From e7584879a3cbec471c6d08b4fb7d4788fd1394ec Mon Sep 17 00:00:00 2001
From: Sky Johnson <skylearj@gmail.com>
Date: Sun, 2 Mar 2025 20:36:52 -0600
Subject: [PATCH] ref 5

---
 scanner.go | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/scanner.go b/scanner.go
index 0d1bf17..7b9fc72 100644
--- a/scanner.go
+++ b/scanner.go
@@ -7,6 +7,15 @@ import (
 	"io"
 )
 
+// Pre-declared errors to reduce allocations
+var (
+	ErrUnterminatedString  = errors.New("unterminated string")
+	ErrUnterminatedEscape  = errors.New("unterminated escape sequence")
+	ErrUnterminatedComment = errors.New("unclosed block comment")
+	ErrInvalidComment      = errors.New("invalid comment")
+	ErrNameStartWithLetter = errors.New("name must start with letter")
+)
+
 // Scanner handles the low-level parsing of the configuration format
 type Scanner struct {
 	reader *bufio.Reader
@@ -158,7 +167,7 @@ func (s *Scanner) NextToken() (Token, error) {
 		// Just a single dash
 		_, _ = s.ReadByte() // consume dash
 		return Token{Type: TokenError, Value: []byte("unexpected '-'")},
-			fmt.Errorf("unexpected '-' at line %d, column %d", startLine, startColumn)
+			s.Error("unexpected '-'")
 
 	case b == '"':
 		return s.scanString(startLine, startColumn)
@@ -171,8 +180,8 @@ func (s *Scanner) NextToken() (Token, error) {
 
 	default:
 		_, _ = s.ReadByte() // consume the unexpected character
-		err := fmt.Errorf("unexpected character: %c", b)
-		return Token{Type: TokenError, Value: []byte(err.Error()), Line: startLine, Column: startColumn}, err
+		return Token{Type: TokenError, Value: []byte(fmt.Sprintf("unexpected character: %c", b)), Line: startLine, Column: startColumn},
+			s.Error(fmt.Sprintf("unexpected character: %c", b))
 	}
 }
 
@@ -190,7 +199,7 @@ func (s *Scanner) scanComment() error {
 		return err
 	}
 	if b != '-' {
-		return s.Error("invalid comment")
+		return ErrInvalidComment
 	}
 
 	// Check for block comment [[
@@ -202,7 +211,7 @@ func (s *Scanner) scanComment() error {
 			for {
 				b, err := s.ReadByte()
 				if err != nil {
-					return s.Error("unclosed block comment")
+					return ErrUnterminatedComment
 				}
 				if b == ']' {
 					if n, err := s.PeekByte(); err == nil && n == ']' {
@@ -243,7 +252,7 @@ func (s *Scanner) scanString(startLine, startColumn int) (Token, error) {
 	for {
 		b, err := s.ReadByte()
 		if err != nil {
-			return Token{Type: TokenError, Value: []byte("unterminated string")}, errors.New("unterminated string")
+			return Token{Type: TokenError, Value: []byte(ErrUnterminatedString.Error())}, ErrUnterminatedString
 		}
 
 		if b == '"' {
@@ -254,7 +263,7 @@ func (s *Scanner) scanString(startLine, startColumn int) (Token, error) {
 		if b == '\\' {
 			escaped, err := s.ReadByte()
 			if err != nil {
-				return Token{Type: TokenError, Value: []byte("unterminated escape sequence")}, errors.New("unterminated escape sequence")
+				return Token{Type: TokenError, Value: []byte(ErrUnterminatedEscape.Error())}, ErrUnterminatedEscape
 			}
 			switch escaped {
 			case '"':
@@ -273,7 +282,7 @@ func (s *Scanner) scanString(startLine, startColumn int) (Token, error) {
 		}
 	}
 
-	// Return token using buffer directly - we'll copy in NextToken if needed
+	// Use the buffer directly - consumer is responsible for copying if needed
 	return Token{
 		Type:   TokenString,
 		Value:  s.buffer,
@@ -294,7 +303,7 @@ func (s *Scanner) scanName(startLine, startColumn int) (Token, error) {
 	}
 
 	if !isLetter(b) {
-		return Token{Type: TokenError, Value: []byte("name must start with letter")}, s.Error("name must start with letter")
+		return Token{Type: TokenError, Value: []byte(ErrNameStartWithLetter.Error())}, ErrNameStartWithLetter
 	}
 	s.buffer = append(s.buffer, b)
 
@@ -314,10 +323,9 @@ func (s *Scanner) scanName(startLine, startColumn int) (Token, error) {
 		_, _ = s.ReadByte()
 	}
 
-	// Check if it's a boolean
+	// Check if it's a boolean - fixed comparison
 	tokenType := TokenName
-	if len(s.buffer) == 4 && (s.buffer[0] == 't' && s.buffer[1] == 'r' && s.buffer[2] == 'u' && s.buffer[3] == 'e' ||
-		s.buffer[0] == 'f' && s.buffer[1] == 'a' && s.buffer[2] == 'l' && s.buffer[3] == 's' && s.buffer[4] == 'e') {
+	if string(s.buffer) == "true" || string(s.buffer) == "false" {
 		tokenType = TokenBoolean
 	}