/// <summary>
/// During a redution, pops the top symbol from the stack and gives it a tree action
/// </summary>
/// <param name="action">The tree action to apply to the symbol</param>
public void ReductionPop(TreeAction action)
{
SubTree sub = stack[stackNext + popCount];
ReductionAddSub(sub, action);
sub.Free();
popCount++;
}
/// <summary>
/// Finalizes the parse tree and returns it
/// </summary>
/// <returns>The final parse tree</returns>
public AST GetTree()
{
// Get the axiom's sub tree
SubTree sub = stack[stackNext - 2];
// Commit the remaining sub-tree
sub.Commit(result);
return(result);
}
/// <summary>
/// Clones this sub-tree
/// </summary>
/// <returns>The clone</returns>
public SubTree Clone()
{
SubTree result = pool != null?pool.Acquire() : new SubTree(null, nodes.Length);
int size = GetSize();
Array.Copy(nodes, result.nodes, size);
Array.Copy(actions, result.actions, size);
return(result);
}
/// <summary>
/// Push a token onto the stack
/// </summary>
/// <param name="index">The token's index in the parsed text</param>
public void StackPushToken(int index)
{
SubTree single = poolSingle.Acquire();
single.SetupRoot(new TableElemRef(TableType.Token, index), TreeAction.None);
if (stackNext == stack.Length)
{
Array.Resize(ref stack, stack.Length + LRkParser.INIT_STACK_SIZE);
}
stack[stackNext++] = single;
}
/// <summary>
/// Copy the root's children of this sub-tree to the given sub-tree's buffer beginning at the given index
/// </summary>
/// <param name="destination">The sub-tree to copy to</param>
/// <param name="index">The starting index in the destination's buffer</param>
/// <remarks>
/// This methods only applies in the case of a depth 1 sub-tree (only a root and its children).
/// The results of this method in the case of a depth 2 sub-tree is undetermined.
/// </remarks>
public void CopyChildrenTo(SubTree destination, int index)
{
if (nodes[0].count == 0)
{
return;
}
int size = GetSize() - 1;
Array.Copy(nodes, 1, destination.nodes, index, size);
Array.Copy(actions, 1, destination.actions, index, size);
}
/// <summary>
/// Copy the content of this sub-tree to the given sub-tree's buffer beginning at the given index
/// </summary>
/// <param name="destination">The sub-tree to copy to</param>
/// <param name="index">The starting index in the destination's buffer</param>
/// <remarks>
/// This methods only applies in the case of a depth 1 sub-tree (only a root and its children).
/// The results of this method in the case of a depth 2 sub-tree is undetermined.
/// </remarks>
public void CopyTo(SubTree destination, int index)
{
if (nodes[0].count == 0)
{
destination.nodes[index] = nodes[0];
destination.actions[index] = actions[0];
}
else
{
int size = nodes[0].count + 1;
Array.Copy(nodes, 0, destination.nodes, index, size);
Array.Copy(actions, 0, destination.actions, index, size);
}
}
/// <summary>
/// Prepares for the forthcoming reduction operations
/// </summary>
/// <param name="varIndex">The reduced variable index</param>
/// <param name="length">The length of the reduction</param>
/// <param name="action">The tree action applied onto the symbol</param>
public void ReductionPrepare(int varIndex, int length, TreeAction action)
{
stackNext -= length;
int estimation = ESTIMATION_BIAS;
for (int i = 0; i != length; i++)
{
estimation += stack[stackNext + i].GetSize();
}
cache = GetSubTree(estimation);
cache.SetupRoot(new TableElemRef(TableType.Variable, varIndex), action);
cacheNext = 1;
handleNext = 0;
popCount = 0;
}
/// <summary>
/// During a reduction, insert the given sub-tree
/// </summary>
/// <param name="sub">The sub-tree</param>
/// <param name="action">The tree action applied onto the symbol</param>
private void ReductionAddSub(SubTree sub, TreeAction action)
{
if (sub.GetActionAt(0) == TreeAction.ReplaceByChildren)
{
int directChildrenCount = sub.GetChildrenCountAt(0);
while (handleNext + directChildrenCount >= handle.Length)
{
Array.Resize(ref handle, handle.Length + INIT_HANDLE_SIZE);
}
// copy the children to the cache
sub.CopyChildrenTo(cache, cacheNext);
// setup the handle
int index = 1;
for (int i = 0; i != directChildrenCount; i++)
{
int size = sub.GetChildrenCountAt(index) + 1;
handle[handleNext++] = cacheNext;
cacheNext += size;
index += size;
}
}
else if (action == TreeAction.Drop)
{
}
else
{
if (action != TreeAction.None)
{
sub.SetActionAt(0, action);
}
// copy the complete sub-tree to the cache
if (handleNext == handle.Length)
{
Array.Resize(ref handle, handle.Length + INIT_HANDLE_SIZE);
}
sub.CopyTo(cache, cacheNext);
handle[handleNext++] = cacheNext;
cacheNext += sub.GetChildrenCountAt(0) + 1;
}
}
