3 files changed, 428 insertions, 1 deletions
diff --git a/src/libutil/Makefile.am b/src/libutil/Makefile.am
index 9d71b66e6287..e10477deb706 100644
--- a/src/libutil/Makefile.am
+++ b/src/libutil/Makefile.am
@@ -1,7 +1,8 @@
 lib_LTLIBRARIES = libutil.la
 
 libutil_la_SOURCES = util.cc util.hh hash.cc hash.hh \
- archive.cc archive.hh aterm.cc aterm.hh
+ archive.cc archive.hh aterm.cc aterm.hh \
+ aterm-map.cc aterm-map.hh
 
 if !HAVE_OPENSSL
 libutil_la_SOURCES += \
diff --git a/src/libutil/aterm-map.cc b/src/libutil/aterm-map.cc
new file mode 100644
index 000000000000..e0cfefa2d5f4
--- /dev/null
+++ b/src/libutil/aterm-map.cc
@@ -0,0 +1,312 @@
+#include "aterm-map.hh"
+
+#include <assert.h>
+#include <stdlib.h>
+
+
+static const unsigned int maxLoadFactor = /* 1 / */ 3;
+static unsigned int nrResizes = 0;
+static unsigned int sizeTotalAlloc = 0;
+static unsigned int sizeCurAlloc = 0;
+static unsigned int sizeMaxAlloc = 0;
+
+
+ATermMap::ATermMap(unsigned int expectedCount)
+{
+    init(expectedCount);
+}
+
+
+ATermMap::ATermMap(const ATermMap & map)
+{
+    init(map.maxCount);
+    copy(map.hashTable, map.capacity);
+}
+
+
+ATermMap & ATermMap::operator = (const ATermMap & map)
+{
+    if (this == &map) return *this;
+    free();
+    init(map.maxCount);
+    copy(map.hashTable, map.capacity);
+    return *this;
+}
+
+
+ATermMap::~ATermMap()
+{
+    free();
+}
+
+
+void ATermMap::init(unsigned int expectedCount)
+{
+    assert(sizeof(ATerm) * 2 == sizeof(KeyValue));
+    capacity = 0;
+    count = 0;
+    maxCount = 0;
+    hashTable = 0;
+    resizeTable(expectedCount);
+}
+
+
+void ATermMap::free()
+{
+    if (hashTable) {
+        ATunprotectArray((ATerm *) hashTable);
+        ::free(hashTable);
+        sizeCurAlloc -= sizeof(KeyValue) * capacity;
+        hashTable = 0;
+    }
+}
+
+
+static unsigned int roundToPowerOf2(unsigned int x)
+{
+    x--;
+    x |= x >> 1; x |= x >> 2; x |= x >> 4; x |= x >> 8; x |= x >> 16;
+    x++;
+    return x;
+}
+
+
+void ATermMap::resizeTable(unsigned int expectedCount)
+{
+    if (expectedCount == 0) expectedCount = 1;
+//     cout << maxCount << " -> " << expectedCount << endl;
+//     cout << maxCount << " " << size << endl;
+//     cout << (double) size / maxCount << endl;
+
+    unsigned int oldCapacity = capacity;
+    KeyValue * oldHashTable = hashTable;
+
+    maxCount = expectedCount;
+    capacity = roundToPowerOf2(maxCount * maxLoadFactor);
+    hashTable = (KeyValue *) calloc(sizeof(KeyValue), capacity);
+    sizeTotalAlloc += sizeof(KeyValue) * capacity;
+    sizeCurAlloc += sizeof(KeyValue) * capacity;
+    if (sizeCurAlloc > sizeMaxAlloc) sizeMaxAlloc = sizeCurAlloc;
+    ATprotectArray((ATerm *) hashTable, capacity * 2);
+    
+//     cout << capacity << endl;
+
+    /* Re-hash the elements in the old table. */
+    if (oldCapacity != 0) {
+        count = 0;
+        copy(oldHashTable, oldCapacity);
+        ATunprotectArray((ATerm *) oldHashTable);
+        ::free(oldHashTable);
+        sizeCurAlloc -= sizeof(KeyValue) * oldCapacity;
+        nrResizes++;
+    }
+}
+
+
+void ATermMap::copy(KeyValue * elements, unsigned int capacity)
+{
+    for (unsigned int i = 0; i < capacity; ++i)
+        if (elements[i].value) /* i.e., non-empty, non-deleted element */
+            set(elements[i].key, elements[i].value);
+}
+
+
+static const unsigned int shift = 16;
+static const unsigned int knuth = (unsigned int) (0.6180339887 * (1 << shift));
+
+
+unsigned int ATermMap::hash1(ATerm key) const
+{
+    /* Don't care about the least significant bits of the ATerm
+       pointer since they're always 0. */
+    unsigned int key2 = ((unsigned int) key) >> 2;
+
+    /* Approximately equal to:
+    double d = key2 * 0.6180339887;
+    unsigned int h = (int) (capacity * (d - floor(d)));
+    */
+ 
+    unsigned int h = (capacity * ((key2 * knuth) & ((1 << shift) - 1))) >> shift;
+
+    return h;
+}
+
+
