[diffoscope] 02/06: presenters: PartialString: preserve {{ and }} escapes when partially formatting stuff
Ximin Luo
infinity0 at debian.org
Mon Jul 3 20:35:58 CEST 2017
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infinity0 pushed a commit to branch WIP/humungous-diffs
in repository diffoscope.
commit 84878586bb5cbf0ee47c6f1f61de6ef69b7feaa7
Author: Ximin Luo <infinity0 at debian.org>
Date: Mon Jun 19 18:02:40 2017 +0200
presenters: PartialString: preserve {{ and }} escapes when partially formatting stuff
---
diffoscope/presenters/utils.py | 74 ++++++++++++++++++++++++++++++++++--------
tests/test_presenters.py | 18 ++++++++++
2 files changed, 78 insertions(+), 14 deletions(-)
diff --git a/diffoscope/presenters/utils.py b/diffoscope/presenters/utils.py
index b50d3ac..4562e8b 100644
--- a/diffoscope/presenters/utils.py
+++ b/diffoscope/presenters/utils.py
@@ -104,12 +104,19 @@ def create_limited_print_func(print_func, max_page_size):
return fn
-class Formatter(string.Formatter):
+class PartialFormatter(string.Formatter):
+ @staticmethod
+ def escape(x):
+ return x.replace("}", "}}").replace("{", "{{")
def get_value(self, key, args, kwargs):
return args[key] if isinstance(key, int) else args[int(key)]
def arg_of_field_name(self, field_name, args):
x = int(_string.formatter_field_name_split(field_name)[0])
return x if x >= 0 else len(args) + x
+ def parse(self, *args, **kwargs):
+ # Preserve {{ and }} escapes when formatting
+ return map(lambda x: (self.escape(x[0]),) + x[1:], super().parse(*args, **kwargs))
+ parse_no_escape = string.Formatter.parse
class FormatPlaceholder(object):
@@ -186,10 +193,41 @@ class PartialString(object):
>>> tmpl.pformatl("(first hole)", "(second hole)", "(object hole)")
PartialString('(first hole) (second hole) (object hole)',)
+ CORNER CASES:
+
+ 1. If you need to include a literal '{' or '}' in the resulting formatted
+ string, you need to give them as "{{" or "}}" respectively in the fmtstr
+ parameter of PartialString.__init__. PartialString.escape() might help to
+ make this a bit easier:
+
+ >>> tmpl = PartialString.numl("find {0} -name {1} " +
+ ... PartialString.escape("-exec ls -la {} \;"), 2)
+ >>> tmpl
+ PartialString('find {0} -name {1} -exec ls -la {{}} \\;', ...)
+ >>> tmpl.size(), tmpl.size(4)
+ (33, 39)
+
+ When using pformat, any string arguments will be escaped automatically. You
+ can take advantage of this to simplify the above example:
+
+ >>> tmpl2 = PartialString.numl("find {0} -name {1} -exec ls -la {2} \;", 3)
+ >>> tmpl2 = tmpl2.pformat({2: "{}"})
+ >>> tmpl2 == tmpl
+ True
+
+ As long as you only use pformat, any "{{" "}}" literals will remain escaped
+ in the resulting PartialString. They only become unescaped after going
+ through a full format.
+
+ >>> tmpl.pformatl("my{}path", "my{}file")
+ PartialString('find my{{}}path -name my{{}}file -exec ls -la {{}} \\;',)
+ >>> tmpl.formatl("my{}path", "my{}file")
+ 'find my{}path -name my{}file -exec ls -la {} \\;'
+
CAVEATS:
- Filling up holes using other PartialStrings, does not play very nicely with
- format specifiers. For example:
+ 1. Filling up holes using other PartialStrings, does not play very nicely
+ with format specifiers. For example:
>>> tmpl = PartialString("{0:20} {1.child}", a, b)
>>> tmpl.pformat({a: tmpl})
@@ -202,12 +240,14 @@ class PartialString(object):
So you probably want to avoid such usages. The exact behaviour of these
might change in the future, too.
