This is Rietveld cbc36f91f3f7
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| 1 | 1 |
| 2 .. _lexical: | 2 .. _lexical: |
| 3 | 3 |
| 4 **************** | 4 **************** |
| 5 Lexical analysis | 5 Lexical analysis |
| 6 **************** | 6 **************** |
| 7 | 7 |
| 8 .. index:: lexical analysis, parser, token | 8 .. index:: lexical analysis, parser, token |
| 9 | 9 |
| 10 A Python program is read by a *parser*. Input to the parser is a stream of | 10 A Python program is read by a *parser*. Input to the parser is a stream of |
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| 394 | 394 |
| 395 String and Bytes literals | 395 String and Bytes literals |
| 396 ------------------------- | 396 ------------------------- |
| 397 | 397 |
| 398 .. index:: string literal, bytes literal, ASCII | 398 .. index:: string literal, bytes literal, ASCII |
| 399 | 399 |
| 400 String literals are described by the following lexical definitions: | 400 String literals are described by the following lexical definitions: |
| 401 | 401 |
| 402 .. productionlist:: | 402 .. productionlist:: |
| 403 stringliteral: [`stringprefix`](`shortstring` | `longstring`) | 403 stringliteral: [`stringprefix`](`shortstring` | `longstring`) |
| 404 stringprefix: "r" | "u" | "R" | "U" | 404 stringprefix: "r" | "u" | "R" | "U" |
| 405 shortstring: "'" `shortstringitem`* "'" | '"' `shortstringitem`* '"' | 405 shortstring: "'" `shortstringitem`* "'" | '"' `shortstringitem`* '"' |
| 406 longstring: "'''" `longstringitem`* "'''" | '"""' `longstringitem`* '"""' | 406 longstring: "'''" `longstringitem`* "'''" | '"""' `longstringitem`* '"""' |
| 407 shortstringitem: `shortstringchar` | `stringescapeseq` | 407 shortstringitem: `shortstringchar` | `stringescapeseq` |
| 408 longstringitem: `longstringchar` | `stringescapeseq` | 408 longstringitem: `longstringchar` | `stringescapeseq` |
| 409 shortstringchar: <any source character except "\" or newline or the quote> | 409 shortstringchar: <any source character except "\" or newline or the quote> |
| 410 longstringchar: <any source character except "\"> | 410 longstringchar: <any source character except "\"> |
| 411 stringescapeseq: "\" <any source character> | 411 stringescapeseq: "\" <any source character> |
| 412 | 412 |
| 413 .. productionlist:: | 413 .. productionlist:: |
| 414 bytesliteral: `bytesprefix`(`shortbytes` | `longbytes`) | 414 bytesliteral: `bytesprefix`(`shortbytes` | `longbytes`) |
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| 449 literal characters. As a result, in string literals, ``'\U'`` and ``'\u'`` | 449 literal characters. As a result, in string literals, ``'\U'`` and ``'\u'`` |
| 450 escapes in raw strings are not treated specially. Given that Python 2.x's raw | 450 escapes in raw strings are not treated specially. Given that Python 2.x's raw |
| 451 unicode literals behave differently than Python 3.x's the ``'ur'`` syntax | 451 unicode literals behave differently than Python 3.x's the ``'ur'`` syntax |
| 452 is not supported. | 452 is not supported. |
| 453 | 453 |
| 454 .. versionadded:: 3.3 | 454 .. versionadded:: 3.3 |
| 455 The ``'rb'`` prefix of raw bytes literals has been added as a synonym | 455 The ``'rb'`` prefix of raw bytes literals has been added as a synonym |
| 456 of ``'br'``. | 456 of ``'br'``. |
| 457 | 457 |
| 458 .. versionadded:: 3.3 | 458 .. versionadded:: 3.3 |
| 459 Support for the unicode legacy literal (``u'value'``) and other | 459 Support for the unicode legacy literal (``u'value'``) and other |
|
storchaka
2012/06/20 09:05:59
"other versions" is not true now.
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| 460 versions were reintroduced to simplify the maintenance of dual | 460 versions were reintroduced to simplify the maintenance of dual |
| 461 Python 2.x and 3.x codebases. See :pep:`414` for more information. | 461 Python 2.x and 3.x codebases. See :pep:`414` for more information. |
| 462 | 462 |
| 463 In triple-quoted strings, unescaped newlines and quotes are allowed (and are | 463 In triple-quoted strings, unescaped newlines and quotes are allowed (and are |
| 464 retained), except that three unescaped quotes in a row terminate the string. (A | 464 retained), except that three unescaped quotes in a row terminate the string. (A |
| 465 "quote" is the character used to open the string, i.e. either ``'`` or ``"``.) | 465 "quote" is the character used to open the string, i.e. either ``'`` or ``"``.) |
| 466 | 466 |
| 467 .. index:: physical line, escape sequence, Standard C, C | 467 .. index:: physical line, escape sequence, Standard C, C |
| 468 | 468 |
| 469 Unless an ``'r'`` or ``'R'`` prefix is present, escape sequences in strings are | 469 Unless an ``'r'`` or ``'R'`` prefix is present, escape sequences in strings are |
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| 722 | 722 |
| 723 The following printing ASCII characters are not used in Python. Their | 723 The following printing ASCII characters are not used in Python. Their |
| 724 occurrence outside string literals and comments is an unconditional error:: | 724 occurrence outside string literals and comments is an unconditional error:: |
| 725 | 725 |
| 726 $ ? ` | 726 $ ? ` |
| 727 | 727 |
| 728 | 728 |
| 729 .. rubric:: Footnotes | 729 .. rubric:: Footnotes |
| 730 | 730 |
| 731 .. [#] http://www.unicode.org/Public/6.1.0/ucd/NameAliases.txt | 731 .. [#] http://www.unicode.org/Public/6.1.0/ucd/NameAliases.txt |
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