diff --git a/lib/rules/utils/char-source.js b/lib/rules/utils/char-source.js
index bb211e2fb6eb..4a31cfc2f8fb 100644
--- a/lib/rules/utils/char-source.js
+++ b/lib/rules/utils/char-source.js
@@ -33,6 +33,21 @@ class SourceReader {
         this.pos = 0;
     }
 
+    /**
+     * Advances the reading position of the specified number of characters.
+     * @param {number} length Number of characters to advance.
+     * @returns {void}
+     */
+    advance(length) {
+        this.pos += length;
+    }
+
+    /**
+     * Reads characters from the source.
+     * @param {number} [offset=0] The offset where reading starts, relative to the current position.
+     * @param {number} [length=1] Number of characters to read.
+     * @returns {string} A substring of source characters.
+     */
     read(offset = 0, length = 1) {
         const start = offset + this.pos;
 
@@ -53,7 +68,7 @@ function readHexSequence(reader, length) {
     const str = reader.read(0, length);
     const charCode = parseInt(str, 16);
 
-    reader.pos += length;
+    reader.advance(length);
     return String.fromCharCode(charCode);
 }
 
@@ -86,7 +101,7 @@ function readUnicodeSequence(reader) {
 function readOctalSequence(reader, maxLength) {
     const [octalStr] = reader.read(-1, maxLength).match(/^[0-7]+/u);
 
-    reader.pos += octalStr.length - 1;
+    reader.advance(octalStr.length - 1);
     const octal = parseInt(octalStr, 8);
 
     return String.fromCharCode(octal);
@@ -100,7 +115,7 @@ function readOctalSequence(reader, maxLength) {
 function readEscapeSequenceOrLineContinuation(reader) {
     const char = reader.read(1);
 
-    reader.pos += 2;
+    reader.advance(2);
     const unitChar = SIMPLE_ESCAPE_SEQUENCES[char];
 
     if (unitChar) {
@@ -113,7 +128,7 @@ function readEscapeSequenceOrLineContinuation(reader) {
             return readUnicodeSequence(reader);
         case "\r":
             if (reader.read() === "\n") {
-                reader.pos += 1;
+                reader.advance(1);
             }
 
             // fallthrough
@@ -169,7 +184,7 @@ function parseStringLiteral(source) {
     const reader = new SourceReader(source);
     const quote = reader.read();
 
-    reader.pos = 1;
+    reader.advance(1);
     const codeUnits = [];
 
     for (;;) {
@@ -182,7 +197,7 @@ function parseStringLiteral(source) {
             codeUnits.push(...mapEscapeSequenceOrLineContinuation(reader));
         } else {
             codeUnits.push(new CodeUnit(reader.pos, char));
-            reader.pos += 1;
+            reader.advance(1);
         }
     }
     return codeUnits;
@@ -196,7 +211,7 @@ function parseStringLiteral(source) {
 function parseTemplateToken(source) {
     const reader = new SourceReader(source);
 
-    reader.pos = 1;
+    reader.advance(1);
     const codeUnits = [];
 
     for (;;) {
@@ -216,7 +231,7 @@ function parseTemplateToken(source) {
                 unitSource = char;
             }
             codeUnits.push(new CodeUnit(reader.pos, unitSource));
-            reader.pos += unitSource.length;
+            reader.advance(unitSource.length);
         }
     }
     return codeUnits;