# HG changeset patch
# User Igor Chubin <igor@chub.in>
# Date 1320085280 -7200
# Node ID f583256b7ab150bcd0d54855b0e07ca8d22b2288
# Parent  abd4080ee5839e2b51b6849221d0cd1da0fb8ff1
-p key support in new-words.py

diff -r abd4080ee583 -r f583256b7ab1 new-words.py
--- a/new-words.py	Sun May 01 20:27:36 2011 +0200
+++ b/new-words.py	Mon Oct 31 20:21:20 2011 +0200
@@ -496,10 +496,54 @@
         for line in lines:
             f.write(line)
 
+def parse_parts_description(parts_description):
+    """
+    Returns triad (start, stop, step)
+    basing on parts_description string.
+     from-to/step
+     from+delta/step
+    """
+    def incorrect_parts_description(pd):
+        raise ValueError("Parts description must be in format: num[[+-]num]/num; this [%s] is incorrect" % pd)
+
+    try:
+        (a, step) = parts_description.split("/", 1)
+        step = int(step)
+        start = 0
+        stop = 0
+        if '-' in a:
+            (start, stop) = a.split("-", 1)
+            start = int(start)
+            stop = int(stop)
+        elif '+' in a:
+            (start, stop) = a.split("+", 1)
+            start = int(start)
+            stop = int(stop)
+        else:
+            start = int(a)
+            stop = start + 1
+        return (start, stop, step)
+
+    except:
+        raise ValueError("Parts description must be in format: num[[+-]num]/num; this [%s] is incorrect" % pd)
+
+
+def take_part(lines, part_description = None):
+    if part_description == None:
+        return lines
+    (start, stop, step) = parse_parts_description(part_description)
+    n = len(lines)
+    part_size = (1.0*n) / step
+    result = []
+    for i in range(n):
+        if part_size * i >= start and part_size * i <= stop:
+            result += lines[i]
+    return result
+
 def filter_get_words_group_words_add_stat(args):
     vocabulary = load_vocabulary()
     notes = load_notes(notes_filenames())
-    lines = readlines_from_stdin()
+    lines = take_part(readlines_from_stdin(), config.get('pages', ''))
     group_by = [1]
 
     if 'GROUP_WORDS_BY_TWO' in os.environ and os.environ['GROUP_WORDS_BY_TWO'] == 'YES':