8000 gh-127833: Reword and expand the Notation section by encukou · Pull Request #134443 · python/cpython · GitHub
[go: up one dir, main page]
Skip to content

gh-127833: Reword and expand the Notation section #134443

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
encukou merged 8 commits into from
Jun 9, 2025
+128 −50
Merged

gh-127833: Reword and expand the Notation section #134443

Changes from 1 commit
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
211f83d
gh-127833: Reword and expand the Notation section
encukou May 21, 2025
ec90d40
Consolidate with the Full Grammar intro
encukou May 21, 2025
3f3a0db
Don't link the examples
encukou May 21, 2025
160ff42
Add Cut
encukou May 21, 2025
231e2ba
Note practical difference between syntactic & lexical definitions
encukou May 28, 2025
fa17c00
Apply suggestions from code review
encukou Jun 3, 2025
327b90d
Constrain `"a"..."z"` and `<...>` to lexical definitions
encukou Jun 4, 2025
3c5caa6
Update Doc/reference/introduction.rst
encukou Jun 7, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Constrain "a"..."z" and <...> to lexical definitions
  • Loading branch information
@encukou
encukou committed Jun 4, 2025
commit 327b90de33b32b0e0a2939875c2136c1eeeeedca
19 changes: 14 additions & 5 deletions Doc/reference/introduction.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -129,11 +129,6 @@ The definition to the right of the colon uses the following syntax elements:
:py:data:`~token.OP` token, that is, a :ref:`delimiter <delimiters>` or
:ref:`operator <operators>`.

* ``"a"..."z"``: Two literal characters separated by three dots mean a choice
of any single character in the given (inclusive) range of ASCII characters.
* ``<...>``: A phrase between angular brackets gives an informal description
of the matched symbol (for example, ``<any ASCII character except "\">``),
or an abbreviation that is defined in nearby text (for example, ``<Lu>``).
* ``e1 e2``: Items separated only by whitespace denote a sequence.
Here, ``e1`` must be followed by ``e2``.
* ``e1 | e2``: A vertical bar is used to separate alternatives.
Expand All @@ -149,6 +144,15 @@ The definition to the right of the colon uses the following syntax elements:
* ``e?``: A question mark has exactly the same meaning as square brackets:
the preceding item is optional.
* ``(e)``: Parentheses are used for grouping.
* ``"a"..."z"``: Two literal characters separated by three dots mean a choice
of any single character in the given (inclusive) range of ASCII characters.
This notation is only used in
:ref:`lexical definitions <notation-lexical-vs-syntactic>`.
* ``<...>``: A phrase between angular brackets gives an informal description
of the matched symbol (for example, ``<any ASCII character except "\">``),
or an abbreviation that is defined in nearby text (for example, ``<Lu>``).
This notation is only used in
:ref:`lexical definitions <notation-lexical-vs-syntactic>`.

The unary operators (``*``, ``+``, ``?``) bind as tightly as possible;
the vertical bar (``|``) binds most loosely.
Expand Down Expand Up @@ -183,6 +187,11 @@ This does *not* mean that there is an empty first alternative.

.. index:: lexical definitions

.. _notation-lexical-vs-syntactic:

Lexical and Syntactic definitions
---------------------------------

There is some difference between *lexical* and *syntactic* analysis:
the :term:`lexical analyzer` operates on the individual characters of the
input source, while the *parser* (syntactic analyzer) operates on the stream
Expand Down
Loading
0