Please disregard v4, see v5.
On 12/6/16 2:01 PM, Kostia Balytskyi wrote:
> # HG changeset patch
> # User Kostia Balytskyi <ikos...@fb.com>
> # Date 1481032446 28800
> # Tue Dec 06 05:54:06 2016 -0800
> # Node ID 008bf4590cd2bed2329ad5eb8f2ad3e2bd121f2d
> # Parent 243ecbd4f5c9f452275d4435866359cf84dc03ff
> scmutil: add a simple key-value file helper
>
> The purpose of the added class is to serve purposes like save files of shelve
> or state files of shelve, rebase and histedit. Keys of these files can be
> alphanumeric and start with letters, while values must not contain newlines.
> Keys which start with an uppercase letter are required, while other keys
> are optional.
>
> In light of Mercurial's reluctancy to use Python's json module, this tries
> to provide a reasonable alternative for a non-nested named data.
> Comparing to current approach of storing state in plain text files, where
> semantic meaning of lines of text is only determined by their oreder,
> simple key-value file allows for reordering lines and thus helps handle
> optional values.
>
> Initial use-case I see for this is obs-shelve's shelve files. Later we
> can possibly migrate state files to this approach.
>
> The test is in a new file beause I did not figure out where to put it
> within existing test suite. If you give me a better idea, I will gladly
> follow it.
>
> diff --git a/mercurial/error.py b/mercurial/error.py
> --- a/mercurial/error.py
> +++ b/mercurial/error.py
> @@ -243,3 +243,19 @@ class UnsupportedBundleSpecification(Exc
>
> class CorruptedState(Exception):
> """error raised when a command is not able to read its state from
> file"""
> +
> +class InvalidKeyValueFile(Exception):
> + """error raised when the file can't be parsed as simple key-value file"""
> +
> +class InvalidKeyInFileException(Exception):
> + """error raised when invalid key is attempted to be written
> +
> + This is used in simple key-value file implementation"""
> +
> +class InvalidValueInFileException(Exception):
> + """error raisesd when invalid value is attempted to be written
> +
> + This is used in simple key-value file implementation"""
> +
> +class MissingRequiredKeyInFileException(Exception):
> + """error raised when simple key-value file misses a required key"""
> diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
> --- a/mercurial/scmutil.py
> +++ b/mercurial/scmutil.py
> @@ -1571,3 +1571,123 @@ class checkambigatclosing(closewrapbase)
> def close(self):
> self._origfh.close()
> self._checkambig()
> +
> +class simplekeyvaluefile(object):
> + """A simple file with key=value lines
> +
> + Keys must be alphanumerics and start with a letter, values might not
> + contain '\n' characters
> +
> + >>> contents = {}
> + >>> class fileobj(object):
> + ... def __init__(self, name):
> + ... self.name = name
> + ... def __enter__(self):
> + ... return self
> + ... def __exit__(self, *args, **kwargs):
> + ... pass
> + ... def write(self, text):
> + ... contents[self.name] = text
> + ... def read(self):
> + ... return contents[self.name]
> + >>> class mockvfs(object):
> + ... def read(self, path):
> + ... return fileobj(path).read()
> + ... def readlines(self, path):
> + ... return fileobj(path).read().split('\\n')
> + ... def __call__(self, path, mode, atomictemp):
> + ... return fileobj(path)
> + >>> vfs = mockvfs()
> +
> + Basic testing of whether simple key-value file works:
> + >>> d = {'key1': 'value1', 'Key2': 'value2'}
> + >>> simplekeyvaluefile(vfs, 'kvfile').write(d)
> + >>> print sorted(vfs.read('kvfile').split('\\n'))
> + ['', 'Key2=value2', 'key1=value1']
> +
> + Testing of whether invalid keys are detected:
> + >>> d = {'0key1': 'value1', 'Key2': 'value2'}
> + >>> simplekeyvaluefile(vfs, 'kvfile').write(d)
> + Traceback (most recent call last):
> + ...
> + InvalidKeyInFileException: keys must start with a letter ...
