stringutil: refactor core of pprint so it emits chunks

This commit splits the core of pprint() to a new function that is
a generator of chunks instead of a function returning a single
value. This will make it possible to stream output without waiting for
all data to be formatted first. And it will make it easier to
implement support for indenting.

Differential Revision: https://phab.mercurial-scm.org/D4397

mercurial/utils/stringutil.py

@@ -1,591 +1,597 b''
 # stringutil.py - utility for generic string formatting, parsing, etc.
 #
 #  Copyright 2005 K. Thananchayan <[e-mail]>
 #  Copyright 2005-2007 Matt Mackall <[e-mail]>
 #  Copyright 2006 Vadim Gelfer <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import ast
 import codecs
 import re as remod
 import textwrap
 import types
 
 from ..i18n import _
 from ..thirdparty import attr
 
 from .. import (
     encoding,
     error,
     pycompat,
 )
 
 # regex special chars pulled from https://bugs.python.org/issue29995
 # which was part of Python 3.7.
 _respecial = pycompat.bytestr(b'()[]{}?*+-|^$\\.&~# \t\n\r\v\f')
 _regexescapemap = {ord(i): (b'\\' + i).decode('latin1') for i in _respecial}
 
 def reescape(pat):
     """Drop-in replacement for re.escape."""
     # NOTE: it is intentional that this works on unicodes and not
     # bytes, as it's only possible to do the escaping with
     # unicode.translate, not bytes.translate. Sigh.
     wantuni = True
     if isinstance(pat, bytes):
         wantuni = False
         pat = pat.decode('latin1')
     pat = pat.translate(_regexescapemap)
     if wantuni:
         return pat
     return pat.encode('latin1')
 
 def pprint(o, bprefix=False):
     """Pretty print an object."""
+    return b''.join(pprintgen(o, bprefix=bprefix))
+
+def pprintgen(o, bprefix=False):
+    """Pretty print an object to a generator of atoms."""
+
     if isinstance(o, bytes):
         if bprefix:
-            return "b'%s'" % escapestr(o)
-        return "'%s'" % escapestr(o)
+            yield "b'%s'" % escapestr(o)
+        else:
+            yield "'%s'" % escapestr(o)
     elif isinstance(o, bytearray):
         # codecs.escape_encode() can't handle bytearray, so escapestr fails
         # without coercion.
-        return "bytearray['%s']" % escapestr(bytes(o))
+        yield "bytearray['%s']" % escapestr(bytes(o))
     elif isinstance(o, list):
-        return '[%s]' % (b', '.join(pprint(a, bprefix=bprefix) for a in o))
+        yield '[%s]' % (b', '.join(pprint(a, bprefix=bprefix) for a in o))
     elif isinstance(o, dict):
-        return '{%s}' % (b', '.join(
+        yield '{%s}' % (b', '.join(
             '%s: %s' % (pprint(k, bprefix=bprefix),
                         pprint(v, bprefix=bprefix))
             for k, v in sorted(o.items())))
     elif isinstance(o, set):
-        return 'set([%s])' % (b', '.join(
+        yield 'set([%s])' % (b', '.join(
             pprint(k, bprefix=bprefix) for k in sorted(o)))
     elif isinstance(o, tuple):
-        return '(%s)' % (b', '.join(pprint(a, bprefix=bprefix) for a in o))
+        yield '(%s)' % (b', '.join(pprint(a, bprefix=bprefix) for a in o))
     elif isinstance(o, types.GeneratorType):
-        return 'gen[%s]' % (b', '.join(pprint(a, bprefix=bprefix) for a in o))
+        yield 'gen[%s]' % (b', '.join(pprint(a, bprefix=bprefix) for a in o))
     else:
-        return pycompat.byterepr(o)
+        yield pycompat.byterepr(o)
 
 def prettyrepr(o):
     """Pretty print a representation of a possibly-nested object"""
     lines = []
     rs = pycompat.byterepr(o)
     p0 = p1 = 0
     while p0 < len(rs):
         # '... field=<type ... field=<type ...'
         #      ~~~~~~~~~~~~~~~~
         #      p0    p1        q0    q1
         q0 = -1
         q1 = rs.find('<', p1 + 1)
         if q1 < 0:
             q1 = len(rs)
         elif q1 > p1 + 1 and rs.startswith('=', q1 - 1):
             # backtrack for ' field=<'
             q0 = rs.rfind(' ', p1 + 1, q1 - 1)
         if q0 < 0:
             q0 = q1
         else:
             q0 += 1  # skip ' '
         l = rs.count('<', 0, p0) - rs.count('>', 0, p0)
         assert l >= 0
         lines.append((l, rs[p0:q0].rstrip()))
         p0, p1 = q0, q1
     return '\n'.join('  ' * l + s for l, s in lines)
 
 def buildrepr(r):
     """Format an optional printable representation from unexpanded bits
 
