1 files changed, 32 insertions, 5 deletions
diff --git a/formats/json/commonMain/src/kotlinx/serialization/json/internal/lexer/StringJsonLexer.kt b/formats/json/commonMain/src/kotlinx/serialization/json/internal/lexer/StringJsonLexer.kt
index 0ff980a2..9f2e5190 100644
--- a/formats/json/commonMain/src/kotlinx/serialization/json/internal/lexer/StringJsonLexer.kt
+++ b/formats/json/commonMain/src/kotlinx/serialization/json/internal/lexer/StringJsonLexer.kt
@@ -73,19 +73,25 @@ internal class StringJsonLexer(override val source: String) : AbstractJsonLexer(
             if (c == expected) return
             unexpectedToken(expected)
         }
+        currentPosition = -1 // for correct EOF reporting
         unexpectedToken(expected) // EOF
     }
 
     override fun consumeKeyString(): String {
         /*
-       * For strings we assume that escaped symbols are rather an exception, so firstly
-       * we optimistically scan for closing quote via intrinsified and blazing-fast 'indexOf',
-       * than do our pessimistic check for backslash and fallback to slow-path if necessary.
-       */
+         * For strings we assume that escaped symbols are rather an exception, so firstly
+         * we optimistically scan for closing quote via intrinsified and blazing-fast 'indexOf',
+         * than do our pessimistic check for backslash and fallback to slow-path if necessary.
+         */
         consumeNextToken(STRING)
         val current = currentPosition
         val closingQuote = source.indexOf('"', current)
-        if (closingQuote == -1) fail(TC_STRING)
+        if (closingQuote == -1) {
+            // advance currentPosition to a token after the end of the string to guess position in the error msg
+            // (not always correct, as `:`/`,` are valid contents of the string, but good guess anyway)
+            consumeStringLenient()
+            fail(TC_STRING, wasConsumed = false)
+        }
         // Now we _optimistically_ know where the string ends (it might have been an escaped quote)
         for (i in current until closingQuote) {
             // Encountered escape sequence, should fallback to "slow" path and symbolic scanning
@@ -96,4 +102,25 @@ internal class StringJsonLexer(override val source: String) : AbstractJsonLexer(
         this.currentPosition = closingQuote + 1
         return source.substring(current, closingQuote)
     }
+
+    override fun consumeStringChunked(isLenient: Boolean, consumeChunk: (stringChunk: String) -> Unit) {
+        (if (isLenient) consumeStringLenient() else consumeString()).chunked(BATCH_SIZE).forEach(consumeChunk)
+    }
+
+    override fun peekLeadingMatchingValue(keyToMatch: String, isLenient: Boolean): String? {
+        val positionSnapshot = currentPosition
+        try {
+            if (consumeNextToken() != TC_BEGIN_OBJ) return null // Malformed JSON, bailout
+            val firstKey = peekString(isLenient)
+            if (firstKey != keyToMatch) return null
+            discardPeeked() // consume firstKey
+            if (consumeNextToken() != TC_COLON) return null
+            return peekString(isLenient)
+        } finally {
+            // Restore the position
+            currentPosition = positionSnapshot
+            discardPeeked()
+        }
+    }
 }
+