public static Tree createStanfordTree(Annotation root, TreeFactory tFact) {
JCas aJCas;
try {
aJCas = root.getCAS().getJCas();
} catch (CASException e) {
throw new IllegalStateException("Unable to get JCas from JCas wrapper");
}
// define the new (root) node
Tree rootNode;
// before we can create a node, we must check if we have any children (we have to know
// whether to create a node or a leaf - not very dynamic)
if (root instanceof Constituent && !isLeaf((Constituent) root)) {
Constituent node = (Constituent) root;
List<Tree> childNodes = new ArrayList<Tree>();
// get childNodes from child annotations
FSArray children = node.getChildren();
for (int i = 0; i < children.size(); i++) {
childNodes.add(createStanfordTree(node.getChildren(i), tFact));
}
// now create the node with its children
rootNode = tFact.newTreeNode(node.getConstituentType(), childNodes);
} else {
// Handle leaf annotations
// Leafs are always Token-annotations
// We also have to insert a Preterminal node with the value of the
// POS-Annotation on the token
// because the POS is not directly stored within the treee
Token wordAnnotation = (Token) root;
// create leaf-node for the tree
Tree wordNode = tFact.newLeaf(wordAnnotation.getCoveredText());
// create information about preceding and trailing whitespaces in the leaf node
StringBuilder preWhitespaces = new StringBuilder();
StringBuilder trailWhitespaces = new StringBuilder();
List<Token> precedingTokenList = selectPreceding(aJCas, Token.class, wordAnnotation, 1);
List<Token> followingTokenList = selectFollowing(aJCas, Token.class, wordAnnotation, 1);
if (precedingTokenList.size() > 0) {
Token precedingToken = precedingTokenList.get(0);
int precedingWhitespaces = wordAnnotation.getBegin() - precedingToken.getEnd();
for (int i = 0; i < precedingWhitespaces; i++) {
preWhitespaces.append(" ");
}
}
if (followingTokenList.size() > 0) {
Token followingToken = followingTokenList.get(0);
int trailingWhitespaces = followingToken.getBegin() - wordAnnotation.getEnd();
for (int i = 0; i < trailingWhitespaces; i++) {
trailWhitespaces.append(" ");
}
}
// write whitespace information as CoreAnnotation.BeforeAnnotation and
// CoreAnnotation.AfterAnnotation to the node add annotation to list and write back to
// node label
((CoreLabel) wordNode.label())
.set(CoreAnnotations.BeforeAnnotation.class, preWhitespaces.toString());
((CoreLabel) wordNode.label())
.set(CoreAnnotations.AfterAnnotation.class, trailWhitespaces.toString());
// get POS-annotation
// get the token that is covered by the POS
List<POS> coveredPos = JCasUtil.selectCovered(aJCas, POS.class, wordAnnotation);
// the POS should only cover one token
assert coveredPos.size() == 1;
POS pos = coveredPos.get(0);
// create POS-Node in the tree and attach word-node to it
rootNode = tFact.newTreeNode(pos.getPosValue(), Arrays.asList((new Tree[] {wordNode})));
}
return rootNode;
}
