From c9634625455d622db90c3fc389e5036943b81d38 Mon Sep 17 00:00:00 2001
From: Nick Dumas <nobodys@business.com>
Date: Sat, 1 Jul 2023 19:25:25 -0400
Subject: [PATCH] Synchronizing access to state

---
 lexer.go  | 72 +++++++++++++++++++++++++++++++++++++++++++------------
 states.go | 22 ++++++-----------
 2 files changed, 64 insertions(+), 30 deletions(-)

diff --git a/lexer.go b/lexer.go
index b488d77..fe50d92 100644
--- a/lexer.go
+++ b/lexer.go
@@ -4,6 +4,7 @@ package wikilink
 import (
 	"fmt"
 	"strings"
+	"sync"
 	// "unicode"
 	"unicode/utf8"
 
@@ -67,19 +68,20 @@ func (l *Lexer) NextItem() Item {
 }
 
 func (l *Lexer) ignore() {
-	l.start = l.pos
+	l.SetStart(l.pos)
 }
 
 func (l *Lexer) backup() {
-	l.pos -= l.width
+	l.SetPos(l.GetPos() - l.GetWidth())
 }
 
 type Lexer struct {
-	L                 *zap.SugaredLogger
-	name, input       string
-	start, pos, width int
-	state             stateFn
-	items             chan Item
+	L                                           *zap.SugaredLogger
+	name, input                                 string
+	start, pos, width                           int
+	state                                       stateFn
+	items                                       chan Item
+	widthMutex, startMutex, posMutex, chanMutex sync.Mutex
 }
 
 func (l *Lexer) peek() rune {
@@ -106,17 +108,19 @@ func (l *Lexer) acceptRun(valid string) {
 }
 
 func (l *Lexer) emit(t ItemType) {
-	i := Item{t, l.input[l.start:l.pos]}
+	defer l.chanMutex.Unlock()
+	l.chanMutex.Lock()
+	i := Item{t, l.input[l.GetStart():l.GetPos()]}
 	L := l.L.With(
-		zap.Int("pos", l.pos),
-		zap.Int("width", l.width),
+		zap.Int("pos", l.GetPos()),
+		zap.Int("width", l.GetWidth()),
 	).Named("emit")
 
 	L.Debugw("emitting item",
 		zap.String("item", i.String()),
 	)
 	l.items <- i
-	l.start = l.pos
+	l.SetStart(l.GetPos())
 }
 
 func (l *Lexer) errorf(format string, args ...interface{}) stateFn {
@@ -135,12 +139,13 @@ func (l *Lexer) errorf(format string, args ...interface{}) stateFn {
 
 func (l *Lexer) next() rune {
 	var r rune
-	if l.pos >= len(l.input) {
-		l.width = 0
+	if l.GetPos() >= len(l.input) {
+		l.SetWidth(0)
 		return EOF
 	}
-	r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
-	l.pos += l.width
+	r, width := utf8.DecodeRuneInString(l.input[l.GetPos():])
+	l.SetWidth(width)
+	l.SetPos(l.GetPos() + l.GetWidth())
 	return r
 }
 
@@ -148,9 +153,46 @@ func (l *Lexer) run() {
 	for state := lexText; state != nil; {
 		state = state(l)
 	}
+	l.chanMutex.Lock()
 	close(l.items)
 }
 
+func (l *Lexer) GetPos() int {
+	defer l.posMutex.Unlock()
+	l.posMutex.Lock()
+	return l.pos
+}
+
+func (l *Lexer) SetPos(pos int) {
+	defer l.posMutex.Unlock()
+	l.posMutex.Lock()
+	l.pos = pos
+}
+
+func (l *Lexer) GetWidth() int {
+	defer l.widthMutex.Unlock()
+	l.widthMutex.Lock()
+	return l.width
+}
+
+func (l *Lexer) SetWidth(width int) {
+	defer l.widthMutex.Unlock()
+	l.widthMutex.Lock()
+	l.width = width
+}
+
+func (l *Lexer) GetStart() int {
+	defer l.startMutex.Unlock()
+	l.startMutex.Lock()
+	return l.start
+}
+
+func (l *Lexer) SetStart(start int) {
+	defer l.startMutex.Unlock()
+	l.startMutex.Lock()
+	l.start = start
+}
+
 type stateFn func(*Lexer) stateFn
 
 type ItemType int
diff --git a/states.go b/states.go
index 07fe9b1..6725eb0 100644
--- a/states.go
+++ b/states.go
@@ -1,7 +1,6 @@
 package wikilink
 
 import (
-	"log"
 	"strings"
 )
 
@@ -26,10 +25,9 @@ func isBlockRef(s string) bool {
 }
 
 func lexIdent(l *Lexer) stateFn {
-	log.Println("lexIdent")
 	for {
 		r := l.next()
-		s := l.input[l.pos:]
+		s := l.input[l.GetPos():]
 		if r == '\\' { // i think this will handle escape characters?
 			break
 		}
@@ -53,33 +51,29 @@ func lexIdent(l *Lexer) stateFn {
 }
 
 func lexHeading(l *Lexer) stateFn {
-	log.Println("lexHeading")
-	l.pos += len(Heading)
+	l.SetPos(l.GetPos() + len(Heading))
 	l.emit(ItemHeading)
 
 	return lexIdent
 }
 
 func lexBlockRef(l *Lexer) stateFn {
-	log.Println("lexBlockRef")
-	l.pos += len(BlockRef)
+	l.SetPos(l.GetPos() + len(BlockRef))
 	l.emit(ItemBlockRef)
 
 	return lexIdent
 }
 
 func lexAlias(l *Lexer) stateFn {
-	log.Println("lexAlias")
-	l.pos += len(Alias)
+	l.SetPos(l.GetPos() + len(Alias))
 	l.emit(ItemAlias)
 
 	return lexIdent
 }
 
 func lexText(l *Lexer) stateFn {
-	log.Println("lexText")
 	for {
-		if isOpenLink(l.input[l.pos:]) {
+		if isOpenLink(l.input[l.GetPos():]) {
 			return lexOpenLink
 		}
 		r := l.next()
@@ -92,16 +86,14 @@ func lexText(l *Lexer) stateFn {
 }
 
 func lexOpenLink(l *Lexer) stateFn {
-	log.Println("lexOpenLink")
-	l.pos += len(OpenLink)
+	l.SetPos(l.GetPos() + len(OpenLink))
 	l.emit(ItemOpenLink)
 
 	return lexIdent
 }
 
 func lexCloseLink(l *Lexer) stateFn {
-	log.Println("lexCloseLink")
-	l.pos += len(CloseLink)
+	l.SetPos(l.GetPos() + len(CloseLink))
 	l.emit(ItemCloseLink)
 
 	return lexText