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167 lines
6.1 KiB
HTML
167 lines
6.1 KiB
HTML
<HTML>
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<HEAD>
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<TITLE>mozilla cross-reference: search help</TITLE>
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</HEAD>
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<BODY BGCOLOR="#FFFFFF" TEXT="#000000"
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LINK="#0000EE" VLINK="#551A8B" ALINK="#FF0000">
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<TABLE BGCOLOR="#000000" WIDTH="100%" BORDER=0 CELLPADDING=0 CELLSPACING=0>
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<TR><TD><A HREF="http://www.mozilla.org/"><IMG
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SRC="http://www.mozilla.org/images/mozilla-banner.gif" ALT=""
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BORDER=0 WIDTH=600 HEIGHT=58></A></TD></TR></TABLE>
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<H1 ALIGN=CENTER>search help<BR>
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<FONT SIZE=3>
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for the<br>
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<A HREF="./"><I>mozilla cross-reference</I></A>
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</FONT></H1>
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<P><BR>
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<BLOCKQUOTE><BLOCKQUOTE>
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<I>
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This text is copied from the Glimpse manual page. I have tried to remove
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things that do not apply to the lxr searcher, but beware, some things might
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have slipped through. I'll try to put together something better when I get
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the time. For more information on glimpse go to the
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<A HREF="http://glimpse.cs.arizona.edu">Glimpse homepage</A>.
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</I>
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</BLOCKQUOTE></BLOCKQUOTE>
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<A NAME="Patterns"></A><H2>Patterns</H2>
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<UL>
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glimpse supports a large variety of patterns, including simple
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strings, strings with classes of characters, sets of strings,
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wild cards, and regular expressions (see <A HREF="#Limitations">Limitations</A>).
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</UL>
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<P> <H3>Strings</H3>
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<UL>
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Strings are any sequence of characters, including the special symbols
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`^' for beginning of line and `$' for end of line. The following
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special characters (`$', `^', `*', `[', `^', `|', `(', `)', `!', and
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`\' ) as well as the following meta characters special to glimpse (and
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agrep): `;', `,', `#', `>', `<', `-', and `.', should be preceded by
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`\\' if they are to be matched as regular characters. For example,
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\\^abc\\\\ corresponds to the string ^abc\\, whereas ^abc corresponds
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to the string abc at the beginning of a line.
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</UL>
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<P> <H3>Classes of characters</H3>
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<UL>
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a list of characters inside [] (in order) corresponds to any character
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from the list. For example, [a-ho-z] is any character between a and h
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or between o and z. The symbol `^' inside [] complements the list.
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For example, [^i-n] denote any character in the character set except
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character 'i' to 'n'.
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The symbol `^' thus has two meanings, but this is consistent with
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egrep.
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The symbol `.' (don't care) stands for any symbol (except for the
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newline symbol).
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</UL>
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<P> <H3>Boolean operations</H3>
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<UL>
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Glimpse
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supports an `AND' operation denoted by the symbol `;'
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an `OR' operation denoted by the symbol `,',
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a limited version of a 'NOT' operation (starting at version 4.0B1)
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denoted by the symbol `~',
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or any combination.
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For example, pizza;cheeseburger' will output all lines containing
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both patterns.
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'{political,computer};science' will match 'political science'
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or 'science of computers'.
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</UL>
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<P><H3>Wild cards</H3>
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<UL>
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The symbol '#' is used to denote a sequence
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of any number (including 0)
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of arbitrary characters (see <A HREF="#Limitations">Limitations</A>).
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The symbol # is equivalent to .* in egrep.
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In fact, .* will work too, because it is a valid regular expression
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(see below), but unless this is part of an actual regular expression,
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# will work faster.
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(Currently glimpse is experiencing some problems with #.)
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</UL>
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<P><H3>Combination of exact and approximate matching</H3>
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<UL>
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Any pattern inside angle brackets <> must match the text exactly even
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if the match is with errors. For example, <mathemat>ics matches
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mathematical with one error (replacing the last s with an a), but
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mathe<matics> does not match mathematical no matter how many errors are
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allowed. (This option is buggy at the moment.)
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</UL>
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<H3>Regular expressions</H3>
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<UL>
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Since the index is word based, a regular expression must match words
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that appear in the index for glimpse to find it. Glimpse first strips
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the regular expression from all non-alphabetic characters, and
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searches the index for all remaining words. It then applies the
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regular expression matching algorithm to the files found in the index.
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For example, glimpse 'abc.*xyz' will search the index for all files
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that contain both 'abc' and 'xyz', and then search directly for
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'abc.*xyz' in those files. (If you use glimpse -w 'abc.*xyz', then
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'abcxyz' will not be found, because glimpse will think that abc and
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xyz need to be matches to whole words.) The syntax of regular
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expressions in glimpse is in general the same as that for agrep. The
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union operation `|', Kleene closure `*', and parentheses () are all
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supported. Currently '+' is not supported. Regular expressions are
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currently limited to approximately 30 characters (generally excluding
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meta characters). The maximal number of errors
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for regular expressions that use '*' or '|' is 4.
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</UL>
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<A NAME="Limitations"></A><H2>Limitations</H2>
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<UL>
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The index of glimpse is word based. A pattern that contains more than
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one word cannot be found in the index. The way glimpse overcomes this
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weakness is by splitting any multi-word pattern into its set of words
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and looking for all of them in the index.
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For example, <I>'linear programming'</I> will first consult the index
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to find all files containing both <I>linear</I> and <I>programming</I>,
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and then apply agrep to find the combined pattern.
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This is usually an effective solution, but it can be slow for
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cases where both words are very common, but their combination is not.
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<P>
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As was mentioned in the section on <A HREF="#Patterns">Patterns</A> above, some characters
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serve as meta characters for glimpse and need to be
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preceded by '\\' to search for them. The most common
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examples are the characters '.' (which stands for a wild card),
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and '*' (the Kleene closure).
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So, "glimpse ab.de" will match abcde, but "glimpse ab\\.de"
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will not, and "glimpse ab*de" will not match ab*de, but
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"glimpse ab\\*de" will.
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The meta character - is translated automatically to a hypen
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unless it appears between [] (in which case it denotes a range of
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characters).
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<P>
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There is no size limit for simple patterns and simple patterns
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within Boolean expressions.
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More complicated patterns, such as regular expressions,
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are currently limited to approximately 30 characters.
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Lines are limited to 1024 characters.
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</UL>
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<P>
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<HR>
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<ADDRESS>
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<A HREF="mailto:lxr@linux.no">
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Arne Georg Gleditsch and Per Kristian Gjermshus</A>
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</ADDRESS>
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</BODY>
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</HTML>
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