vm: rename variables to be more like the python original code

Author: ncw

vm/eval.go

@@ -1,10 +1,6 @@
 // Evaluate opcodes
 package vm
 
-// FIXME vm.result -> retval
-// vm.exit -> vm.why
-// why codes
-
 // FIXME make opcode its own type so can stringer
 
 // FIXME use LocalVars instead of storing everything in the Locals dict
@@ -119,13 +115,13 @@ func (vm *Vm) AddTraceback(exc *py.ExceptionInfo){
 // The exception must be a valid exception instance (eg as returned by
 // py.MakeException)
 //
-// It sets vm.curexc.* and sets vm.exit to exitException
+// It sets vm.curexc.* and sets vm.why to whyException
 func (vm*Vm) SetException(exception py.Object){
 vm.curexc.Value=exception
 vm.curexc.Type=exception.Type()
 vm.curexc.Traceback=nil
 vm.AddTraceback(&vm.curexc)
-vm.exit=exitException
+vm.why=whyException
 }
 
 // Check for an exception (panic)
@@ -136,7 +132,7 @@ func (vm *Vm) CheckExceptionRecover(r interface{}){
 ifexc, ok:=r.(py.ExceptionInfo); ok{
 vm.curexc=exc
 vm.AddTraceback(&vm.curexc)
-vm.exit=exitException
+vm.why=whyException
 debugf("*** Propagating exception: %s\n", exc.Error())
  } else{
 // Coerce whatever was raised into a *Exception
@@ -489,15 +485,15 @@ func do_PRINT_EXPR(vm *Vm, arg int32){
 // Terminates a loop due to a break statement.
 funcdo_BREAK_LOOP(vm*Vm, argint32){
 defervm.CheckException()
-vm.exit=exitBreak
+vm.why=whyBreak
 }
 
 // Continues a loop due to a continue statement. target is the address
 // to jump to (which should be a FOR_ITER instruction).
 funcdo_CONTINUE_LOOP(vm*Vm, targetint32){
 defervm.CheckException()
-vm.result=py.Int(target)
-vm.exit=exitContinue
+vm.retval=py.Int(target)
+vm.why=whyContinue
 }
 
 // Iterate v argcnt times and store the results on the stack (via decreasing
@@ -599,13 +595,13 @@ func do_MAP_ADD(vm *Vm, i int32){
 // Returns with TOS to the caller of the function.
 funcdo_RETURN_VALUE(vm*Vm, argint32){
 defervm.CheckException()
-vm.result=vm.POP()
+vm.retval=vm.POP()
 iflen(vm.frame.Stack) !=0{
 debugf("vmstack = %#v\n", vm.frame.Stack)
 panic("vm stack should be empty at this point")
  }
 vm.frame.Yielded=false
-vm.exit=exitReturn
+vm.why=whyReturn
 }
 
 // Pops TOS and delegates to it as a subiterator from a generator.
@@ -627,21 +623,21 @@ func do_YIELD_FROM(vm *Vm, arg int32){
  }
 // x remains on stack, retval is value to be yielded
 // FIXME vm.frame.Stacktop = stack_pointer
-//why = exitYield
+//why = whyYield
 // and repeat...
 vm.frame.Lasti--
 
-vm.result=retval
+vm.retval=retval
 vm.frame.Yielded=true
-vm.exit=exitYield
+vm.why=whyYield
 }
 
 // Pops TOS and yields it from a generator.
 funcdo_YIELD_VALUE(vm*Vm, argint32){
 defervm.CheckException()
-vm.result=vm.POP()
+vm.retval=vm.POP()
 vm.frame.Yielded=true
-vm.exit=exitYield
+vm.why=whyYield
 }
 
