// view.cpp -- // $Id$ // This is part of Metakit, the homepage is http://www.equi4.com/metakit/ /** @file * Implementation of main classes not involved in persistence */ #include "header.h" #include "derived.h" #include "custom.h" #include "store.h" // for RelocateRows #include "field.h" // for RelocateRows #include "persist.h" #include "remap.h" #if !q4_INLINE #include "mk4.inl" #endif ///////////////////////////////////////////////////////////////////////////// // c4_ThreadLock class c4_ThreadLock { public: c4_ThreadLock (); class Hold { public: Hold (); ~Hold (); }; }; ///////////////////////////////////////////////////////////////////////////// #if q4_MULTI #if q4_WIN32 /* * On Win32, use a critical section to protect the global symbol table. * Also uses special thread-safe calls to inc/dec all reference counts. * * This implementation tqreplaces the previous use of TLS, which cannot * be used without special tricks in dynamically loaded DLL's, as is * required for OCX/ActiveX use (which uses LoadLibrary). * * Note: Could have used MFC's CCriticalSection and CSingleLock classes, * but the code below is so trivial that it hardly matters. */ #if q4_MSVC && !q4_STRICT #pragma warning(disable: 4201) // nonstandard extension used : ... #endif #include static CRITICAL_SECTION gCritSect; c4_ThreadLock::c4_ThreadLock () { InitializeCriticalSection(&gCritSect); } c4_ThreadLock::Hold::Hold () { EnterCriticalSection(&gCritSect); } c4_ThreadLock::Hold::~Hold () { LeaveCriticalSection(&gCritSect); } #else /* q4_WIN32 */ #include static pthread_mutex_t gMutex; d4_inline c4_ThreadLock::c4_ThreadLock () { pthread_mutex_init(&gMutex, 0); } d4_inline c4_ThreadLock::Hold::Hold () { d4_dbgdef(int r =) pthread_mutex_lock(&gMutex); d4_assert(r == 0); } d4_inline c4_ThreadLock::Hold::~Hold () { d4_dbgdef(int r =) pthread_mutex_unlock(&gMutex); d4_assert(r == 0); } #endif /* q4_WIN32 */ #else /* q4_MULTI */ // All other implementations revert to the simple "thread-less" case. d4_inline c4_ThreadLock::c4_ThreadLock () { } d4_inline c4_ThreadLock::Hold::Hold () { } d4_inline c4_ThreadLock::Hold::~Hold () { } #endif ///////////////////////////////////////////////////////////////////////////// #if q4_LOGPROPMODS static FILE* sPropModsFile = 0; static int sPropModsProp = -1; FILE* f4_LogPropMods(FILE* fp_, int propId_) { FILE* prevfp = sPropModsFile; sPropModsFile = fp_; sPropModsProp = propId_; return prevfp; } void f4_DoLogProp(const c4_Handler* hp_, int id_, const char* fmt_, int arg_) { if (sPropModsFile != 0 && (sPropModsProp < 0 || sPropModsProp == id_)) { fprintf(sPropModsFile, "handler 0x%x id %d: ", hp_, id_); fprintf(sPropModsFile, fmt_, arg_); } } #endif ///////////////////////////////////////////////////////////////////////////// /** @class c4_View * * A collection of data rows. This is the central public data structure of * Metakit (often called "table", "array", or "relation" in other systems). * * Views are smart pointers to the actual collections, setting a view to a new * value does not alter the collection to which this view pointed previously. * * The elements of views can be referred to by their 0-based index, which * produces a row-reference of type c4_RowRef. These row references can * be copied, used to get or set properties, or dereferenced (in which case * an object of class c4_Row is returned). Taking the address of a row * reference produces a c4_Cursor, which acts very much like a pointer. * * The following code creates a view with 1 row and 2 properties: * @code * c4_StringProp pName ("name"); * c4_IntProp pAge ("age"); * * c4_Row data; * pName (data) = "John Williams"; * pAge (data) = 43; * * c4_View myView; * myView.Add(row); * @endcode */ /// Construct a view based on a sequence c4_View::c4_View (c4_Sequence* seq_) : _seq (seq_) { if (!