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As a first step toward aligning the grammar documentation with Python's actual grammar, this overrides the ReST `productionlist` directive to: - use `:` instead of the `::=` symbol - add syntax highlighting for strings (using a Pygments highlighting class) All links and link targets should be preserved. (Unfortunately, this reaches into some Sphinx internals; I don't see a better way to do exactly what Sphinx does.) This also adds a new directive, `grammar-snippet`, which formats the snippet almost exactly like what's in the source, modulo syntax highlighting and keeping the backtick character to mark links to other rules. This will allow formatting the snippets as in the grammar file (file:///home/encukou/dev/cpython/Doc/build/html/reference/grammar.html). The new directive is applied to two simple rules in toplevel_components.rst --------- Co-authored-by: Blaise Pabon <blaise@gmail.com> Co-authored-by: William Ferreira <wqferr@gmail.com> Co-authored-by: bswck <bartoszpiotrslawecki@gmail.com> Co-authored-by: Adam Turner <9087854+aa-turner@users.noreply.github.com>
111 lines
3.1 KiB
ReStructuredText
111 lines
3.1 KiB
ReStructuredText
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.. _top-level:
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********************
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Top-level components
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********************
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.. index:: single: interpreter
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The Python interpreter can get its input from a number of sources: from a script
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passed to it as standard input or as program argument, typed in interactively,
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from a module source file, etc. This chapter gives the syntax used in these
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cases.
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.. _programs:
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Complete Python programs
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========================
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.. index:: single: program
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.. index::
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pair: module; sys
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pair: module; __main__
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pair: module; builtins
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While a language specification need not prescribe how the language interpreter
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is invoked, it is useful to have a notion of a complete Python program. A
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complete Python program is executed in a minimally initialized environment: all
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built-in and standard modules are available, but none have been initialized,
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except for :mod:`sys` (various system services), :mod:`builtins` (built-in
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functions, exceptions and ``None``) and :mod:`__main__`. The latter is used to
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provide the local and global namespace for execution of the complete program.
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The syntax for a complete Python program is that for file input, described in
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the next section.
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.. index::
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single: interactive mode
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pair: module; __main__
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The interpreter may also be invoked in interactive mode; in this case, it does
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not read and execute a complete program but reads and executes one statement
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(possibly compound) at a time. The initial environment is identical to that of
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a complete program; each statement is executed in the namespace of
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:mod:`__main__`.
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.. index::
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single: UNIX
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single: Windows
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single: command line
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single: standard input
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A complete program can be passed to the interpreter
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in three forms: with the :option:`-c` *string* command line option, as a file
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passed as the first command line argument, or as standard input. If the file
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or standard input is a tty device, the interpreter enters interactive mode;
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otherwise, it executes the file as a complete program.
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.. _file-input:
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File input
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==========
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All input read from non-interactive files has the same form:
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.. grammar-snippet::
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:group: python-grammar
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file_input: (NEWLINE | `statement`)*
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This syntax is used in the following situations:
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* when parsing a complete Python program (from a file or from a string);
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* when parsing a module;
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* when parsing a string passed to the :func:`exec` function;
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.. _interactive:
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Interactive input
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=================
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Input in interactive mode is parsed using the following grammar:
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.. grammar-snippet::
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:group: python-grammar
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interactive_input: [`stmt_list`] NEWLINE | `compound_stmt` NEWLINE
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Note that a (top-level) compound statement must be followed by a blank line in
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interactive mode; this is needed to help the parser detect the end of the input.
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.. _expression-input:
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Expression input
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================
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.. index:: single: input
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.. index:: pair: built-in function; eval
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:func:`eval` is used for expression input. It ignores leading whitespace. The
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string argument to :func:`eval` must have the following form:
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.. productionlist:: python-grammar
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eval_input: `expression_list` NEWLINE*
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