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==========
Change Log
==========
NOTE: In the future release 3.2.0, use of many of the pre-PEP8 methods (such as
`ParserElement.parseString`) will start to raise `DeprecationWarnings`. 3.2.0 should
get released some time later in 2023. I currently plan to completely
drop the pre-PEP8 methods in pyparsing 4.0, though we won't see that release until
at least late 2023 if not 2024. So there is plenty of time to convert existing parsers to
the new function names before the old functions are completely removed. (Big
help from Devin J. Pohly in structuring the code to enable this peaceful transition.)
Version 3.2.0 will also discontinue support for Python versions 3.6 and 3.7.
Version 3.1.2 - in development
------------------------------
- Updated pep8 synonym wrappers for better type checking compatibility. PR submitted
by Ricardo Coccioli.
- Some code refactoring to reduce code nesting, PRs submitted by InSync.
Version 3.1.1 - July, 2023
--------------------------
- Fixed regression in Word(min), reported by Ricardo Coccioli, good catch! (Issue #502)
- Fixed bug in bad exception messages raised by Forward expressions. PR submitted
by Kyle Sunden, thanks for your patience and collaboration on this (#493).
- Fixed regression in SkipTo, where ignored expressions were not checked when looking
for the target expression. Reported by catcombo, Issue #500.
- Fixed type annotation for enable_packrat, PR submitted by Mike Urbach, thanks! (Issue #498)
- Some general internal code cleanup. (Instigated by Michal Čihař, Issue #488)
Version 3.1.0 - June, 2023
--------------------------
- Added `tag_emitter.py` to examples. This example demonstrates how to insert
tags into your parsed results that are not part of the original parsed text.
Version 3.1.0b2 - May, 2023
---------------------------
- Updated `create_diagram()` code to be compatible with railroad-diagrams package
version 3.0. Fixes Issue #477 (railroad diagrams generated with black bars),
reported by Sam Morley-Short.
- Fixed bug in `NotAny`, where parse actions on the negated expr were not being run.
This could cause `NotAny` to incorrectly fail if the expr would normally match,
but would fail to match if a condition used as a parse action returned False.
Fixes Issue #482, raised by byaka, thank you!
- Fixed `create_diagram()` to accept keyword args, to be passed through to the
`template.render()` method to generate the output HTML (PR submitted by Aussie Schnore,
good catch!)
- Fixed bug in `python_quoted_string` regex.
- Added `examples/bf.py` Brainf*ck parser/executor example. Illustrates using
a pyparsing grammar to parse language syntax, and attach executable AST nodes to
the parsed results.
Version 3.1.0b1 - April, 2023
-----------------------------
- Added support for Python 3.12.
- API CHANGE: A slight change has been implemented when unquoting a quoted string
parsed using the `QuotedString` class. Formerly, when unquoting and processing
whitespace markers such as \t and \n, these substitutions would occur first, and
then any additional '\' escaping would be done on the resulting string. This would
parse "\\n" as "\<newline>". Now escapes and whitespace markers are all processed
in a single pass working left to right, so the quoted string "\\n" would get unquoted
to "\n" (a backslash followed by "n"). Fixes issue #474 raised by jakeanq,
thanks!
- Added named field "url" to `pyparsing.common.url`, returning the entire
parsed URL string.
- Fixed bug when parse actions returned an empty string for an expression that
had a results name, that the results name was not saved. That is:
expr = Literal("X").add_parse_action(lambda tokens: "")("value")
result = expr.parse_string("X")
print(result["value"])
would raise a `KeyError`. Now empty strings will be saved with the associated
results name. Raised in Issue #470 by Nicco Kunzmann, thank you.
- Fixed bug in `SkipTo` where ignore expressions were not properly handled while
scanning for the target expression. Issue #475, reported by elkniwt, thanks
(this bug has been there for a looooong time!).
- Updated `ci.yml` permissions to limit default access to source - submitted by Joyce
Brum of Google. Thanks so much!
- Updated the `lucene_grammar.py` example (better support for '*' and '?' wildcards)
and corrected the test cases - brought to my attention by Elijah Nicol, good catch!
Version 3.1.0a1 - March, 2023
-----------------------------
- API ENHANCEMENT: `Optional(expr)` may now be written as `expr | ""`
This will make this code:
"{" + Optional(Literal("A") | Literal("a")) + "}"
writable as:
"{" + (Literal("A") | Literal("a") | "") + "}"
Some related changes implemented as part of this work:
- `Literal("")` now internally generates an `Empty()` (and no longer raises an exception)
- `Empty` is now a subclass of `Literal`
Suggested by Antony Lee (issue #412), PR (#413) by Devin J. Pohly.