     ========  =================================
     type(r)   example
     ========  =================================
     tuple     ('<not %r>', other)
     bytes     '<branch closed>'
     callable  lambda: '<branch %r>' % sorted(b)
     object    other
     ========  =================================
     """
     if r is None:
         return ''
     elif isinstance(r, tuple):
         return r[0] % pycompat.rapply(pycompat.maybebytestr, r[1:])
     elif isinstance(r, bytes):
         return r
     elif callable(r):
         return r()
     else:
         return pprint(r)
 
 def binary(s):
     """return true if a string is binary data"""
     return bool(s and '\0' in s)
 
 def stringmatcher(pattern, casesensitive=True):
     """
     accepts a string, possibly starting with 're:' or 'literal:' prefix.
     returns the matcher name, pattern, and matcher function.
     missing or unknown prefixes are treated as literal matches.
 
     helper for tests:
     >>> def test(pattern, *tests):
     ...     kind, pattern, matcher = stringmatcher(pattern)
     ...     return (kind, pattern, [bool(matcher(t)) for t in tests])
     >>> def itest(pattern, *tests):
     ...     kind, pattern, matcher = stringmatcher(pattern, casesensitive=False)
     ...     return (kind, pattern, [bool(matcher(t)) for t in tests])
 
     exact matching (no prefix):
     >>> test(b'abcdefg', b'abc', b'def', b'abcdefg')
     ('literal', 'abcdefg', [False, False, True])
 
     regex matching ('re:' prefix)
     >>> test(b're:a.+b', b'nomatch', b'fooadef', b'fooadefbar')
     ('re', 'a.+b', [False, False, True])
 
     force exact matches ('literal:' prefix)
     >>> test(b'literal:re:foobar', b'foobar', b're:foobar')
     ('literal', 're:foobar', [False, True])
 
     unknown prefixes are ignored and treated as literals
     >>> test(b'foo:bar', b'foo', b'bar', b'foo:bar')
     ('literal', 'foo:bar', [False, False, True])
 
     case insensitive regex matches
     >>> itest(b're:A.+b', b'nomatch', b'fooadef', b'fooadefBar')
     ('re', 'A.+b', [False, False, True])
 
     case insensitive literal matches
     >>> itest(b'ABCDEFG', b'abc', b'def', b'abcdefg')
     ('literal', 'ABCDEFG', [False, False, True])
     """
     if pattern.startswith('re:'):
         pattern = pattern[3:]
         try:
             flags = 0
             if not casesensitive:
                 flags = remod.I
             regex = remod.compile(pattern, flags)
         except remod.error as e:
             raise error.ParseError(_('invalid regular expression: %s')
                                    % e)
         return 're', pattern, regex.search
     elif pattern.startswith('literal:'):
         pattern = pattern[8:]
 
     match = pattern.__eq__
 
     if not casesensitive:
         ipat = encoding.lower(pattern)
         match = lambda s: ipat == encoding.lower(s)
     return 'literal', pattern, match
 
 def shortuser(user):
     """Return a short representation of a user name or email address."""
     f = user.find('@')
     if f >= 0:
         user = user[:f]
     f = user.find('<')
     if f >= 0:
         user = user[f + 1:]
     f = user.find(' ')
     if f >= 0:
         user = user[:f]
     f = user.find('.')
     if f >= 0:
         user = user[:f]
     return user
 
 def emailuser(user):
     """Return the user portion of an email address."""
     f = user.find('@')
     if f >= 0:
         user = user[:f]
     f = user.find('<')
     if f >= 0:
         user = user[f + 1:]
     return user
 
 def email(author):
     '''get email of author.'''
     r = author.find('>')
     if r == -1:
         r = None
     return author[author.find('<') + 1:r]
 
 def person(author):
     """Returns the name before an email address,
     interpreting it as per RFC 5322
 
