From: Francesco Chemolli <kinkie@squid-cache.org>
Date: Mon, 27 Jul 2015 17:41:03 +0000 (+0200)
Subject: Implement std::hash<SBuf>
X-Git-Tag: merge-candidate-3-v1~24^2^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bf7550ff17ed1bf76eabb3d46763a675c81ded05;p=thirdparty%2Fsquid.git

Implement std::hash<SBuf>
---

diff --git a/src/SBuf.cc b/src/SBuf.cc
index 412f2fde39..27432bde1e 100644
--- a/src/SBuf.cc
+++ b/src/SBuf.cc
@@ -17,6 +17,7 @@
 #include "util.h"
 
 #include <cstring>
+#include <functional>
 #include <iostream>
 #include <sstream>
 
@@ -952,3 +953,16 @@ SBuf::cow(SBuf::size_type newsize)
     reAlloc(newsize);
 }
 
+std::size_t std::hash<SBuf>::operator() (const SBuf & sbuf) const noexcept
+{
+    //ripped and adapted from hash_string
+    const char *s = sbuf.rawContent();
+    size_t rv = 0;
+    SBuf::size_type len=sbuf.length();
+    while (len != 0) {
+        rv ^= 271 * *s;
+        ++s;
+        --len;
+    }
+    return rv ^ (sbuf.length() * 271);
+}
diff --git a/src/SBuf.h b/src/SBuf.h
index 6f39f4bd17..5858a1ff0d 100644
--- a/src/SBuf.h
+++ b/src/SBuf.h
@@ -722,6 +722,15 @@ ToLower(SBuf buf)
     return buf;
 }
 
+namespace std {
+    /// default hash functor to support std::unordered_map<SBuf,*>
+    template <>
+    struct hash<SBuf>
+    {
+        size_t operator()(const SBuf &) const noexcept;
+    };
+}
+
 inline
 SBufIterator::SBufIterator(const SBuf &s, size_type pos)
     : iter(s.rawContent()+pos)
@@ -742,4 +751,3 @@ SBufIterator::operator!=(const SBufIterator &s) const
 }
 
 #endif /* SQUID_SBUF_H */
-
diff --git a/src/tests/testSBuf.cc b/src/tests/testSBuf.cc
index b7858ed985..e406e459ed 100644
--- a/src/tests/testSBuf.cc
+++ b/src/tests/testSBuf.cc
@@ -17,6 +17,7 @@
 
 #include <iostream>
 #include <stdexcept>
+#include <unordered_map>
 
 CPPUNIT_TEST_SUITE_REGISTRATION( testSBuf );
 
@@ -952,3 +953,31 @@ testSBuf::testIterators()
     }
 }
 
+void
+testSBuf::testSBufHash()
+{
+    // same SBuf must have same hash
+    auto hasher=std::hash<SBuf>();
+    CPPUNIT_ASSERT_EQUAL(hasher(literal),hasher(literal));
+
+    // same content must have same hash
+    CPPUNIT_ASSERT_EQUAL(hasher(literal),hasher(SBuf(fox)));
+    CPPUNIT_ASSERT_EQUAL(hasher(SBuf(fox)),hasher(SBuf(fox)));
+
+    //differen content should have different hash
+    CPPUNIT_ASSERT(hasher(SBuf(fox)) != hasher(SBuf(fox1)));
+
+    {
+        std::unordered_map<SBuf, int> um;
+        um[SBuf("one")] = 1;
+        um[SBuf("two")] = 2;
+
+        auto i = um.find(SBuf("one"));
+        CPPUNIT_ASSERT(i != um.end());
+        CPPUNIT_ASSERT(i->second == 1);
+
+        i = um.find(SBuf("eleventy"));
+        CPPUNIT_ASSERT(i == um.end());
+
+    }
+}
diff --git a/src/tests/testSBuf.h b/src/tests/testSBuf.h
index 838356c727..a3a04e6f65 100644
--- a/src/tests/testSBuf.h
+++ b/src/tests/testSBuf.h
@@ -53,6 +53,7 @@ class testSBuf : public CPPUNIT_NS::TestFixture
     CPPUNIT_TEST( testAutoFind );
     CPPUNIT_TEST( testStdStringOps );
     CPPUNIT_TEST( testIterators );
+    CPPUNIT_TEST( testSBufHash );
 //    CPPUNIT_TEST( testDumpStats ); //fake test, to print alloc stats
     CPPUNIT_TEST_SUITE_END();
 protected:
@@ -93,6 +94,7 @@ protected:
     void testAutoFind();
     void testStdStringOps();
     void testIterators();
+    void testSBufHash();
 };
 
 #endif