ref

REF(1)                      General Commands Manual                     REF(1)



NAME
       ref - Display a C function header

SYNOPSIS
       ref [options]...  [restrictions]...

DESCRIPTION
       This page describes the ref program that is distributed with elvis(1).

       ref quickly locates and displays the header of a function.  To do this,
       ref looks in the "tags" file for the line that describes the function,
       and then scans the source file for the function.  When it locates the
       function, it displays an introductory comment (if there is one), the
       function's declaration, and the declarations of all arguments.

OPTIONS
       -t     Output tag info, instead of the function header.  The tag info
              consists of the three standard fields from each tag.  The fields
              will be separated by tab characters, just like records from the
              traditional tags file format.  Consequently, you can use "ref -t
              -a >oldtags" to convert a new-style tags file back to an old-
              style tags file.

       -v     Output verbose tag info, instead of the function header.  The
              verbose tag info shows the names and values of all attributes
              for each matching tag.  Each name/value pair is shown on a
              separate line.  It also shows the "match" factor that is used
              for sorting tags which have the same tagname.

       -h     Output HTML browser info, instead of the function header.  This
              is an HTML table with hypertext links into the source files
              where the tags are defined.  You can use Netscape or another
              browser to use this, but they won't move the cursor to the
              correct line within the source file; only elvis knows how to do
              that.

              This resembles elvis' :browse command.

       -c     Don't output introductory comments before each tag definition
              line.

       -d     Don't output other lines of the definition.  The line where the
              tag is defined is shown but any preceding or following lines
              which are part of the definition will be omitted.

       -a     List all matching tags.  (Without this option, ref would only
              output the single most likely tag.)

       -s     Search all tags files.  Without this option, ref would stop
              searching after processing the first tags file which contained
              any tags which met the restrictions.

       -p tagpath
              List of directories or tags files to search through.  By
              default, ref would use the value from the TAGPATH environment
              variable or a hardcoded default value for each operating system.

       -l taglength
              Only check the first taglength characters of tag names.  The
              default behavior is to check all characters.

RESTRICTIONS AND HINTS
       Other than options, any argument on ref's command line is interpreted
       as a restriction or sorting hint.  Elvis parses all of the restrictions
       and sorting hints, and then scans the tags files (i.e., every file
       listed in the tag path, or a file named "tags" in every directory
       listed in the tag path).  Tags which fail to meet any restriction are
       discarded.

       Other tags are inserted into a list.  The list is sorted primarily by
       each tag's tagname.  If multiple tags have the same overloaded name,
       then those tags will be sorted according to the sorting hints.  In the
       absence of hints, the tags will be added in the same order in which
       they appear in the tags file.

       The restrictions can be given in any of the following forms:

       name:value[,value...]
              Reject tags which have an attribute named name, but that
              attribute's value isn't in the list of acceptable values.  E.g.,
              "class:Foo" rejects tags from a different class, but accepts
              tags which have no class.

       name:=value[,value...]
              Reject tags which have an attribute named name, but that
              attribute's value isn't in the list of acceptable values.  Also
              reject tags which don't have an attribute named name.  E.g.,
              "class:=Foo" only accepts tags which have class "Foo".

       name:/value[,value...]
              Like "name:value" except that the tagaddress field is required
              to contain value as a substring.  So "class:/Foo" would find
              tags in class "Foo" PLUS global tags whose address mentions
              "Foo" - probably friends of the Foo class.

       value[,value...]
              Short for tagname:value[,value...]

       The sorting hints follow a similar form:

       name:+value[,value...]
              Pretend that recent successful searches had attributes named
              "name" with the given values.  This causes any similar tags in
              the new search to appear near the top of the list.

       name:-value[,value...]
              Pretend that recent failed searches had attribute named "name"
              with the given values.  This causes any similar tags in the new
              search to appear near the bottom of the list.

       A null value string matches anything.  So "struct:=" would accept any
       tag with a "struct" attribute, and reject those without it.  This would
       be handy when you're trying to do tag lookup for a word which follows a
       '.' character - you know it is a field name, but you don't know from
       which struct type.

       Note that if you invoke ref without giving any restrictions, then all
       tags will match and will (if invoked with the -a flag) be output.

A REAL-WORLD EXAMPLE
       While converting some code from K&R C to ANSI C, I needed to generate
       extern declarations for all the functions.  To find the global function
       headers, I used the command...

                 ref -a kind:f file:dummy

       The "-a" causes ref to output all headers, instead of just the first
       one that it finds.  "kind:f" causes it to exclude any non-functions.
       "file:dummy" is tricky -- it causes ref to exclude static tags from all
       files except "dummy", and since there were no C functions defined in
       any file named "dummy", all statics were excluded.  I only got globals.

       Once I had a list of all global functions, I still had to do some
       editing to convert them into ANSI declarations (ref couldn't help me
       there) but at least I could be confident that my list of functions was
       complete and accurate.

       For each source file, I also needed to find the static functions
       defined there, so for each "file.c" I used the command...

                 ref -a kind:f file:=file.c

       This is very similar to the earlier command.
       The main difference is that we're using "file:="
       (with an '=', to exclude globals)
       and a real file name (instead of "dummy") so we do include the static
       tags from that particular file.


