xsdfacm.java

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    } // endContentModel(int[]):  boolean

    // Killed off whatCanGoHere; we may need it for DOM canInsert(...) etc.,
    // but we can put it back later.

    //
    // Private methods
    //

    /**
     * Builds the internal DFA transition table from the given syntax tree.
     *
     * @param syntaxTree The syntax tree.
     *
     * @exception RuntimeException Thrown if DFA cannot be built.
     */
    private void buildDFA(CMNode syntaxTree) {
        //
        //  The first step we need to take is to rewrite the content model
        //  using our CMNode objects, and in the process get rid of any
        //  repetition short cuts, converting them into '*' style repetitions
        //  or getting rid of repetitions altogether.
        //
        //  The conversions done are:
        //
        //  x+ -> (x|x*)
        //  x? -> (x|epsilon)
        //
        //  This is a relatively complex scenario. What is happening is that
        //  we create a top level binary node of which the special EOC value
        //  is set as the right side node. The the left side is set to the
        //  rewritten syntax tree. The source is the original content model
        //  info from the decl pool. The rewrite is done by buildSyntaxTree()
        //  which recurses the decl pool's content of the element and builds
        //  a new tree in the process.
        //
        //  Note that, during this operation, we set each non-epsilon leaf
        //  node's DFA state position and count the number of such leafs, which
        //  is left in the fLeafCount member.
        //
        //  The nodeTmp object is passed in just as a temp node to use during
        //  the recursion. Otherwise, we'd have to create a new node on every
        //  level of recursion, which would be piggy in Java (as is everything
        //  for that matter.)
        //

        /* MODIFIED (Jan, 2001)
         *
         * Use following rules.
         *   nullable(x+) := nullable(x), first(x+) := first(x),  last(x+) := last(x)
         *   nullable(x?) := true, first(x?) := first(x),  last(x?) := last(x)
         *
         * The same computation of follow as x* is applied to x+
         *
         * The modification drastically reduces computation time of
         * "(a, (b, a+, (c, (b, a+)+, a+, (d,  (c, (b, a+)+, a+)+, (b, a+)+, a+)+)+)+)+"
         */

        //
        //  And handle specially the EOC node, which also must be numbered
        //  and counted as a non-epsilon leaf node. It could not be handled
        //  in the above tree build because it was created before all that
        //  started. We save the EOC position since its used during the DFA
        //  building loop.
        //
        int EOCPos = fLeafCount;
        XSCMLeaf nodeEOC = new XSCMLeaf(XSParticleDecl.PARTICLE_ELEMENT, null, -1, fLeafCount++);
        fHeadNode = new XSCMBinOp(
            XSModelGroupImpl.MODELGROUP_SEQUENCE,
            syntaxTree,
            nodeEOC
        );

        //
        //  Ok, so now we have to iterate the new tree and do a little more
        //  work now that we know the leaf count. One thing we need to do is
        //  to calculate the first and last position sets of each node. This
        //  is cached away in each of the nodes.
        //
        //  Along the way we also set the leaf count in each node as the
        //  maximum state count. They must know this in order to create their
        //  first/last pos sets.
        //
        //  We also need to build an array of references to the non-epsilon
        //  leaf nodes. Since we iterate it in the same way as before, this
        //  will put them in the array according to their position values.
        //
        fLeafList = new XSCMLeaf[fLeafCount];
        fLeafListType = new int[fLeafCount];
        postTreeBuildInit(fHeadNode);

        //
        //  And, moving onward... We now need to build the follow position
        //  sets for all the nodes. So we allocate an array of state sets,
        //  one for each leaf node (i.e. each DFA position.)
        //
        fFollowList = new CMStateSet[fLeafCount];
        for (int index = 0; index < fLeafCount; index++)
            fFollowList[index] = new CMStateSet(fLeafCount);
        calcFollowList(fHeadNode);
        //
        //  And finally the big push... Now we build the DFA using all the
        //  states and the tree we've built up. First we set up the various
        //  data structures we are going to use while we do this.
        //
        //  First of all we need an array of unique element names in our
        //  content model. For each transition table entry, we need a set of
        //  contiguous indices to represent the transitions for a particular
        //  input element. So we need to a zero based range of indexes that
        //  map to element types. This element map provides that mapping.
        //
        fElemMap = new Object[fLeafCount];
        fElemMapType = new int[fLeafCount];
        fElemMapId = new int[fLeafCount];
        fElemMapSize = 0;
        for (int outIndex = 0; outIndex < fLeafCount; outIndex++) {
            // optimization from Henry Zongaro:
            //fElemMap[outIndex] = new Object ();
            fElemMap[outIndex] = null;

            int inIndex = 0;
            final int id = fLeafList[outIndex].getParticleId();
            for (; inIndex < fElemMapSize; inIndex++) {
                if (id == fElemMapId[inIndex])
                    break;
            }

            // If it was not in the list, then add it, if not the EOC node
            if (inIndex == fElemMapSize) {
                fElemMap[fElemMapSize] = fLeafList[outIndex].getLeaf();
                fElemMapType[fElemMapSize] = fLeafListType[outIndex];
                fElemMapId[fElemMapSize] = id;
                fElemMapSize++;
            }
        }

        // the last entry in the element map must be the EOC element.
        // remove it from the map.
        if (DEBUG) {
            if (fElemMapId[fElemMapSize-1] != -1)
                System.err.println("interal error in DFA: last element is not EOC.");
        }
        fElemMapSize--;