     >>> person(b'foo@bar')
     'foo'
     >>> person(b'Foo Bar <foo@bar>')
     'Foo Bar'
     >>> person(b'"Foo Bar" <foo@bar>')
     'Foo Bar'
     >>> person(b'"Foo \"buz\" Bar" <foo@bar>')
     'Foo "buz" Bar'
     >>> # The following are invalid, but do exist in real-life
     ...
     >>> person(b'Foo "buz" Bar <foo@bar>')
     'Foo "buz" Bar'
     >>> person(b'"Foo Bar <foo@bar>')
     'Foo Bar'
     """
     if '@' not in author:
         return author
     f = author.find('<')
     if f != -1:
         return author[:f].strip(' "').replace('\\"', '"')
     f = author.find('@')
     return author[:f].replace('.', ' ')
 
 @attr.s(hash=True)
 class mailmapping(object):
     '''Represents a username/email key or value in
     a mailmap file'''
     email = attr.ib()
     name = attr.ib(default=None)
 
 def _ismailmaplineinvalid(names, emails):
     '''Returns True if the parsed names and emails
     in a mailmap entry are invalid.
 
     >>> # No names or emails fails
     >>> names, emails = [], []
     >>> _ismailmaplineinvalid(names, emails)
     True
     >>> # Only one email fails
     >>> emails = [b'[e-mail]']
     >>> _ismailmaplineinvalid(names, emails)
     True
     >>> # One email and one name passes
     >>> names = [b'Test Name']
     >>> _ismailmaplineinvalid(names, emails)
     False
     >>> # No names but two emails passes
     >>> names = []
     >>> emails = [b'[e-mail]', b'[e-mail]']
     >>> _ismailmaplineinvalid(names, emails)
     False
     '''
     return not emails or not names and len(emails) < 2
 
 def parsemailmap(mailmapcontent):
     """Parses data in the .mailmap format
 
     >>> mmdata = b"\\n".join([
     ... b'# Comment',
     ... b'Name <[e-mail]>',
     ... b'<[e-mail]> <[e-mail]>',
     ... b'Name <[e-mail]> <[e-mail]>',
     ... b'Name <[e-mail]> Commit <[e-mail]>',
     ... ])
     >>> mm = parsemailmap(mmdata)
     >>> for key in sorted(mm.keys()):
     ...     print(key)
     mailmapping(email='[e-mail]', name=None)
     mailmapping(email='[e-mail]', name=None)
     mailmapping(email='[e-mail]', name=None)
     mailmapping(email='[e-mail]', name='Commit')
     >>> for val in sorted(mm.values()):
     ...     print(val)
     mailmapping(email='[e-mail]', name='Name')
     mailmapping(email='[e-mail]', name=None)
     mailmapping(email='[e-mail]', name='Name')
     mailmapping(email='[e-mail]', name='Name')
     """
     mailmap = {}
 
     if mailmapcontent is None:
         return mailmap
 
     for line in mailmapcontent.splitlines():
 
         # Don't bother checking the line if it is a comment or
         # is an improperly formed author field
         if line.lstrip().startswith('#'):
             continue
 
         # names, emails hold the parsed emails and names for each line
         # name_builder holds the words in a persons name
         names, emails = [], []
         namebuilder = []
 
         for element in line.split():
             if element.startswith('#'):
                 # If we reach a comment in the mailmap file, move on
                 break
 
             elif element.startswith('<') and element.endswith('>'):
                 # We have found an email.
                 # Parse it, and finalize any names from earlier
                 emails.append(element[1:-1])  # Slice off the "<>"
 
                 if namebuilder:
                     names.append(' '.join(namebuilder))
                     namebuilder = []
 
                 # Break if we have found a second email, any other
                 # data does not fit the spec for .mailmap
                 if len(emails) > 1:
                     break
 
             else:
                 # We have found another word in the committers name
                 namebuilder.append(element)
 
         # Check to see if we have parsed the line into a valid form
         # We require at least one email, and either at least one
         # name or a second email
         if _ismailmaplineinvalid(names, emails):
             continue
 
         mailmapkey = mailmapping(
             email=emails[-1],
             name=names[-1] if len(names) == 2 else None,
         )
 
         mailmap[mailmapkey] = mailmapping(
             email=emails[0],
             name=names[0] if names else None,
         )
 
     return mailmap
 
 def mapname(mailmap, author):
     """Returns the author field according to the mailmap cache, or
     the original author field.
 
