Fix mappedTokenChoices and add tokenCanContainArbitraryText

Author: fwcd

Sources/SwiftSyntaxBuilderGeneration/Child.swift

@@ -26,6 +26,7 @@ class Child {
   let classification: SyntaxClassification?
   /// A restricted set of token kinds that will be accepted for this child.
   let tokenChoices: [Token]
+  let tokenCanContainArbitraryText: Bool
 
   var swiftName: String {
     return lowercaseFirstWord(name: name)
@@ -95,14 +96,18 @@ class Child {
     self.requiresLeadingNewline = requiresLeadingNewline
     self.isOptional = isOptional
 
+    let isToken = syntaxKind.hasSuffix("Token")
     var mappedTokenChoices = [Token]()
 
-    if syntaxKind.hasSuffix("Token"), let token = SYNTAX_TOKEN_MAP[syntaxKind] {
+    if isToken, let token = SYNTAX_TOKEN_MAP[syntaxKind] {
       mappedTokenChoices.append(token)
     }
 
-    mappedTokenChoices.append(contentsOf: tokenChoices.compactMap { SYNTAX_TOKEN_MAP[$0] })
+    mappedTokenChoices.append(contentsOf: tokenChoices.compactMap { SYNTAX_TOKEN_MAP["\($0)Token"] })
     self.tokenChoices = mappedTokenChoices
+
+    // If mappedTokenChoices contains `nil`, the token can contain arbitrary text
+    self.tokenCanContainArbitraryText = mappedTokenChoices.contains { $0.text == nil }
 
     // A list of valid text for tokens, if specified.
     // This will force validation logic to check the text passed into the

Sources/SwiftSyntaxBuilderGeneration/SyntaxBuildableChild.swift

@@ -79,14 +79,11 @@ extension Child {
     let choices: [String]
     if !textChoices.isEmpty {
       choices = textChoices
+    } else if tokenCanContainArbitraryText {
+      // Don't generate an assert statement if token can contain arbitrary text.
+      return nil
     } else if !tokenChoices.isEmpty {
-      let optionalChoices = tokenChoices.map { SYNTAX_TOKEN_MAP["\($0.name)Token"]?.text }
-      choices = optionalChoices.compactMap { $0 }
-      guard choices.count == optionalChoices.count else {
-        // If `nil` is in the text choices, one of the token options can contain arbitrary
-        // text. Don't generate an assert statement.
-        return nil
-      }
+      choices = tokenChoices.compactMap(\.text)
     } else {
       return nil
     }