<HTML>
<HEAD>
<!-- Created by texi2html 1.56k + clip patches and <A href="http://www.clip.dia.fi.upm.es/Software">lpdoc</A> from ciao.texi on 28 January 2007 -->
<LINK rel="stylesheet" href="ciao.css" type="text/css">
<TITLE>The Ciao Prolog System - String processing</TITLE>
</HEAD>
<BODY>
Go to the <A HREF="ciao_1.html">first</A>, <A HREF="ciao_68.html">previous</A>, <A HREF="ciao_70.html">next</A>, <A HREF="ciao_241.html">last</A> section, <A HREF="ciao_toc.html">table of contents</A>.
<P><HR><P>
<H1><A NAME="SEC300" HREF="ciao_toc.html#TOC300">String processing</A></H1>
<P>
<A NAME="IDX4320"></A>
<P>
<STRONG>Author(s):</STRONG> Daniel Cabeza.
<P>
<STRONG>Version:</STRONG> 0.4#5 (1998/2/24)
<P>
This module provides predicates for doing input/output with strings (character code lists) and for including in grammars defining strings.
<UL>
<LI><A HREF="ciao_69.html#SEC301">Usage and interface (strings)</A>
<LI><A HREF="ciao_69.html#SEC302">Documentation on exports (strings)</A>
<LI><A HREF="ciao_69.html#SEC303">Documentation on internals (strings)</A>
</UL>
<H2><A NAME="SEC301" HREF="ciao_toc.html#TOC301">Usage and interface (<CODE>strings</CODE>)</A></H2>
<div class="cartouche">
<UL>
<LI><STRONG>Library usage:</STRONG>
<CODE>:- use_module(library(strings)).</CODE>
<LI><STRONG>Exports:</STRONG>
<UL>
<LI><EM>Predicates:</EM>
<A NAME="IDX4321"></A>
<CODE>get_line/2</CODE>,
<A NAME="IDX4322"></A>
<CODE>get_line/1</CODE>,
<A NAME="IDX4323"></A>
<CODE>write_string/2</CODE>,
<A NAME="IDX4324"></A>
<CODE>write_string/1</CODE>,
<A NAME="IDX4325"></A>
<CODE>whitespace/2</CODE>,
<A NAME="IDX4326"></A>
<CODE>whitespace0/2</CODE>,
<A NAME="IDX4327"></A>
<CODE>string/3</CODE>.
</UL>
</UL>
</div class="cartouche">
<H2><A NAME="SEC302" HREF="ciao_toc.html#TOC302">Documentation on exports (<CODE>strings</CODE>)</A></H2>
<P>
<A NAME="IDX4328"></A>
<A NAME="IDX4329"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>get_line/2:</B>
<DD><A NAME="IDX4330"></A>
<P>
<CODE>get_line(Stream, Line)</CODE>
<P>
Reads from <CODE>Stream</CODE> a line of text and unifies <CODE>Line</CODE> with it. The end of the line can have UNIX [10] or MS-DOS [13 10] termination, which is not included in <CODE>Line</CODE>. At EOF, the term end_of_file is returned.
</DL>
<P>
<A NAME="IDX4331"></A>
<A NAME="IDX4332"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>get_line/1:</B>
<DD><A NAME="IDX4333"></A>
<P>
<CODE>get_line(Line)</CODE>
<P>
Behaves like <CODE>current_input(S), get_line(S,Line)</CODE>.
</DL>
<P>
<A NAME="IDX4334"></A>
<A NAME="IDX4335"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>write_string/2:</B>
<DD><A NAME="IDX4336"></A>
<P>
<CODE>write_string(Stream, String)</CODE>
<P>
Writes <CODE>String</CODE> onto <CODE>Stream</CODE>.
</DL>
<P>
<A NAME="IDX4337"></A>
<A NAME="IDX4338"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>write_string/1:</B>
<DD><A NAME="IDX4339"></A>
<P>
<CODE>write_string(String)</CODE>
<P>
Behaves like <CODE>current_input(S), write_string(S, String)</CODE>.
</DL>
<P>
<A NAME="IDX4340"></A>
<A NAME="IDX4341"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>whitespace/2:</B>
<DD><A NAME="IDX4342"></A>
<P>
<CODE>whitespace(String, Rest)</CODE>
<P>
In a grammar rule, as <CODE>whitespace/0</CODE>, represents whitespace (a positive number of space (32), tab (9), newline (10) or return (13) characters). Thus, <CODE>Rest</CODE> is a proper suffix of <CODE>String</CODE> with one or more whitespace characters removed. An example of use would be:
<PRE>
attrs([]) --> ""
attrs([N|Ns]) -->
whitespace,
attr(N),
attrs(Ns).
</PRE>
</DL>
<P>
<A NAME="IDX4343"></A>
<A NAME="IDX4344"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>whitespace0/2:</B>
<DD><A NAME="IDX4345"></A>
<P>
<CODE>whitespace0(String, Rest)</CODE>
<P>
In a grammar rule, as <CODE>whitespace0/0</CODE>, represents possible whitespace (any number of space (32), tab (9), newline (10) or return (13) characters). Thus, <CODE>Rest</CODE> is <CODE>String</CODE> or a proper suffix of <CODE>String</CODE> with one or more whitespace characters removed. An example of use would be:
<PRE>
assignment(N,V) -->
variable_name(N), whitespace0, "=", whitespace0, value(V).
</PRE>
</DL>
<P>
<A NAME="IDX4346"></A>
<A NAME="IDX4347"></A>
<DL>
<DT><span class="define">PREDICATE:</span> <B>string/3:</B>
<DD><A NAME="IDX4348"></A>
<P>
<CODE>string(String, Head, Tail)</CODE>
<P>
In a
<A NAME="IDX4349"></A>
grammar rule, as <CODE>string/1</CODE>, represents literally <CODE>String</CODE>. An example of use would be:
<PRE>
double(A) -->
string(A),
string(A).
</PRE>
</DL>
<H2><A NAME="SEC303" HREF="ciao_toc.html#TOC303">Documentation on internals (<CODE>strings</CODE>)</A></H2>
<P>
<A NAME="IDX4350"></A>
<A NAME="IDX4351"></A>
<DL>
<DT><span class="define">PROPERTY:</span> <B>line/1:</B>
<DD><A NAME="IDX4352"></A>
<P>
A property, defined as follows:
<PRE>
<PRE>
line(L) :-
string(L).
line(end_of_file).
</PRE>
</PRE>
</DL>
<P><HR><P>
Go to the <A HREF="ciao_1.html">first</A>, <A HREF="ciao_68.html">previous</A>, <A HREF="ciao_70.html">next</A>, <A HREF="ciao_241.html">last</A> section, <A HREF="ciao_toc.html">table of contents</A>.
</BODY>
</HTML>