- Added new class property `identifier` to all Unicode set classes in `pyparsing.unicode`,
using the class's values for `cls.identchars` and `cls.identbodychars`. Now Unicode-aware
parsers that formerly wrote:
ppu = pyparsing.unicode
ident = Word(ppu.Greek.identchars, ppu.Greek.identbodychars)
can now write:
ident = ppu.Greek.identifier
# or
# ident = ppu.Ελληνικά.identifier
- `ParseResults` now has a new method `deepcopy()`, in addition to the current
`copy()` method. `copy()` only makes a shallow copy - any contained `ParseResults`
are copied as references - changes in the copy will be seen as changes in the original.
In many cases, a shallow copy is sufficient, but some applications require a deep copy.
`deepcopy()` makes a deeper copy: any contained `ParseResults` or other mappings or
containers are built with copies from the original, and do not get changed if the
original is later changed. Addresses issue #463, reported by Bryn Pickering.
- Reworked `delimited_list` function into the new `DelimitedList` class.
`DelimitedList` has the same constructor interface as `delimited_list`, and
in this release, `delimited_list` changes from a function to a synonym for
`DelimitedList`. `delimited_list` and the older `delimitedList` method will be
deprecated in a future release, in favor of `DelimitedList`.
- Error messages from `MatchFirst` and `Or` expressions will try to give more details
if one of the alternatives matches better than the others, but still fails.
Question raised in Issue #464 by msdemlei, thanks!
- Added new class method `ParserElement.using_each`, to simplify code
that creates a sequence of `Literals`, `Keywords`, or other `ParserElement`
subclasses.
For instance, to define suppressible punctuation, you would previously
write:
LPAR, RPAR, LBRACE, RBRACE, SEMI = map(Suppress, "(){};")
You can now write:
LPAR, RPAR, LBRACE, RBRACE, SEMI = Suppress.using_each("(){};")
`using_each` will also accept optional keyword args, which it will
pass through to the class initializer. Here is an expression for
single-letter variable names that might be used in an algebraic
expression:
algebra_var = MatchFirst(
Char.using_each(string.ascii_lowercase, as_keyword=True)
)
- Added new builtin `python_quoted_string`, which will match any form
of single-line or multiline quoted strings defined in Python. (Inspired
by discussion with Andreas Schörgenhumer in Issue #421.)
- Extended `expr[]` notation for repetition of `expr` to accept a
slice, where the slice's stop value indicates a `stop_on`
expression:
test = "BEGIN aaa bbb ccc END"
BEGIN, END = Keyword.using_each("BEGIN END".split())
body_word = Word(alphas)
expr = BEGIN + Group(body_word[...:END]) + END
# equivalent to
# expr = BEGIN + Group(ZeroOrMore(body_word, stop_on=END)) + END
print(expr.parse_string(test))
Prints:
['BEGIN', ['aaa', 'bbb', 'ccc'], 'END']
- `ParserElement.validate()` is deprecated. It predates the support for left-recursive
parsers, and was prone to false positives (warning that a grammar was invalid when
it was in fact valid). It will be removed in a future pyparsing release. In its
place, developers should use debugging and analytical tools, such as `ParserElement.set_debug()`
and `ParserElement.create_diagram()`.
(Raised in Issue #444, thanks Andrea Micheli!)
- Added bool `embed` argument to `ParserElement.create_diagram()`.
When passed as True, the resulting diagram will omit the `<DOCTYPE>`,
`<HEAD>`, and `<BODY>` tags so that it can be embedded in other
HTML source. (Useful when embedding a call to `create_diagram()` in
a PyScript HTML page.)
- Added `recurse` argument to `ParserElement.set_debug` to set the
debug flag on an expression and all of its sub-expressions. Requested
by multimeric in Issue #399.
- Added '·' (Unicode MIDDLE DOT) to the set of Latin1.identbodychars.
- Fixed bug in `Word` when `max=2`. Also added performance enhancement
when specifying `exact` argument. Reported in issue #409 by
panda-34, nice catch!
- `Word` arguments are now validated if `min` and `max` are both
given, that `min` <= `max`; raises `ValueError` if values are invalid.
- Fixed bug in srange, when parsing escaped '/' and '\' inside a
range set.
- Fixed exception messages for some `ParserElements` with custom names,
which instead showed their contained expression names.
- Fixed bug in pyparsing.common.url, when input URL is not alone
on an input line. Fixes Issue #459, reported by David Kennedy.
- Multiple added and corrected type annotations. With much help from
Stephen Rosen, thanks!
- Some documentation and error message clarifications on pyparsing's
keyword logic, cited by Basil Peace.