_seq) _seq = d4_new c4_HandlerSeq (0); _IncSeqRef(); } /// Construct a view based on a custom viewer c4_View::c4_View (c4_CustomViewer* viewer_) : _seq (0) { d4_assert(viewer_); _seq = d4_new c4_CustomSeq (viewer_); _IncSeqRef(); } /// Construct a view based on an input stream c4_View::c4_View (c4_Stream* stream_) : _seq (c4_Persist::Load(stream_)) { if (_seq == 0) _seq = d4_new c4_HandlerSeq (0); _IncSeqRef(); } /// Construct an empty view with one property c4_View::c4_View (const c4_Property& prop_) : _seq (d4_new c4_HandlerSeq (0)) { _IncSeqRef(); _seq->PropIndex(prop_); } /// Copy constructor c4_View::c4_View (const c4_View& view_) : _seq (view_._seq) { _IncSeqRef(); } /// Makes this view the same as another one. c4_View& c4_View::operator= (const c4_View& view_) { if (_seq != view_._seq) { _DecSeqRef(); _seq = view_._seq; _IncSeqRef(); } return *this; } /** Get a single data item in a generic way * * This can be used to access view data in a generalized way. * Useful for c4_CustomViewers which are based on other views. * @return true if the item is non-empty */ bool c4_View::GetItem(int row_, int col_, c4_Bytes& buf_) const { const c4_Property& prop = NthProperty(col_); return prop (GetAt(row_)).GetData(buf_); } /// Set a single data item in a generic way void c4_View::SetItem(int row_, int col_, const c4_Bytes& buf_) const { const c4_Property& prop = NthProperty(col_); prop (GetAt(row_)).SetData(buf_); } /// Set an entry, growing the view if needed void c4_View::SetAtGrow(int index_, const c4_RowRef& newElem_) { if (index_ >= GetSize()) SetSize(index_ + 1); _seq->SetAt(index_, &newElem_); } /** Add a new entry, same as "SetAtGrow(GetSize(), ...)" * @return the index of the newly added row */ int c4_View::Add(const c4_RowRef& newElem_) { int i = GetSize(); InsertAt(i, newElem_); return i; } /** Construct a new view with a copy of the data * * The copy is a deep copy, because subviews are always copied in full. */ c4_View c4_View::Duplicate() const { // insert all rows, sharing any subviews as needed c4_View result = Clone(); result.InsertAt(0, _seq); return result; } /** Constructs a new view with the same structure but no data * * Structural information can only be maintain for the top level, * subviews will be included but without any properties themselves. */ c4_View c4_View::Clone() const { c4_View view; for (int i = 0; i < NumProperties(); ++i) view._seq->PropIndex(NthProperty(i)); return view; } /** Adds a property column to a view if not already present * @return 0-based column position of the property */ int c4_View::AddProperty(const c4_Property& prop_) { return _seq->PropIndex(prop_); } /** Returns the N-th property (using zero-based indexing) * @return reference to the specified property */ const c4_Property& c4_View::NthProperty( int index_ ///< the zero-based property index ) const { return _seq->NthHandler(index_).Property(); } /** Find the index of a property, given its name * @return 0-based column index * @retval -1 property not present in this view */ int c4_View::FindPropIndexByName( const char* name_ ///< property name (case insensitive) ) const { // use a slow linear scan to find the untyped property by name for (int i = 0; i < NumProperties(); ++i) { c4_String s = NthProperty(i).Name(); if (s.CompareNoCase(name_) == 0) return i; } return -1; } /** Defines a column for a property. * * The following code defines an empty view with three properties: * @code * c4_IntProp p1, p2, p3; * c4_View myView = (p1, p2, p3); * @endcode * @return the new view object (without any data rows) * @sa c4_Property */ c4_View c4_View::operator, (const c4_Property& prop_) const { c4_View view = Clone(); view.AddProperty(prop_); return view; } /// Insert copies of all rows of the specified view void c4_View::InsertAt(int index_, const c4_View& view_) { int n = view_.GetSize(); if (n > 0) { c4_Row empty; InsertAt(index_, empty, n); for (int i = 0; i < n; ++i) SetAt(index_ + i, view_[i]); } } bool c4_View::IsCompatibleWith(const c4_View& dest_) const { // can't determine table without handlers (and can't be a table) if (NumProperties() == 0 || dest_.NumProperties() == 0) return false; c4_Sequence* s1 = _seq; c4_Sequence* s2 = dest_._seq; c4_HandlerSeq* h1 = (c4_HandlerSeq*) s1->HandlerContext(0); c4_HandlerSeq* h2 = (c4_HandlerSeq*) s2->HandlerContext(0); // both must be real handler views, not derived ones if (h1 != s1 || h2 != s2) return false; // both must not contain any temporary handlers if (s1->NumHandlers() != h1->NumFields() || s2->NumHandlers() != h2->NumFields()) return false; // both must be in the same