# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1290730050 -3600
# Node ID ea2944f51430299339fd9e4490773d1b447668ab
# Parent  e0bd00412dbc9ac14807de7a3c70b1d8ec0e0ea8
Introduced support for higher-level sequential access to indexes.

diff -r e0bd00412dbc -r ea2944f51430 iixr/index.py
--- a/iixr/index.py	Fri Nov 26 01:06:44 2010 +0100
+++ b/iixr/index.py	Fri Nov 26 01:07:30 2010 +0100
@@ -184,6 +184,16 @@
         self.dict_reader = get_term_reader(pathname, "merged")
         self.field_dict_reader = get_field_reader(pathname, "merged")
 
+    # Sequential access.
+
+    def read_term(self):
+        return self.dict_reader.read_term()
+
+    def go_to_term(self, term):
+        return self.dict_reader._get_term_and_positions(*self.dict_reader.go_to_term(term))
+
+    # Query access.
+
     def get_terms(self):
         return self.dict_reader.get_terms()
 
diff -r e0bd00412dbc -r ea2944f51430 iixr/terms.py
--- a/iixr/terms.py	Fri Nov 26 01:06:44 2010 +0100
+++ b/iixr/terms.py	Fri Nov 26 01:07:30 2010 +0100
@@ -301,6 +301,15 @@
         else:
             return None
 
+    def _get_term_and_positions(self, term, offset, frequency, doc_frequency):
+
+        """
+        Return the term plus positions details using the given 'term', 'offset',
+        'frequency' and 'doc_frequency'.
+        """
+
+        return term, frequency, doc_frequency, self._get_positions(offset, doc_frequency)
+
     def _get_positions(self, offset, doc_frequency):
 
         """
@@ -335,7 +344,24 @@
         """
 
         term, offset, frequency, doc_frequency = self.info_reader.read_term()
-        return term, frequency, doc_frequency, self._get_positions(offset, doc_frequency)
+        return self._get_term_and_positions(term, offset, frequency, doc_frequency)
+
+    def go_to_term(self, term):
+
+        """
+        Navigate to 'term' in the dictionary, returning the details from its
+        entry. The returned details can be augmented with position information
+        when presented to the _get_term_and_positions method.
+        """
+
+        found_term, offset, frequency, doc_frequency, info_offset = self._find_closest_term(term)
+
+        # Position the reader, if necessary.
+
+        if info_offset is not None:
+            self.info_reader.go_to_term(found_term, offset, info_offset)
+
+        return found_term, offset, frequency, doc_frequency
 
     # Query methods.
 
@@ -351,12 +377,7 @@
 
         terms = []
 
-        found_term, offset, frequency, doc_frequency, info_offset = self._find_closest_term(term)
-
-        # Position the reader, if necessary.
-
-        if info_offset is not None:
-            self.info_reader.go_to_term(found_term, offset, info_offset)
+        found_term, offset, frequency, doc_frequency = self.go_to_term(term)
 
         # Read and record terms.