- General docstring cleanup for Sphinx doc generation, PRs submitted
by Devin J. Pohly. A dirty job, but someone has to do it - much
appreciated!
- `invRegex.py` example renamed to `inv_regex.py` and updated to PEP-8
variable and method naming. PR submitted by Ross J. Duff, thanks!
- Removed examples `sparser.py` and `pymicko.py`, since each included its
own GPL license in the header. Since this conflicts with pyparsing's
MIT license, they were removed from the distribution to avoid
confusion among those making use of them in their own projects.
Version 3.0.9 - May, 2022
-------------------------
- Added Unicode set `BasicMultilingualPlane` (may also be referenced
as `BMP`) representing the Basic Multilingual Plane (Unicode
characters up to code point 65535). Can be used to parse
most language characters, but omits emojis, wingdings, etc.
Raised in discussion with Dave Tapley (issue #392).
- To address mypy confusion of `pyparsing.Optional` and `typing.Optional`
resulting in `error: "_SpecialForm" not callable` message
reported in issue #365, fixed the import in `exceptions.py`. Nice
sleuthing by Iwan Aucamp and Dominic Davis-Foster, thank you!
(Removed definitions of `OptionalType`, `DictType`, and `IterableType`
and replaced them with `typing.Optional`, `typing.Dict`, and
`typing.Iterable` throughout.)
- Fixed typo in jinja2 template for railroad diagrams, thanks for the
catch Nioub (issue #388).
- Removed use of deprecated `pkg_resources` package in
railroad diagramming code (issue #391).
- Updated `bigquery_view_parser.py` example to parse examples at
https://cloud.google.com/bigquery/docs/reference/legacy-sql
Version 3.0.8 - April, 2022
---------------------------
- API CHANGE: modified `pyproject.toml` to require Python version
3.6.8 or later for pyparsing 3.x. Earlier minor versions of 3.6
fail in evaluating the `version_info` class (implemented using
`typing.NamedTuple`). If you are using an earlier version of Python
3.6, you will need to use pyparsing 2.4.7.
- Improved pyparsing import time by deferring regex pattern compiles.
PR submitted by Anthony Sottile to fix issue #362, thanks!
- Updated build to use flit, PR by Michał Górny, added `BUILDING.md`
doc and removed old Windows build scripts - nice cleanup work!
- More type-hinting added for all arithmetic and logical operator
methods in `ParserElement`. PR from Kazantcev Andrey, thank you.
- Fixed `infix_notation`'s definitions of `lpar` and `rpar`, to accept
parse expressions such that they do not get suppressed in the parsed
results. PR submitted by Philippe Prados, nice work.
- Fixed bug in railroad diagramming with expressions containing `Combine`
elements. Reported by Jeremy White, thanks!
- Added `show_groups` argument to `create_diagram` to highlight grouped
elements with an unlabeled bounding box.
- Added `unicode_denormalizer.py` to the examples as a demonstration
of how Python's interpreter will accept Unicode characters in
identifiers, but normalizes them back to ASCII so that identifiers
`print` and `𝕡𝓻ᵢ𝓃𝘁` and `𝖕𝒓𝗂𝑛ᵗ` are all equivalent.
- Removed imports of deprecated `sre_constants` module for catching
exceptions when compiling regular expressions. PR submitted by
Serhiy Storchaka, thank you.
Version 3.0.7 - January, 2022
-----------------------------
- Fixed bug #345, in which delimitedList changed expressions in place
using `expr.streamline()`. Reported by Kim Gräsman, thanks!
- Fixed bug #346, when a string of word characters was passed to WordStart
or `WordEnd` instead of just taking the default value. Originally posted
as a question by Parag on StackOverflow, good catch!
- Fixed bug #350, in which `White` expressions could fail to match due to
unintended whitespace-skipping. Reported by Fu Hanxi, thank you!
- Fixed bug #355, when a `QuotedString` is defined with characters in its
quoteChar string containing regex-significant characters such as ., *,
?, [, ], etc.
- Fixed bug in `ParserElement.run_tests` where comments would be displayed
using `with_line_numbers`.
- Added optional "min" and "max" arguments to `delimited_list`. PR
submitted by Marius, thanks!
- Added new API change note in `whats_new_in_pyparsing_3_0_0`, regarding
a bug fix in the `bool()` behavior of `ParseResults`.
Prior to pyparsing 3.0.x, the `ParseResults` class implementation of
`__bool__` would return `False` if the `ParseResults` item list was empty,
even if it contained named results. In 3.0.0 and later, `ParseResults` will
return `True` if either the item list is not empty *or* if the named
results dict is not empty.