storage if (h1->Persist() == 0 || h1->Persist() != h2->Persist()) return false; // both must have the same structure (is this expensive?) c4_String d1 = h1->Definition().Description(true); c4_String d2 = h1->Definition().Description(true); return d1 == d2; // ignores all names } /** Move attached rows to somewhere else in same storage * * There is a lot of trickery going on here. The whole point of this * code is that moving rows between (compatible!) subviews should not * use copying when potentially large memo's and subviews are involved. * In that case, the best solution is really to move pointers, not data. */ void c4_View::RelocateRows(int from_, int count_, c4_View& dest_, int pos_) { if (count_ < 0) count_ = GetSize() - from_; if (pos_ < 0) pos_ = dest_.GetSize(); d4_assert(0 <= from_ && from_ <= GetSize()); d4_assert(0 <= count_ && from_ + count_ <= GetSize()); d4_assert(0 <= pos_ && pos_ <= dest_.GetSize()); if (count_ > 0) { // the destination must not be inside the source rows d4_assert(&dest_ != this || from_ > pos_ || pos_ >= from_ + count_); // this test is slow, so do it only as a debug check d4_assert(IsCompatibleWith(dest_)); // make space, swap rows, drop originals c4_Row empty; dest_.InsertAt(pos_, empty, count_); // careful if insert moves origin if (&dest_ == this && pos_ <= from_) from_ += count_; for (int i = 0; i < count_; ++i) ((c4_HandlerSeq*) _seq)->ExchangeEntries(from_ + i, *(c4_HandlerSeq*) dest_._seq, pos_ + i); RemoveAt(from_, count_); } } /** Create view with all rows in natural (property-wise) order * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but unfortunately there are some major * limitations with this scheme - one of them being that deriving another * view from this sorted one will not properly track changes. */ c4_View c4_View::Sort() const { return f4_CreateSort(*_seq); } /** Create view sorted according to the specified properties * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but unfortunately there are some major * limitations with this scheme - one of them being that deriving another * view from this sorted one will not properly track changes. */ c4_View c4_View::SortOn(const c4_View& up_) const { c4_Sequence* seq = f4_CreateProject(*_seq, *up_._seq, true); return f4_CreateSort(*seq); } /** Create sorted view, with some properties sorted in reverse * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but unfortunately there are some major * limitations with this scheme - one of them being that deriving another * view from this sorted one will not properly track changes. */ c4_View c4_View::SortOnReverse( const c4_View& up_, ///< the view which defines the sort order const c4_View& down_ ///< subset of up_, defines reverse order ) const { c4_Sequence* seq = f4_CreateProject(*_seq, *up_._seq, true); return f4_CreateSort(*seq, down_._seq); } /** Create view with rows matching the specified value * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but this only works when based on views * which properly generate change notifications (.e. raw views, other * selections, and projections). */ c4_View c4_View::Select(const c4_RowRef& crit_) const { return f4_CreateFilter(*_seq, &crit_, &crit_); } /** Create view with row values within the specified range * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but this only works when based on views * which properly generate change notifications (.e. raw views, other * selections, and projections). */ c4_View c4_View::SelectRange( const c4_RowRef& low_, ///< values of the lower bounds (inclusive) const c4_RowRef& high_ ///< values of the upper bounds (inclusive) ) const { return f4_CreateFilter(*_seq, &low_, &high_); } /** Create view with the specified property arrangement * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but this only works when based on views * which properly generate change notifications (.e. raw views, selections, * and other projections). */ c4_View c4_View::Project(const c4_View& in_) const { return f4_CreateProject(*_seq, *in_._seq, false); } /** Create derived view with some properties omitted * * The result is virtual, it merely maintains a permutation to access the * underlying view. This "derived" view