Add build tag: expr_debug (#521)

Author: antonmedv

.github/workflows/test.yml

@@ -20,3 +20,14 @@ jobs:
           go-version: ${{ matrix.go-version }}
       - name: Test
         run: go test ./...
+
+  debug:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup Go 1.18
+        uses: actions/setup-go@v4
+        with:
+          go-version: 1.18
+      - name: Test
+        run: go test -tags=expr_debug -run=TestDebugger -v ./vm

debug/debugger.go

@@ -7,9 +7,10 @@ import (
 	"strings"
 	"time"
 
-	. "github.com/expr-lang/expr/vm"
 	"github.com/gdamore/tcell/v2"
 	"github.com/rivo/tview"
+
+	. "github.com/expr-lang/expr/vm"
 )
 
 func StartDebugger(program *Program, env any) {
@@ -112,14 +113,17 @@ func StartDebugger(program *Program, env any) {
 			}
 
 			stack.Clear()
-			for i, value := range vm.Stack() {
+			for i, value := range vm.Stack {
 				stack.SetCellSimple(i, 0, fmt.Sprintf("% *d: ", 2, i))
 				stack.SetCellSimple(i, 1, fmt.Sprintf("%#v", value))
 			}
 			stack.ScrollToEnd()
 
 			scope.Clear()
-			s := vm.Scope()
+			var s *Scope
+			if len(vm.Scopes) > 0 {
+				s = vm.Scopes[len(vm.Scopes)-1]
+			}
 			if s != nil {
 				type pair struct {
 					key   string

vm/debug.go

@@ -0,0 +1,5 @@
+//go:build expr_debug
+
+package vm
+
+const debug = true

vm/debug_off.go

@@ -0,0 +1,5 @@
+//go:build !expr_debug
+
+package vm
+
+const debug = false

vm/debug_test.go

@@ -0,0 +1,40 @@
+//go:build expr_debug
+
+package vm_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/expr-lang/expr/compiler"
+	"github.com/expr-lang/expr/parser"
+	"github.com/expr-lang/expr/vm"
+)
+
+func TestDebugger(t *testing.T) {
+	input := `[1, 2]`
+
+	node, err := parser.Parse(input)
+	require.NoError(t, err)
+
+	program, err := compiler.Compile(node, nil)
+	require.NoError(t, err)
+
+	debug := vm.Debug()
+	go func() {
+		debug.Step()
+		debug.Step()
+		debug.Step()
+		debug.Step()
+	}()
+	go func() {
+		for range debug.Position() {
+		}
+	}()
+
+	_, err = debug.Run(program, nil)
+	require.NoError(t, err)
+	require.Len(t, debug.Stack, 0)
+	require.Nil(t, debug.Scopes)
+}

vm/utils.go

@@ -0,0 +1,11 @@
+package vm
+
+import (
+	"reflect"
+)
+
+type Function = func(params ...any) (any, error)
+
+var MemoryBudget uint = 1e6
+
+var errorType = reflect.TypeOf((*error)(nil)).Elem()

vm/vm.go

@@ -13,11 +13,6 @@ import (
 	"github.com/expr-lang/expr/vm/runtime"
 )
 
-var MemoryBudget uint = 1e6
-var errorType = reflect.TypeOf((*error)(nil)).Elem()
-
-type Function = func(params ...any) (any, error)
-
 func Run(program *Program, env any) (any, error) {
 	if program == nil {
 		return nil, fmt.Errorf("program is nil")
@@ -27,15 +22,24 @@ func Run(program *Program, env any) (any, error) {
 	return vm.Run(program, env)
 }
 
+func Debug() *VM {
+	vm := &VM{
+		debug: true,
+		step:  make(chan struct{}, 0),
+		curr:  make(chan int, 0),
+	}
+	return vm
+}
+
 type VM struct {
-	stack        []any
+	Stack        []any
+	Scopes       []*Scope
 	ip           int
-	scopes       []*Scope
+	memory       uint
+	memoryBudget uint
 	debug        bool
 	step         chan struct{}
 	curr         chan int
-	memory       uint
-	memoryBudget uint
 }
 
 type Scope struct {
@@ -47,15 +51,6 @@ type Scope struct {
 	Acc     any
 }
 
-func Debug() *VM {
-	vm := &VM{
-		debug: true,
-		step:  make(chan struct{}, 0),
-		curr:  make(chan int, 0),
-	}
-	return vm
-}
-
 func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 	defer func() {
 		if r := recover(); r != nil {
@@ -74,22 +69,22 @@ func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 		}
 	}()
 
-	if vm.stack == nil {
-		vm.stack = make([]any, 0, 2)
+	if vm.Stack == nil {
+		vm.Stack = make([]any, 0, 2)
 	} else {
-		vm.stack = vm.stack[0:0]
+		vm.Stack = vm.Stack[0:0]
 	}
 
-	if vm.scopes != nil {
-		vm.scopes = vm.scopes[0:0]
+	if vm.Scopes != nil {
+		vm.Scopes = vm.Scopes[0:0]
 	}
 
 	vm.memoryBudget = MemoryBudget
 	vm.memory = 0
 	vm.ip = 0
 
 	for vm.ip < len(program.Bytecode) {
-		if vm.debug {
+		if debug && vm.debug {
 			<-vm.step
 		}
 
