From edfc7aa91b542978ce28eb109b99a257650b62b4 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Sat, 18 Feb 2023 21:57:39 -0700
Subject: decode_scan, jsonparse: Rework the behavior to make a bit more sense

 - decode_scan: Don't have .Reset() re-play an erroring rune
 - decode_Scan: Have RuneTypeEOF always be zero-width
 - jsonparse: Don't replace syntax errors with RuneTypeEOF if there's no barrier
---
 decode_scan.go | 71 ++++++++++------------------------------------------------
 1 file changed, 12 insertions(+), 59 deletions(-)

(limited to 'decode_scan.go')

diff --git a/decode_scan.go b/decode_scan.go
index 7911c01..fcf47ff 100644
--- a/decode_scan.go
+++ b/decode_scan.go
@@ -31,8 +31,7 @@ type runeTypeScanner struct {
 // The returned error is a *ReadError, a *SyntaxError, or nil.
 // An EOF condition is represented as one of:
 //
-//	end of value but not file:      (_, >0, RuneTypeEOF, nil)
-//	end of both value and file:     (_, 0, RuneTypeEOF, nil)
+//	end of value:                   (_, 0, RuneTypeEOF, nil)
 //	end of file in middle of value: (_, 0, RuneTypeError, &DecodeSyntaxError{Offset: offset: Err: io.ErrUnexepctedEOF})
 //	end of file at start of value:  (_, 0, RuneTypeError, &DecodeSyntaxError{Offset: offset: Err: io.EOF})
 func (sc *runeTypeScanner) ReadRuneType() (rune, int, jsonparse.RuneType, error) {
@@ -59,8 +58,14 @@ func (sc *runeTypeScanner) ReadRuneType() (rune, int, jsonparse.RuneType, error)
 			} else {
 				sc.rErr = nil
 			}
-			if sc.rType == jsonparse.RuneTypeSpace {
+			switch sc.rType {
+			case jsonparse.RuneTypeSpace:
 				goto again
+			case jsonparse.RuneTypeEOF:
+				sc.offset -= int64(sc.rSize)
+				sc.rRune = 0
+				sc.rSize = 0
+				_ = sc.inner.UnreadRune()
 			}
 		case io.EOF:
 			sc.rType, err = sc.parser.HandleEOF()
@@ -122,65 +127,13 @@ func (sc *runeTypeScanner) PopReadBarrier() {
 		} else {
 			sc.rErr = nil
 		}
-	case sc.rType == jsonparse.RuneTypeEOF && sc.rSize > 0:
-		// re-figure the rType and rErr
-		var err error
-		sc.rType, err = sc.parser.HandleRune(sc.rRune)
-		if err != nil {
-			sc.rErr = &DecodeSyntaxError{
-				Offset: sc.offset - int64(sc.rSize),
-				Err:    err,
-			}
-		} else {
-			sc.rErr = nil
-		}
-		// tell it to use that rType and rErr
-		_ = sc.UnreadRune() // we set it up to always succeed
-	case sc.rType == jsonparse.RuneTypeEOF:
-		// re-figure the rType and rErr
-		var err error
-		sc.rType, err = sc.parser.HandleEOF()
-		if err != nil {
-			sc.rErr = &DecodeSyntaxError{
-				Offset: sc.offset,
-				Err:    err,
-			}
-		} else {
-			sc.rErr = nil
-		}
+	case sc.rTypeOK && sc.rType == jsonparse.RuneTypeEOF:
+		sc.rTypeOK = false // forget the sticky EOF
 	}
 }
 
 func (sc *runeTypeScanner) Reset() {
 	sc.parser.Reset()
-	switch {
-	case sc.repeat:
-		// re-figure the rType and rErr
-		var err error
-		sc.rType, err = sc.parser.HandleRune(sc.rRune)
-		if err != nil {
-			sc.rErr = &DecodeSyntaxError{
-				Offset: sc.offset - int64(sc.rSize),
-				Err:    err,
-			}
-		} else {
-			sc.rErr = nil
-		}
-	case sc.rType == jsonparse.RuneTypeEOF && sc.rSize > 0:
-		// re-figure the rType and rErr
-		var err error
-		sc.rType, err = sc.parser.HandleRune(sc.rRune)
-		if err != nil {
-			sc.rErr = &DecodeSyntaxError{
-				Offset: sc.offset - int64(sc.rSize),
-				Err:    err,
-			}
-		} else {
-			sc.rErr = nil
-		}
-		// tell it to use that rType and rErr
-		_ = sc.UnreadRune() // we set it up to always succeed
-	default:
-		sc.rTypeOK = false
-	}
+	sc.rTypeOK = false // forget any sticky errors/EOF
+	sc.repeat = false  // feed the rune (if any) through the parser again
 }
-- 
cgit v1.2.3-54-g00ecf