'''scancontext''' is the first of a set of commands (in the [TclX] package) intended to 
be used together to search through a file for regular expression
matches and then executing Tcl code on the match. This provides a facility similar to [awk].

'''scancontext''' creates a handle for the collection of regular expressions and tcl commands to execute when the expressions are located.


The '''scancontext''' command manages file scan contexts.  A scan ''context'' is a collection of regular expressions and commands to execute when a specific regular expression matches a line of the file.  A context may also have a single default match, to be applied against lines that do not match any of the regular expressions.  Multiple scan contexts may be defined and they may be reused on multiple files.  A scan context is identified by a context handle.

The '''scancontext''' command takes the following forms:

   '''scancontext create''':   Create a new scan context.  The [scanmatch] command is used to define patterns in the context.  A ''contexthandle'' is returned, which the Tcl programmer uses to refer to the newly created scan context in calls to the Tcl file scanning commands.
   '''scancontext delete''' ''contexthandle'':   Delete the scan context identified by ''contexthandle'', and free all of the match statements and compiled regular expressions associated with the specified context.
   '''scancontext copyfile''' ''contexthandle'' ''?filehandle?'':   Set or return the file handle that unmatched lines are copied to.  (See [scanfile]).  If ''filehandle'' is omitted, the copy file handle is returned.  If no copy file is associated with the context, {} is returned.  If a file handle is specified, it becomes the copy file for this context.  If ''filehandle'' is {}, then it removes any copy file specification for the context.


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See also [scanmatch] and [scanfile].
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