Merge pull request #4295 from mgaitan/1093_boundary_load_magic

Implement boundary option for load magic

`%load -r 1-10` now does what one should expect.

closes  #1093

IPython/core/magics/code.py

@@ -18,6 +18,7 b' import io'
 import os
 import re
 import sys
+from itertools import chain
 
 # Our own packages
 from IPython.core.error import TryNext, StdinNotImplementedError, UsageError
@@ -39,6 +40,43 b' class MacroToEdit(ValueError): pass'
 
 ipython_input_pat = re.compile(r"<ipython\-input\-(\d+)-[a-z\d]+>$")
 
+# To match, e.g. 8-10 1:5 :10 3-
+range_re = re.compile(r"""
+(?P<start>\d+)?
+((?P<sep>[\-:])
+ (?P<end>\d+)?)?
+$""", re.VERBOSE)
+
+
+def extract_code_ranges(ranges_str):
+    """Turn a string of range for %%load into 2-tuples of (start, stop)
+    ready to use as a slice of the content splitted by lines.
+
+    Examples
+    --------
+    list(extract_input_ranges("5-10 2"))
+    [(4, 10), (1, 2)]
+    """
+    for range_str in ranges_str.split():
+        rmatch = range_re.match(range_str)
+        if not rmatch:
+            continue
+        sep = rmatch.group("sep")
+        start = rmatch.group("start")
+        end = rmatch.group("end")
+
+        if sep == '-':
+            start = int(start) - 1 if start else None
+            end = int(end) if end else None
+        elif sep == ':':
+            start = int(start) - 1 if start else None
+            end = int(end) - 1 if end else None
+        else:
+            end = int(start)
+            start = int(start) - 1
+        yield (start, end)
+
+
 class InteractivelyDefined(Exception):
     """Exception for interactively defined variable in magic_edit"""
     def __init__(self, index):
@@ -174,6 +212,11 b' class CodeMagics(Magics):'
 
         Options:
         --------
+          -r <lines>: Specify lines or ranges of lines to load from the source.
+          Ranges could be specified as x-y (x..y) or in python-style x:y 
+          (x..(y-1)). Both limits x and y can be left blank (meaning the 
+          beginning and end of the file, respectively).
+
           -y : Don't ask confirmation for loading source above 200 000 characters.
 
         This magic command can either take a local filename, a URL, an history
@@ -185,15 +228,27 b' class CodeMagics(Magics):'
         %load 7-27
         %load myMacro
         %load http://www.example.com/myscript.py
+        %load -r 5-10 myscript.py
+        %load -r 10-20,30,40: foo.py
         """
-        opts,args = self.parse_options(arg_s,'y')
+        opts,args = self.parse_options(arg_s,'yr:')
+
         if not args:
             raise UsageError('Missing filename, URL, input history range, '
                              'or macro.')
 
         contents = self.shell.find_user_code(args)
+
+        if 'r' in opts:
+            ranges = opts['r'].replace(',', ' ')
+            lines = contents.split('\n')
+            slices = extract_code_ranges(ranges)
+            contents = [lines[slice(*slc)] for slc in slices]
+            contents = '\n'.join(chain.from_iterable(contents))
+
         l = len(contents)
 
+
         # 200 000 is ~ 2500 full 80 caracter lines
         # so in average, more than 5000 lines
         if l > 200000 and 'y' not in opts:

IPython/core/tests/test_magic.py

@@ -45,6 +45,21 b' from IPython.utils.process import find_cmd'
 @magic.magics_class
 class DummyMagics(magic.Magics): pass
 
+def test_extract_code_ranges():
+    instr = "1 3 5-6 7-9 10:15 17: :10 10- -13 :"
+    expected = [(0, 1), 
+                (2, 3),
+                (4, 6),
+                (6, 9),
+                (9, 14),
+                (16, None),
+                (None, 9),
+                (9, None),
+                (None, 13),
+                (None, None)]
+    actual = list(code.extract_code_ranges(instr))
+    nt.assert_equal(actual, expected)
+
 def test_rehashx():
     # clear up everything
     _ip = get_ipython()