INTERACTION WITH ELVIS
       ref is used by elvis' shift-K command.  If the cursor is located on a
       word such as "splat", in the file "foo.c", then elvis will invoke ref
       with the command "ref splat file:foo.c".

TAGS
       A tag is a collection of attributes.  Each attribute has a name and a
       value.  Every tag has attributes with the following names:

       tagname
              The name of the tag; usually the same as the function (or
              whatever) that the tag refers to.

       tagfile
              The name of your source code file, in which the tag's definition
              occurred.

       tagaddress
              Either a line number, or a "nomagic" regular expression, which
              allows elvis or ref to locate the tag's definition within your
              source file.

       In addition, any tag can have additional, optional attributes.  These
       extra tags are meant to serve as hints, describing the contexts in
       which the tagname is permitted to occur in your source code.  The list
       of additional attribute names is not preset; any tags file can use
       whatever seem appropriate.  The following are typical:

       kind   This value is a single letter indicating the lexical type of the
              tag.  It can be "f" for functions, "v" for variables, and so on.

       file   If the tag can only be used within a single source file, then
              this should be the name of that file.  E.g., in C, a "static"
              function can only be used in the function in which it is
              defined, so if a function is static then its tag will usually
              have a file attribute, and its value will be the same as that of
              its tagfile attribute.

       function
              For local variables.  The value is name of function in which
              they're defined.

       struct For fields of a struct or union.  The value is the name of the
              struct or union.  If it has no name (not even a typedef) then
              "struct=struct" is better than nothing.

       enum   For values in an enum data type.  The value is the name of the
              enum type.  If it has no name (not even a typedef) then
              "enum=enum" is better than nothing.

       class  Member functions of a class in C++ could use this to identify
              which class they're in.  The class name itself, however, is
              global so it doesn't have a class attribute.

       scope  Intended mostly for class member functions.  It will usually be
              "public" or "private", so users can restrict tag searches to
              only public members.

       arity  For functions.  Its value is the number of arguments.

       Currently, the hacked-up version of ctags(1) (sometimes installed as
       elvtags(1)) included with elvis will only generate kind, file, and
       class hints, and it doesn't do a very good job on class hints.

THE TAGS FILE
       The tags file is a text file, in which each line describes a single
       tag.  Each line is divided into fields, delimited by tab characters.

       The first 3 fields are implicitly defined to be the values of the
       tagname, tagfile, and tagaddress attributes, in that order.  Note that
       this is identical to the traditional format of the tags file.

       If there are other fields, then semicolon-doublequote will be appended
       to the tagaddress field; vi ignores anything after that, so the extra
       fields won't interfere with vi's ability to perform tag searches.
       Other editors such as elvis and vim use the extra fields though.

       The extra fields are required to have the format "<tab>name:value".
       I.e., a ':' is required, and everything before the ':' is used as an
       attribute name, and everything after it is used as this tag's value for
       that attribute.  There are two exceptions:

       *      If an extra field lacks a colon, then the field is assumed to be
              the value of an attribute named "kind".  (Some versions of ctags
              generate a single-letter "kind" value to indicate whether a tag
              is a function, variable, typedef, etc.)  Since nearly all tags
              have this field, omitting "kind:" significantly reduces the size
              of the tags file, and the time needed to search it.

       *      Static tags are usually marked with "file:", with no file name
              after the ":".  In this case the file name is understood to be
              identical to the "tagfile" field.  This does more than just
              reduce the size of the tags file -- "tagfile" values are
              relative to the directory containing the tags file, and this
              rule offers a way to make "file" values be relative, too.

       Different tags may have differently named  hints.  Since each hint
       includes an explicit name with each value, they can appear in any
       order, and you can omit any which don't apply to a given tag.

       Ref and elvis store attribute names are stored in a fixed-size array,
       which is shared among all tags from a given file.  Consequently, the
       number of distinct attribute names within a tags file is limited.  As
       currently configured, that limit is 10 names - the 3 standard ones plus
       up to 7 other names for hints.

THE REFS FILE
       When ref has found a tag entry and is searching for the source of that
       tag, if it can't read the original source file then it will try to read
       a file named "refs".  The "refs" file should contain a copy of all
       source code, with the bodies of functions replaced by "{}".  Elvis'
       version of ctags(1) can generate a "refs" file.

FILES
       The following files can be found in any directory named in the tagpath.

       tags   List of function names and their locations, generated by ctags.

       refs   Function headers extracted from source files (optional).

ENVIRONMENT
       TAGPATH
              List of directories or files to be searched.  In the case of
              directories, ref looks for a file named "tags" in that
              directory.  The elements in the list are separated by either
              colons (for Unix) or semicolons (for most other operating
              systems).  For each operating system, ref has a built-in default
              which is probably adequate.

NOTES
       You might want to generate a "tags" file for the directory that
       contains the source code for standard C library on your system.  This
       will allow ref to serve as a quick reference for any library function
       in addition to your project's functions.

       If licensing restrictions prevent you from making the library source
       readable by everybody, then you can have elvis' version of ctags
       generate a "refs" file, and make "refs" readable by everybody.  If your
       system doesn't come with the library source code, then perhaps you can
       produce something workable from the lint(1) libraries.

SEE ALSO
       elvis(1), ctags(1), lint(1)

       Note that on some systems, ctags(1) is installed as elvtags(1).


AUTHOR
       Steve Kirkendall
       kirkenda@cs.pdx.edu



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