# generate an empty ParseResults by parsing a blank string with
# a ZeroOrMore
result = Word(alphas)[...].parse_string("")
print(result.as_list())
print(result.as_dict())
print(bool(result))
# add a results name to the result
result["name"] = "empty result"
print(result.as_list())
print(result.as_dict())
print(bool(result))
Prints:
[]
{}
False
[]
{'name': 'empty result'}
True
In previous versions, the second call to `bool()` would return `False`.
- Minor enhancement to Word generation of internal regular expression, to
emit consecutive characters in range, such as "ab", as "ab", not "a-b".
- Fixed character ranges for search terms using non-Western characters
in booleansearchparser, PR submitted by tc-yu, nice work!
- Additional type annotations on public methods.
Version 3.0.6 - November, 2021
------------------------------
- Added `suppress_warning()` method to individually suppress a warning on a
specific ParserElement. Used to refactor `original_text_for` to preserve
internal results names, which, while undocumented, had been adopted by
some projects.
- Fix bug when `delimited_list` was called with a str literal instead of a
parse expression.
Version 3.0.5 - November, 2021
------------------------------
- Added return type annotations for `col`, `line`, and `lineno`.
- Fixed bug when `warn_ungrouped_named_tokens_in_collection` warning was raised
when assigning a results name to an `original_text_for` expression.
(Issue #110, would raise warning in packaging.)
- Fixed internal bug where `ParserElement.streamline()` would not return self if
already streamlined.
- Changed `run_tests()` output to default to not showing line and column numbers.
If line numbering is desired, call with `with_line_numbers=True`. Also fixed
minor bug where separating line was not included after a test failure.
Version 3.0.4 - October, 2021
-----------------------------
- Fixed bug in which `Dict` classes did not correctly return tokens as nested
`ParseResults`, reported by and fix identified by Bu Sun Kim, many thanks!!!
- Documented API-changing side-effect of converting `ParseResults` to use `__slots__`
to pre-define instance attributes. This means that code written like this (which
was allowed in pyparsing 2.4.7):
result = Word(alphas).parseString("abc")
result.xyz = 100
now raises this Python exception:
AttributeError: 'ParseResults' object has no attribute 'xyz'
To add new attribute values to ParseResults object in 3.0.0 and later, you must
assign them using indexed notation:
result["xyz"] = 100
You will still be able to access this new value as an attribute or as an
indexed item.
- Fixed bug in railroad diagramming where the vertical limit would count all
expressions in a group, not just those that would create visible railroad
elements.
Version 3.0.3 - October, 2021
-----------------------------
- Fixed regex typo in `one_of` fix for `as_keyword=True`.
- Fixed a whitespace-skipping bug, Issue #319, introduced as part of the revert
of the `LineStart` changes. Reported by Marc-Alexandre Côté,
thanks!
- Added header column labeling > 100 in `with_line_numbers` - some input lines
are longer than others.
Version 3.0.2 - October, 2021
-----------------------------
- Reverted change in behavior with `LineStart` and `StringStart`, which changed the
interpretation of when and how `LineStart` and `StringStart` should match when
a line starts with spaces. In 3.0.0, the `xxxStart` expressions were not
really treated like expressions in their own right, but as modifiers to the
following expression when used like `LineStart() + expr`, so that if there
were whitespace on the line before `expr` (which would match in versions prior
to 3.0.0), the match would fail.
3.0.0 implemented this by automatically promoting `LineStart() + expr` to
`AtLineStart(expr)`, which broke existing parsers that did not expect `expr` to
necessarily be right at the start of the line, but only be the first token
found on the line. This was reported as a regression in Issue #317.
In 3.0.2, pyparsing reverts to the previous behavior, but will retain the new
`AtLineStart` and `AtStringStart` expression classes, so that parsers can chose
whichever behavior applies in their specific instance. Specifically:
# matches expr if it is the first token on the line
# (allows for leading whitespace)
LineStart() + expr
# matches only if expr is found in column 1
AtLineStart(expr)
- Performance enhancement to `one_of` to always generate an internal `Regex`,
even if `caseless` or `as_keyword` args are given as `True` (unless explicitly
disabled by passing `use_regex=False`).
- `IndentedBlock` class now works with `recursive` flag. By default, the
results parsed by an `IndentedBlock` are grouped. This can be disabled by constructing
the `IndentedBlock` with `grouped=False`.
Version 3.0.1 - October, 2021
-----------------------------
- Fixed bug where `Word(max=n)` did not match word groups less than length 'n'.
Thanks to Joachim Metz for catching this!
- Fixed bug where `ParseResults` accidentally created recursive contents.
