compat/json: Correctly handle syntax-error-in-decode

1 files changed, 15 insertions, 0 deletions

diff --git a/internal/jsonparse/parse.go b/internal/jsonparse/parse.go
index 1c35533..6432d75 100644
--- a/internal/jsonparse/parse.go
+++ b/internal/jsonparse/parse.go
@@ -525,6 +525,21 @@ func (par *Parser) HandleEOF() (RuneType, error) {
 	}
 }
 
+// IsAtBarrier returns whether a read-barrier has been reached and the
+// next HandleRune call would definitely return RuneTypeEOF.
+func (par *Parser) IsAtBarrier() bool {
+	return par.initialized &&
+		// HandleRune wouldn't return early with an error.
+		!par.closed &&
+		par.err == nil &&
+		// The current (sub-)parser has reached its end, and
+		len(par.stack) == 0 &&
+		// there is a barrier, and
+		len(par.barriers) > 0 &&
+		// that barrier would definitely return RuneTypeEOF.
+		!par.barriers[len(par.barriers)-1].allowWS
+}
+
 // HandleRune feeds a Unicode rune to the Parser.
 //
 // An error is returned if and only if the RuneType is RuneTypeError.