 // Loads all symbols not starting with '_' directly from the module
@@ -702,16 +698,16 @@ func do_END_FINALLY(vm *Vm, arg int32){
 // None exception
 debugf(" END_FINALLY: None\n")
  } elseifvInt, ok:=v.(py.Int); ok{
-vm.exit=vmExit(vInt)
-debugf(" END_FINALLY: Int %v\n", vm.exit)
-switchvm.exit{
-caseexitYield:
-panic("Unexpected exitYield in END_FINALLY")
-caseexitException:
-panic("Unexpected exitException in END_FINALLY")
-caseexitReturn, exitContinue:
-vm.result=vm.POP()
-caseexitSilenced:
+vm.why=vmStatus(vInt)
+debugf(" END_FINALLY: Int %v\n", vm.why)
+switchvm.why{
+casewhyYield:
+panic("Unexpected whyYield in END_FINALLY")
+casewhyException:
+panic("Unexpected whyException in END_FINALLY")
+casewhyReturn, whyContinue:
+vm.retval=vm.POP()
+casewhySilenced:
 // An exception was silenced by 'with', we must
 // manually unwind the EXCEPT_HANDLER block which was
 // created when the exception was caught, otherwise
@@ -723,7 +719,7 @@ func do_END_FINALLY(vm *Vm, arg int32){
 panic("Expecting EXCEPT_HANDLER in END_FINALLY")
  }
 vm.UnwindExceptHandler(frame, b)
-vm.exit=exitNot
+vm.why=whyNot
  }
  } elseifpy.ExceptionClassCheck(v){
 w:=vm.POP()
@@ -733,11 +729,11 @@ func do_END_FINALLY(vm *Vm, arg int32){
 vm.curexc.Type, _=v.(*py.Type)
 vm.curexc.Value=w
 vm.curexc.Traceback, _=u.(*py.Traceback)
-vm.exit=exitException
+vm.why=whyException
  } else{
 vm.SetException(py.ExceptionNewf(py.SystemError, "'finally' pops bad exception %#v", v))
  }
-debugf("END_FINALLY: vm.exit = %v\n", vm.exit)
+debugf("END_FINALLY: vm.why = %v\n", vm.why)
 }
 
 // Loads the __build_class__ helper function to the stack which
@@ -1250,7 +1246,7 @@ func (vm *Vm) raise(exc, cause py.Object){
 // Resignal the exception
 vm.curexc=vm.exc
 // Signal the existing exception again
-vm.exit=exitException
+vm.why=whyException
 
  }
  } else{
@@ -1518,7 +1514,7 @@ func RunFrame(frame *py.Frame) (res py.Object, err error){
 
 varopcodebyte
 varargint32
-forvm.exit==exitNot{
+forvm.why==whyNot{
 frame:=vm.frame
 debugf("* %4d:", frame.Lasti)
 opcodes:=frame.Code.Code
@@ -1546,21 +1542,21 @@ func RunFrame(frame *py.Frame) (res py.Object, err error){
 // }
 // }
  }
-ifvm.exit==exitYield{
+ifvm.why==whyYield{
 goto fast_yield
  }
 
 // Something exceptional has happened - unwind the block stack
 // and find out what
-forvm.exit!=exitNot&&vm.frame.Block!=nil{
+forvm.why!=whyNot&&vm.frame.Block!=nil{
 // Peek at the current block.
 frame:=vm.frame
 b:=frame.Block
 debugf("*** Unwinding %#v vm %#v\n", b, vm)
 
-ifb.Type==SETUP_LOOP&&vm.exit==exitContinue{
-vm.exit=exitNot
-dest:=vm.result.(py.Int)
+ifb.Type==SETUP_LOOP&&vm.why==whyContinue{
+vm.why=whyNot
+dest:=vm.retval.(py.Int)
 frame.Lasti=int32(dest)
 break
  }
@@ -1574,13 +1570,13 @@ func RunFrame(frame *py.Frame) (res py.Object, err error){
 continue
  }
 vm.UnwindBlock(frame, b)
-ifb.Type==SETUP_LOOP&&vm.exit==exitBreak{
+ifb.Type==SETUP_LOOP&&vm.why==whyBreak{
 debugf("*** Loop\n")
-vm.exit=exitNot
+vm.why=whyNot
 frame.Lasti=b.Handler
 break
  }
-ifvm.exit==exitException&& (b.Type==SETUP_EXCEPT||b.Type==SETUP_FINALLY){
+ifvm.why==whyException&& (b.Type==SETUP_EXCEPT||b.Type==SETUP_FINALLY){
 debugf("*** Exception\n")
 handler:=b.Handler
 // This invalidates b
@@ -1615,29 +1611,29 @@ func RunFrame(frame *py.Frame) (res py.Object, err error){
  } else{
 vm.PUSH(exc)
  }
-vm.exit=exitNot
+vm.why=whyNot
 frame.Lasti=handler
 break
  }
 ifb.Type==SETUP_FINALLY{
-ifvm.exit==exitReturn||vm.exit==exitContinue{
-vm.PUSH(vm.result)
+ifvm.why==whyReturn||vm.why==whyContinue{
+vm.PUSH(vm.retval)
  }
-vm.PUSH(py.Int(vm.exit))
-vm.exit=exitNot
+vm.PUSH(py.Int(vm.why))
+vm.why=whyNot
 frame.Lasti=b.Handler
 break
  }
  }
  }
-debugf("EXIT with %v\n", vm.exit)
-ifvm.exit!=exitReturn{
-vm.result=nil
+debugf("EXIT with %v\n", vm.why)
+ifvm.why!=whyReturn{
+vm.retval=nil
  }
-ifvm.result==nil&&!vm.curexc.IsSet(){
+ifvm.retval==nil&&!vm.curexc.IsSet(){
 panic("vm: no result or exception")
  }
-ifvm.result!=nil&&vm.curexc.IsSet(){
+ifvm.retval!=nil&&vm.curexc.IsSet(){
 panic("vm: result and exception")
  }
 
