1 files changed, 119 insertions, 0 deletions
diff --git a/name-hash.c b/name-hash.c
new file mode 100644
index 0000000000..0031d78e8c
--- /dev/null
+++ b/name-hash.c
@@ -0,0 +1,119 @@
+/*
+ * name-hash.c
+ *
+ * Hashing names in the index state
+ *
+ * Copyright (C) 2008 Linus Torvalds
+ */
+#define NO_THE_INDEX_COMPATIBILITY_MACROS
+#include "cache.h"
+
+/*
+ * This removes bit 5 if bit 6 is set.
+ *
+ * That will make US-ASCII characters hash to their upper-case
+ * equivalent. We could easily do this one whole word at a time,
+ * but that's for future worries.
+ */
+static inline unsigned char icase_hash(unsigned char c)
+{
+	return c & ~((c & 0x40) >> 1);
+}
+
+static unsigned int hash_name(const char *name, int namelen)
+{
+	unsigned int hash = 0x123;
+
+	do {
+		unsigned char c = *name++;
+		c = icase_hash(c);
+		hash = hash*101 + c;
+	} while (--namelen);
+	return hash;
+}
+
+static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
+{
+	void **pos;
+	unsigned int hash;
+
+	if (ce->ce_flags & CE_HASHED)
+		return;
+	ce->ce_flags |= CE_HASHED;
+	ce->next = NULL;
+	hash = hash_name(ce->name, ce_namelen(ce));
+	pos = insert_hash(hash, ce, &istate->name_hash);
+	if (pos) {
+		ce->next = *pos;
+		*pos = ce;
+	}
+}
+
+static void lazy_init_name_hash(struct index_state *istate)
+{
+	int nr;
+
+	if (istate->name_hash_initialized)
+		return;
+	for (nr = 0; nr < istate->cache_nr; nr++)
+		hash_index_entry(istate, istate->cache[nr]);
+	istate->name_hash_initialized = 1;
+}
+
+void add_name_hash(struct index_state *istate, struct cache_entry *ce)
+{
+	ce->ce_flags &= ~CE_UNHASHED;
+	if (istate->name_hash_initialized)
+		hash_index_entry(istate, ce);
+}
+
+static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
+{
+	if (len1 != len2)
+		return 0;
+
+	while (len1) {
+		unsigned char c1 = *name1++;
+		unsigned char c2 = *name2++;
+		len1--;
+		if (c1 != c2) {
+			c1 = toupper(c1);
+			c2 = toupper(c2);
+			if (c1 != c2)
+				return 0;
+		}
+	}
+	return 1;
+}
+
+static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
+{
+	int len = ce_namelen(ce);
+
+	/*
+	 * Always do exact compare, even if we want a case-ignoring comparison;
+	 * we do the quick exact one first, because it will be the common case.
+	 */
+	if (len == namelen && !cache_name_compare(name, namelen, ce->name, len))
+		return 1;
+
+	return icase && slow_same_name(name, namelen, ce->name, len);
+}
+
+struct cache_entry *index_name_exists(struct index_state *istate, const char *name, int namelen, int icase)
+{
+	unsigned int hash = hash_name(name, namelen);
+	struct cache_entry *ce;
+
+	lazy_init_name_hash(istate);
+	ce = lookup_hash(hash, &istate->name_hash);
+
+	while (ce) {
+		if (!(ce->ce_flags & CE_UNHASHED)) {
+			if (same_name(ce, name, namelen, icase))
+				return ce;
+		}
+		ce = ce->next;
+	}
+	return NULL;
+}