctx.environment(), ctx.engine);
+        setCtx(ctx.environment, ctx.engine);
         stackTrace.add(el);
         return this;
     }

src/me/topchetoeu/jscript/lib/AsyncFunctionLib.java

@@ -20,12 +20,11 @@ import me.topchetoeu.jscript.interop.Native;
 
         private void next(Context ctx, Object inducedValue, Object inducedError) {
             Object res = null;
-            ctx.pushFrame(frame);
 
             awaiting = false;
             while (!awaiting) {
                 try {
-                    res = frame.next(ctx, inducedValue, Runners.NO_RETURN, inducedError == Runners.NO_RETURN ? null : new EngineException(inducedError));
+                    res = frame.next(inducedValue, Runners.NO_RETURN, inducedError == Runners.NO_RETURN ? null : new EngineException(inducedError));
                     inducedValue = inducedError = Runners.NO_RETURN;
                     if (res != Runners.NO_RETURN) {
                         promise.fulfill(ctx, res);
@@ -38,8 +37,6 @@ import me.topchetoeu.jscript.interop.Native;
                 }
             }
 
-            ctx.popFrame(frame);
-
             if (awaiting) {
                 PromiseLib.then(ctx, frame.pop(), new NativeFunction(this::fulfill), new NativeFunction(this::reject));
             }

src/me/topchetoeu/jscript/lib/AsyncGeneratorLib.java

@@ -28,12 +28,11 @@ import me.topchetoeu.jscript.interop.Native;
         }
 
         Object res = null;
-        ctx.pushFrame(frame);
         state = 0;
 
         while (state == 0) {
             try {
-                res = frame.next(ctx, inducedValue, inducedReturn, inducedError == Runners.NO_RETURN ? null : new EngineException(inducedError));
+                res = frame.next(inducedValue, inducedReturn, inducedError == Runners.NO_RETURN ? null : new EngineException(inducedError));
                 inducedValue = inducedReturn = inducedError = Runners.NO_RETURN;
                 if (res != Runners.NO_RETURN) {
                     var obj = new ObjectValue();
@@ -49,8 +48,6 @@ import me.topchetoeu.jscript.interop.Native;
             }
         }
 
-        ctx.popFrame(frame);
-
         if (state == 1) {
             PromiseLib.then(ctx, frame.pop(), new NativeFunction(this::fulfill), new NativeFunction(this::reject));
         }

src/me/topchetoeu/jscript/lib/GeneratorLib.java

@@ -24,12 +24,11 @@ import me.topchetoeu.jscript.interop.Native;
         }
 
         Object res = null;
-        ctx.pushFrame(frame);
         yielding = false;
 
         while (!yielding) {
             try {
-                res = frame.next(ctx, inducedValue, inducedReturn, inducedError == Runners.NO_RETURN ? null : new EngineException(inducedError));
+                res = frame.next(inducedValue, inducedReturn, inducedError == Runners.NO_RETURN ? null : new EngineException(inducedError));
                 inducedReturn = inducedError = Runners.NO_RETURN;
                 if (res != Runners.NO_RETURN) {
                     done = true;
@@ -42,7 +41,6 @@ import me.topchetoeu.jscript.interop.Native;
             }
         }
 
-        ctx.popFrame(frame);
         if (done) frame = null;
         else res = frame.pop();
 

src/me/topchetoeu/jscript/lib/Internals.java

@@ -58,7 +58,7 @@ public class Internals {
             }
             catch (InterruptedException e) { return; }
 
-            ctx.engine.pushMsg(false, ctx.environment(), func, null, args);
+            ctx.engine.pushMsg(false, ctx.environment, func, null, args);
         });
         thread.start();
 
@@ -75,7 +75,7 @@ public class Internals {
                 }
                 catch (InterruptedException e) { return; }
 
-                ctx.engine.pushMsg(false, ctx.environment(), func, null, args);
+                ctx.engine.pushMsg(false, ctx.environment, func, null, args);
             }
         });
 

src/me/topchetoeu/jscript/lib/PromiseLib.java

@@ -253,7 +253,7 @@ import me.topchetoeu.jscript.interop.Native;
                     this.val = val;
                     this.state = STATE_FULFILLED;
 
-                    ctx.engine.pushMsg(true, ctx.environment(), new NativeFunction((_ctx, _thisArg, _args) -> {
+                    ctx.engine.pushMsg(true, ctx.environment, new NativeFunction((_ctx, _thisArg, _args) -> {
                         for (var handle : handles) {
                             handle.fulfilled.call(handle.ctx, null, val);
                         }
@@ -288,10 +288,10 @@ import me.topchetoeu.jscript.interop.Native;
                     this.val = val;
                     this.state = STATE_REJECTED;
 
-                    ctx.engine.pushMsg(true, ctx.environment(), new NativeFunction((_ctx, _thisArg, _args) -> {
+                    ctx.engine.pushMsg(true, ctx.environment, new NativeFunction((_ctx, _thisArg, _args) -> {
                         for (var handle : handles) handle.rejected.call(handle.ctx, null, val);
                         if (!handled) {
-                            Values.printError(new EngineException(val).setCtx(ctx.environment(), ctx.engine), "(in promise)");
+                            Values.printError(new EngineException(val).setCtx(ctx.environment, ctx.engine), "(in promise)");
                         }
                         handles = null;
                         return null;
@@ -305,9 +305,9 @@ import me.topchetoeu.jscript.interop.Native;
     }
 
     private void handle(Context ctx, FunctionValue fulfill, FunctionValue reject) {
-        if (state == STATE_FULFILLED) ctx.engine.pushMsg(true, ctx.environment(), fulfill, null, val);
+        if (state == STATE_FULFILLED) ctx.engine.pushMsg(true, ctx.environment, fulfill, null, val);
         else if (state == STATE_REJECTED) {
-            ctx.engine.pushMsg(true, ctx.environment(), reject, null, val);
+            ctx.engine.pushMsg(true, ctx.environment, reject, null, val);
             handled = true;
         }
         else handles.add(new Handle(ctx, fulfill, reject));

src/me/topchetoeu/jscript/modules/ModuleRepo.java

@@ -25,7 +25,7 @@ public interface ModuleRepo {
 
             if (modules.containsKey(name)) return modules.get(name);
 
-            var env = ctx.environment().child();
+            var env = ctx.environment.child();
             env.add(CWD, fs.normalize(name, ".."));
 
             var mod = new SourceModule(filename, src, env);