uses change notification to track * changes to the underlying view, but this only works when based on views * which properly generate change notifications (.e. raw views, selections, * and other projections). */ c4_View c4_View::ProjectWithout(const c4_View& out_) const { return f4_CreateProject(*_seq, *_seq, false, out_._seq); } /** Create view which is a segment/slice (default is up to end) * * Returns a view which is a subset, either a contiguous range, or * a "slice" with element taken from every step_ entries. If the * step is negative, the same entries are returned, but in reverse * order (start_ is still lower index, it'll then be returned last). * * This view operation is based on a custom viewer and is modifiable. */ c4_View c4_View::Slice(int first_, int limit_, int step_) const { return f4_CustSlice(*_seq, first_, limit_, step_); } /** Create view which is the cartesian product with given view * * The cartesian product is defined as every combination of rows * in both views. The number of entries is the product of the * number of entries in the two views, properties which are present * in both views will use the values defined in this view. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Product(const c4_View& view_) const { return f4_CustProduct(*_seq, view_); } /** Create view which remaps another given view * * Remapping constructs a view with the rows indicated by another * view. The first property in the order_ view must be an int * property with index values referring to this one. The size of * the resulting view is determined by the order_ view and can * differ, for example to act as a subset selection (if smaller). * * This view operation is based on a custom viewer and is modifiable. */ c4_View c4_View::RemapWith(const c4_View& view_) const { return f4_CustRemapWith(*_seq, view_); } /** Create view which pairs each row with corresponding row * * This is like a row-by-row concatenation. Both views must have * the same number of rows, the result has all properties from * this view plus any other properties from the other view. * * This view operation is based on a custom viewer and is modifiable. */ c4_View c4_View::Pair(const c4_View& view_) const { return f4_CustPair(*_seq, view_); } /** Create view with rows from another view appended * * Constructs a view which has all rows of this view, and all rows * of the second view appended. The structure of the second view * is assumed to be identical to this one. This operation is a bit * similar to appending all rows from the second view, but it does * not actually store the result anywhere, it just looks like it. * * This view operation is based on a custom viewer and is modifiable. */ c4_View c4_View::Concat(const c4_View& view_) const { return f4_CustConcat(*_seq, view_); } /** Create view with one property renamed (must be of same type) * * This view operation is based on a custom viewer and is modifiable. */ c4_View c4_View::Rename(const c4_Property& old_, const c4_Property& new_) const { return f4_CustRename(*_seq, old_, new_); } /** Create view with a subview, grouped by the specified properties * * This operation is similar to the SQL 'GROUP BY', but it takes * advantage of the fact that Metakit supports nested views. The * view returned from this member has one row per distinct group, * with an extra view property holding the remaining properties. * If there are N rows in the original view matching key X, then * the result is a row for key X, with a subview of N rows. The * properties of the subview are all the properties not in the key. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::GroupBy( const c4_View& keys_, ///< properties in this view determine grouping const c4_ViewProp& result_ ///< name of new subview defined in result ) const { return f4_CustGroupBy(*_seq, keys_, result_); } /** Create view with count of duplicates, when grouped by key * * This is similar to c4_View::GroupBy, but it determines only the * number of rows in each group and does not create a nested view. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Counts( const c4_View& keys_, ///< properties in this view determine grouping const c4_IntProp& result_ ///< new count property defined in result ) const { return f4_CustGroupBy(*_seq, keys_, result_); // third arg is c4_IntProp } /** Create view with all duplicate rows omitted * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Unique() const { c4_IntProp count ("#N#"); return Counts(Clone(), count).ProjectWithout(count); } /** Create view which is the set union (assumes no duplicate rows) * * Calculates the set union. This will only work if both input * views are sets, i.e. they have no duplicate rows in them. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Union(const c4_View& view_) const { return Concat(view_).Unique(); } /** Create view with all rows also in the given view (no dups) * * Calculates the set intersection. This will only work if both * input views are sets, i.e. they have no duplicate rows in them. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Intersect(const c4_View& view_) const { c4_View v = Concat(view_); // assume neither view has any duplicates c4_IntProp count ("#N#"); return v.Counts(Clone(), count).Select(count [2]).ProjectWithout(count); } /** Create view with all rows not in both views (no dups) * * Calculates the "XOR" of two sets. This will only work if both * input views are sets, i.e. they have no duplicate rows in them. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Different(const c4_View& view_) const { c4_View v = Concat(view_); // assume neither view has any duplicates c4_IntProp count ("#N#"); return v.Counts(Clone(), count).Select(count [1]).ProjectWithout(count); } /** Create view with all rows not in the given view (no dups) * * Calculates set-difference of this view minus arg view. Result * is a subset, unlike c4_View::Different. Will only work if both * input views are sets, i.e. they have no duplicate rows in them. * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Minus( const c4_View& view_ ///< the second view ) const { // inefficient: calculate difference, then keep only those in self return Intersect(Different(view_)); } /** Create view with a specific subview expanded, like a join * * This operation is the inverse of c4_View::GroupBy, expanding * all rows in specified subview and returning a view which looks * as if the rows in each subview were "expanded in place". * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::JoinProp( const c4_ViewProp& sub_, ///< name of the subview to expand bool outer_ ///< true: keep rows with empty subviews ) const { return f4_CustJoinProp(*_seq, sub_, outer_); } /** Create view which is the relational join on the given keys * * This view operation is based on a read-only custom viewer. */ c4_View c4_View::Join( const c4_View& keys_, ///< properties in this view determine the join const c4_View& view_, ///< second view participating in the join bool outer_ ///< true: keep rows with no match in second view ) const { // inefficient: calculate difference, then keep only those in self return f4_CustJoin(*_seq, keys_, view_, outer_); } /** Create an identity view which only allows reading * * This view operation is based on a custom viewer. */ c4_View c4_View::ReadOnly() const { return f4_CreateReadOnly(*_seq); } /** Create mapped view which adds a hash lookup layer * * This view creates and manages a special hash map view, to implement a * fast find on the key. The key is defined to consist of the first * numKeys_ properties of the underlying view. * * The map_ view must be empty the first time this hash view is used, so * that Metakit can fill it based on whatever rows are already present in * the underlying view. After that, neither the underlying view nor the * map view may be modified other than through this hash mapping layer. * The defined structure of the map view must be "_H:I,_R:I". * * This view is modifiable. Insertions and changes to key field properties * can cause rows to be repositioned to maintain hash uniqueness. Careful: * when a row is changed in such a way that its key is the same as in another * row, that other row will be deleted from the view. * * Example of use: * @code * c4_View data = storage.GetAs("people[name:S,age:I]"); * c4_View datah = storage.GetAs("people_H[_H:I,_R:I]"); * c4_View hash = raw.Hash(datah, 