Merge branch 'master' into iwyu

1 files changed, 86 insertions, 0 deletions

diff --git a/src/intern.cpp b/src/intern.cpp
new file mode 100644
index 00000000..2ec0af8a
--- /dev/null
+++ b/src/intern.cpp
@@ -0,0 +1,86 @@
+/** \file intern.c
+
+    Library for pooling common strings
+
+*/
+#include "config.h" // IWYU pragma: keep
+
+#include <wchar.h>
+#include <pthread.h>
+#include <vector>
+#include <algorithm>
+
+#include "fallback.h" // IWYU pragma: keep
+#include "common.h"
+#include "intern.h"
+
+/** Comparison function for intern'd strings */
+class string_table_compare_t
+{
+public:
+    bool operator()(const wchar_t *a, const wchar_t *b) const
+    {
+        return wcscmp(a, b) < 0;
+    }
+};
+
+/* A sorted vector ends up being a little more memory efficient than a std::set for the intern'd string table */
+#define USE_SET 0
+#if USE_SET
+/** The table of intern'd strings */
+typedef std::set<const wchar_t *, string_table_compare_t> string_table_t;
+#else
+/** The table of intern'd strings */
+typedef std::vector<const wchar_t *> string_table_t;
+#endif
+
+static string_table_t string_table;
+
+/** The lock to provide thread safety for intern'd strings */
+static pthread_mutex_t intern_lock = PTHREAD_MUTEX_INITIALIZER;
+
+static const wchar_t *intern_with_dup(const wchar_t *in, bool dup)
+{
+    if (!in)
+        return NULL;
+
+//  debug( 0, L"intern %ls", in );
+    scoped_lock lock(intern_lock);
+    const wchar_t *result;
+
+#if USE_SET
+    string_table_t::const_iterator iter = string_table.find(in);
+    if (iter != string_table.end())
+    {
+        result = *iter;
+    }
+    else
+    {
+        result = dup ? wcsdup(in) : in;
+        string_table.insert(result);
+    }
+#else
+    string_table_t::iterator iter = std::lower_bound(string_table.begin(), string_table.end(), in, string_table_compare_t());
+    if (iter != string_table.end() && wcscmp(*iter, in) == 0)
+    {
+        result = *iter;
+    }
+    else
+    {
+        result = dup ? wcsdup(in) : in;
+        string_table.insert(iter, result);
+    }
+#endif
+    return result;
+}
+
+const wchar_t *intern(const wchar_t *in)
+{
+    return intern_with_dup(in, true);
+}
+
+
+const wchar_t *intern_static(const wchar_t *in)
+{
+    return intern_with_dup(in, false);
+}