mirror of https://github.com/lua/lua
"locale" support + better uniformity in formating
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Roberto Ierusalimschy
parent
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97
manual.tex
97
manual.tex
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@ -1,8 +1,7 @@
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% $Id: manual.tex,v 2.8 1997/06/27 22:38:49 roberto Exp roberto $
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% $Id: manual.tex,v 2.9 1997/07/01 17:41:34 roberto Exp roberto $
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\documentstyle[fullpage,11pt,bnf]{article}
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\newcommand{\rw}[1]{{\bf #1}}
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\newcommand{\See}[1]{Section~\ref{#1}}
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\newcommand{\see}[1]{(see \See{#1})}
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\newcommand{\M}[1]{\emph{#1}}
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@ -39,7 +38,7 @@ Waldemar Celes
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\tecgraf\ --- Computer Science Department --- PUC-Rio
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}
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\date{\small \verb$Date: 1997/06/27 22:38:49 $}
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\date{\small \verb$Date: 1997/07/01 17:41:34 $}
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\maketitle
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@ -167,14 +166,14 @@ Before the first assignment, the value of a global variable is \nil;
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this default can be changed \see{tag-method}.
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The unit of execution of Lua is called a \Def{chunk}.
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The syntax%
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\footnote{As usual, \rep{\emph{a}} means 0 or more \emph{a}'s,
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\opt{\emph{a}} means an optional \emph{a} and \oneormore{\emph{a}} means
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one or more \emph{a}'s.}
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for chunks is:
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The syntax for chunks is:
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\begin{Produc}
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\produc{chunk}{\rep{stat \Or function} \opt{ret}}
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\end{Produc}%
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(As usual, \rep{\emph{a}} means 0 or more \emph{a}'s,
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\opt{\emph{a}} means an optional \emph{a} and \oneormore{\emph{a}} means
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one or more \emph{a}'s.)
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A chunk may contain statements and function definitions,
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and may be in a file or in a string inside the host program.
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A chunk may optionally end with a \verb|return| statement \see{return}.
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@ -182,10 +181,10 @@ When a chunk is executed, first all its functions and statements are compiled,
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then the statements are executed in sequential order.
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All modifications a chunk effects on the global environment persist
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after its end.
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Those include modifications to global variables and definitions
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of new functions%
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\footnote{Actually, a function definition is an
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assignment to a global variable \see{TypesSec}.}.
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Those include modifications to global variables
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and definitions of new functions
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(actually, a function definition is an
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assignment to a global variable \see{TypesSec}).
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Chunks may be pre-compiled into binary form;
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see program \IndexVerb{luac} for details.
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@ -207,7 +206,9 @@ There are six \Index{basic types} in Lua: \Def{nil}, \Def{number},
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\emph{Nil} is the type of the value \nil,
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whose main property is to be different from any other value.
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\emph{Number} represents real (floating-point) numbers,
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while \emph{string} has the usual meaning.
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while \emph{string} has the usual meaning;
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notice that Lua is \Index{eight-bit clean},
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so strings can have ISO characters.
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The function \verb|type| returns a string describing the type
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of a given value \see{pdf-type}.
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@ -275,9 +276,11 @@ This section describes the lexis, the syntax and the semantics of Lua.
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\subsection{Lexical Conventions} \label{lexical}
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Lua is a case-sensitive language.
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\Index{Identifiers} can be any string of letters, digits, and underscores,
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not beginning with a digit.
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The definition of letter depends on the current locale:
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Any character considered alphabetic by the current locale
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can be used in an identifier.
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The following words are reserved, and cannot be used as identifiers:
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\index{reserved words}
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\begin{verbatim}
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@ -286,6 +289,9 @@ The following words are reserved, and cannot be used as identifiers:
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nil not or repeat
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return then until while
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\end{verbatim}
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Lua is a case-sensitive language:
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\T{and} is a reserved word, but \T{And} and \T{\'and}
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(if the locale permits) are two other different identifiers.
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The following strings denote other \Index{tokens}:
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\begin{verbatim}
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@ -307,9 +313,9 @@ other quoted strings.
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\Index{Comments} start anywhere outside a string with a
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double hyphen (\verb|--|) and run until the end of the line.
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Moreover,
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the first line of a chunk file is skipped if it starts with \verb|#|%
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\footnote{This facility allows the use of Lua as a script interpreter
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in Unix systems \see{lua-sa}.}.
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the first line of a chunk file is skipped if it starts with \verb|#|.
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This facility allows the use of Lua as a script interpreter
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in Unix systems \see{lua-sa}.
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\Index{Numerical constants} may be written with an optional decimal part,
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and an optional decimal exponent.
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@ -325,9 +331,9 @@ The \verb|$| can be followed by any of the following directives:
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\begin{description}
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\item[\T{debug}] --- turn on some debugging facilities \see{pragma}.
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\item[\T{nodebug}] --- turn off some debugging facilities \see{pragma}.
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\item[{\tt if \M{cond}}] --- starts a conditional part.
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\item[\T{if \M{cond}}] --- starts a conditional part.
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If \M{cond} is false, then this part is skipped by the lexical analyzer.
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\item[{\tt ifnot \M{cond}}] --- starts a conditional part.
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\item[\T{ifnot \M{cond}}] --- starts a conditional part.
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If \M{cond} is true, then this part is skipped by the lexical analyzer.
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\item[\T{end}] --- ends a conditional part.
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\item[\T{else}] --- starts an ``else'' conditional part,
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@ -439,9 +445,9 @@ an assignment \verb|x = val|, where \verb|x| is a global variable,
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is equivalent to a call \verb|setglobal('x', val)|;
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an assignment \verb|t[i] = val| is equivalent to
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\verb|settable_event(t, i, val)|.
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See \See{tag-method} for a description of these functions%
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\footnote{Function \verb|setglobal| is pre-defined in Lua.
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Function \T{settable\_event} is used only for explanatory purposes.}.
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See \See{tag-method} for a description of these functions.
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(Function \verb|setglobal| is pre-defined in Lua.
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Function \T{settable\_event} is used only for explanatory purposes.)
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The syntax \verb|var.NAME| is just syntactic sugar for
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\verb|var["NAME"]|:
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@ -515,9 +521,9 @@ An access to a global variable \verb|x| is equivalent to a
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call \verb|getglobal('x')|;
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an access to an indexed variable \verb|t[i]| is equivalent to
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a call \verb|gettable_event(t, i)|.
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See \See{tag-method} for a description of these functions%
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\footnote{Function \verb|getglobal| is pre-defined in Lua.
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Function \T{gettable\_event} is used only for explanatory purposes.}.
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See \See{tag-method} for a description of these functions.
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(Function \verb|getglobal| is pre-defined in Lua.
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Function \T{gettable\_event} is used only for explanatory purposes.)
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The non-terminal \M{exp1} is used to indicate that the values
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returned by an expression must be adjusted to one single value:
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@ -563,9 +569,6 @@ If both arguments are numbers, then they are compared as such.
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Otherwise, if both arguments are strings,
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their values are compared using lexicographical order.
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Otherwise, the ``order'' tag method is called \see{tag-method}.
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%Note that the conversion rules of Section~\ref{coercion}
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%do apply to order operators.
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%Thus, \verb|"2">"12"| evaluates to true.
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\subsubsection{Logical Operators}
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Like control structures, all logical operators
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@ -643,7 +646,7 @@ is essentially equivalent to:
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The form \emph{ffieldlist1} initializes other fields in a table:
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\begin{Produc}
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\produc{ffieldlist1}{ffield \rep{\ter{,} ffield} \opt{\ter{,}}}
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\produc{ffield}{\ter{[} exp \ter{]} \ter {=} exp \Or name \ter{=} exp}
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\produc{ffield}{\ter{[} exp \ter{]} \ter{=} exp \Or name \ter{=} exp}
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\end{Produc}%
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For example:
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\begin{verbatim}
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@ -1322,7 +1325,7 @@ The use of explicit nested blocks is strongly encouraged.
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\subsection{Executing Lua Code}
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A host program can execute Lua chunks written in a file or in a string
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using the following functions:%
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using the following functions:
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\Deffunc{lua_dofile}\Deffunc{lua_dostring}
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\begin{verbatim}
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int lua_dofile (char *filename);
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@ -1967,7 +1970,7 @@ The following combinations are allowed in describing a character class:
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\item[\T{\%U}] --- represents all non upper case letter characters.
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\item[\T{\%w}] --- represents all alphanumeric characters.
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\item[\T{\%W}] --- represents all non alphanumeric characters.
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\item[{\tt \%\M{x}}] (where \M{x} is any non alphanumeric character) ---
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\item[\T{\%\M{x}}] (where \M{x} is any non alphanumeric character) ---
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represents the character \M{x}.
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This is the standard way to escape the magic characters \verb|()%.[*-?|.
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\item[\T{[char-set]}] ---
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@ -1976,17 +1979,21 @@ characters in char-set.
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To include a \verb|]| in char-set, it must be the first character.
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A range of characters may be specified by
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separating the end characters of the range with a \verb|-|;
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e.g., \verb|A-Z| specifies the upper case characters.
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e.g., \verb|A-Z| specifies the English upper case characters.
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If \verb|-| appears as the first or last character of char-set,
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then it represents itself.
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All classes \verb|%|\emph{x} described above can also be used as
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components in a char-set.
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All other characters in char-set represent themselves.
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\item[{\tt [\^{ }char-set]}] ---
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\item[\T{[\^{ }char-set]}] ---
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represents the complement of char-set,
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where char-set is interpreted as above.
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\end{description}
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The definitions of letter, space, etc depend on the current locale.
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In particular, the class \verb|[a-z]| may not be equivalent to \verb|%l|.
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The second form should be preferred for more portable programs.
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\paragraph{Pattern Item:}
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a \Def{pattern item} may be:
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\begin{itemize}
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@ -2006,11 +2013,11 @@ these repetition items will always match the shortest possible sequence.
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a single character class followed by \verb|?|,
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which matches 0 or 1 occurrence of a character in the class;
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\item
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{\tt \%\M{n}}, for \M{n} between 1 and 9;
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\T{\%\M{n}}, for \M{n} between 1 and 9;
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such item matches a sub-string equal to the n-th captured string
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(see below);
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\item
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{\tt \%b\M{xy}}, where \M{x} and \M{y} are two distinct characters;
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\T{\%b\M{xy}}, where \M{x} and \M{y} are two distinct characters;
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such item matches strings that start with \M{x}, end with \M{y},
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and where the \M{x} and \M{y} are \emph{balanced}.
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That means that, if one reads the string from left to write,
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@ -2039,6 +2046,7 @@ stored as the first capture (and therefore has number 1);
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the character matching \verb|.| is captured with number 2,
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and the part matching \verb|%s*| has number 3.
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\subsection{Mathematical Functions} \label{mathlib}
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This library is an interface to some functions of the standard C math library.
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@ -2101,8 +2109,6 @@ When called with a file name, it opens the named file,
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sets its handle as the value of \verb|_INPUT|,
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and returns this value.
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It does not close the current input file.
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%When called with a file handle returned by a previous call,
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%it simply assigns it to \verb|_INPUT|.
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When called without parameters,
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it closes the \verb|_INPUT| file,
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and restores \verb|stdin| as the value of \verb|_INPUT|.
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@ -2130,8 +2136,6 @@ and returns this value.
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It does not close the current output file.
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Notice that, if the file already exists,
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then it will be \emph{completely erased} with this operation.
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%When called with a file handle returned by a previous call,
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%it restores the file as the current output.
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When called without parameters,
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this function closes the \verb|_OUTPUT| file,
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and restores \verb|stdout| as the value of \verb|_OUTPUT|.
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@ -2203,15 +2207,13 @@ from the input if it belongs to the class;
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it never fails.
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A character class followed by \verb|*| reads until a character that
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does not belong to the class, or end of file;
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since it can match a sequence of zero characters, it never fails.%
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\footnote{
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since it can match a sequence of zero characters, it never fails.
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Notice that the behavior of read patterns is different from
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the regular pattern matching behavior,
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where a \verb|*| expands to the maximum length \emph{such that}
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the rest of the pattern does not fail.
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With the read pattern behavior
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there is no need for backtracking the reading.
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}
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A pattern item may contain sub-patterns enclosed in curly brackets,
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that describe \Def{skips}.
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@ -2270,6 +2272,17 @@ This function is equivalent to the C function \verb|system|.
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It passes \verb|command| to be executed by an operating system shell.
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It returns an error code, which is system-dependent.
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\subsubsection*{\ff \T{setlocale (locale [, category])}}\Deffunc{setlocale}
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This function is an interface to the ANSI C function \verb|setlocale|.
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\verb|locale| is a string specifing a locale;
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\verb|category| is a number describing which category to change:
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0 is \verb|LC_ALL|, 1 is \verb|LC_COLLATE|, 2 is \verb|LC_CTYPE|,
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3 is \verb|LC_MONETARY|, 4 is \verb|LC_NUMERIC|, and 5 is \verb|LC_TIME|;
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the default category is \verb|LC_ALL|.
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The function returns the name of the new locale,
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or \nil\ if the request cannot be honored.
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\section{The Debugger Interface} \label{debugI}
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