1); * ... hash.GetSize() ... * hash.Add(...) * @endcode */ c4_View c4_View::Hash(const c4_View& map_, int numKeys_) const { return f4_CreateHash(*_seq, numKeys_, map_._seq); } /** Create mapped view which blocks its rows in two levels * * This view acts like a large flat view, even though the actual rows are * stored in blocks, which are rebalanced automatically to maintain a good * trade-off between block size and number of blocks. * * The underlying view must be defined with a single view property, with * the structure of the subview being as needed. An example of a blocked * view definition which will act like a single one containing 2 properties: * @code * c4_View raw = storage.GetAs("people[_B[name:S,age:I]]"); * c4_View flat = raw.Blocked(); * ... flat.GetSize() ... * flat.InsertAt(...) * @endcode * * This view operation is based on a custom viewer and is modifiable. */ c4_View c4_View::Blocked() const { return f4_CreateBlocked(*_seq); } /** Create mapped view which keeps its rows ordered * * This is an identity view, which has as only use to inform Metakit that * the underlying view can be considered to be sorted on its first numKeys_ * properties. The effect is that c4_View::Find will try to use binary * search when the search includes key properties (results will be identical * to unordered views, the find will just be more efficient). * * This view is modifiable. Insertions and changes to key field properties * can cause rows to be repositioned to maintain the sort order. Careful: * when a row is changed in such a way that its key is the same as in another * row, that other row will be deleted from the view. * * This view can be combined with c4_View::Blocked, to create a 2-level * btree structure. */ c4_View c4_View::Ordered(int numKeys_) const { return f4_CreateOrdered(*_seq, numKeys_); } /** Create mapped view which maintains an index permutation * * This is an identity view which somewhat resembles the ordered view, it * maintains a secondary "map" view to contain the permutation to act as * an index. The indexed view presents the same order of rows as the * underlying view, but the index map is set up in such a way that binary * search is possible on the keys specified. When the "unique" parameter * is true, insertions which would create a duplicate key are ignored. * * This view is modifiable. Careful: when a row is changed in such a way * that its key is the same as in another row, that other row will be * deleted from the view. */ c4_View c4_View::Indexed(const c4_View& map_, const c4_View& props_, bool unique_) const { return f4_CreateIndexed(*_seq, *map_._seq, props_, unique_); } /** Return the index of the specified row in this view (or -1) * * This function can be used to "unmap" an index of a derived view back * to the original underlying view. */ int c4_View::GetIndexOf(const c4_RowRef& row_) const { c4_Cursor cursor = &row_; return cursor._seq->RemapIndex(cursor._index, _seq); } /// Restrict the search range for rows int c4_View::RestrictSearch(const c4_RowRef& c_, int& pos_, int& count_) { return _seq->RestrictSearch(&c_, pos_, count_) ? 0 : ~0; } /** Find index of the the next entry matching the specified key. * * Defaults to linear search, but hash- and ordered-views will use a better * algorithm if possible. Only the properties present in the search key * are used to determine whether a row matches the key. * @return position where match occurred * @retval -1 if not found */ int c4_View::Find( const c4_RowRef& crit_, ///< the value to look for int start_ ///< the index to start with ) const { d4_assert(start_ >= 0); c4_Row copy = crit_; // the lazy (and slow) solution: make a copy int count = GetSize() - start_; if (_seq->RestrictSearch(©, start_, count)) { c4_View refView = copy.Container(); c4_Sequence* refSeq = refView._seq; d4_assert(refSeq != 0); c4_Bytes data; for (int j = 0; j < count; ++j) { int i; for (i = 0; i < refSeq->NumHandlers(); ++i) { c4_Handler& h = refSeq->NthHandler(i); // no context issues if (!