Completed full block splitting for block-based frontends.

IPython/core/blockbreaker.py

@@ -1,260 +1,375 b''
 """Analysis of text input into executable blocks.
 
 This is a simple example of how an interactive terminal-based client can use
 this tool::
 
     bb = BlockBreaker()
     while not bb.interactive_block_ready():
         bb.push(raw_input('>>> '))
     print 'Input source was:\n', bb.source,
 """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 # stdlib
 import codeop
 import re
 import sys
 
 #-----------------------------------------------------------------------------
 # Utilities
 #-----------------------------------------------------------------------------
 
 # FIXME: move these utilities to the general ward...
 
 # compiled regexps for autoindent management
 dedent_re = re.compile(r'^\s+raise|^\s+return|^\s+pass')
 ini_spaces_re = re.compile(r'^([ \t\r\f\v]+)')
 
 
 def num_ini_spaces(s):
     """Return the number of initial spaces in a string.
 
     Note that tabs are counted as a single space.  For now, we do *not* support
     mixing of tabs and spaces in the user's input.
 
     Parameters
     ----------
     s : string
     """
 
     ini_spaces = ini_spaces_re.match(s)
     if ini_spaces:
         return ini_spaces.end()
     else:
         return 0
 
 
 def remove_comments(src):
     """Remove all comments from input source.
 
     Note: comments are NOT recognized inside of strings!
 
     Parameters
     ----------
     src : string
       A single or multiline input string.
 
     Returns
     -------
     String with all Python comments removed.
     """
 
     return re.sub('#.*', '', src)
 
 
 def get_input_encoding():
     """Return the default standard input encoding."""
     return getattr(sys.stdin, 'encoding', 'ascii')
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 class BlockBreaker(object):
     # Command compiler
     compile = None
     # Number of spaces of indentation
     indent_spaces = 0
+    # Mark when input has changed indentation all the way back to flush-left
+    full_dedent = False
     # String, indicating the default input encoding
     encoding = ''
     # String where the current full source input is stored, properly encoded
     source = ''
     # Code object corresponding to the current source
     code = None
     # Boolean indicating whether the current block is complete
     is_complete = None
     # Input mode
     input_mode = 'append'
     
     # Private attributes
     
     # List
     _buffer = None
     
     def __init__(self, input_mode=None):
         """Create a new BlockBreaker instance.
 
         Parameters
         ----------
         input_mode : str
 
           One of 'append', 'replace', default is 'append'.  This controls how
           new inputs are used: in 'append' mode, they are appended to the
           existing buffer and the whole buffer is compiled; in 'replace' mode,
           each new input completely replaces all prior inputs.  Replace mode is
           thus equivalent to prepending a full reset() to every push() call.
 
           In practice, line-oriented clients likely want to use 'append' mode
           while block-oriented ones will want to use 'replace'.
         """
         self._buffer = []
         self.compile = codeop.CommandCompiler()
         self.encoding = get_input_encoding()
         self.input_mode = BlockBreaker.input_mode if input_mode is None \
                           else input_mode
 
     def reset(self):
         """Reset the input buffer and associated state."""
         self.indent_spaces = 0
         self._buffer[:] = []
         self.source = ''
         self.code = None
+        self.is_complete = False
+        self.full_dedent = False
 
     def source_reset(self):
         """Return the input source and perform a full reset.
         """
         out = self.source
         self.reset()
         return out
 
     def push(self, lines):
         """Push one ore more lines of input.
 
         This stores the given lines and returns a status code indicating
         whether the code forms a complete Python block or not.
 
         Any exceptions generated in compilation are allowed to propagate.
 
         Parameters
         ----------
         lines : string
           One or more lines of Python input.
         