> + >>> d = {'key1@': 'value1', 'Key2': 'value2'}
> + >>> simplekeyvaluefile(vfs, 'kvfile').write(d)
> + Traceback (most recent call last):
> + ...
> + InvalidKeyInFileException: invalid key name in a simple key-value file
> +
> + Testing of whether invalid values are detected:
> + >>> d = {'key1': 'value1', 'Key2': 'value2\\n'}
> + >>> simplekeyvaluefile(vfs, 'kvfile').write(d)
> + Traceback (most recent call last):
> + ...
> + InvalidValueInFileException: invalid value in a simple key-value file
> +
> + Test cases when necessary keys are present
> + >>> d = {'key1': 'value1', 'Key2': 'value2'}
> + >>> simplekeyvaluefile(vfs, 'allkeyshere').write(d)
> + >>> class kvf(simplekeyvaluefile):
> + ... KEYS = [('key3', False), ('Key2', True)]
> + >>> print sorted(kvf(vfs, 'allkeyshere').read().items())
> + [('Key2', 'value'), ('key1', 'value')]
> +
> + Test cases when necessary keys are absent
> + >>> d = {'key1': 'value1', 'Key3': 'value2'}
> + >>> simplekeyvaluefile(vfs, 'missingkeys').write(d)
> + >>> class kvf(simplekeyvaluefile):
> + ... KEYS = [('key3', False), ('Key2', True)]
> + >>> print sorted(kvf(vfs, 'missingkeys').read().items())
> + Traceback (most recent call last):
> + ...
> + MissingRequiredKeyInFileException: missing a required key: 'Key2'
> +
> + Test cases when file is not really a simple key-value file
> + >>> contents['badfile'] = 'ababagalamaga\\n'
> + >>> simplekeyvaluefile(vfs, 'badfile').read()
> + Traceback (most recent call last):
> + ...
> + InvalidKeyValueFile: dictionary ... element #0 has length 1; 2 is
> required
> + """
> +
> + # if KEYS is non-empty, read values are validated against it:
> + # each key is a tuple (keyname, required)
> + KEYS = []
> +
> + def __init__(self, vfs, path):
> + self.vfs = vfs
> + self.path = path
> +
> + def validate(self, d):
> + for key, req in self.KEYS:
> + if req and key not in d:
> + e = "missing a required key: '%s'" % key
> + raise error.MissingRequiredKeyInFileException(e)
> +
> + def read(self):
> + lines = self.vfs.readlines(self.path)
> + try:
> + d = dict(line[:-1].split('=', 1) for line in lines if line)
> + except ValueError as e:
> + raise error.InvalidKeyValueFile(str(e))
> + self.validate(d)
> + return d
> +
> + def write(self, data):
> + """Write key=>value mapping to a file
> + data is a dict. Keys should be alphanumerical and start with a
> letter.
> + Values should not contain newline characters."""
> + lines = []
> + for k, v in data.items():
> + if not k[0].isalpha():
> + e = "keys must start with a letter in a key-value file"
> + raise error.InvalidKeyInFileException(e)
> + if not k.isalnum():
> + e = "invalid key name in a simple key-value file"
> + raise error.InvalidKeyInFileException(e)
> + if '\n' in v:
> + e = "invalid value in a simple key-value file"
> + raise error.InvalidValueInFileException(e)
> + lines.append("%s=%s\n" % (k, v))
> + with self.vfs(self.path, mode='wb', atomictemp=True) as fp:
> + fp.write(''.join(lines))
> diff --git a/tests/test-doctest.py b/tests/test-doctest.py
> --- a/tests/test-doctest.py
> +++ b/tests/test-doctest.py
> @@ -28,6 +28,7 @@ testmod('mercurial.patch')
> testmod('mercurial.pathutil')
> testmod('mercurial.parser')
> testmod('mercurial.revset')
> +testmod('mercurial.scmutil', optionflags=doctest.ELLIPSIS)
> testmod('mercurial.store')
> testmod('mercurial.subrepo')
> testmod('mercurial.templatefilters')
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