"""
- formatter = Formatter()
+ formatter = PartialFormatter()
+ escape = staticmethod(PartialFormatter.escape)
def __init__(self, fmtstr="", *holes):
# Ensure the format string is valid, and figure out some basic stats
fmt = self.formatter
- pieces = [(len(l), f) for l, f, _, _ in fmt.parse(fmtstr)]
+ # use parse_no_escape so lengths are preserved
+ pieces = [(len(l), f) for l, f, _, _ in fmt.parse_no_escape(fmtstr)]
used_args = set(fmt.arg_of_field_name(f, holes) for _, f in pieces if f is not None)
self.num_holes = sum(1 for _, f in pieces if f is not None)
self.base_len = sum(l for l, _ in pieces)
@@ -227,10 +267,14 @@ class PartialString(object):
def __repr__(self):
return "%s%r" % (self.__class__.__name__, (self._fmtstr,) + self.holes)
+ def _format(self, *mapping):
+ # format a string but preserve {{ and }} escapes
+ return self.formatter.vformat(self._fmtstr, mapping, None)
+
def _offset_fmtstr(self, offset):
- return self._fmtstr.format(*(FormatPlaceholder(i + offset) for i in range(len(self.holes))))
+ return self._format(*(FormatPlaceholder(i + offset) for i in range(len(self.holes))))
- def _pformat(self, mapping):
+ def _pformat(self, mapping, escapestr):
new_holes = []
real_mapping = []
for i, k in enumerate(self.holes):
@@ -239,32 +283,34 @@ class PartialString(object):
if isinstance(v, PartialString):
out = v._offset_fmtstr(len(new_holes))
new_holes.extend(v.holes)
+ elif isinstance(v, str) and escapestr:
+ out = PartialString.escape(v)
else:
out = v
else:
out = FormatPlaceholder(len(new_holes))
new_holes.append(k)
real_mapping.append(out)
- return self._fmtstr.format(*real_mapping), new_holes
+ return real_mapping, new_holes
def size(self, hole_size=1):
return self.base_len + hole_size * self.num_holes
- def pformat(self, mapping):
+ def pformat(self, mapping={}):
"""Partially apply a mapping, returning a new PartialString."""
- new_fmtstr, new_holes = self._pformat(mapping)
- return self.__class__(new_fmtstr, *new_holes)
+ real_mapping, new_holes = self._pformat(mapping, True)
+ return self.__class__(self._format(*real_mapping), *new_holes)
def pformatl(self, *args):
"""Partially apply a list, implicitly mapped from self.holes."""
return self.pformat(dict(zip(self.holes, args)))
- def format(self, mapping):
+ def format(self, mapping={}):
"""Fully apply a mapping, returning a string."""
- new_fmtstr, new_holes = self._pformat(mapping)
+ real_mapping, new_holes = self._pformat(mapping, False)
if new_holes:
raise ValueError("not all holes filled: %r" % new_holes)
- return new_fmtstr
+ return self._fmtstr.format(*real_mapping)
def formatl(self, *args):
"""Fully apply a list, implicitly mapped from self.holes."""
diff --git a/tests/test_presenters.py b/tests/test_presenters.py
index 12bea69..85e9d17 100644
--- a/tests/test_presenters.py
+++ b/tests/test_presenters.py
@@ -184,3 +184,21 @@ def test_partial_string_numl():
assert tmpl.holes[:2] == (0, 1)
assert tmpl.pformatl("(1)", "(2)", "(o)") == PartialString('(1) (2) (o)')
+def test_partial_string_escape():
+ tmpl = PartialString.numl("find {0} -name {1} " +
+ PartialString.escape("-exec ls -la {} \;"), 2)
+ assert tmpl == PartialString('find {0} -name {1} -exec ls -la {{}} \\;', *tmpl.holes)
+ assert tmpl.size() == 33
+ assert tmpl.size(4) == 39
+ assert tmpl == PartialString.numl("find {0} -name {1} -exec ls -la {2} \;", 3).pformat({2: "{}"})
+
+ assert (tmpl.pformatl("my{}path", "my{}file") ==
+ PartialString('find my{{}}path -name my{{}}file -exec ls -la {{}} \\;'))
+ assert (tmpl.formatl("my{}path", "my{}file") ==
+ 'find my{}path -name my{}file -exec ls -la {} \\;')
+
+ esc = PartialString("{{}} {0}", None)
+ assert esc.pformat({None: PartialString.of(None)}) == esc
+ assert esc.format({None: "0"}) == "{} 0"
+ with pytest.raises(ValueError):
+ PartialString("{}")
--
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