The root of a tregex expression now keeps track of what variables it …

…knows about

src/edu/stanford/nlp/trees/tregex/TregexParser.java

@@ -28,7 +28,7 @@ class TregexParser implements TregexParserConstants {
   // keep track of which variables we've seen, so that we can reject
   // some nonsense patterns such as ones that reset variables or link
   // to variables that haven't been set
-  private Set<String> knownVariables = Generics.newHashSet();
+  Set<String> knownVariables = Generics.newHashSet();
 
   public TregexParser(java.io.Reader stream,
                       Function<String, String> basicCatFunction,

src/edu/stanford/nlp/trees/tregex/TregexParser.jj

@@ -33,7 +33,7 @@ class TregexParser {
   // keep track of which variables we've seen, so that we can reject
   // some nonsense patterns such as ones that reset variables or link
   // to variables that haven't been set
-  private Set<String> knownVariables = Generics.newHashSet();
+  Set<String> knownVariables = Generics.newHashSet();
 
   public TregexParser(java.io.Reader stream,
                       Function<String, String> basicCatFunction,

src/edu/stanford/nlp/trees/tregex/TregexPattern.java

@@ -361,6 +361,7 @@ public abstract class TregexPattern implements Serializable  {
   private boolean neg; // = false;
   private boolean opt; // = false;
   private String patternString;
+  private Set<String> knownVariables;
 
   void negate() {
     neg = true;
@@ -484,6 +485,15 @@ void setPatternString(String patternString) {
     this.patternString = patternString;
   }
 
+  /** Only used by the TregexPatternCompiler to track the known variables in the tregex (and only at the root). Pseudo-final. */
+  void setKnownVariables(Set<String> knownVariables) {
+    this.knownVariables = knownVariables;
+  }
+
+  public Set<String> knownVariables() {
+    return Collections.unmodifiableSet(knownVariables);
+  }
+
   /**
    * @return A single-line string representation of the pattern
    */

src/edu/stanford/nlp/trees/tregex/TregexPatternCompiler.java

@@ -138,6 +138,7 @@ public TregexPattern compile(String tregex) {
       TregexParser parser = new TregexParser(new StringReader(tregex + '\n'),
                                              basicCatFunction, headFinder);
       pattern = parser.Root();
+      pattern.setKnownVariables(parser.knownVariables);
     } catch (TokenMgrError tme) {
       throw new TregexParseException("Could not parse " + tregex, tme);
     } catch (ParseException e) {