diff options
Diffstat (limited to 'Doc/ref/ref7.tex')
| -rw-r--r-- | Doc/ref/ref7.tex | 111 |
1 files changed, 68 insertions, 43 deletions
diff --git a/Doc/ref/ref7.tex b/Doc/ref/ref7.tex index e43faec..c9e33f9 100644 --- a/Doc/ref/ref7.tex +++ b/Doc/ref/ref7.tex @@ -40,13 +40,18 @@ if x < y < z: print x; print y; print z Summarizing: -\begin{verbatim} -compound_stmt: if_stmt | while_stmt | for_stmt - | try_stmt | funcdef | classdef -suite: stmt_list NEWLINE | NEWLINE INDENT statement+ DEDENT -statement: stmt_list NEWLINE | compound_stmt -stmt_list: simple_stmt (";" simple_stmt)* [";"] -\end{verbatim} +\begin{productionlist} + \production{compound_stmt} + {\token{if_stmt} | \token{while_stmt} | \token{for_stmt} + | \token{try_stmt} | \token{funcdef} | \token{classdef}} + \production{suite} + {\token{stmt_list} NEWLINE + | NEWLINE INDENT \token{statement}+ DEDENT} + \production{statement} + {\token{stmt_list} NEWLINE | \token{compound_stmt}} + \production{stmt_list} + {\token{simple_stmt} (";" \token{simple_stmt})* [";"]} +\end{productionlist} Note that statements always end in a \code{NEWLINE}\index{NEWLINE token} possibly followed by a @@ -66,11 +71,12 @@ each clause on a separate line for clarity. The \keyword{if} statement is used for conditional execution: -\begin{verbatim} -if_stmt: "if" expression ":" suite - ("elif" expression ":" suite)* - ["else" ":" suite] -\end{verbatim} +\begin{productionlist} + \production{if_stmt} + {"if" \token{expression} ":" \token{suite} + ( "elif" \token{expression} ":" \token{suite} )* + ["else" ":" \token{suite}]} +\end{productionlist} It selects exactly one of the suites by evaluating the expressions one by one until one is found to be true (see section \ref{Booleans} for @@ -89,10 +95,11 @@ present, is executed. The \keyword{while} statement is used for repeated execution as long as an expression is true: -\begin{verbatim} -while_stmt: "while" expression ":" suite - ["else" ":" suite] -\end{verbatim} +\begin{productionlist} + \production{while_stmt} + {"while" \token{expression} ":" \token{suite} + ["else" ":" \token{suite}]} +\end{productionlist} This repeatedly tests the expression and, if it is true, executes the first suite; if the expression is false (which may be the first time it @@ -116,10 +123,12 @@ The \keyword{for} statement is used to iterate over the elements of a sequence (such as a string, tuple or list) or other iterable object: \obindex{sequence} -\begin{verbatim} -for_stmt: "for" target_list "in" expression_list ":" suite - ["else" ":" suite] -\end{verbatim} +\begin{productionlist} + \production{for_stmt} + {"for" \token{target_list} "in" \token{expression_list} + ":" \token{suite} + ["else" ":" \token{suite}]} +\end{productionlist} The expression list is evaluated once; it should yield a sequence. The suite is then executed once for each item in the sequence, in the @@ -179,14 +188,18 @@ for x in a[:]: The \keyword{try} statement specifies exception handlers and/or cleanup code for a group of statements: -\begin{verbatim} -try_stmt: try_exc_stmt | try_fin_stmt -try_exc_stmt: "try" ":" suite - ("except" [expression ["," target]] ":" suite)+ - ["else" ":" suite] -try_fin_stmt: "try" ":" suite - "finally" ":" suite -\end{verbatim} +\begin{productionlist} + \production{try_stmt} + {\token{try_exc_stmt} | \token{try_fin_stmt}} + \production{try_exc_stmt} + {"try" ":" \token{suite} + ("except" [\token{expression} ["," \token{target}]] ":" + \token{suite})+ + ["else" ":" \token{suite}]} + \production{try_fin_stmt} + {"try" ":" \token{suite} + "finally" ":" \token{suite}} +\end{productionlist} There are two forms of \keyword{try} statement: \keyword{try}...\keyword{except} and @@ -291,16 +304,24 @@ section \ref{types}): \obindex{user-defined function} \obindex{function} -\begin{verbatim} -funcdef: "def" funcname "(" [parameter_list] ")" ":" suite -parameter_list: (defparameter ",")* ("*" identifier [, "**" identifier] - | "**" identifier - | defparameter [","]) -defparameter: parameter ["=" expression] -sublist: parameter ("," parameter)* [","] -parameter: identifier | "(" sublist ")" -funcname: identifier -\end{verbatim} +\begin{productionlist} + \production{funcdef} + {"def" \token{funcname} "(" [\token{parameter_list}] ")" + ":" \token{suite}} + \production{parameter_list} + {(\token{defparameter} ",")* + ("*" \token{identifier} [, "**" \token{identifier}] + | "**" \token{identifier} + | \token{defparameter} [","])} + \production{defparameter} + {\token{parameter} ["=" \token{expression}]} + \production{sublist} + {\token{parameter} ("," \token{parameter})* [","]} + \production{parameter} + {\token{identifier} | "(" \token{sublist} ")"} + \production{funcname} + {\token{identifier}} +\end{productionlist} A function definition is an executable statement. Its execution binds the function name in the current local namespace to a function object @@ -376,11 +397,15 @@ description of the new semantics. A class definition defines a class object (see section \ref{types}): \obindex{class} -\begin{verbatim} -classdef: "class" classname [inheritance] ":" suite -inheritance: "(" [expression_list] ")" -classname: identifier -\end{verbatim} +\begin{productionlist} + \production{classdef} + {"class" \token{classname} [\token{inheritance}] ":" + \token{suite}} + \production{inheritance} + {"(" [\token{expression_list}] ")"} + \production{classname} + {\token{identifier}} +\end{productionlist} A class definition is an executable statement. It first evaluates the inheritance list, if present. Each item in the inheritance list |