Joachim Metz on this one also!
- Fixed bug where `warn_on_multiple_string_args_to_oneof` warning is raised
even when not enabled.
Version 3.0.0 - October, 2021
-----------------------------
- A consolidated list of all the changes in the 3.0.0 release can be found in
`docs/whats_new_in_3_0_0.rst`.
(https://github.com/pyparsing/pyparsing/blob/master/docs/whats_new_in_3_0_0.rst)
Version 3.0.0.final - October, 2021
-----------------------------------
- Added support for python `-W` warning option to call `enable_all_warnings`() at startup.
Also detects setting of `PYPARSINGENABLEALLWARNINGS` environment variable to any non-blank
value. (If using `-Wd` for testing, but wishing to disable pyparsing warnings, add
`-Wi:::pyparsing`.)
- Fixed named results returned by `url` to match fields as they would be parsed
using `urllib.parse.urlparse`.
- Early response to `with_line_numbers` was positive, with some requested enhancements:
. added a trailing "|" at the end of each line (to show presence of trailing spaces);
can be customized using `eol_mark` argument
. added expand_tabs argument, to control calling str.expandtabs (defaults to True
to match `parseString`)
. added mark_spaces argument to support display of a printing character in place of
spaces, or Unicode symbols for space and tab characters
. added mark_control argument to support highlighting of control characters using
'.' or Unicode symbols, such as "␍" and "␊".
- Modified helpers `common_html_entity` and `replace_html_entity()` to use the HTML
entity definitions from `html.entities.html5`.
- Updated the class diagram in the pyparsing docs directory, along with the supporting
.puml file (PlantUML markup) used to create the diagram.
- Added global method `autoname_elements()` to call `set_name()` on all locally
defined `ParserElements` that haven't been explicitly named using `set_name()`, using
their local variable name. Useful for setting names on multiple elements when
creating a railroad diagram.
a = pp.Literal("a")
b = pp.Literal("b").set_name("bbb")
pp.autoname_elements()
`a` will get named "a", while `b` will keep its name "bbb".
Version 3.0.0rc2 - October, 2021
--------------------------------
- Added `url` expression to `pyparsing_common`. (Sample code posted by Wolfgang Fahl,
very nice!)
This new expression has been added to the `urlExtractorNew.py` example, to show how
it extracts URL fields into separate results names.
- Added method to `pyparsing_test` to help debugging, `with_line_numbers`.
Returns a string with line and column numbers corresponding to values shown
when parsing with expr.set_debug():
data = """\
A
100"""
expr = pp.Word(pp.alphanums).set_name("word").set_debug()
print(ppt.with_line_numbers(data))
expr[...].parseString(data)
prints:
1
1234567890
1: A
2: 100
Match word at loc 3(1,4)
A
^
Matched word -> ['A']
Match word at loc 11(2,7)
100
^
Matched word -> ['100']
- Added new example `cuneiform_python.py` to demonstrate creating a new Unicode
range, and writing a Cuneiform->Python transformer (inspired by zhpy).
- Fixed issue #272, reported by PhasecoreX, when `LineStart`() expressions would match
input text that was not necessarily at the beginning of a line.
As part of this fix, two new classes have been added: AtLineStart and AtStringStart.
The following expressions are equivalent:
LineStart() + expr and AtLineStart(expr)
StringStart() + expr and AtStringStart(expr)
[`LineStart` and `StringStart` changes reverted in 3.0.2.]
- Fixed `ParseFatalExceptions` failing to override normal exceptions or expression
matches in `MatchFirst` expressions. Addresses issue #251, reported by zyp-rgb.
- Fixed bug in which `ParseResults` replaces a collection type value with an invalid
type annotation (as a result of changed behavior in Python 3.9). Addresses issue #276, reported by
Rob Shuler, thanks.
- Fixed bug in `ParseResults` when calling `__getattr__` for special double-underscored
methods. Now raises `AttributeError` for non-existent results when accessing a
name starting with '__'. Addresses issue #208, reported by Joachim Metz.
- Modified debug fail messages to include the expression name to make it easier to sync
up match vs success/fail debug messages.
Version 3.0.0rc1 - September, 2021
----------------------------------
- Railroad diagrams have been reformatted:
. creating diagrams is easier - call
expr.create_diagram("diagram_output.html")
create_diagram() takes 3 arguments:
. the filename to write the diagram HTML
. optional 'vertical' argument, to specify the minimum number of items in a path
to be shown vertically; default=3
. optional 'show_results_names' argument, to specify whether results name
annotations should be shown; default=False
. every expression that gets a name using `setName()` gets separated out as
a separate subdiagram
. results names can be shown as annotations to diagram items
. `Each`, `FollowedBy`, and `PrecededBy` elements get [ALL], [LOOKAHEAD], and [LOOKBEHIND]
annotations
. removed annotations for Suppress elements
. some diagram cleanup when a grammar contains Forward elements
. check out the examples make_diagram.py and railroad_diagram_demo.py
- Type annotations have been added to most public API methods and classes.
