Eskil

2015-03-18
 Allow plugins to yield if Eskil is run in Tcl 8.6 or newer.
 Added swap plugin to exemplify this.

2015-03-18
 Added command line flag "-pluginallow" to allow a plugin to run in a standard
 interpreter instead of a safe one.
 Added pdf plugin.

2015-03-17
 Added command line flag "-sep" to set a separator for table-like files

<title>Changes</title>

Upcoming changes (not yet released):

  *  Mercurial support for Directory Diff, Commit, Revert and Log.
  *  Plugins can read ::argv to know the given command line.
  *  New plugin for CSV files
  *  Added option -sep, to set a separator that makes input be interpreted
     in a table like manner.
  *  New plugin for PDF files
  *  Added option -pluginallow to run plugins in a standard interpreter instead
     of a safe one. Thus a plugin could use e.g. exec.
  *  Allow plugins to yield if Eskil is run in Tcl 8.6 or newer.
     Added swap plugin to exemplify this.

Changes in v2.7 (2015-03-09):

  *  Directory Diff support for GIT, Fossil and Subversion.
     Directly browse and compare two revisions.
  *  Plugins in Directory Diff.
  *  Added option -printFont to select font for PDF generation.

A plugin may give a result that has a line-by-line correspondence to
the original, in which case the preprocessed data is used for comparing
while the original is used for displaying.  The PreProcess procedure
should return 0 to signify this case.

If the PreProcess procedure returns 1, the processed data is used also for
displaying.

If Eskil is run with Tcl 8.6 or newer, PreProcess is run as a couroutine
and may yield. The left and right side will then be called alternately
until they return. This allows a plugin to take both sides into account
for decisions if needed.

<h1>Directory plugin</h1>

To be used for file comparison in a directory diff, the following procedure
should be defined in the plugin file:

<pre>proc FileCompare {ch1 ch2 info1 info2} {...}</pre>

##Eskil Plugin : Swap sides of contents

# Example file for a plugin.
# A plugin must start exactly like this one.
# The text after : is the summary you can get at the command line

# This plugin swaps data between files. A fairly useless thing.
# This is to test and exemplify how to use yield in a plugin.

# A plugin must define this procedure to do the job.
# side: left or right
# chi:  An input channel for reading the original file.
# cho:  An output channel for writing the processed file.
proc PreProcess {side chi cho} {
    if {[info commands yield] eq ""} {
        puts $cho "Swap plugin must be run with Tcl 8.6 or newer"
        return 1
    }
    # Read all data from both sides
    set ::data($side) [read $chi]
    yield

    # Output data from other side
    if {$side eq "left"} {
        puts $cho $::data(right)
    } else {
        puts $cho $::data(left)
    }

    # Signal that the file after processing should be used both
    # for comparison and for displaying.
    return 1
}

    set chi2 [open $::eskil($top,rightFile) r]
    set cho2 [open $out2 w]
    interp share {} $chi $::eskil($top,plugin)
    interp share {} $cho $::eskil($top,plugin)
    interp share {} $chi2 $::eskil($top,plugin)
    interp share {} $cho2 $::eskil($top,plugin)

    set cmd1 [list PreProcess left $chi $cho]
    set cmd2 [list PreProcess right $chi2 $cho2]
    if {[info commands yield] ne ""} {
        # When in 8.6, this is done in coroutines allowing each call
        # to yield and to alternate between them until done
        set c1 __plugin_cr1$top
        set c2 __plugin_cr2$top
        set cmd1 [linsert $cmd1 0 coroutine $c1]
        set cmd2 [linsert $cmd2 0 coroutine $c2]
        set usenew1 [$::eskil($top,plugin) eval $cmd1]
        set usenew2 [$::eskil($top,plugin) eval $cmd2]
        interp alias {} pnw $::eskil($top,plugin) namespace which
        while {[pnw $c1] ne {} || [pnw $c2] ne {}} {
            if {[pnw $c1] ne {}} {
                set usenew1 [$::eskil($top,plugin) eval $c1]
            }
            if {[pnw $c2] ne {}} {
                set usenew2 [$::eskil($top,plugin) eval $c2]
            }
        }
    } else {
        set usenew1 [$::eskil($top,plugin) eval $cmd1]
        set usenew2 [$::eskil($top,plugin) eval $cmd2]
    }

    if {$allow} {
        $::eskil($top,plugin) eval close $chi
        $::eskil($top,plugin) eval close $cho
        $::eskil($top,plugin) eval close $chi2
        $::eskil($top,plugin) eval close $cho2
    } else {