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PEP 617: Fix typos and other minor edits (GH-1356) 

* Fix typo in PEP 617.
* Fix what appears to be meant as a numbered list that was reflowed incorrectly.
* Clarify a slightly awkward sentence about the EXTRA C macro.
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T. Wouters 2020-04-03 13:07:14 +02:00 committed by GitHub
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@ -555,7 +555,7 @@ maintainable. This AST generation process is supported by the use of some helper
functions that factor out common AST object manipulations and some other required functions that factor out common AST object manipulations and some other required
operations that are not directly related to the grammar. operations that are not directly related to the grammar.
To indicate these actions each alternative can be followed by a the action code To indicate these actions each alternative can be followed by the action code
inside curly-braces, which specifies the return value of the alternative::: inside curly-braces, which specifies the return value of the alternative:::
rule_name[return_type]: rule_name[return_type]:
@ -563,11 +563,13 @@ inside curly-braces, which specifies the return value of the alternative:::
| second_alt1 second_alt2 { second_alt1 } | second_alt1 second_alt2 { second_alt1 }
If the action is omitted and C code is being generated, then there are two If the action is omitted and C code is being generated, then there are two
different possibilities: 1. If there’s a single name in the alternative, this gets different possibilities:
returned. 2. If not, a dummy name object gets returned (this case should be avoided).
If Python code is being generated, then a list with all the parsed 1. If there’s a single name in the alternative, this gets returned.
expressions get returned if no action is specified (this is meant for debugging). 2. If not, a dummy name object gets returned (this case should be avoided).
If the action is omitted and Python code is being generated, then a list
with all the parsed expressions get returned (this is meant for debugging).
As an illustrative example this simple grammar file allows to directly generate a full As an illustrative example this simple grammar file allows to directly generate a full
parser that can parse simple aritmetic expressions and that returns a valid Python AST: parser that can parse simple aritmetic expressions and that returns a valid Python AST:
@ -593,10 +595,10 @@ parser that can parse simple aritmetic expressions and that returns a valid Pyth
| s=STRING { s } | s=STRING { s }
) )
here ``EXTRA`` is a macro that expands to ``start_lineno, start_col_offset, Here ``EXTRA`` is a macro that expands to ``start_lineno, start_col_offset,
end_lineno, end_col_offset, p->arena``, being the values for this variables end_lineno, end_col_offset, p->arena``, those being variables automatically
automatically injected by the parser; ``p`` points to an object injected by the parser; ``p`` points to an object that holds on to all state
that holds on to all state for the parser. for the parser.
============== ==============
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