         Returns
         -------
         is_complete : boolean
           True if the current input source (the result of the current input
         plus prior inputs) forms a complete Python execution block.  Note that
         this value is also stored as an attribute so it can be queried at any
         time.
         """
         if self.input_mode == 'replace':
             self.reset()
         
         # If the source code has leading blanks, add 'if 1:\n' to it
         # this allows execution of indented pasted code. It is tempting
         # to add '\n' at the end of source to run commands like ' a=1'
         # directly, but this fails for more complicated scenarios
         if not self._buffer and lines[:1] in [' ', '\t']:
             lines = 'if 1:\n%s' % lines
         
         self._store(lines)
         source = self.source
 
         # Before calling compile(), reset the code object to None so that if an
         # exception is raised in compilation, we don't mislead by having
         # inconsistent code/source attributes.
         self.code, self.is_complete = None, None
+
+        self._update_indent(lines)
         try:
             self.code = self.compile(source)
         # Invalid syntax can produce any of a number of different errors from
         # inside the compiler, so we have to catch them all.  Syntax errors
         # immediately produce a 'ready' block, so the invalid Python can be
         # sent to the kernel for evaluation with possible ipython
         # special-syntax conversion.
-        except (SyntaxError, OverflowError, ValueError, TypeError, MemoryError):
+        except (SyntaxError, OverflowError, ValueError, TypeError,
+                MemoryError):
             self.is_complete = True
         else:
             # Compilation didn't produce any exceptions (though it may not have
             # given a complete code object)
             self.is_complete = self.code is not None
-            self._update_indent(lines)
 
         return self.is_complete
 
     def interactive_block_ready(self):
         """Return whether a block of interactive input is ready for execution.
 
         This method is meant to be used by line-oriented frontends, who need to
         guess whether a block is complete or not based solely on prior and
         current input lines.  The BlockBreaker considers it has a complete
         interactive block when *all* of the following are true:
 
         1. The input compiles to a complete statement.
         
         2. The indentation level is flush-left (because if we are indented,
            like inside a function definition or for loop, we need to keep
            reading new input).
           
         3. There is one extra line consisting only of whitespace.
 
         Because of condition #3, this method should be used only by
         *line-oriented* frontends, since it means that intermediate blank lines
         are not allowed in function definitions (or any other indented block).
 
         Block-oriented frontends that have a separate keyboard event to
         indicate execution should use the :meth:`split_blocks` method instead.
         """
+        #print 'complete?', self.source # dbg
+        #if self.full_dedent:
+        #    True
+            
         if not self.is_complete:
             return False
         if self.indent_spaces==0:
             return True
         last_line = self.source.splitlines()[-1]
         if not last_line or last_line.isspace():
             return True
         else:
             return False
 
     def split_blocks(self, lines):
-        """Split a multiline string into multiple input blocks"""
-        raise NotImplementedError
+        """Split a multiline string into multiple input blocks.
+
+        Note: this method starts by performing a full reset().
+        
+        Parameters
+        ----------
+        lines : str
+          A possibly multiline string.
+
+        Returns
+        -------
+        blocks : list
+          A list of strings, each possibly multiline.  Each string corresponds
+          to a single block that can be compiled in 'single' mode (unless it
+          has a syntax error)."""
+
+        # This code is fairly delicate.  If you make any changes here, make
+        # absolutely sure that you do run the full test suite and ALL tests
+        # pass.
+
+        self.reset()
+        blocks = []
+        
+        # Reversed copy so we can use pop() efficiently and consume the input
+        # as a stack
+        lines = lines.splitlines()[::-1]
+        # Outer loop over all input
+        while lines:
+            # Inner loop to build each block
+            while True:
+                # Safety exit from inner loop
+                if not lines:
+                    break
+                # Grab next line but don't push it yet
+                next_line = lines.pop()
+                # Blank/empty lines are pushed as-is
+                if not next_line or next_line.isspace():
+                    self.push(next_line)
+                    continue
+
+                # Check indentation changes caused by the *next* line
+                indent_spaces, full_dedent = self._find_indent(next_line)
+
+                # If the next line causes a dedent, it can be for two differnt
+                # reasons: either an explicit de-dent by the user or a
+                # return/raise/pass statement.  These MUST be handled
+                # separately:
+                #
+                # 1. the first case is only detected when the actual explicit
+                # dedent happens, and that would be the *first* line of a *new*
+                # block.  Thus, we must put the line back into the input buffer
+                # so that it starts a new block on the next pass.
+                #
+                # 2. the second case is detected in the line before the actual
+                # dedent happens, so , we consume the line and we can break out
+                # to start a new block.
+
+                # Case 1, explicit dedent causes a break
+                if full_dedent and not next_line.startswith(' '):
+                    lines.append(next_line)
+                    break
+                
+                # Otherwise any line is pushed
+                self.push(next_line)
+
+                # Case 2, full dedent with full block ready:
+                if full_dedent or \
+                       self.indent_spaces==0 and self.interactive_block_ready():
+                    break
+            # Form the new block with the current source input
+            blocks.append(self.source_reset())
+            
+        return blocks
 
