From c0f0614e6b7647fd4703abf4c455024c2ade8cd7 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Sat, 19 Sep 2020 21:04:38 +0900
Subject: [PATCH] Cache file search results

---
 preprocess.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/preprocess.c b/preprocess.c
index de09177..e2575aa 100644
--- a/preprocess.c
+++ b/preprocess.c
@@ -684,11 +684,18 @@ char *search_include_paths(char *filename) {
   if (filename[0] == '/')
     return filename;
 
+  static HashMap cache;
+  char *cached = hashmap_get(&cache, filename);
+  if (cached)
+    return cached;
+
   // Search a file from the include paths.
   for (int i = 0; i < include_paths.len; i++) {
     char *path = format("%s/%s", include_paths.data[i], filename);
-    if (file_exists(path))
-      return path;
+    if (!file_exists(path))
+      continue;
+    hashmap_put(&cache, filename, path);
+    return path;
   }
   return NULL;
 }