Fix SNBT Parsing and writing of single quoted strings, and strings with quotes or single quotes within.

lib/nbt/Stream.dart

@@ -503,18 +503,31 @@ class StringReader {
     return result.toString();
   }
 
-  // Read a string enclosed in double quotes
+  /// Read a string enclosed in double quotes
   String readQuotedString() {
     _quotedString = true;
-    if (next() != '"') {
-      throw Exception('Expected double quotes at the start of a string');
+    var nxtChar = next();
+
+    if (nxtChar != '"' && nxtChar != "'") {
+      throw Exception(
+          'Expected double quotes or single quotes at the start of a string');
     }
     StringBuffer result = StringBuffer();
+    bool escaping = false;
+    String quoteDigit = nxtChar;
+
     while (canRead) {
       String char = next();
-      if (char == '"') {
+
+      if (char == '"' && quoteDigit == "\"") {
         break;
+      } else if (char == '\\' && peek() == '\'' && quoteDigit == '\'') {
+        escaping = true;
+        continue;
+      } else if (char == '\'' && quoteDigit == '\'') {
+        if (!escaping) break;
       }
+      escaping = false;
       result.write(char);
     }
     _quotedString = false;
@@ -552,13 +565,15 @@ class StringReader {
   }
 
   String readString() {
-    if (peek() == "\"") {
+    if (peek() == "\"" || peek() == "'") {
       return readQuotedString();
     } else
       return readUnquotedString();
   }
 
-  // Read a specific character and throw an exception if it's not found
+  /// Read a specific character and throw an exception if it's not found
+  ///
+  /// Parameter is case-insensitive
   void expect(String expectedChar) {
     if (next().toLowerCase() != expectedChar.toLowerCase()) {
       throw Exception('Expected $expectedChar');
@@ -573,4 +588,10 @@ class StringReader {
     _position = _lastPostion;
     _lastPostion = 0;
   }
+
+  @override
+  String toString() {
+    // Returns the entire value starting from position
+    return _buffer.substring(_position);
+  }
 }

lib/nbt/Tag.dart

@@ -67,6 +67,12 @@ enum TagType {
         break;
       }
 
+      if (val == "'") {
+        reader.next();
+        isQuoted = true;
+        break;
+      }
+
       if (val == '{') {
         ret = TagType.Compound; // Detected a CompoundTag
         reader.next(); // Consume '{'
@@ -251,7 +257,13 @@ abstract class Tag {
     TagType type = TagType.getStringifiedTagType(string);
     Tag tag = Tag.makeTagOfType(type);
     tag._key = name;
-    tag.readStringifiedValue(string);
+    try {
+      tag.readStringifiedValue(string);
+    } catch (E, stack) {
+      print(E);
+      print(string.getSnapshot());
+      print(stack);
+    }
 
     return tag;
   }
@@ -286,6 +298,14 @@ abstract class Tag {
     }
   }
 
+  bool shouldUseSingleQuotes(String value) {
+    return value.contains("\"");
+  }
+
+  bool shouldEscapeSingleQuotes(String value) {
+    return value.contains("'");
+  }
+
   void writeStringifiedValue(StringBuilder builder, int indent, bool isList);
   void readStringifiedValue(StringReader reader);
 

lib/nbt/impl/IntArrayTag.dart

@@ -66,6 +66,11 @@ class IntArrayTag extends Tag {
     while (reader.peek() != "]") {
       value.add(int.parse(reader.readNumber()));
 
+      // The SNBT standard does not require a integer to be suffixed by a 'I'.
+      // This implementation honors that by making it optional.
+      // FIX 1/21/25 @Aria: Int Array was lacking the skipping of the I digit when it might possibly be present
+      if (reader.peek().toLowerCase() == "i") reader.expect("I");
+
       if (reader.peek() == ",") reader.next();
     }
     reader.expect("]");

lib/nbt/impl/StringTag.dart

@@ -46,10 +46,17 @@ class StringTag extends Tag {
 
   @override
   void writeStringifiedValue(StringBuilder builder, int indent, bool isList) {
-    if (shouldQuote(value))
-      builder.append("${isList ? "".padLeft(indent, '\t') : ""}\"${value}\"");
-    else
-      builder.append("${isList ? "".padLeft(indent, '\t') : ""}${value}");
+    final useSingleQuotes = shouldUseSingleQuotes(value);
+    final quote = useSingleQuotes ? '\'' : '"';
+    final escapeQuote = useSingleQuotes ? '\\\'' : '\\"';
+
+    String escapedValue = value;
+    if (shouldEscapeSingleQuotes(value) && useSingleQuotes) {
+      escapedValue = value.replaceAll('\'', escapeQuote);
+    }
+
+    builder.append(
+        "${isList ? "".padLeft(indent, '\t') : ""}${quote}${escapedValue}${quote}");
   }
 
   @override