1 files changed, 21 insertions, 0 deletions
diff --git a/extractor/precomputation.h b/extractor/precomputation.h
index 2c1eccf8..e3c4d26a 100644
--- a/extractor/precomputation.h
+++ b/extractor/precomputation.h
@@ -20,8 +20,19 @@ typedef unordered_map<vector<int>, vector<int>, VectorHash> Index;
 
 class SuffixArray;
 
+/**
+ * Data structure wrapping an index with all the occurrences of the most
+ * frequent discontiguous collocations in the source data.
+ *
+ * Let a, b, c be contiguous collocations. The index will contain an entry for
+ * every collocation of the form:
+ * - aXb, where a and b are frequent
+ * - aXbXc, where a and b are super-frequent and c is frequent or
+ *                b and c are super-frequent and a is frequent.
+ */
 class Precomputation {
  public:
+  // Constructs the index using the suffix array.
   Precomputation(
       shared_ptr<SuffixArray> suffix_array, int num_frequent_patterns,
       int num_super_frequent_patterns, int max_rule_span,
@@ -32,6 +43,7 @@ class Precomputation {
 
   void WriteBinary(const fs::path& filepath) const;
 
+  // Returns a reference to the index.
   virtual const Index& GetCollocations() const;
 
   static int FIRST_NONTERMINAL;
@@ -41,14 +53,23 @@ class Precomputation {
   Precomputation();
 
  private:
+  // Finds the most frequent contiguous collocations.
   vector<vector<int> > FindMostFrequentPatterns(
       shared_ptr<SuffixArray> suffix_array, const vector<int>& data,
       int num_frequent_patterns, int max_frequent_phrase_len,
       int min_frequency);
+
+  // Given the locations of the frequent contiguous collocations in a sentence,
+  // it adds new entries to the index for each discontiguous collocation
+  // matching the criteria specified in the class description.
   void AddCollocations(
       const vector<std::tuple<int, int, int> >& matchings, const vector<int>& data,
       int max_rule_span, int min_gap_size, int max_rule_symbols);
+
+  // Adds an occurrence of a binary collocation.
   void AddStartPositions(vector<int>& positions, int pos1, int pos2);
+
+  // Adds an occurrence of a ternary collocation.
   void AddStartPositions(vector<int>& positions, int pos1, int pos2, int pos3);
 
   Index collocations;