Merge pull request #118 from MinchinWeb/fix-102

Provides a smart way to determine the number 'top' lines

test/test_list_command.py

@@ -16,6 +16,8 @@
 
 import codecs
 import re
+import os
+import sys
 import unittest
 from collections import namedtuple
 
@@ -339,12 +341,16 @@ class ListCommandTest(CommandTest):
         self.assertEqual(self.errors, "")
 
     @mock.patch('topydo.commands.ListCommand.get_terminal_size')
+    @mock.patch.dict(os.environ, {'PROMPT':'', 'PS1':''})
     def test_list44(self, mock_terminal_size):
         """
         Test 'N' parameter with output longer than available terminal lines.
         """
         self.todolist = load_file_to_todolist("test/data/ListCommand_50_items.txt")
-        mock_terminal_size.return_value = self.terminal_size(80, 23)
+        if "win32" in sys.platform:
+            mock_terminal_size.return_value = self.terminal_size(80, 23)
+        else:
+            mock_terminal_size.return_value = self.terminal_size(80, 22)
 
         command = ListCommand(["-N"], self.todolist, self.out, self.error)
         command.execute()
@@ -353,11 +359,15 @@ class ListCommandTest(CommandTest):
         self.assertEqual(self.errors, "")
 
     @mock.patch('topydo.commands.ListCommand.get_terminal_size')
+    @mock.patch.dict(os.environ, {'PROMPT':'', 'PS1':''})
     def test_list45(self, mock_terminal_size):
         """Test basic 'N' parameter with nine line terminal."""
         # have 9 lines on the terminal will print 7 items and leave 2 lines
         # for the next prompt
-        mock_terminal_size.return_value = self.terminal_size(100, 9)
+        if "win32" in sys.platform:
+            mock_terminal_size.return_value = self.terminal_size(100, 9)
+        else:
+            mock_terminal_size.return_value = self.terminal_size(100, 8)
         self.todolist = load_file_to_todolist("test/data/ListCommand_50_items.txt")
 
         command = ListCommand(["-N"], self.todolist, self.out, self.error)
@@ -367,6 +377,7 @@ class ListCommandTest(CommandTest):
         self.assertEqual(self.errors, "")
 
     @mock.patch('topydo.commands.ListCommand.get_terminal_size')
+    @mock.patch.dict(os.environ, {'PROMPT':'', 'PS1':''})
     def test_list46(self, mock_terminal_size):
         """Test basic 'N' parameter with zero height terminal."""
         # we still print at least 1 item
@@ -379,7 +390,26 @@ class ListCommandTest(CommandTest):
         self.assertEqual(self.output, "|  1| (A) item 1\n")
         self.assertEqual(self.errors, "")
 
-    def test_list47(self):
+    @mock.patch('topydo.commands.ListCommand.get_terminal_size')
+    @mock.patch.dict(os.environ, {'PROMPT':'$E[1;34m%username%@%computername%$E[0m$S$E[1;32m$P$E[0m$_$E[1;37m--$E[0m$S',
+                                  'PS1':'username@hostname\n--'})
+    def test_list47(self, mock_terminal_size):
+        """
+        Test 'N' parameter with multiline prompt.
+        """
+        self.todolist = load_file_to_todolist("test/data/ListCommand_50_items.txt")
+        if "win32" in sys.platform:
+            mock_terminal_size.return_value = self.terminal_size(80, 23)
+        else:
+            mock_terminal_size.return_value = self.terminal_size(80, 22)
+
+        command = ListCommand(["-N"], self.todolist, self.out, self.error)
+        command.execute()
+
+        self.assertEqual(self.output, "|  1| (A) item 1\n| 27| (A) item 27\n|  2| (B) item 2\n| 28| (B) item 28\n|  3| (C) item 3\n| 29| (C) item 29\n|  4| (D) item 4\n| 30| (D) item 30\n|  5| (E) item 5\n| 31| (E) item 31\n|  6| (F) item 6\n| 32| (F) item 32\n|  7| (G) item 7\n| 33| (G) item 33\n|  8| (H) item 8\n| 34| (H) item 34\n|  9| (I) item 9\n| 35| (I) item 35\n| 10| (J) item 10\n| 36| (J) item 36\n")
+        self.assertEqual(self.errors, "")
+
+    def test_list48(self):
         command = ListCommand(["created:2015-11-05"], self.todolist, self.out, self.error)
         command.execute()
 

topydo/commands/ListCommand.py

@@ -14,6 +14,10 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import re
+import sys
+import os
+
 from topydo.lib.Config import config
 from topydo.lib.ExpressionCommand import ExpressionCommand
 from topydo.lib.Filter import InstanceFilter
@@ -73,7 +77,7 @@ class ListCommand(ExpressionCommand):
             elif opt == '-N':
                 # 2 lines are assumed to be taken up by printing the next prompt
                 # display at least one item
-                self.limit = max(get_terminal_size().lines - 2, 1)
+                self.limit = self._N_lines()
             elif opt == '-n':
                 try:
                     self.limit = int(value)
@@ -130,6 +134,36 @@ class ListCommand(ExpressionCommand):
 
         self.out(self.printer.print_list(self._view().todos))
 
+    def _N_lines(self):
+        ''' Determine how many lines to print, such that the number of items
+            displayed will fit on the terminal (i.e one 'screen-ful' of items)
+
+            This looks at the environmental prompt variable, and tries to determine
+            how many lines it takes up.
+
+            On Windows, it does this by looking for the '$_' sequence, which indicates
+            a new line, in the environmental variable PROMPT.
+
+            Otherwise, it looks for a newline ('\n') in the environmental variable
+            PS1.
+        '''  
+        lines_in_prompt = 1     # prompt is assumed to take up one line, even
+                                #   without any newlines in it
+        if "win32" in sys.platform:
+            lines_in_prompt += 1  # Windows will typically print a free line after
+                                  #   the program output
+            a = re.findall('\$_', os.getenv('PROMPT', ''))
+            lines_in_prompt += len(a)
+        else:
+            a = re.findall('\\n', os.getenv('PS1', ''))
+            lines_in_prompt += len(a)
+        n_lines = get_terminal_size().lines - lines_in_prompt
+
+        # print a minimum of one item
+        n_lines = max(n_lines, 1)
+
+        return n_lines
+
     def execute(self):
         if not super().execute():
             return False