Class RewriteRuleElementStream

java.lang.Object
org.antlr.runtime.tree.RewriteRuleElementStream
Direct Known Subclasses:
RewriteRuleNodeStream, RewriteRuleSubtreeStream, RewriteRuleTokenStream

public abstract class RewriteRuleElementStream extends Object
A generic list of elements tracked in an alternative to be used in a -> rewrite rule. We need to subclass to fill in the next() method, which returns either an AST node wrapped around a token payload or an existing subtree. Once you start next()ing, do not try to add more elements. It will break the cursor tracking I believe.
See Also:
  • Field Details

    • cursor

      protected int cursor
      Cursor 0..n-1. If singleElement!=null, cursor is 0 until you next(), which bumps it to 1 meaning no more elements.
    • singleElement

      protected Object singleElement
      Track single elements w/o creating a list. Upon 2nd add, alloc list
    • elements

      protected List<Object> elements
      The list of tokens or subtrees we are tracking
    • dirty

      protected boolean dirty
      Once a node / subtree has been used in a stream, it must be dup'd from then on. Streams are reset after subrules so that the streams can be reused in future subrules. So, reset must set a dirty bit. If dirty, then next() always returns a dup. I wanted to use "naughty bit" here, but couldn't think of a way to use "naughty". TODO: unused?
    • elementDescription

      protected String elementDescription
      The element or stream description; usually has name of the token or rule reference that this list tracks. Can include rulename too, but the exception would track that info.
    • adaptor

      protected TreeAdaptor adaptor
  • Constructor Details

    • RewriteRuleElementStream

      public RewriteRuleElementStream(TreeAdaptor adaptor, String elementDescription)
    • RewriteRuleElementStream

      public RewriteRuleElementStream(TreeAdaptor adaptor, String elementDescription, Object oneElement)
      Create a stream with one element
    • RewriteRuleElementStream

      public RewriteRuleElementStream(TreeAdaptor adaptor, String elementDescription, List<Object> elements)
      Create a stream, but feed off an existing list
  • Method Details

    • reset

      public void reset()
      Reset the condition of this stream so that it appears we have not consumed any of its elements. Elements themselves are untouched. Once we reset the stream, any future use will need duplicates. Set the dirty bit.
    • add

      public void add(Object el)
    • nextTree

      public Object nextTree()
      Return the next element in the stream. If out of elements, throw an exception unless size()==1. If size is 1, then return elements[0]. Return a duplicate node/subtree if stream is out of elements and size==1. If we've already used the element, dup (dirty bit set).
    • _next

      protected Object _next()
      do the work of getting the next element, making sure that it's a tree node or subtree. Deal with the optimization of single- element list versus list of size > 1. Throw an exception if the stream is empty or we're out of elements and size>1. protected so you can override in a subclass if necessary.
    • dup

      protected abstract Object dup(Object el)
      When constructing trees, sometimes we need to dup a token or AST subtree. Dup'ing a token means just creating another AST node around it. For trees, you must call the adaptor.dupTree() unless the element is for a tree root; then it must be a node dup.
    • toTree

      protected Object toTree(Object el)
      Ensure stream emits trees; tokens must be converted to AST nodes. AST nodes can be passed through unmolested.
    • hasNext

      public boolean hasNext()
    • size

      public int size()
    • getDescription

      public String getDescription()