- Better exception messages to show full word where an exception occurred.
Word(alphas, alphanums)[...].parseString("ab1 123", parseAll=True)
Was:
pyparsing.ParseException: Expected end of text, found '1' (at char 4), (line:1, col:5)
Now:
pyparsing.exceptions.ParseException: Expected end of text, found '123' (at char 4), (line:1, col:5)
- Suppress can be used to suppress text skipped using "...".
source = "lead in START relevant text END trailing text"
start_marker = Keyword("START")
end_marker = Keyword("END")
find_body = Suppress(...) + start_marker + ... + end_marker
print(find_body.parseString(source).dump())
Prints:
['START', 'relevant text ', 'END']
- _skipped: ['relevant text ']
- New string constants `identchars` and `identbodychars` to help in defining identifier Word expressions
Two new module-level strings have been added to help when defining identifiers, `identchars` and `identbodychars`.
Instead of writing::
import pyparsing as pp
identifier = pp.Word(pp.alphas + "_", pp.alphanums + "_")
you will be able to write::
identifier = pp.Word(pp.identchars, pp.identbodychars)
Those constants have also been added to all the Unicode string classes::
import pyparsing as pp
ppu = pp.pyparsing_unicode
cjk_identifier = pp.Word(ppu.CJK.identchars, ppu.CJK.identbodychars)
greek_identifier = pp.Word(ppu.Greek.identchars, ppu.Greek.identbodychars)
- Added a caseless parameter to the `CloseMatch` class to allow for casing to be
ignored when checking for close matches. (Issue #281) (PR by Adrian Edwards, thanks!)
- Fixed bug in Located class when used with a results name. (Issue #294)
- Fixed bug in `QuotedString` class when the escaped quote string is not a
repeated character. (Issue #263)
- `parseFile()` and `create_diagram()` methods now will accept `pathlib.Path`
arguments.
Version 3.0.0b3 - August, 2021
------------------------------
- PEP-8 compatible names are being introduced in pyparsing version 3.0!
All methods such as `parseString` have been replaced with the PEP-8
compliant name `parse_string`. In addition, arguments such as `parseAll`
have been renamed to `parse_all`. For backward-compatibility, synonyms for
all renamed methods and arguments have been added, so that existing
pyparsing parsers will not break. These synonyms will be removed in a future
release.
In addition, the Optional class has been renamed to Opt, since it clashes
with the common typing.Optional type specifier that is used in the Python
type annotations. A compatibility synonym is defined for now, but will be
removed in a future release.
- HUGE NEW FEATURE - Support for left-recursive parsers!
Following the method used in Python's PEG parser, pyparsing now supports
left-recursive parsers when left recursion is enabled.
import pyparsing as pp
pp.ParserElement.enable_left_recursion()
# a common left-recursion definition
# define a list of items as 'list + item | item'
# BNF:
# item_list := item_list item | item
# item := word of alphas
item_list = pp.Forward()
item = pp.Word(pp.alphas)
item_list <<= item_list + item | item
item_list.run_tests("""\
To parse or not to parse that is the question
""")
Prints:
['To', 'parse', 'or', 'not', 'to', 'parse', 'that', 'is', 'the', 'question']
Great work contributed by Max Fischer!
- `delimited_list` now supports an additional flag `allow_trailing_delim`,
to optionally parse an additional delimiter at the end of the list.
Contributed by Kazantcev Andrey, thanks!
- Removed internal comparison of results values against b"", which
raised a `BytesWarning` when run with `python -bb`. Fixes issue #271 reported
by Florian Bruhin, thank you!
- Fixed STUDENTS table in sql2dot.py example, fixes issue #261 reported by
legrandlegrand - much better.
- Python 3.5 will not be supported in the pyparsing 3 releases. This will allow
for future pyparsing releases to add parameter type annotations, and to take
advantage of dict key ordering in internal results name tracking.
Version 3.0.0b2 - December, 2020
--------------------------------
- API CHANGE
`locatedExpr` is being replaced by the class `Located`. `Located` has the same
constructor interface as `locatedExpr`, but fixes bugs in the returned
`ParseResults` when the searched expression contains multiple tokens, or
has internal results names.
`locatedExpr` is deprecated, and will be removed in a future release.