+unsigned int ATermMap::hash2(ATerm key) const
+{
+    unsigned int key2 = ((unsigned int) key) >> 2;
+    /* Note: the result must be relatively prime to `capacity' (which
+       is a power of 2), so we make sure that the result is always
+       odd. */
+    unsigned int h = ((key2 * 134217689) & (capacity - 1)) | 1;
+    return h;
+}
+
+
+static unsigned int nrItemsSet = 0;
+static unsigned int nrSetProbes = 0;
+
+
+void ATermMap::set(ATerm key, ATerm value)
+{
+    if (count == maxCount) resizeTable(capacity * 2 / maxLoadFactor);
+    
+    nrItemsSet++;
+    for (unsigned int i = 0, h = hash1(key); i < capacity;
+         ++i, h = (h + hash2(key)) & (capacity - 1))
+    {
+        // assert(h < capacity);
+        nrSetProbes++;
+        /* Note: to see whether a slot is free, we check
+           hashTable[h].value, not hashTable[h].key, since we use
+           value == 0 to mark deleted slots. */
+        if (hashTable[h].value == 0 || hashTable[h].key == key) {
+            if (hashTable[h].value == 0) count++;
+            hashTable[h].key = key;
+            hashTable[h].value = value;
+            return;
+        }
+    }
+        
+    abort();
+}
+
+
+static unsigned int nrItemsGet = 0;
+static unsigned int nrGetProbes = 0;
+
+
+ATerm ATermMap::get(ATerm key) const
+{
+    nrItemsGet++;
+    for (unsigned int i = 0, h = hash1(key); i < capacity;
+         ++i, h = (h + hash2(key)) & (capacity - 1))
+    {
+        nrGetProbes++;
+        if (hashTable[h].key == 0) return 0;
+        if (hashTable[h].key == key) return hashTable[h].value;
+    }
+    return 0;
+}
+
+
+void ATermMap::remove(ATerm key)
+{
+    for (unsigned int i = 0, h = hash1(key); i < capacity;
+         ++i, h = (h + hash2(key)) & (capacity - 1))
+    {
+        if (hashTable[h].key == 0) return;
+        if (hashTable[h].key == key) {
+            if (hashTable[h].value != 0) {
+                hashTable[h].value = 0;
+                count--;
+            }
+            return;
+        }
+    }
+}
+
+
+unsigned int ATermMap::size()
+{
+    return count; /* STL nomenclature */
+}
+
+
+#if 0
+int main(int argc, char * * argv)
+{
+    ATerm bottomOfStack;
+    ATinit(argc, argv, &bottomOfStack);
+
+    /* Make test terms. */
+    int nrTestTerms = 100000;
+    ATerm testTerms[nrTestTerms];
+
+    for (int i = 0; i < nrTestTerms; ++i) {
+        char name[10];
+        sprintf(name, "%d", (int) random() % 37);
+
+        int arity = i == 0 ? 0 : (random() % 37);
+        ATerm kids[arity];
+        for (int j = 0; j < arity; ++j)
+            kids[j] = testTerms[random() % i];
+        
+        testTerms[i] = (ATerm) ATmakeApplArray(ATmakeAFun(name, arity, ATfalse), kids);
+//         ATwriteToSharedTextFile(testTerms[i], stdout);
+//         printf("\n");
+    }
+
+
+    cout << "testing...\n";
+
+    
+    #define someTerm() (testTerms[(int) random() % nrTestTerms])
+
+
+    for (int test = 0; test < 100000; ++test) {
+        //cerr << test << endl;
+        unsigned int n = 300;
+        ATermMap map(300);
+        ATerm keys[n], values[n];
+        for (unsigned int i = 0; i < n; ++i) {
+            keys[i] = someTerm();
+            values[i] = someTerm();
+            map.set(keys[i], values[i]);
+            //cerr << "INSERT: " << keys[i] << " " << values[i] << endl;
+        }
+
+        unsigned int size = map.size();
+        assert(size <= n);
+        values[n - 1] = 0;
+        map.remove(keys[n - 1]);
+        assert(map.size() == size - 1);
+
+        unsigned int checksum;
+        unsigned int count = 0;
+        for (ATermMap::const_iterator i = map.begin(); i != map.end(); ++i, ++count) {
+            assert(i->key);
+            assert(i->value);
+            checksum += (unsigned int) (*i).key;
+            checksum += (unsigned int) (*i).value;
+            // cout << (*i).key << " " << (*i).value << endl;
+        }
+        assert(count == size - 1);
+
