Add literalEscaped utility function

Author: fwcd

Sources/SwiftSyntaxBuilderGeneration/SyntaxBuildableChild.swift

@@ -100,7 +100,7 @@ extension Child {
       assertChoices.append(SequenceExpr {
         MemberAccessExpr(base: type.forceUnwrapped(expr: varName), name: "text")
         BinaryOperatorExpr("==")
-        StringLiteralExpr(textChoice.replacingOccurrences(of: "\\", with: "\\\\"))
+        StringLiteralExpr(literalEscaped(string: textChoice))
       })
     }
     let disjunction = ExprList(assertChoices.flatMap { [$0, BinaryOperatorExpr("||")] }.dropLast())

Sources/SwiftSyntaxBuilderGeneration/Utils.swift

@@ -70,3 +70,10 @@ func flattened(indentedDocumentation: String) -> String {
     .replacingOccurrences(of: "\n", with: "")
     .trimmingCharacters(in: .whitespacesAndNewlines)
 }
+
+/// Escapes a string for use in a string literal.
+func literalEscaped(string: String) -> String {
+  string
+    .replacingOccurrences(of: "\\", with: "\\\\")
+    .replacingOccurrences(of: "\"", with: "\\\"")
+}