From 460425c490bf1ac5f4a4838f2b40723bf0d5239b Mon Sep 17 00:00:00 2001
From: Tristan Morgan <tristanmorgan@users.noreply.github.com>
Date: Fri, 10 May 2024 12:35:46 +1000
Subject: [PATCH] cleanup common code.

---
 parser/instruction.go      |  8 ++++++++
 parser/instruction_test.go | 30 ++++++++++++++++++++++++++++++
 parser/tokenise.go         |  8 ++------
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/parser/instruction.go b/parser/instruction.go
index 30d71a4..39c315c 100644
--- a/parser/instruction.go
+++ b/parser/instruction.go
@@ -78,3 +78,11 @@ func (inst Instruction) SameOp(instTwo Instruction) bool {
 func (inst Instruction) Complement(instTwo Instruction) bool {
 	return inst.SameOp(instTwo) && inst.operand+instTwo.operand == 0
 }
+
+// IsZeroOp returns true for ops that have left the pointer on a zero
+func (inst Instruction) IsZeroOp() bool {
+	return inst.operator == opJmpNz ||
+		inst.operator == opNoop ||
+		inst.operator == opMove ||
+		(inst.operator == opSetVal && inst.operand == 0)
+}
diff --git a/parser/instruction_test.go b/parser/instruction_test.go
index 5c6cee3..64652dd 100644
--- a/parser/instruction_test.go
+++ b/parser/instruction_test.go
@@ -32,6 +32,36 @@ func TestNewInstruction(t *testing.T) {
 	}
 }
 
+func TestIsZeroOp(t *testing.T) {
+	program := []Instruction{
+		{opNoop, 0},
+		{opAddDp, 1},
+		{opAddVal, 1},
+		{opSetVal, -1},
+		{opSetVal, 0},
+		{opOut, 1},
+		{opIn, 1},
+		{opJmpZ, 0},
+		{opJmpNz, 0},
+	}
+	want := []bool{
+		true,
+		false,
+		false,
+		false,
+		true,
+		false,
+		false,
+		false,
+		true,
+	}
+
+	for idx, val := range program {
+		if want[idx] != val.IsZeroOp() {
+			t.Errorf("testing %v got %v want %v", val, val.IsZeroOp(), want[idx])
+		}
+	}
+}
 func TestSameOp(t *testing.T) {
 	opsList := []Opcode{
 		opNoop,
diff --git a/parser/tokenise.go b/parser/tokenise.go
index c434445..e71f988 100644
--- a/parser/tokenise.go
+++ b/parser/tokenise.go
@@ -36,9 +36,7 @@ func Tokenise(input io.ByteReader) (program []Instruction, err error) {
 				program[pc-1].operand += instruction.operand
 				program = program[:pc]
 				pc--
-			} else if program[pc-1].SameOp(NewInstruction(']')) ||
-				program[pc-1].operator == opMove ||
-				program[pc-1].operator == opNoop {
+			} else if program[pc-1].IsZeroOp() {
 				operand := instruction.operand
 				program = program[:pc]
 				program = append(program, Instruction{opSetVal, operand})
@@ -53,9 +51,7 @@ func Tokenise(input io.ByteReader) (program []Instruction, err error) {
 			jmpStack = jmpStack[:len(jmpStack)-1]
 			program[pc].operand = jmpPc
 			program[jmpPc].operand = pc
-			if jmpPc == 1 ||
-				program[jmpPc-1].Complement(Instruction{opSetVal, 0}) ||
-				program[jmpPc-1].SameOp(NewInstruction(']')) {
+			if program[jmpPc-1].IsZeroOp() {
 				pc = jmpPc
 				program = program[:pc]
 				pc--