From a3cff3a152becc9dc49388dd991d387b284de2d4 Mon Sep 17 00:00:00 2001
From: Tristan Morgan <tristanmorgan@users.noreply.github.com>
Date: Fri, 1 Nov 2024 14:41:45 +1100
Subject: [PATCH] Print iterator.

---
 parser/print.go      | 111 +++++++++++++++++++++----------------------
 parser/print_test.go |  34 ++++++-------
 2 files changed, 72 insertions(+), 73 deletions(-)

diff --git a/parser/print.go b/parser/print.go
index 1e50604..9e618e2 100644
--- a/parser/print.go
+++ b/parser/print.go
@@ -3,6 +3,7 @@ package parser
 import (
 	"bufio"
 	"fmt"
+	"iter"
 	"strings"
 )
 
@@ -20,68 +21,66 @@ func repeatDirection(neg, pos string, vect int) string {
 	return strings.Repeat(neg, abs(vect))
 }
 
-func instPrint(inst, lastInst, lastlastInst Instruction) string {
-	switch inst.operator {
-	case opAddDp:
-		return repeatDirection("<", ">", inst.operand)
-	case opAddVal:
-		return repeatDirection("-", "+", inst.operand)
-	case opSetVal:
-		prefix := "[-]"
-		if lastInst.IsZeroOp() && inst.operand != 0 {
-			prefix = ""
-		}
-		return prefix + repeatDirection("-", "+", inst.operand)
-	case opOut:
-		return "."
-	case opIn:
-		return ","
-	case opJmpZ:
-		return "["
-	case opJmpNz:
-		return "]"
-	case opMove:
-		return "[-" + repeatDirection("<", ">", inst.operand) + "+" + repeatDirection(">", "<", inst.operand) + "]"
-	case opMovN:
-		return "[-" + repeatDirection("<", ">", inst.operand) + "-" + repeatDirection(">", "<", inst.operand) + "]"
-	case opSkip:
-		return "[" + repeatDirection("<", ">", inst.operand) + "]"
-	case opNoop:
-		if lastInst.operator == opMulVal {
-			multiplier := repeatDirection("-", "+", inst.operand)
-			return "[-" + repeatDirection("<", ">", lastInst.operand) + multiplier + repeatDirection(">", "<", lastInst.operand) + "]"
-		} else if lastInst.operator == opDupVal {
-			return "[-" + repeatDirection("<", ">", lastInst.operand) + "+" + repeatDirection("<", ">", inst.operand-lastInst.operand) + "+" + repeatDirection(">", "<", inst.operand) + "]"
-		} else if lastlastInst.operator == opVec {
-			multiplier := repeatDirection("-", "+", lastInst.operand)
-			return "[-" + repeatDirection("<", ">", lastlastInst.operand) + multiplier + repeatDirection("<", ">", inst.operand-lastlastInst.operand) + multiplier + repeatDirection(">", "<", inst.operand) + "]"
+func instPrints(program []Instruction) iter.Seq[string] {
+	return func(yield func(string) bool) {
+
+		depth := 0
+		indent := ""
+		for pc, inst := range program {
+			indent = strings.Repeat("\t", depth)
+			str := ""
+			switch inst.operator {
+			case opAddDp:
+				str = repeatDirection("<", ">", inst.operand)
+			case opAddVal:
+				str = repeatDirection("-", "+", inst.operand)
+			case opSetVal:
+				prefix := "[-]"
+				if program[pc-1].IsZeroOp() && inst.operand != 0 {
+					prefix = ""
+				}
+				str = prefix + repeatDirection("-", "+", inst.operand)
+			case opOut:
+				str = "."
+			case opIn:
+				str = ","
+			case opJmpZ:
+				str = "["
+				depth++
+			case opJmpNz:
+				str = "]"
+				depth--
+				indent = strings.Repeat("\t", depth)
+			case opMove:
+				str = "[-" + repeatDirection("<", ">", inst.operand) + "+" + repeatDirection(">", "<", inst.operand) + "]"
+			case opMovN:
+				str = "[-" + repeatDirection("<", ">", inst.operand) + "-" + repeatDirection(">", "<", inst.operand) + "]"
+			case opSkip:
+				str = "[" + repeatDirection("<", ">", inst.operand) + "]"
+			case opMulVal:
+				multiplier := repeatDirection("-", "+", program[pc+1].operand)
+				str = "[-" + repeatDirection("<", ">", inst.operand) + multiplier + repeatDirection(">", "<", inst.operand) + "]"
+			case opDupVal:
+				str = "[-" + repeatDirection("<", ">", inst.operand) + "+" + repeatDirection("<", ">", program[pc+1].operand-inst.operand) + "+" + repeatDirection(">", "<", program[pc+1].operand) + "]"
+			case opVec:
+				multiplier := repeatDirection("-", "+", program[pc+1].operand)
+				str = "[-" + repeatDirection("<", ">", inst.operand) + multiplier + repeatDirection("<", ">", program[pc+2].operand-inst.operand) + multiplier + repeatDirection(">", "<", program[pc+2].operand) + "]"
+			case opNoop:
+				continue
+			default:
+				return
+			}
+			if !yield(indent + str) {
+				return
+			}
 		}
-		return ""
-	default:
-		return ""
 	}
 }
 
 // Print pretty prints out the parsed program.
 func Print(program []Instruction, writer *bufio.Writer) {
-	depth := 0
-	startLoop := NewInstruction('[')
-	endLoop := NewInstruction(']')
-	lastInst := NewInstruction('!')
-	lastlastInst := NewInstruction('!')
-	for _, inst := range program {
-		if inst.SameOp(endLoop) {
-			depth--
-		}
-		printout := instPrint(inst, lastInst, lastlastInst)
-		if printout != "" {
-			fmt.Fprintln(writer, strings.Repeat("\t", depth), printout)
-		}
-		if inst.SameOp(startLoop) {
-			depth++
-		}
-		lastlastInst = lastInst
-		lastInst = inst
+	for printout := range instPrints(program) {
+		fmt.Fprintln(writer, printout)
 	}
 	writer.Flush()
 }
diff --git a/parser/print_test.go b/parser/print_test.go
index 0a875c6..7e33fa0 100644
--- a/parser/print_test.go
+++ b/parser/print_test.go
@@ -8,23 +8,23 @@ import (
 	"testing"
 )
 
-var testprogram = ` >>>>>
- [-]+++++
- [->>+<<]
- >
- [
-	 ,
-	 [<<<]
-	 ++
-	 [->>++<<]
-	 >>
-	 [->+>+<<]
-	 >
-	 [->+++>+++<<]
- ]
- >>
- .
- [->>-<<]
+var testprogram = `>>>>>
+[-]+++++
+[->>+<<]
+>
+[
+	,
+	[<<<]
+	++
+	[->>++<<]
+	>>
+	[->+>+<<]
+	>
+	[->+++>+++<<]
+]
+>>
+.
+[->>-<<]
 `
 
 func TestPrint(t *testing.T) {