_seq->Get(start_ + j, h.PropId(), data)) h.ClearBytes(data); if (h.Compare(0, data) != 0) // always row 0 break; } if (i == refSeq->NumHandlers()) return start_ + j; } } return -1; } /** Search for a key, using the native sort order of the view * @return position where found, or where it may be inserted, * this position can also be just past the last row */ int c4_View::Search(const c4_RowRef& crit_) const { int l = -1, u = GetSize(); while (l + 1 != u) { const int m = (l + u) >> 1; if (_seq->Compare(m, &crit_) < 0) //if (crit_ > (*this)[m]) // Dec 2001: see comments below l = m; else u = m; } return u; } /// Return number of matching keys, and pos of first one as arg int c4_View::Locate(const c4_RowRef& crit_, int* pos_) const { // Dec 2001: fixed a problem with searching of partial rows. // // There is an *extremely* tricky issue in here, in that the // comparison operator for rows is not symmetric. So in the // general case, "a == b" is not euivalent to "b == a". This // is without doubt a design mistake (and should have at least // been named differently). // // The reason is that the number of properties in both rowrefs // need not be the same. Only the properties of the leftmost // rowref are compared against the other one. This also applies // to the other comparisons, i.e. !=, <, >, <=, and >=. // // All Compare calls below have been changed to use comparisons // in the proper order and now use "rowref rowref" syntax. c4_Cursor curr (*(c4_Sequence*) _seq, 0); // loses const int l = -1, u = GetSize(); while (l + 1 != u) { curr._index = (l + u) >> 1; if (crit_ > *curr) l = curr._index; else u = curr._index; } if (pos_ != 0) *pos_ = u; // only look for more if the search hit an exact match curr._index = u; if (u == GetSize() || crit_ != *curr) return 0; // as Jon Bentley wrote in DDJ Apr 2000, setting l2 to -1 is better than u int l2 = -1, u2 = GetSize(); while (l2 + 1 != u2) { curr._index = (l2 + u2) >> 1; if (crit_ >= *curr) l2 = curr._index; else u2 = curr._index; } return u2 - u; } /// Compare two views lexicographically (rows 0..N-1). int c4_View::Compare(const c4_View& view_) const { if (_seq == view_._seq) return 0; int na = GetSize(); int nb = view_.GetSize(); int i; for (i = 0; i < na && i < nb; ++i) if (GetAt(i) != view_.GetAt(i)) return GetAt(i) < view_.GetAt(i) ? -1 : +1; return na == nb ? 0 : i < na ? +1 : -1; } ///////////////////////////////////////////////////////////////////////////// /** @class c4_Cursor * * An iterator for collections of rows (views). * * Cursor objects can be used to point to specific entries in a view. * A cursor acts very much like a pointer to a row in a view, and is * returned when taking the address of a c4_RowRef. Dereferencing * a cursor leads to the original row reference again. You can construct a * cursor for a c4_Row, but since such rows are not part of a collection, * incrementing or decrementing these cursors is meaningless (and wrong). * * The usual range of pointer operations can be applied to these objects: * pre/post-increment and decrement, adding or subtracting integer offsets, * as well as the full range of comparison operators. If two cursors * point to entries in the same view, their difference can be calculated. * * As with regular pointers, care must be taken to avoid running off of * either end of a view (the debug build includes assertions to check this). */ /** @class c4_RowRef * * Reference to a data row, can be used on either side of an assignment. * * Row references are created when dereferencing a c4_Cursor or when * indexing an element of a c4_View. Assignment will change the * corresponding item. Rows (objects of type c4_Row) are a special * case of row references, consisting of a view with exactly one item. * * Internally, row references are very similar to cursors, in fact they are * little more than a wrapper around them. The essential difference is one * of semantics: comparing row references compares contents, copying row * references copies the contents, whereas cursor comparison and copying * deals with the pointer to the row, not its contents. */ ///////////////////////////////////////////////////////////////////////////// // c4_Row c4_Row::c4_Row () : c4_RowRef (* Allocate()) { } c4_Row::c4_Row (const c4_Row& row_) : c4_RowRef (* Allocate()) { operator= (row_); } c4_Row::c4_Row (const c4_RowRef& rowRef_) : c4_RowRef (* Allocate()) { operator= (rowRef_); } c4_Row::~c4_Row () { Release(_cursor); } c4_Row& c4_Row::operator= (const c4_Row& row_) { return operator= ((const c4_RowRef&) row_); } /// Assignment from a reference to a row. c4_Row& c4_Row::operator= (const c4_RowRef& rowRef_) { d4_assert(_cursor._seq != 0); if (_cursor != &rowRef_) { d4_assert(_cursor._index == 0); _cursor._seq->SetAt(0, &rowRef_); } return *this; } /// Adds all properties and values into this row. void c4_Row::ConcatRow(const c4_RowRef& rowRef_) { d4_assert(_cursor._seq != 0); c4_Cursor cursor = &rowRef_; // trick to access private rowRef_._cursor d4_assert(cursor._seq != 0); c4_Sequence& rhSeq = * cursor._seq; c4_Bytes data; for (int i = 0; i < rhSeq.NumHandlers(); ++i) { c4_Handler& h = rhSeq.NthHandler(i); h.GetBytes(cursor._index, data); _cursor._seq->Set(_cursor._index, h.Property(), data); } } c4_Row operator+ (const c4_RowRef& a_, const c4_RowRef& b_) { c4_Row row = a_; row.ConcatRow(b_); return row; } c4_Cursor c4_Row::Allocate() { c4_Sequence* seq = d4_new c4_HandlerSeq (0); seq->IncRef(); seq->Resize(1); return c4_Cursor (*seq, 0); } void c4_Row::Release(c4_Cursor row_) { d4_assert(row_._seq != 0); d4_assert(row_._index == 0); row_._seq->DecRef(); } ///////////////////////////////////////////////////////////////////////////// /** @class c4_Property * * Base class for the basic data types. * * Property objects exist independently of view, row, and storage objects. * They have a name and type, and can appear in any number of views. * You will normally only use derived classes, to maintain strong typing. */ // This is a workaround for the fact that the initialization order of // static objects is not always adequate (implementation dependent). // Extremely messy solution, to allow statically declared properties. // // These are the only static variables in the entire Metakit core lib. static c4_ThreadLock* sThreadLock = 0; static c4_StringArray* sPropNames = 0; static c4_DWordArray* sPropCounts = 0; /// Call this to get rid of some internal datastructues (on exit) void c4_Property::CleanupInternalData() { delete sPropNames; sPropNames = 0; // race delete sPropCounts; sPropCounts = 0; // race delete sThreadLock; sThreadLock = 0; // race } c4_Property::c4_Property (char type_, const char* name_) : _type (type_) { if (sThreadLock == 0) sThreadLock = d4_new c4_ThreadLock; c4_ThreadLock::Hold lock; // grabs the lock until end of scope if (sPropNames == 0) sPropNames = d4_new c4_StringArray; if (sPropCounts == 0) sPropCounts = d4_new c4_DWordArray; c4_String temp = name_; _id = sPropNames->GetSize(); while (-- _id >= 0) { const char* p = sPropNames->GetAt(_id); // optimize for first char case-insensitive match if (((*p ^ *name_) & ~0x20) == 0 && temp.CompareNoCase(p) == 0) break; } if (_id < 0) { int size = sPropCounts->GetSize(); for (_id = 0; _id < size; ++_id) if (sPropCounts->GetAt(_id) == 0) break; if (_id >= size) { sPropCounts->SetSize(_id + 1); sPropNames->SetSize(_id + 1); } sPropCounts->SetAt(_id, 0); sPropNames->SetAt(_id, name_); } Refs(+1); } c4_Property::c4_Property (const c4_Property& prop_) : _id (prop_.GetId()), _type (prop_.Type()) { c4_ThreadLock::Hold lock; d4_assert(sPropCounts != 0); d4_assert(sPropCounts->GetAt(_id) > 0); Refs(+1); } c4_Property::~c4_Property () { c4_ThreadLock::Hold lock; Refs(-1); } void c4_Property::operator= (const c4_Property& prop_) { c4_ThreadLock::Hold lock; prop_.Refs(+1); Refs(-1); _id = prop_.GetId(); _type = prop_.Type(); } /// Return the name of this property const char* c4_Property::Name() const { c4_ThreadLock::Hold lock; d4_assert(sPropNames != 0); return sPropNames->GetAt(_id); } /** Adjust the reference count * * This is part of the implementation and shouldn't normally be called. * This code is only called with the lock held, and always thread-safe. */ void c4_Property::Refs(int diff_) const { d4_assert(diff_ == -1 || diff_ == +1); d4_assert(sPropCounts != 0); sPropCounts->ElementAt(_id) += diff_; #if q4_CHECK // get rid of the cache when the last property goes away static t4_i32 sPropTotals; sPropTotals += diff_; if (sPropTotals == 0) CleanupInternalData(); #endif } /////////////////////////////////////////////////////////////////////////////