     >>> mmdata = b"\\n".join([
     ...     b'# Comment',
     ...     b'Name <[e-mail]>',
     ...     b'<[e-mail]> <[e-mail]>',
     ...     b'Name <[e-mail]> <[e-mail]>',
     ...     b'Name <[e-mail]> Commit <[e-mail]>',
     ... ])
     >>> m = parsemailmap(mmdata)
     >>> mapname(m, b'Commit <[e-mail]>')
     'Name <[e-mail]>'
     >>> mapname(m, b'Name <[e-mail]>')
     'Name <[e-mail]>'
     >>> mapname(m, b'Commit <[e-mail]>')
     'Name <[e-mail]>'
     >>> mapname(m, b'Commit <[e-mail]>')
     'Name <[e-mail]>'
     >>> mapname(m, b'Unknown Name <[e-mail]>')
     'Unknown Name <[e-mail]>'
     """
     # If the author field coming in isn't in the correct format,
     # or the mailmap is empty just return the original author field
     if not isauthorwellformed(author) or not mailmap:
         return author
 
     # Turn the user name into a mailmapping
     commit = mailmapping(name=person(author), email=email(author))
 
     try:
         # Try and use both the commit email and name as the key
         proper = mailmap[commit]
 
     except KeyError:
         # If the lookup fails, use just the email as the key instead
         # We call this commit2 as not to erase original commit fields
         commit2 = mailmapping(email=commit.email)
         proper = mailmap.get(commit2, mailmapping(None, None))
 
     # Return the author field with proper values filled in
     return '%s <%s>' % (
         proper.name if proper.name else commit.name,
         proper.email if proper.email else commit.email,
     )
 
 _correctauthorformat = remod.compile(br'^[^<]+\s\<[^<>]+@[^<>]+\>$')
 
 def isauthorwellformed(author):
     '''Return True if the author field is well formed
     (ie "Contributor Name <[e-mail]>")
 
     >>> isauthorwellformed(b'Good Author <[e-mail]>')
     True
     >>> isauthorwellformed(b'Author <[e-mail]>')
     True
     >>> isauthorwellformed(b'Bad Author')
     False
     >>> isauthorwellformed(b'Bad Author <[e-mail]')
     False
     >>> isauthorwellformed(b'Bad Author [e-mail]')
     False
     >>> isauthorwellformed(b'<[e-mail]>')
     False
     >>> isauthorwellformed(b'Bad Author <author>')
     False
     '''
     return _correctauthorformat.match(author) is not None
 
 def ellipsis(text, maxlength=400):
     """Trim string to at most maxlength (default: 400) columns in display."""
     return encoding.trim(text, maxlength, ellipsis='...')
 
 def escapestr(s):
     if isinstance(s, memoryview):
         s = bytes(s)
     # call underlying function of s.encode('string_escape') directly for
     # Python 3 compatibility
     return codecs.escape_encode(s)[0]
 
 def unescapestr(s):
     return codecs.escape_decode(s)[0]
 
 def forcebytestr(obj):
     """Portably format an arbitrary object (e.g. exception) into a byte
     string."""
     try:
         return pycompat.bytestr(obj)
     except UnicodeEncodeError:
         # non-ascii string, may be lossy
         return pycompat.bytestr(encoding.strtolocal(str(obj)))
 
 def uirepr(s):
     # Avoid double backslash in Windows path repr()
     return pycompat.byterepr(pycompat.bytestr(s)).replace(b'\\\\', b'\\')
 
 # delay import of textwrap
 def _MBTextWrapper(**kwargs):
     class tw(textwrap.TextWrapper):
         """
         Extend TextWrapper for width-awareness.
 
         Neither number of 'bytes' in any encoding nor 'characters' is
         appropriate to calculate terminal columns for specified string.
 
         Original TextWrapper implementation uses built-in 'len()' directly,
         so overriding is needed to use width information of each characters.
 
         In addition, characters classified into 'ambiguous' width are
         treated as wide in East Asian area, but as narrow in other.
 
