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226 lines
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226 lines
8.8 KiB
ReStructuredText
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:mod:`curses.ascii` --- Utilities for ASCII characters
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======================================================
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.. module:: curses.ascii
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:synopsis: Constants and set-membership functions for ASCII characters.
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.. moduleauthor:: Eric S. Raymond <esr@thyrsus.com>
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.. sectionauthor:: Eric S. Raymond <esr@thyrsus.com>
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The :mod:`curses.ascii` module supplies name constants for ASCII characters and
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functions to test membership in various ASCII character classes. The constants
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supplied are names for control characters as follows:
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+--------------+----------------------------------------------+
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| Name | Meaning |
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+==============+==============================================+
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| :const:`NUL` | |
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+--------------+----------------------------------------------+
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| :const:`SOH` | Start of heading, console interrupt |
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+--------------+----------------------------------------------+
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| :const:`STX` | Start of text |
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+--------------+----------------------------------------------+
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| :const:`ETX` | End of text |
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+--------------+----------------------------------------------+
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| :const:`EOT` | End of transmission |
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+--------------+----------------------------------------------+
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| :const:`ENQ` | Enquiry, goes with :const:`ACK` flow control |
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+--------------+----------------------------------------------+
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| :const:`ACK` | Acknowledgement |
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+--------------+----------------------------------------------+
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| :const:`BEL` | Bell |
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+--------------+----------------------------------------------+
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| :const:`BS` | Backspace |
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+--------------+----------------------------------------------+
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| :const:`TAB` | Tab |
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+--------------+----------------------------------------------+
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| :const:`HT` | Alias for :const:`TAB`: "Horizontal tab" |
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+--------------+----------------------------------------------+
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| :const:`LF` | Line feed |
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+--------------+----------------------------------------------+
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| :const:`NL` | Alias for :const:`LF`: "New line" |
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+--------------+----------------------------------------------+
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| :const:`VT` | Vertical tab |
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+--------------+----------------------------------------------+
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| :const:`FF` | Form feed |
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+--------------+----------------------------------------------+
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| :const:`CR` | Carriage return |
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+--------------+----------------------------------------------+
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| :const:`SO` | Shift-out, begin alternate character set |
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+--------------+----------------------------------------------+
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| :const:`SI` | Shift-in, resume default character set |
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+--------------+----------------------------------------------+
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| :const:`DLE` | Data-link escape |
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+--------------+----------------------------------------------+
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| :const:`DC1` | XON, for flow control |
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+--------------+----------------------------------------------+
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| :const:`DC2` | Device control 2, block-mode flow control |
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+--------------+----------------------------------------------+
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| :const:`DC3` | XOFF, for flow control |
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+--------------+----------------------------------------------+
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| :const:`DC4` | Device control 4 |
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+--------------+----------------------------------------------+
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| :const:`NAK` | Negative acknowledgement |
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+--------------+----------------------------------------------+
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| :const:`SYN` | Synchronous idle |
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+--------------+----------------------------------------------+
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| :const:`ETB` | End transmission block |
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+--------------+----------------------------------------------+
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| :const:`CAN` | Cancel |
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+--------------+----------------------------------------------+
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| :const:`EM` | End of medium |
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+--------------+----------------------------------------------+
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| :const:`SUB` | Substitute |
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+--------------+----------------------------------------------+
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| :const:`ESC` | Escape |
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+--------------+----------------------------------------------+
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| :const:`FS` | File separator |
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+--------------+----------------------------------------------+
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| :const:`GS` | Group separator |
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+--------------+----------------------------------------------+
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| :const:`RS` | Record separator, block-mode terminator |
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+--------------+----------------------------------------------+
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| :const:`US` | Unit separator |
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+--------------+----------------------------------------------+
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| :const:`SP` | Space |
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+--------------+----------------------------------------------+
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| :const:`DEL` | Delete |
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+--------------+----------------------------------------------+
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Note that many of these have little practical significance in modern usage. The
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mnemonics derive from teleprinter conventions that predate digital computers.
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The module supplies the following functions, patterned on those in the standard
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C library:
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.. function:: isalnum(c)
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Checks for an ASCII alphanumeric character; it is equivalent to ``isalpha(c) or
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isdigit(c)``.
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.. function:: isalpha(c)
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Checks for an ASCII alphabetic character; it is equivalent to ``isupper(c) or
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islower(c)``.
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.. function:: isascii(c)
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Checks for a character value that fits in the 7-bit ASCII set.
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.. function:: isblank(c)
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Checks for an ASCII whitespace character.
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.. function:: iscntrl(c)
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Checks for an ASCII control character (in the range 0x00 to 0x1f).
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.. function:: isdigit(c)
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Checks for an ASCII decimal digit, ``'0'`` through ``'9'``. This is equivalent
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to ``c in string.digits``.
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.. function:: isgraph(c)
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Checks for ASCII any printable character except space.
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.. function:: islower(c)
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Checks for an ASCII lower-case character.
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.. function:: isprint(c)
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Checks for any ASCII printable character including space.
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.. function:: ispunct(c)
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Checks for any printable ASCII character which is not a space or an alphanumeric
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character.
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.. function:: isspace(c)
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Checks for ASCII white-space characters; space, line feed, carriage return, form
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feed, horizontal tab, vertical tab.
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.. function:: isupper(c)
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Checks for an ASCII uppercase letter.
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.. function:: isxdigit(c)
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Checks for an ASCII hexadecimal digit. This is equivalent to ``c in
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string.hexdigits``.
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.. function:: isctrl(c)
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Checks for an ASCII control character (ordinal values 0 to 31).
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.. function:: ismeta(c)
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Checks for a non-ASCII character (ordinal values 0x80 and above).
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These functions accept either integers or strings; when the argument is a
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string, it is first converted using the built-in function :func:`ord`.
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Note that all these functions check ordinal bit values derived from the first
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character of the string you pass in; they do not actually know anything about
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the host machine's character encoding. For functions that know about the
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character encoding (and handle internationalization properly) see the
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:mod:`string` module.
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The following two functions take either a single-character string or integer
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byte value; they return a value of the same type.
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.. function:: ascii(c)
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Return the ASCII value corresponding to the low 7 bits of *c*.
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.. function:: ctrl(c)
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Return the control character corresponding to the given character (the character
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bit value is bitwise-anded with 0x1f).
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.. function:: alt(c)
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Return the 8-bit character corresponding to the given ASCII character (the
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character bit value is bitwise-ored with 0x80).
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The following function takes either a single-character string or integer value;
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it returns a string.
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.. function:: unctrl(c)
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Return a string representation of the ASCII character *c*. If *c* is printable,
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this string is the character itself. If the character is a control character
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(0x00-0x1f) the string consists of a caret (``'^'``) followed by the
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corresponding uppercase letter. If the character is an ASCII delete (0x7f) the
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string is ``'^?'``. If the character has its meta bit (0x80) set, the meta bit
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is stripped, the preceding rules applied, and ``'!'`` prepended to the result.
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.. data:: controlnames
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A 33-element string array that contains the ASCII mnemonics for the thirty-two
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ASCII control characters from 0 (NUL) to 0x1f (US), in order, plus the mnemonic
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``SP`` for the space character.
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