From 2d8658e1b24a89ad1e09ddce50f91e88e25a4ba9 Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Thu, 27 Dec 2007 17:32:46 +0000
Subject: [PATCH] I'll have a need for inserting substrings into a stringpool.

---
 src/hash.h    | 10 ++++++++++
 src/strpool.c | 21 ++++++++++++++++-----
 src/strpool.h |  7 +++++++
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/hash.h b/src/hash.h
index 731a3e7..829085d 100644
--- a/src/hash.h
+++ b/src/hash.h
@@ -41,6 +41,16 @@ strhash(const char *str)
   return r;
 }
 
+static inline Hashval
+strnhash(const char *str, unsigned len)
+{
+  Hashval r = 0;
+  unsigned int c;
+  while (len-- && (c = *(const unsigned char *)str++) != 0)
+    r += (r << 3) + c;
+  return r;
+}
+
 /* hash for rel
  * rel -> hash
  */
diff --git a/src/strpool.c b/src/strpool.c
index 622664f..7b0d765 100644
--- a/src/strpool.c
+++ b/src/strpool.c
@@ -37,7 +37,7 @@ stringpool_init (Stringpool *ss, const char *strs[])
 }
 
 Id
-stringpool_str2id (Stringpool *ss, const char *str, int create)
+stringpool_strn2id (Stringpool *ss, const char *str, unsigned len, int create)
 {
   Hashval h;
   unsigned int hh;
@@ -79,12 +79,13 @@ stringpool_str2id (Stringpool *ss, const char *str, int create)
 
   // compute hash and check for match
 
-  h = strhash(str) & hashmask;
+  h = strnhash(str, len) & hashmask;
   hh = HASHCHAIN_START;
   while ((id = hashtbl[h]) != 0)  // follow hash overflow chain
     {
       // break if string already hashed
-      if(!strcmp(ss->stringspace + ss->strings[id], str))
+      if(!memcmp(ss->stringspace + ss->strings[id], str, len)
+         && ss->stringspace[ss->strings[id] + len] == 0)
 	break;
       h = HASHCHAIN_NEXT(h, hh, hashmask);
     }
@@ -101,19 +102,29 @@ stringpool_str2id (Stringpool *ss, const char *str, int create)
   // 'pointer' into stringspace is Offset of next free pos: sstrings
   ss->strings[id] = ss->sstrings;
 
-  space_needed = strlen(str) + 1;
+  space_needed = len + 1;
 
   // resize string buffer if needed
   if (((ss->sstrings + space_needed - 1) | STRINGSPACE_BLOCK) != ((ss->sstrings - 1) | STRINGSPACE_BLOCK))
     ss->stringspace = xrealloc(ss->stringspace, (ss->sstrings + space_needed + STRINGSPACE_BLOCK) & ~STRINGSPACE_BLOCK);
   // copy new string into buffer
-  memcpy(ss->stringspace + ss->sstrings, str, space_needed);
+  memcpy(ss->stringspace + ss->sstrings, str, space_needed - 1);
+  // add the sentinel, we can't rely on it being in the source string (in
+  // case the LEN is not really strlen(str))
+  ss->stringspace[ss->sstrings + space_needed - 1] = 0;
   // next free pos is behind new string
   ss->sstrings += space_needed;
 
   return id;
 }
 
+Id
+stringpool_str2id (Stringpool *ss, const char *str, int create)
+{
+  unsigned len = strlen (str);
+  return stringpool_strn2id (ss, str, len, create);
+}
+
 void
 stringpool_shrink (Stringpool *ss)
 {
diff --git a/src/strpool.h b/src/strpool.h
index d326c4f..c8429b9 100644
--- a/src/strpool.h
+++ b/src/strpool.h
@@ -26,6 +26,13 @@ struct _Stringpool
 
 void stringpool_init (Stringpool *ss, const char *strs[]);
 Id stringpool_str2id (Stringpool *ss, const char *str, int create);
+Id stringpool_strn2id (Stringpool *ss, const char *str, unsigned len, int create);
 void stringpool_shrink (Stringpool *ss);
 
+static inline const char *
+stringpool_id2str (Stringpool *ss, Id id)
+{
+  return ss->stringspace + ss->strings[id];
+}
+
 #endif
-- 
2.7.4