+        for (unsigned int i = 0; i < n; ++i) {
+            for (unsigned int j = i + 1; j < n; ++j)
+                if (keys[i] == keys[j]) goto x;
+            if (map.get(keys[i]) != values[i]) {
+                cerr << "MISMATCH: " << keys[i] << " " << values[i] << " " << map.get(keys[i]) << " " << i << endl;
+                abort();
+            }
+            if (values[i] != 0) {
+                checksum -= (unsigned int) keys[i];
+                checksum -= (unsigned int) values[i];
+            }
+        x:  ;
+        }
+
+        assert(checksum == 0);
+        
+        for (unsigned int i = 0; i < 100; ++i)
+            map.get(someTerm());
+        
+    }
+
+    cout << "RESIZES: " << nrResizes << " "
+         << sizeTotalAlloc << " "
+         << sizeCurAlloc << " "
+         << sizeMaxAlloc << endl;
+        
+    cout << "SET: "
+         << nrItemsSet << " "
+         << nrSetProbes << " "
+         << (double) nrSetProbes / nrItemsSet << endl;
+
+    cout << "GET: "
+         << nrItemsGet << " "
+         << nrGetProbes << " "
+         << (double) nrGetProbes / nrItemsGet << endl;
+}
+#endif
diff --git a/src/libutil/aterm-map.hh b/src/libutil/aterm-map.hh
new file mode 100644
index 000000000000..d7aed2ca21ac
--- /dev/null
+++ b/src/libutil/aterm-map.hh
@@ -0,0 +1,114 @@
+#ifndef __ATERM_MAP_H
+#define __ATERM_MAP_H
+
+#include <aterm2.h>
+#include <assert.h>
+
+using namespace std;
+
+
+class ATermMap
+{
+public:
+
+    struct KeyValue
+    {
+        ATerm key;
+        ATerm value;
+    };
+
+private:
+
+    /* Hash table for the map.  We use open addressing, i.e., all
+       key/value pairs are stored directly in the table, and there are
+       no pointers.  Collisions are resolved through probing. */
+    KeyValue * hashTable;
+
+    /* Current size of the hash table. */
+    unsigned int capacity;
+
+    /* Number of elements in the hash table. */
+    unsigned int count;
+
+    /* Maximum number of elements in the hash table.  If `count'
+       exceeds this number, the hash table is expanded. */
+    unsigned int maxCount;
+    
+public:
+
+    /* Create a map.  `expectedCount' is the number of elements the
+       map is expected to hold. */
+    ATermMap(unsigned int expectedCount);
+    
+    ATermMap(const ATermMap & map);
+    
+    ~ATermMap();
+
+    ATermMap & operator = (const ATermMap & map);
+        
+    void set(ATerm key, ATerm value);
+
+    ATerm get(ATerm key) const;
+
+    void remove(ATerm key);
+
+    unsigned int size();
+
+    struct const_iterator
+    {
+        const ATermMap & map;
+        unsigned int pos;
+        const_iterator(const ATermMap & map, int pos) : map(map)
+        {
+            this->pos = pos;
+        }
+        bool operator !=(const const_iterator & i)
+        {
+            return pos != i.pos;
+        }
+        void operator ++()
+        {
+            if (pos == map.capacity) return;
+            do { ++pos; 
+            } while (pos < map.capacity && map.hashTable[pos].value == 0);
+        }
+        const KeyValue & operator *()
+        {
+            assert(pos < map.capacity);
+            return map.hashTable[pos];
+        }
+        const KeyValue * operator ->()
+        {
+            assert(pos < map.capacity);
+            return &map.hashTable[pos];
+        }
+    };
+
+    const_iterator begin() const
+    {
+        unsigned int i = 0;
+        while (i < capacity && hashTable[i].value == 0) ++i;
+        return const_iterator(*this, i);
+    }
+    
+    const_iterator end() const
+    {
+        return const_iterator(*this, capacity);
+    }
+
+private:
+    
+    void init(unsigned int expectedCount);
+
+    void free();
+
+    void resizeTable(unsigned int expectedCount);
+
+    void copy(KeyValue * elements, unsigned int capacity);
+    
+    inline unsigned int hash1(ATerm key) const;
+    inline unsigned int hash2(ATerm key) const;
+};
+
+
+#endif /* !__ATERM_MAP_H */