Version 3.0.0b1 - November, 2020
--------------------------------
- API CHANGE
Diagnostic flags have been moved to an enum, `pyparsing.Diagnostics`, and
they are enabled through module-level methods:
- `pyparsing.enable_diag()`
- `pyparsing.disable_diag()`
- `pyparsing.enable_all_warnings()`
- API CHANGE
Most previous `SyntaxWarnings` that were warned when using pyparsing
classes incorrectly have been converted to `TypeError` and `ValueError` exceptions,
consistent with Python calling conventions. All warnings warned by diagnostic
flags have been converted from `SyntaxWarnings` to `UserWarnings`.
- To support parsers that are intended to generate native Python collection
types such as lists and dicts, the `Group` and `Dict` classes now accept an
additional boolean keyword argument `aslist` and `asdict` respectively. See
the `jsonParser.py` example in the `pyparsing/examples` source directory for
how to return types as `ParseResults` and as Python collection types, and the
distinctions in working with the different types.
In addition parse actions that must return a value of list type (which would
normally be converted internally to a `ParseResults`) can override this default
behavior by returning their list wrapped in the new `ParseResults.List` class:
# this parse action tries to return a list, but pyparsing
# will convert to a ParseResults
def return_as_list_but_still_get_parse_results(tokens):
return tokens.asList()
# this parse action returns the tokens as a list, and pyparsing will
# maintain its list type in the final parsing results
def return_as_list(tokens):
return ParseResults.List(tokens.asList())
This is the mechanism used internally by the `Group` class when defined
using `aslist=True`.
- A new `IndentedBlock` class is introduced, to eventually replace the
current `indentedBlock` helper method. The interface is largely the same,
however, the new class manages its own internal indentation stack, so
it is no longer necessary to maintain an external `indentStack` variable.
- API CHANGE
Added `cache_hit` keyword argument to debug actions. Previously, if packrat
parsing was enabled, the debug methods were not called in the event of cache
hits. Now these methods will be called, with an added argument
`cache_hit=True`.
If you are using packrat parsing and enable debug on expressions using a
custom debug method, you can add the `cache_hit=False` keyword argument,
and your method will be called on packrat cache hits. If you choose not
to add this keyword argument, the debug methods will fail silently,
behaving as they did previously.
- When using `setDebug` with packrat parsing enabled, packrat cache hits will
now be included in the output, shown with a leading '*'. (Previously, cache
hits and responses were not included in debug output.) For those using custom
debug actions, see the previous item regarding an optional API change
for those methods.
- `setDebug` output will also show more details about what expression
is about to be parsed (the current line of text being parsed, and
the current parse position):
Match integer at loc 0(1,1)
1 2 3
^
Matched integer -> ['1']
The current debug location will also be indicated after whitespace
has been skipped (was previously inconsistent, reported in Issue #244,
by Frank Goyens, thanks!).
- Modified the repr() output for `ParseResults` to include the class
name as part of the output. This is to clarify for new pyparsing users
who misread the repr output as a tuple of a list and a dict. pyparsing
results will now read like:
ParseResults(['abc', 'def'], {'qty': 100}]
instead of just:
(['abc', 'def'], {'qty': 100}]
- Fixed bugs in Each when passed `OneOrMore` or `ZeroOrMore` expressions:
. first expression match could be enclosed in an extra nesting level
. out-of-order expressions now handled correctly if mixed with required
expressions
. results names are maintained correctly for these expressions
- Fixed traceback trimming, and added `ParserElement.verbose_traceback`
save/restore to `reset_pyparsing_context()`.
- Default string for `Word` expressions now also include indications of
`min` and `max` length specification, if applicable, similar to regex length
specifications:
Word(alphas) -> "W:(A-Za-z)"
Word(nums) -> "W:(0-9)"
Word(nums, exact=3) -> "W:(0-9){3}"
Word(nums, min=2) -> "W:(0-9){2,...}"
Word(nums, max=3) -> "W:(0-9){1,3}"
Word(nums, min=2, max=3) -> "W:(0-9){2,3}"
For expressions of the `Char` class (similar to `Word(..., exact=1)`, the expression
is simply the character range in parentheses:
Char(nums) -> "(0-9)"
Char(alphas) -> "(A-Za-z)"
- Removed `copy()` override in `Keyword` class which did not preserve definition
of ident chars from the original expression. PR #233 submitted by jgrey4296,
thanks!
- In addition to `pyparsing.__version__`, there is now also a `pyparsing.__version_info__`,
following the same structure and field names as in `sys.version_info`.