     #------------------------------------------------------------------------
     # Private interface
     #------------------------------------------------------------------------
     
-    def _update_indent(self, lines):
-        """Keep track of the indent level."""
+    def _find_indent(self, line):
+        """Compute the new indentation level for a single line.
 
-        for line in remove_comments(lines).splitlines():
+        Parameters
+        ----------
+        line : str
+          A single new line of non-whitespace, non-comment Python input.
+          
+        Returns
+        -------
+        indent_spaces : int
+          New value for the indent level (it may be equal to self.indent_spaces
+        if indentation doesn't change.
+
+        full_dedent : boolean
+          Whether the new line causes a full flush-left dedent.
+        """
+        indent_spaces = self.indent_spaces
+        full_dedent = self.full_dedent
             
-            if line and not line.isspace():
-                if self.code is not None:
                     inisp = num_ini_spaces(line)
-                    if inisp < self.indent_spaces:
-                        self.indent_spaces = inisp
+        if inisp < indent_spaces:
+            indent_spaces = inisp
+            if indent_spaces <= 0:
+                #print 'Full dedent in text',self.source # dbg
+                full_dedent = True
 
                 if line[-1] == ':':
-                    self.indent_spaces += 4
+            indent_spaces += 4
                 elif dedent_re.match(line):
-                    self.indent_spaces -= 4
+            indent_spaces -= 4
+            if indent_spaces <= 0:
+                full_dedent = True
+
+        # Safety
+        if indent_spaces < 0:
+            indent_spaces = 0
+            #print 'safety' # dbg
+            
+        return indent_spaces, full_dedent
+        
+    def _update_indent(self, lines):
+        for line in remove_comments(lines).splitlines():
+            if line and not line.isspace():
+                self.indent_spaces, self.full_dedent = self._find_indent(line)
 
     def _store(self, lines):
         """Store one or more lines of input.
 
         If input lines are not newline-terminated, a newline is automatically
         appended."""
 
         if lines.endswith('\n'):
             self._buffer.append(lines)
         else:
             self._buffer.append(lines+'\n')
+        self._set_source()
+
+    def _set_source(self):
         self.source = ''.join(self._buffer).encode(self.encoding)
+

IPython/core/tests/test_blockbreaker.py

@@ -1,189 +1,276 b''
 """Tests for the blockbreaker module.
 """
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 # stdlib
 import unittest
 
 # Third party
 import nose.tools as nt
 
 # Our own
 from IPython.core import blockbreaker as BB
 
 #-----------------------------------------------------------------------------
+# Test utilities, just for local use
+#-----------------------------------------------------------------------------
+
+def assemble(block):
+    """Assemble a block into multi-line sub-blocks."""
+    return ['\n'.join(sub_block)+'\n' for sub_block in block]
+
+#-----------------------------------------------------------------------------
 # Tests
 #-----------------------------------------------------------------------------
 def test_spaces():
     tests = [('', 0),
              (' ', 1),
              ('\n', 0),
              (' \n', 1),
              ('x', 0),
              (' x', 1),
              ('  x',2),
              ('    x',4),
              # Note: tabs are counted as a single whitespace!
              ('\tx', 1),
              ('\t x', 2),
              ]
     
     for s, nsp in tests:
         nt.assert_equal(BB.num_ini_spaces(s), nsp)
 
 
 def test_remove_comments():
     tests = [('text', 'text'),
              ('text # comment', 'text '),
              ('text # comment\n', 'text \n'),
              ('text # comment \n', 'text \n'),
              ('line # c \nline\n','line \nline\n'),
              ('line # c \nline#c2  \nline\nline #c\n\n',
               'line \nline\nline\nline \n\n'),
              ]
 
     for inp, out in tests:
         nt.assert_equal(BB.remove_comments(inp), out)
 
 
 def test_get_input_encoding():
     encoding = BB.get_input_encoding()
     nt.assert_true(isinstance(encoding, basestring))
     # simple-minded check that at least encoding a simple string works with the
     # encoding we got.
     nt.assert_equal('test'.encode(encoding), 'test')
 
 
 class BlockBreakerTestCase(unittest.TestCase):
     def setUp(self):
         self.bb = BB.BlockBreaker()
 
     def test_reset(self):
         bb = self.bb
         bb.push('x=1')
         bb.reset()
         self.assertEqual(bb._buffer, [])
         self.assertEqual(bb.indent_spaces, 0)
         self.assertEqual(bb.source, '')
         self.assertEqual(bb.code, None)
+        self.assertEqual(bb.is_complete, False)
 
     def test_source(self):
         self.bb._store('1')
         self.bb._store('2')
         self.assertEqual(self.bb.source, '1\n2\n')
         self.assertTrue(len(self.bb._buffer)>0)
         self.assertEqual(self.bb.source_reset(), '1\n2\n')
         self.assertEqual(self.bb._buffer, [])
         self.assertEqual(self.bb.source, '')
         
     def test_indent(self):
         bb = self.bb # shorthand
         bb.push('x=1')
         self.assertEqual(bb.indent_spaces, 0)
         bb.push('if 1:\n    x=1')
         self.assertEqual(bb.indent_spaces, 4)
         bb.push('y=2\n')
         self.assertEqual(bb.indent_spaces, 0)
         bb.push('if 1:')
         self.assertEqual(bb.indent_spaces, 4)
         bb.push('    x=1')
         self.assertEqual(bb.indent_spaces, 4)
         # Blank lines shouldn't change the indent level
         bb.push(' '*2)
         self.assertEqual(bb.indent_spaces, 4)
 
     def test_indent2(self):
         bb = self.bb
         # When a multiline statement contains parens or multiline strings, we
         # shouldn't get confused.
         bb.push("if 1:")
         bb.push("    x = (1+\n    2)")
         self.assertEqual(bb.indent_spaces, 4)
 
     def test_dedent(self):
         bb = self.bb # shorthand
         bb.push('if 1:')
         self.assertEqual(bb.indent_spaces, 4)
         bb.push('    pass')
         self.assertEqual(bb.indent_spaces, 0)
         
     def test_push(self):
         bb = self.bb
         bb.push('x=1')
         self.assertTrue(bb.is_complete)
 
     def test_push2(self):
         bb = self.bb
         bb.push('if 1:')
         self.assertFalse(bb.is_complete)
         for line in ['  x=1', '# a comment', '  y=2']:
             bb.push(line)
             self.assertTrue(bb.is_complete)
             
     def test_push3(self):
         """Test input with leading whitespace"""
         bb = self.bb
         bb.push('  x=1')
         bb.push('  y=2')
         self.assertEqual(bb.source, 'if 1:\n  x=1\n  y=2\n')
 
     def test_replace_mode(self):
         bb = self.bb
         bb.input_mode = 'replace'
         bb.push('x=1')
         self.assertEqual(bb.source, 'x=1\n')
         bb.push('x=2')
         self.assertEqual(bb.source, 'x=2\n')
 
     def test_interactive_block_ready(self):
         bb = self.bb
         bb.push('x=1')
         self.assertTrue(bb.interactive_block_ready())
 
     def test_interactive_block_ready2(self):
         bb = self.bb
         bb.push('if 1:')
         self.assertFalse(bb.interactive_block_ready())
         bb.push('  x=1')
         self.assertFalse(bb.interactive_block_ready())
         bb.push('')
         self.assertTrue(bb.interactive_block_ready())
         
     def test_interactive_block_ready3(self):
         bb = self.bb
         bb.push("x = (2+\n3)")
         self.assertTrue(bb.interactive_block_ready())
 
     def test_interactive_block_ready4(self):
         bb = self.bb
         # When a multiline statement contains parens or multiline strings, we
         # shouldn't get confused.
         # FIXME: we should be able to better handle de-dents in statements like
         # multiline strings and multiline expressions (continued with \ or
         # parens).  Right now we aren't handling the indentation tracking quite
         # correctly with this, though in practice it may not be too much of a
         # problem.  We'll need to see.
         bb.push("if 1:")
         bb.push("    x = (2+")
         bb.push("    3)")
         self.assertFalse(bb.interactive_block_ready())
         bb.push("    y = 3")
         self.assertFalse(bb.interactive_block_ready())
         bb.push('')
         self.assertTrue(bb.interactive_block_ready())
 
     def test_syntax_error(self):
         bb = self.bb
         # Syntax errors immediately produce a 'ready' block, so the invalid
         # Python can be sent to the kernel for evaluation with possible ipython
         # special-syntax conversion.
         bb.push('run foo')
         self.assertTrue(bb.interactive_block_ready())
+
+    def check_split(self, block_lines, compile=True):
+        blocks = assemble(block_lines)
+        lines = ''.join(blocks)
+        oblock = self.bb.split_blocks(lines)
+        self.assertEqual(oblock, blocks)
+        if compile:
+            for block in blocks:
+                self.bb.compile(block)
+
+    def test_split(self):
+        # All blocks of input we want to test in a list.  The format for each
+        # block is a list of lists, with each inner lists consisting of all the
+        # lines (as single-lines) that should make up a sub-block.
+
+        # Note: do NOT put here sub-blocks that don't compile, as the
+        # check_split() routine makes a final verification pass to check that
+        # each sub_block, as returned by split_blocks(), does compile
+        # correctly.
+        all_blocks = [ [['x=1']],
+
+                       [['x=1'],
+                        ['y=2']],
+
+                       [['x=1'],
+                        ['# a comment'],
+                        ['y=11']],
+
+                       [['if 1:',
+                         '  x=1'],
+                        ['y=3']],
+
+                       [['def f(x):',
+                         '  return x'],
+                        ['x=1']],
+
+                       [['def f(x):',
+                         '  x+=1',
+                         '  ',
+                         '  return x'],
+                        ['x=1']],
+
+                       [['def f(x):',
+                         '  if x>0:',
+                         '    y=1',
+                         '  # a comment',
+                         '  else:',
+                         '    y=4',
+                         ' ',
+                         '  return y'],
+                        ['x=1'],
+                        ['if 1:',
+                         '  y=11'] ],
+                       
+                       [['for i in range(10):'
+                         '  x=i**2']],
+
+                       [['for i in range(10):'
+                         '  x=i**2'],
+                        ['z = 1']],
+                       ]
+        for block_lines in all_blocks:
+            self.check_split(block_lines)
+        
+    def test_split_syntax_errors(self):
+        # Block splitting with invalid syntax
+        all_blocks = [ [['a syntax error']],
+            
+                       [['x=1'],
+                        ['a syntax error']],
+
+                       [['for i in range(10):'
+                         '  an error']],
+                       
+                       ]
+        for block_lines in all_blocks:
+            self.check_split(block_lines, compile=False)
+