Merge pull request #10835 from takluyver/i10814

Identify position after a newline as the start of the next line

IPython/utils/tests/test_tokenutil.py

@@ -105,8 +105,20 b' def test_attrs():'
 def test_line_at_cursor():
     cell = ""
     (line, offset) = line_at_cursor(cell, cursor_pos=11)
-    assert line == "", ("Expected '', got %r" % line)
-    assert offset == 0, ("Expected '', got %r" % line)
+    nt.assert_equal(line, "")
+    nt.assert_equal(offset, 0)
+
+    # The position after a newline should be the start of the following line.
+    cell = "One\nTwo\n"
+    (line, offset) = line_at_cursor(cell, cursor_pos=4)
+    nt.assert_equal(line, "Two\n")
+    nt.assert_equal(offset, 4)
+
+    # The end of a cell should be on the last line
+    cell = "pri\npri"
+    (line, offset) = line_at_cursor(cell, cursor_pos=7)
+    nt.assert_equal(line, "pri")
+    nt.assert_equal(offset, 4)
 
 def test_muliline_statement():
     cell = """a = (1,

IPython/utils/tokenutil.py

@@ -44,7 +44,12 b' def line_at_cursor(cell, cursor_pos=0):'
     lines = cell.splitlines(True)
     for line in lines:
         next_offset = offset + len(line)
-        if next_offset >= cursor_pos:
+        if not line.endswith('\n'):
+            # If the last line doesn't have a trailing newline, treat it as if
+            # it does so that the cursor at the end of the line still counts
+            # as being on that line.
+            next_offset += 1
+        if next_offset > cursor_pos:
             break
         offset = next_offset
     else: