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diff --git a/Doc/ref1.tex b/Doc/ref1.tex deleted file mode 100644 index 30bfcce..0000000 --- a/Doc/ref1.tex +++ /dev/null @@ -1,81 +0,0 @@ -\chapter{Introduction} - -This reference manual describes the Python programming language. -It is not intended as a tutorial. - -While I am trying to be as precise as possible, I chose to use English -rather than formal specifications for everything except syntax and -lexical analysis. This should make the document more understandable -to the average reader, but will leave room for ambiguities. -Consequently, if you were coming from Mars and tried to re-implement -Python from this document alone, you might have to guess things and in -fact you would probably end up implementing quite a different language. -On the other hand, if you are using -Python and wonder what the precise rules about a particular area of -the language are, you should definitely be able to find them here. - -It is dangerous to add too many implementation details to a language -reference document --- the implementation may change, and other -implementations of the same language may work differently. On the -other hand, there is currently only one Python implementation, and -its particular quirks are sometimes worth being mentioned, especially -where the implementation imposes additional limitations. Therefore, -you'll find short ``implementation notes'' sprinkled throughout the -text. - -Every Python implementation comes with a number of built-in and -standard modules. These are not documented here, but in the separate -{\em Python Library Reference} document. A few built-in modules are -mentioned when they interact in a significant way with the language -definition. - -\section{Notation} - -The descriptions of lexical analysis and syntax use a modified BNF -grammar notation. This uses the following style of definition: -\index{BNF} -\index{grammar} -\index{syntax} -\index{notation} - -\begin{verbatim} -name: lc_letter (lc_letter | "_")* -lc_letter: "a"..."z" -\end{verbatim} - -The first line says that a \verb@name@ is an \verb@lc_letter@ followed by -a sequence of zero or more \verb@lc_letter@s and underscores. An -\verb@lc_letter@ in turn is any of the single characters `a' through `z'. -(This rule is actually adhered to for the names defined in lexical and -grammar rules in this document.) - -Each rule begins with a name (which is the name defined by the rule) -and a colon. A vertical bar (\verb@|@) is used to separate -alternatives; it is the least binding operator in this notation. A -star (\verb@*@) means zero or more repetitions of the preceding item; -likewise, a plus (\verb@+@) means one or more repetitions, and a -phrase enclosed in square brackets (\verb@[ ]@) means zero or one -occurrences (in other words, the enclosed phrase is optional). The -\verb@*@ and \verb@+@ operators bind as tightly as possible; -parentheses are used for grouping. Literal strings are enclosed in -quotes. White space is only meaningful to separate tokens. -Rules are normally contained on a single line; rules with many -alternatives may be formatted alternatively with each line after the -first beginning with a vertical bar. - -In lexical definitions (as the example above), two more conventions -are used: Two literal characters separated by three dots mean a choice -of any single character in the given (inclusive) range of \ASCII{} -characters. A phrase between angular brackets (\verb@<...>@) gives an -informal description of the symbol defined; e.g. this could be used -to describe the notion of `control character' if needed. -\index{lexical definitions} -\index{ASCII} - -Even though the notation used is almost the same, there is a big -difference between the meaning of lexical and syntactic definitions: -a lexical definition operates on the individual characters of the -input source, while a syntax definition operates on the stream of -tokens generated by the lexical analysis. All uses of BNF in the next -chapter (``Lexical Analysis'') are lexical definitions; uses in -subsequent chapters are syntactic definitions. |