         This requires use decision to determine width of such characters.
         """
         def _cutdown(self, ucstr, space_left):
             l = 0
             colwidth = encoding.ucolwidth
             for i in pycompat.xrange(len(ucstr)):
                 l += colwidth(ucstr[i])
                 if space_left < l:
                     return (ucstr[:i], ucstr[i:])
             return ucstr, ''
 
         # overriding of base class
         def _handle_long_word(self, reversed_chunks, cur_line, cur_len, width):
             space_left = max(width - cur_len, 1)
 
             if self.break_long_words:
                 cut, res = self._cutdown(reversed_chunks[-1], space_left)
                 cur_line.append(cut)
                 reversed_chunks[-1] = res
             elif not cur_line:
                 cur_line.append(reversed_chunks.pop())
 
         # this overriding code is imported from TextWrapper of Python 2.6
         # to calculate columns of string by 'encoding.ucolwidth()'
         def _wrap_chunks(self, chunks):
             colwidth = encoding.ucolwidth
 
             lines = []
             if self.width <= 0:
                 raise ValueError("invalid width %r (must be > 0)" % self.width)
 
             # Arrange in reverse order so items can be efficiently popped
             # from a stack of chucks.
             chunks.reverse()
 
             while chunks:
 
                 # Start the list of chunks that will make up the current line.
                 # cur_len is just the length of all the chunks in cur_line.
                 cur_line = []
                 cur_len = 0
 
                 # Figure out which static string will prefix this line.
                 if lines:
                     indent = self.subsequent_indent
                 else:
                     indent = self.initial_indent
 
                 # Maximum width for this line.
                 width = self.width - len(indent)
 
                 # First chunk on line is whitespace -- drop it, unless this
                 # is the very beginning of the text (i.e. no lines started yet).
                 if self.drop_whitespace and chunks[-1].strip() == r'' and lines:
                     del chunks[-1]
 
                 while chunks:
                     l = colwidth(chunks[-1])
 
                     # Can at least squeeze this chunk onto the current line.
                     if cur_len + l <= width:
                         cur_line.append(chunks.pop())
                         cur_len += l
 
                     # Nope, this line is full.
                     else:
                         break
 
                 # The current line is full, and the next chunk is too big to
                 # fit on *any* line (not just this one).
                 if chunks and colwidth(chunks[-1]) > width:
                     self._handle_long_word(chunks, cur_line, cur_len, width)
 
                 # If the last chunk on this line is all whitespace, drop it.
                 if (self.drop_whitespace and
                     cur_line and cur_line[-1].strip() == r''):
                     del cur_line[-1]
 
                 # Convert current line back to a string and store it in list
                 # of all lines (return value).
                 if cur_line:
                     lines.append(indent + r''.join(cur_line))
 
             return lines
 
     global _MBTextWrapper
     _MBTextWrapper = tw
     return tw(**kwargs)
 
 def wrap(line, width, initindent='', hangindent=''):
     maxindent = max(len(hangindent), len(initindent))
     if width <= maxindent:
         # adjust for weird terminal size
         width = max(78, maxindent + 1)
     line = line.decode(pycompat.sysstr(encoding.encoding),
                        pycompat.sysstr(encoding.encodingmode))
     initindent = initindent.decode(pycompat.sysstr(encoding.encoding),
                                    pycompat.sysstr(encoding.encodingmode))
     hangindent = hangindent.decode(pycompat.sysstr(encoding.encoding),
                                    pycompat.sysstr(encoding.encodingmode))
     wrapper = _MBTextWrapper(width=width,
                              initial_indent=initindent,
                              subsequent_indent=hangindent)
     return wrapper.fill(line).encode(pycompat.sysstr(encoding.encoding))
 
 _booleans = {'1': True, 'yes': True, 'true': True, 'on': True, 'always': True,
              '0': False, 'no': False, 'false': False, 'off': False,
              'never': False}
 
 def parsebool(s):
     """Parse s into a boolean.
 
     If s is not a valid boolean, returns None.
     """
     return _booleans.get(s.lower(), None)
 
 def evalpythonliteral(s):
     """Evaluate a string containing a Python literal expression"""
     # We could backport our tokenizer hack to rewrite '' to u'' if we want
     if pycompat.ispy3:
         return ast.literal_eval(s.decode('latin1'))
     return ast.literal_eval(s)