Move some general code generation helpers into their own file

src/compiler/generate_code/helpers.cpp

@@ -0,0 +1,42 @@
+#include "./helpers.h"
+
+namespace tree_sitter {
+    namespace generate_code {
+        static void str_replace(string &input, const string &search, const string &replace) {
+            size_t pos = 0;
+            while (1) {
+                pos = input.find(search, pos);
+                if (pos == string::npos) break;
+                input.erase(pos, search.length());
+                input.insert(pos, replace);
+                pos += replace.length();
+            }
+        }
+        
+        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 = "    ";
+            str_replace(input, "\n", "\n" + tab);
+            return tab + input;
+        }
+        
+        string escape_string(string input) {
+            str_replace(input, "\"", "\\\"");
+            return input;
+        }
+    }
+}