Strip prompts even if the prompt isn't present on the first line.

Users (including me) often copy and paste examples from just after the first
prompt. This checks for prompts in the first two lines of a block, but if they
aren't found there, it will ignore prompt-like prefixes in later lines, to
minimise interference with multi-line strings etc.

Closes gh-3206

IPython/core/inputtransformer.py

@@ -348,22 +348,31 b' def cellmagic(end_on_blank_line=False):'
         line = tpl % (magic_name, first, u'\n'.join(body))
 
 
-def _strip_prompts(prompt1_re, prompt2_re):
+def _strip_prompts(prompt_re):
     """Remove matching input prompts from a block of input."""
     line = ''
     while True:
         line = (yield line)
         
+        # First line of cell
         if line is None:
             continue
+        out, n1 = prompt_re.subn('', line, count=1)
+        line = (yield out)
+        
+        # Second line of cell, because people often copy from just after the
+        # first prompt, so we might not see it in the first line.
+        if line is None:
+            continue
+        out, n2 = prompt_re.subn('', line, count=1)
+        line = (yield out)
+        
+        if n1 or n2:
+            # Found the input prompt in the first two lines - check for it in
+            # the rest of the cell as well.
+            while line is not None:
+                line = (yield prompt_re.sub('', line, count=1))
         
-        m = prompt1_re.match(line)
-        if m:
-            while m:
-                line = (yield line[len(m.group(0)):])
-                if line is None:
-                    break
-                m = prompt2_re.match(line)
         else:
             # Prompts not in input - wait for reset
             while line is not None:
@@ -372,16 +381,14 b' def _strip_prompts(prompt1_re, prompt2_re):'
 @CoroutineInputTransformer.wrap
 def classic_prompt():
     """Strip the >>>/... prompts of the Python interactive shell."""
-    prompt1_re = re.compile(r'^(>>> )')
-    prompt2_re = re.compile(r'^(>>> |^\.\.\. )')
-    return _strip_prompts(prompt1_re, prompt2_re)
+    prompt_re = re.compile(r'^(>>> |^\.\.\. )')
+    return _strip_prompts(prompt_re)
 
 @CoroutineInputTransformer.wrap
 def ipy_prompt():
     """Strip IPython's In [1]:/...: prompts."""
-    prompt1_re = re.compile(r'^In \[\d+\]: ')
-    prompt2_re = re.compile(r'^(In \[\d+\]: |^\ \ \ \.\.\.+: )')
-    return _strip_prompts(prompt1_re, prompt2_re)
+    prompt_re = re.compile(r'^(In \[\d+\]: |^\ \ \ \.\.\.+: )')
+    return _strip_prompts(prompt_re)
 
 
 @CoroutineInputTransformer.wrap

IPython/core/tests/test_inputtransformer.py

@@ -173,7 +173,12 b' syntax_ml = \\'
           ('... 123"""','123"""'),
           ],
          [('a="""','a="""'),
-          ('... 123"""','... 123"""'),
+          ('... 123','123'),
+          ('... 456"""','456"""'),
+          ],
+         [('a="""','a="""'),
+          ('123','123'),
+          ('... 456"""','... 456"""'),
           ],
         ],
 
@@ -186,7 +191,12 b' syntax_ml = \\'
           ('   ...: 123"""','123"""'),
           ],
          [('a="""','a="""'),
-          ('   ...: 123"""','   ...: 123"""'),
+          ('   ...: 123','123'),
+          ('   ...: 456"""','456"""'),
+          ],
+         [('a="""','a="""'),
+          ('123','123'),
+          ('   ...: 456"""','   ...: 456"""'),
           ],
          ],