        /***
         * Optimization(Jan, 2001); We sort fLeafList according to
         * elemIndex which is *uniquely* associated to each leaf.
         * We are *assuming* that each element appears in at least one leaf.
         **/

        int[] fLeafSorter = new int[fLeafCount + fElemMapSize];
        int fSortCount = 0;

        for (int elemIndex = 0; elemIndex < fElemMapSize; elemIndex++) {
            final int id = fElemMapId[elemIndex];
            for (int leafIndex = 0; leafIndex < fLeafCount; leafIndex++) {
                if (id == fLeafList[leafIndex].getParticleId())
                    fLeafSorter[fSortCount++] = leafIndex;
            }
            fLeafSorter[fSortCount++] = -1;
        }

        /* Optimization(Jan, 2001) */

        //
        //  Next lets create some arrays, some that hold transient
        //  information during the DFA build and some that are permament.
        //  These are kind of sticky since we cannot know how big they will
        //  get, but we don't want to use any Java collections because of
        //  performance.
        //
        //  Basically they will probably be about fLeafCount*2 on average,
        //  but can be as large as 2^(fLeafCount*2), worst case. So we start
        //  with fLeafCount*4 as a middle ground. This will be very unlikely
        //  to ever have to expand, though it if does, the overhead will be
        //  somewhat ugly.
        //
        int curArraySize = fLeafCount * 4;
        CMStateSet[] statesToDo = new CMStateSet[curArraySize];
        fFinalStateFlags = new boolean[curArraySize];
        fTransTable = new int[curArraySize][];

        //
        //  Ok we start with the initial set as the first pos set of the
        //  head node (which is the seq node that holds the content model
        //  and the EOC node.)
        //
        CMStateSet setT = fHeadNode.firstPos();

        //
        //  Init our two state flags. Basically the unmarked state counter
        //  is always chasing the current state counter. When it catches up,
        //  that means we made a pass through that did not add any new states
        //  to the lists, at which time we are done. We could have used a
        //  expanding array of flags which we used to mark off states as we
        //  complete them, but this is easier though less readable maybe.
        //
        int unmarkedState = 0;
        int curState = 0;

        //
        //  Init the first transition table entry, and put the initial state
        //  into the states to do list, then bump the current state.
        //
        fTransTable[curState] = makeDefStateList();
        statesToDo[curState] = setT;
        curState++;

        /* Optimization(Jan, 2001); This is faster for
         * a large content model such as, "(t001+|t002+|.... |t500+)".
         */

        java.util.Hashtable stateTable = new java.util.Hashtable();

        /* Optimization(Jan, 2001) */

        //
        //  Ok, almost done with the algorithm... We now enter the
        //  loop where we go until the states done counter catches up with
        //  the states to do counter.
        //
        while (unmarkedState < curState) {
            //
            //  Get the first unmarked state out of the list of states to do.
            //  And get the associated transition table entry.
            //
            setT = statesToDo[unmarkedState];
            int[] transEntry = fTransTable[unmarkedState];

            // Mark this one final if it contains the EOC state
            fFinalStateFlags[unmarkedState] = setT.getBit(EOCPos);

            // Bump up the unmarked state count, marking this state done
            unmarkedState++;

            // Loop through each possible input symbol in the element map
            CMStateSet newSet = null;
            /* Optimization(Jan, 2001) */
            int sorterIndex = 0;
            /* Optimization(Jan, 2001) */
            for (int elemIndex = 0; elemIndex < fElemMapSize; elemIndex++) {
                //
                //  Build up a set of states which is the union of all of
                //  the follow sets of DFA positions that are in the current
                //  state. If we gave away the new set last time through then
                //  create a new one. Otherwise, zero out the existing one.
                //
                if (newSet == null)
                    newSet = new CMStateSet(fLeafCount);
                else
                    newSet.zeroBits();

                /* Optimization(Jan, 2001) */
                int leafIndex = fLeafSorter[sorterIndex++];

                while (leafIndex != -1) {
                    // If this leaf index (DFA position) is in the current set...
                    if (setT.getBit(leafIndex)) {
                        //
                        //  If this leaf is the current input symbol, then we
                        //  want to add its follow list to the set of states to
                        //  transition to from the current state.
                        //
                        newSet.union(fFollowList[leafIndex]);
                    }

                   leafIndex = fLeafSorter[sorterIndex++];
                }
                /* Optimization(Jan, 2001) */

                //
                //  If this new set is not empty, then see if its in the list
                //  of states to do. If not, then add it.
                //
                if (!newSet.isEmpty()) {
                    //
                    //  Search the 'states to do' list to see if this new
                    //  state set is already in there.
                    //

                    /* Optimization(Jan, 2001) */
                    Integer stateObj = (Integer)stateTable.get(newSet);
                    int stateIndex = (stateObj == null ? curState : stateObj.intValue());
                    /* Optimization(Jan, 2001) */

                    // If we did not find it, then add it
                    if (stateIndex == curState) {
                        //
                        //  Put this new state into the states to do and init
                        //  a new entry at the same index in the transition
                        //  table.
                        //
                        statesToDo[curState] = newSet;
                        fTransTable[curState] = makeDefStateList();

                        /* Optimization(Jan, 2001) */
                        stateTable.put(newSet, new Integer(curState));
                        /* Optimization(Jan, 2001) */

                        // We now have a new state to do so bump the count
                        curState++;

                        //
                        //  Null out the new set to indicate we adopted it.
                        //  This will cause the creation of a new set on the
                        //  next time around the loop.
                        //
                        newSet = null;
                    }

                    //
                    //  Now set this state in the transition table's entry
                    //  for this element (using its index), with the DFA
                    //  state we will move to from the current state when we
                    //  see this input element.
                    //
                    transEntry[elemIndex] = stateIndex;

                    // Expand the arrays if we're full
                    if (curState == curArraySize) {
                        //
                        //  Yikes, we overflowed the initial array size, so
                        //  we've got to expand all of these arrays. So adjust
                        //  up the size by 50% and allocate new arrays.