Fixed standard input error handling

pkg/pointer/exec.go

@@ -177,9 +177,17 @@ func (p *Pointer) eval(c int, f *field.Field) (done bool, returnValue *int) {
 	case ',':
 		p.CharacterOutput(p.ss.head.Pop())
 	case '&':
-		p.ss.head.Push(p.DecimalInput())
+		if v, err := p.DecimalInput(); err != nil {
+			p.Reverse()
+		} else {
+			p.ss.head.Push(v)
+		}
 	case '~':
-		p.ss.head.Push(p.CharacterInput())
+		if v, err := p.CharacterInput(); err != nil {
+			p.Reverse()
+		} else {
+			p.ss.head.Push(v)
+		}
 	case 'y':
 		n := p.ss.head.Pop()
 		now := time.Now()

pkg/pointer/intput-output.go

@@ -2,37 +2,42 @@ package pointer
 
 import (
 	"fmt"
-	"log"
 	"os"
 )
 
 var defaultInputLastChar *int = nil
 
-func DefaultCharacterInput() int {
+func DefaultCharacterInput() (int, error) {
 	if defaultInputLastChar != nil {
 		c := *defaultInputLastChar
 		defaultInputLastChar = nil
-		return c
+		return c, nil
 	}
 	b := make([]byte, 1)
 	i, err := os.Stdin.Read(b)
 	if err != nil {
-		log.Fatalf("Error in DefaultCharacterInput { b: %c, i: %d, err: %+v }", b[0], i, err)
+		return 0, fmt.Errorf("Error in DefaultCharacterInput { b: %c, i: %d, err: %w }", b[0], i, err)
 	}
-	return int(b[0])
+	return int(b[0]), nil
 }
 
-func DefaultDecimalInput() int {
+func DefaultDecimalInput() (int, error) {
 	var v int
 	for {
-		c := DefaultCharacterInput()
+		c, err := DefaultCharacterInput()
+		if err != nil {
+			return 0, err
+		}
 		if c >= '0' && c <= '9' {
 			v = c - '0'
 			break
 		}
 	}
 	for {
-		c := DefaultCharacterInput()
+		c, err := DefaultCharacterInput()
+		if err != nil {
+			break
+		}
 		if c >= '0' && c <= '9' {
 			v = v*10 + c - '0'
 		} else {
@@ -40,7 +45,7 @@ func DefaultDecimalInput() int {
 			break
 		}
 	}
-	return v
+	return v, nil
 }
 
 func DefaultCharacterOutput(c int) {

pkg/pointer/pointer.go

@@ -9,7 +9,7 @@ import (
 
 var myRand = rand.New(rand.NewSource(time.Now().UnixNano()))
 
-type InputFunction func() int
+type InputFunction func() (int, error)
 type OutputFunction func(v int)
 
 type Pointer struct {