Simple string interning.

1 files changed, 16 insertions, 0 deletions

diff --git a/util.c b/util.c
index 9ed1c50..5cede75 100644
--- a/util.c
+++ b/util.c
@@ -76,6 +76,22 @@ char *xmemdup(const char *s, size_t n) {
 
 char *xstrdup(const char *s) { return xmemdup(s, strlen(s) + 1); }
 
+const char *internstring(const char *s) {
+  size_t idx, len;
+  const char *interned;
+  static const char *cache[4096] = {0};
+
+  len = strlen(s);
+  idx = murmurhash64a(s, len) % sizeof(cache)/sizeof(cache[0]);
+  interned = cache[idx];
+  if (interned && strcmp(s, cache[idx]) == 0) {
+    return interned;
+  }
+  interned = xstrdup(s);
+  cache[idx] = interned;
+  return interned;
+}
+
 void htabkey(struct hashtablekey *k, const char *s, size_t n) {
   k->str = s;
   k->len = n;