@@ -204,7 +199,7 @@ func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 			}
 
 		case OpJumpIfEnd:
-			scope := vm.Scope()
+			scope := vm.scope()
 			if scope.Index >= scope.Len {
 				vm.ip += arg
 			}
@@ -399,7 +394,7 @@ func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 
 		case OpValidateArgs:
 			fn := vm.pop().(Function)
-			mem, err := fn(vm.stack[len(vm.stack)-arg:]...)
+			mem, err := fn(vm.Stack[len(vm.Stack)-arg:]...)
 			if err != nil {
 				panic(err)
 			}
@@ -443,49 +438,49 @@ func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 			vm.push(runtime.Deref(a))
 
 		case OpIncrementIndex:
-			vm.Scope().Index++
+			vm.scope().Index++
 
 		case OpDecrementIndex:
-			scope := vm.Scope()
+			scope := vm.scope()
 			scope.Index--
 
 		case OpIncrementCount:
-			scope := vm.Scope()
+			scope := vm.scope()
 			scope.Count++
 
 		case OpGetIndex:
-			vm.push(vm.Scope().Index)
+			vm.push(vm.scope().Index)
 
 		case OpSetIndex:
-			scope := vm.Scope()
+			scope := vm.scope()
 			scope.Index = vm.pop().(int)
 
 		case OpGetCount:
-			scope := vm.Scope()
+			scope := vm.scope()
 			vm.push(scope.Count)
 
 		case OpGetLen:
-			scope := vm.Scope()
+			scope := vm.scope()
 			vm.push(scope.Len)
 
 		case OpGetGroupBy:
-			vm.push(vm.Scope().GroupBy)
+			vm.push(vm.scope().GroupBy)
 
 		case OpGetAcc:
-			vm.push(vm.Scope().Acc)
+			vm.push(vm.scope().Acc)
 
 		case OpSetAcc:
-			vm.Scope().Acc = vm.pop()
+			vm.scope().Acc = vm.pop()
 
 		case OpPointer:
-			scope := vm.Scope()
+			scope := vm.scope()
 			vm.push(scope.Array.Index(scope.Index).Interface())
 
 		case OpThrow:
 			panic(vm.pop().(error))
 
 		case OpGroupBy:
-			scope := vm.Scope()
+			scope := vm.scope()
 			if scope.GroupBy == nil {
 				scope.GroupBy = make(map[any][]any)
 			}
@@ -496,46 +491,46 @@ func (vm *VM) Run(program *Program, env any) (_ any, err error) {
 		case OpBegin:
 			a := vm.pop()
 			array := reflect.ValueOf(a)
-			vm.scopes = append(vm.scopes, &Scope{
+			vm.Scopes = append(vm.Scopes, &Scope{
 				Array: array,
 				Len:   array.Len(),
 			})
 
 		case OpEnd:
-			vm.scopes = vm.scopes[:len(vm.scopes)-1]
+			vm.Scopes = vm.Scopes[:len(vm.Scopes)-1]
 
 		default:
 			panic(fmt.Sprintf("unknown bytecode %#x", op))
 		}
 
-		if vm.debug {
+		if debug && vm.debug {
 			vm.curr <- vm.ip
 		}
 	}
 
-	if vm.debug {
+	if debug && vm.debug {
 		close(vm.curr)
 		close(vm.step)
 	}
 
-	if len(vm.stack) > 0 {
+	if len(vm.Stack) > 0 {
 		return vm.pop(), nil
 	}
 
 	return nil, nil
 }
 
 func (vm *VM) push(value any) {
-	vm.stack = append(vm.stack, value)
+	vm.Stack = append(vm.Stack, value)
 }
 
 func (vm *VM) current() any {
-	return vm.stack[len(vm.stack)-1]
+	return vm.Stack[len(vm.Stack)-1]
 }
 
 func (vm *VM) pop() any {
-	value := vm.stack[len(vm.stack)-1]
-	vm.stack = vm.stack[:len(vm.stack)-1]
+	value := vm.Stack[len(vm.Stack)-1]
+	vm.Stack = vm.Stack[:len(vm.Stack)-1]
 	return value
 }
 
@@ -546,15 +541,8 @@ func (vm *VM) memGrow(size uint) {
 	}
 }
 
-func (vm *VM) Stack() []any {
-	return vm.stack
-}
-
-func (vm *VM) Scope() *Scope {
-	if len(vm.scopes) > 0 {
-		return vm.scopes[len(vm.scopes)-1]
-	}
-	return nil
+func (vm *VM) scope() *Scope {
+	return vm.Scopes[len(vm.Scopes)-1]
 }
 
 func (vm *VM) Step() {

vm/vm_test.go

@@ -20,33 +20,6 @@ func TestRun_NilProgram(t *testing.T) {
 	require.Error(t, err)
 }
 
-func TestRun_Debugger(t *testing.T) {
-	input := `[1, 2]`
-
-	node, err := parser.Parse(input)
-	require.NoError(t, err)
-
-	program, err := compiler.Compile(node, nil)
-	require.NoError(t, err)
-
-	debug := vm.Debug()
-	go func() {
-		debug.Step()
-		debug.Step()
-		debug.Step()
-		debug.Step()
-	}()
-	go func() {
-		for range debug.Position() {
-		}
-	}()
-
-	_, err = debug.Run(program, nil)
-	require.NoError(t, err)
-	require.Len(t, debug.Stack(), 0)
-	require.Nil(t, debug.Scope())
-}
-
 func TestRun_ReuseVM(t *testing.T) {
 	node, err := parser.Parse(`map(1..2, {#})`)
 	require.NoError(t, err)