v.token: add manual .str() methods for KeywordsMatcherTrie and TrieNode, to workaround cgen errors

vlib/v/token/keywords_matcher_trie.v

@@ -11,6 +11,11 @@ pub mut:
 	max_len int
 }
 
+// str returns a short representation of matcher
+pub fn (km &KeywordsMatcherTrie) str() string {
+	return 'KeywordsMatcherTrie{ /* nodes.len: ${km.nodes.len} */ min_len: ${km.min_len}, max_len: ${km.max_len} }'
+}
+
 // TrieNode is a single node from a trie, used by KeywordsMatcherTrie
 pub struct TrieNode {
 pub mut:
@@ -18,6 +23,14 @@ pub mut:
 	value    int = -1 // when != -1, it is a leaf node representing a match
 }
 
+// str returns a string representation of the node content
+pub fn (node &TrieNode) str() string {
+	if isnil(node) {
+		return '&TrieNode(nil)'
+	}
+	return '&TrieNode{value: ${node.value}}'
+}
+
 // find tries to find the given `word` in the set of all previously added words
 // to the KeywordsMatcherTrie instance. It returns -1 if the word was NOT found
 // there at all. If the word was found, find will return the `value` (value => 0),