@@ -1664,9 +1660,9 @@ fast_yield:
 // }
 
 ifvm.curexc.IsSet(){
-returnvm.result, vm.curexc
+returnvm.retval, vm.curexc
  }
-returnvm.result, nil
+returnvm.retval, nil
 }
 
 // Run the virtual machine on a Code object

vm/stringer.go

@@ -1,16 +1,16 @@
-// generated by stringer -type=vmExit -output stringer.go; DO NOT EDIT
+// generated by stringer -type=vmStatus -output stringer.go; DO NOT EDIT
 
 package vm
 
 import"fmt"
 
-const_vmExit_name="exitNotexitExceptionexitReturnexitBreakexitContinueexitYieldexitSilenced"
+const_vmStatus_name="whyNotwhyExceptionwhyReturnwhyBreakwhyContinuewhyYieldwhySilenced"
 
-var_vmExit_index= [...]uint8{0, 7, 20, 30, 39, 51, 60, 72}
+var_vmStatus_index= [...]uint8{0, 6, 18, 27, 35, 46, 54, 65}
 
-func (ivmExit) String() string{
-ifi+1>=vmExit(len(_vmExit_index)){
-returnfmt.Sprintf("vmExit(%d)", i)
+func (ivmStatus) String() string{
+ifi+1>=vmStatus(len(_vmStatus_index)){
+returnfmt.Sprintf("vmStatus(%d)", i)
  }
-return_vmExit_name[_vmExit_index[i]:_vmExit_index[i+1]]
+return_vmStatus_name[_vmStatus_index[i]:_vmStatus_index[i+1]]
 }

vm/vm.go

@@ -5,20 +5,20 @@ import (
 "github.com/ncw/gpython/py"
 )
 
-//go:generate stringer -type=vmExit -output stringer.go
+//go:generate stringer -type=vmStatus -output stringer.go
 
-// VM exit type
-typevmExitbyte
+// VM status code
+typevmStatusbyte
 
-// VM exit values
+// VM Status code for main loop (reason for stack unwind)
 const (
-exitNotvmExit=iota// No error
-exitException// Exception occurred
-exitReturn// 'return' statement
-exitBreak// 'break' statement
-exitContinue// 'continue' statement
-exitYield// 'yield' operator
-exitSilenced// Exception silenced by 'with'
+whyNotvmStatus=iota// No error
+whyException// Exception occurred
+whyReturn// 'return' statement
+whyBreak// 'break' statement
+whyContinue// 'continue' statement
+whyYield// 'yield' operator
+whySilenced// Exception silenced by 'with'
 )
 
 // Virtual machine state
@@ -30,9 +30,9 @@ type Vm struct{
 // 16 bit extension for argument for next opcode
 extint32
 // Return value
-result py.Object
-// Exit value
-exitvmExit
+retval py.Object
+// VM Status code for main loop
+whyvmStatus
 // Current Pending exception type, value and traceback
 curexc py.ExceptionInfo
 // Previous exception type, value and traceback