Version 3.0.0a2 - June, 2020
----------------------------
- Summary of changes for 3.0.0 can be found in "What's New in Pyparsing 3.0.0"
documentation.
- API CHANGE
Changed result returned when parsing using `countedArray`,
the array items are no longer returned in a doubly-nested
list.
- An excellent new enhancement is the new railroad diagram
generator for documenting pyparsing parsers:
import pyparsing as pp
from pyparsing.diagram import to_railroad, railroad_to_html
from pathlib import Path
# define a simple grammar for parsing street addresses such
# as "123 Main Street"
# number word...
number = pp.Word(pp.nums).setName("number")
name = pp.Word(pp.alphas).setName("word")[1, ...]
parser = number("house_number") + name("street")
parser.setName("street address")
# construct railroad track diagram for this parser and
# save as HTML
rr = to_railroad(parser)
Path('parser_rr_diag.html').write_text(railroad_to_html(rr))
Very nice work provided by Michael Milton, thanks a ton!
- Enhanced default strings created for Word expressions, now showing
string ranges if possible. `Word(alphas)` would formerly
print as `W:(ABCD...)`, now prints as `W:(A-Za-z)`.
- Added `ignoreWhitespace(recurse:bool = True)`` and added a
recurse argument to `leaveWhitespace`, both added to provide finer
control over pyparsing's whitespace skipping. Also contributed
by Michael Milton.
- The unicode range definitions for the various languages were
recalculated by interrogating the unicodedata module by character
name, selecting characters that contained that language in their
Unicode name. (Issue #227)
Also, pyparsing_unicode.Korean was renamed to Hangul (Korean
is also defined as a synonym for compatibility).
- Enhanced `ParseResults` dump() to show both results names and list
subitems. Fixes bug where adding a results name would hide
lower-level structures in the `ParseResults`.
- Added new __diag__ warnings:
"warn_on_parse_using_empty_Forward" - warns that a Forward
has been included in a grammar, but no expression was
attached to it using '<<=' or '<<'
"warn_on_assignment_to_Forward" - warns that a Forward has
been created, but was probably later overwritten by
erroneously using '=' instead of '<<=' (this is a common
mistake when using Forwards)
(**currently not working on PyPy**)
- Added `ParserElement`.recurse() method to make it simpler for
grammar utilities to navigate through the tree of expressions in
a pyparsing grammar.
- Fixed bug in `ParseResults` repr() which showed all matching
entries for a results name, even if `listAllMatches` was set
to False when creating the `ParseResults` originally. Reported
by Nicholas42 on GitHub, good catch! (Issue #205)
- Modified refactored modules to use relative imports, as
pointed out by setuptools project member jaraco, thank you!
- Off-by-one bug found in the roman_numerals.py example, a bug
that has been there for about 14 years! PR submitted by
Jay Pedersen, nice catch!
- A simplified Lua parser has been added to the examples
(lua_parser.py).
- Added make_diagram.py to the examples directory to demonstrate
creation of railroad diagrams for selected pyparsing examples.
Also restructured some examples to make their parsers importable
without running their embedded tests.
Version 3.0.0a1 - April, 2020
-----------------------------
- Removed Py2.x support and other deprecated features. Pyparsing
now requires Python 3.5 or later. If you are using an earlier
version of Python, you must use a Pyparsing 2.4.x version
Deprecated features removed:
. `ParseResults.asXML()` - if used for debugging, switch
to using `ParseResults.dump()`; if used for data transfer,
use `ParseResults.asDict()` to convert to a nested Python
dict, which can then be converted to XML or JSON or
other transfer format
. `operatorPrecedence` synonym for `infixNotation` -
convert to calling `infixNotation`
. `commaSeparatedList` - convert to using
pyparsing_common.comma_separated_list
. `upcaseTokens` and `downcaseTokens` - convert to using
`pyparsing_common.upcaseTokens` and `downcaseTokens`
. __compat__.collect_all_And_tokens will not be settable to
False to revert to pre-2.3.1 results name behavior -
review use of names for `MatchFirst` and Or expressions
containing And expressions, as they will return the
complete list of parsed tokens, not just the first one.
Use `__diag__.warn_multiple_tokens_in_named_alternation`
to help identify those expressions in your parsers that
will have changed as a result.
- Removed support for running `python setup.py test`. The setuptools
maintainers consider the test command deprecated (see
<https://github.com/pypa/setuptools/issues/1684>). To run the Pyparsing test,
use the command `tox`.
- API CHANGE:
The staticmethod `ParseException.explain` has been moved to
`ParseBaseException.explain_exception`, and a new `explain` instance
method added to `ParseBaseException`. This will make calls to `explain`
much more natural: