Add rule precedence construct

Still need to add some way of expressing left and right
associativity

src/compiler/util/string_helpers.cc

@@ -1,7 +1,10 @@
 #include "compiler/util/string_helpers.h"
+#include <vector>
 
 namespace tree_sitter {
     using std::string;
+    using std::vector;
+    using std::set;
 
     namespace util {
         void str_replace(string *input, const string &search, const string &replace) {
@@ -20,5 +23,45 @@ namespace tree_sitter {
             str_replace(&input, "\n", "\\n");
             return input;
         }
+        
+        string join(vector<string> lines, string separator) {
+            string result;
+            bool started = false;
+            for (auto line : lines) {
+                if (started) result += separator;
+                started = true;
+                result += line;
+            }
+            return result;
+        }
+
+        string join(vector<string> lines) {
+            return join(lines, "\n");
+        }
+        
+        string indent(string input) {
+            string tab = "    ";
+            util::str_replace(&input, "\n", "\n" + tab);
+            return tab + input;
+        }
+        
+        string character_code(char character) {
+            switch (character) {
+                case '\0':
+                    return "\\0";
+                case '"':
+                    return "\\\"";
+                case '\n':
+                    return "\\n";
+                case '\r':
+                    return "\\r";
+                case '\t':
+                    return "\\t";
+                case '\\':
+                    return "\\\\";
+                default:
+                    return string() + character;
+            }
+        }
     }
 }