Implement blocks and make while loop work. Fix args > 255 also

Author: ncw

notes.txt

@@ -16,7 +16,7 @@ Testing
   python3 -m dis hello.py
   python3 -mcompileall hello.py 
   mv __pycache__/hello.cpython-33.pyc hello.pyc
-  python -c 'import hello; import dis; dis.dis(hello.fn)'
+  python3 -c 'import hello; import dis; dis.dis(hello.fn)'
 
   go build ./... && go build
   ./gpython hello.pyc

py/frame.go

@@ -8,9 +8,9 @@ import (
 
 // Store information about try blocks
 type TryBlock struct {
-	Type    int // what kind of block this is
-	Handler int // where to jump to find handler
-	Level   int // value stack level to pop to
+	Type    byte  // what kind of block this is (the opcode)
+	Handler int32 // where to jump to find handler
+	Level   int   // value stack level to pop to
 }
 
 // A python Frame object
@@ -51,6 +51,7 @@ type Frame struct {
 	Iblock     int        // index in f_blockstack
 	Executing  byte       // whether the frame is still executing
 	Blockstack []TryBlock // for try and loop blocks
+	Block      *TryBlock  // pointer to current block or nil
 	Localsplus []Object   // locals+stack, dynamically sized
 }
 
@@ -90,3 +91,23 @@ func (f *Frame) Lookup(name string) (obj Object) {
 	// FIXME this should be a NameError
 	panic(fmt.Sprintf("NameError: name '%s' is not defined", name))
 }
+
+// Make a new Block (try/for/while)
+func (f *Frame) PushBlock(Type byte, Handler int32, Level int) {
+	f.Blockstack = append(f.Blockstack, TryBlock{
+		Type:    Type,
+		Handler: Handler,
+		Level:   Level,
+	})
+	f.Block = &f.Blockstack[len(f.Blockstack)-1]
+}
+
+// Pop the current block off
+func (f *Frame) PopBlock() {
+	f.Blockstack = f.Blockstack[:len(f.Blockstack)-1]
+	if len(f.Blockstack) > 0 {
+		f.Block = &f.Blockstack[len(f.Blockstack)-1]
+	} else {
+		f.Block = nil
+	}
+}

vm/eval.go

@@ -379,7 +379,7 @@ func do_IMPORT_STAR(vm *Vm, arg int32) {
 // Removes one block from the block stack. Per frame, there is a stack
 // of blocks, denoting nested loops, try statements, and such.
 func do_POP_BLOCK(vm *Vm, arg int32) {
-	vm.NotImplemented("POP_BLOCK", arg)
+	vm.frame.PopBlock()
 }
 
 // Removes one block from the block stack. The popped block must be an
@@ -620,19 +620,19 @@ func do_LOAD_GLOBAL(vm *Vm, namei int32) {
 // Pushes a block for a loop onto the block stack. The block spans
 // from the current instruction with a size of delta bytes.
 func do_SETUP_LOOP(vm *Vm, delta int32) {
-	vm.NotImplemented("SETUP_LOOP", delta)
+	vm.frame.PushBlock(SETUP_LOOP, vm.frame.Lasti+delta, len(vm.stack))
 }
 
 // Pushes a try block from a try-except clause onto the block
 // stack. delta points to the first except block.
 func do_SETUP_EXCEPT(vm *Vm, delta int32) {
-	vm.NotImplemented("SETUP_EXCEPT", delta)
+	vm.frame.PushBlock(SETUP_EXCEPT, vm.frame.Lasti+delta, len(vm.stack))
 }
 
 // Pushes a try block from a try-except clause onto the block
 // stack. delta points to the finally block.
 func do_SETUP_FINALLY(vm *Vm, delta int32) {
-	vm.NotImplemented("SETUP_FINALLY", delta)
+	vm.frame.PushBlock(SETUP_FINALLY, vm.frame.Lasti+delta, len(vm.stack))
 }
 
 // Store a key and value pair in a dictionary. Pops the key and value
@@ -931,7 +931,7 @@ func Run(globals, locals py.StringDict, code *py.Code) (err error) {
 		if HAS_ARG(opcode) {
 			arg = int32(opcodes[frame.Lasti])
 			frame.Lasti++
-			arg += int32(opcodes[frame.Lasti] << 8)
+			arg += int32(opcodes[frame.Lasti]) << 8
 			frame.Lasti++
 			if vm.extended {
 				arg += vm.ext << 16