388 lines
12 KiB
Tcl
388 lines
12 KiB
Tcl
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# -*- tcl -*-
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#
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# Searching for Tcl Modules. Defines a procedure, declares it as the
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# primary command for finding packages, however also uses the former
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# 'package unknown' command as a fallback.
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#
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# Locates all possible packages in a directory via a less restricted
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# glob. The targeted directory is derived from the name of the
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# requested package. I.e. the TM scan will look only at directories
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# which can contain the requested package. It will register all
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# packages it found in the directory so that future requests have a
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# higher chance of being fulfilled by the ifneeded database without
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# having to come to us again.
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#
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# We do not remember where we have been and simply rescan targeted
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# directories when invoked again. The reasoning is this:
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#
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# - The only way we get back to the same directory is if someone is
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# trying to [package require] something that wasn't there on the
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# first scan.
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#
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# Either
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# 1) It is there now: If we rescan, you get it; if not you don't.
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#
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# This covers the possibility that the application asked for a
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# package late, and the package was actually added to the
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# installation after the application was started. It shoukld
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# still be able to find it.
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#
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# 2) It still is not there: Either way, you don't get it, but the
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# rescan takes time. This is however an error case and we dont't
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# care that much about it
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#
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# 3) It was there the first time; but for some reason a "package
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# forget" has been run, and "package" doesn't know about it
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# anymore.
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#
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# This can be an indication that the application wishes to reload
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# some functionality. And should work as well.
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#
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# Note that this also strikes a balance between doing a glob targeting
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# a single package, and thus most likely requiring multiple globs of
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# the same directory when the application is asking for many packages,
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# and trying to glob for _everything_ in all subdirectories when
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# looking for a package, which comes with a heavy startup cost.
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#
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# We scan for regular packages only if no satisfying module was found.
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namespace eval ::tcl::tm {
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# Default paths. None yet.
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variable paths {}
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# The regex pattern a file name has to match to make it a Tcl Module.
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set pkgpattern {^([_[:alpha:]][:_[:alnum:]]*)-([[:digit:]].*)[.]tm$}
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# Export the public API
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namespace export path
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namespace ensemble create -command path -subcommands {add remove list}
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}
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# ::tcl::tm::path implementations --
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#
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# Public API to the module path. See specification.
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#
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# Arguments
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# cmd - The subcommand to execute
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# args - The paths to add/remove. Must not appear querying the
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# path with 'list'.
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#
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# Results
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# No result for subcommands 'add' and 'remove'. A list of paths
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# for 'list'.
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#
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# Sideeffects
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# The subcommands 'add' and 'remove' manipulate the list of
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# paths to search for Tcl Modules. The subcommand 'list' has no
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# sideeffects.
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proc ::tcl::tm::add {path args} {
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# PART OF THE ::tcl::tm::path ENSEMBLE
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#
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# The path is added at the head to the list of module paths.
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#
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# The command enforces the restriction that no path may be an
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# ancestor directory of any other path on the list. If the new
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# path violates this restriction an error wil be raised.
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#
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# If the path is already present as is no error will be raised and
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# no action will be taken.
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variable paths
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# We use a copy of the path as source during validation, and
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# extend it as well. Because we not only have to detect if the new
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# paths are bogus with respect to the existing paths, but also
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# between themselves. Otherwise we can still add bogus paths, by
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# specifying them in a single call. This makes the use of the new
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# paths simpler as well, a trivial assignment of the collected
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# paths to the official state var.
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set newpaths $paths
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foreach p [linsert $args 0 $path] {
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if {$p in $newpaths} {
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# Ignore a path already on the list.
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continue
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}
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# Search for paths which are subdirectories of the new one. If
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# there are any then the new path violates the restriction
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# about ancestors.
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set pos [lsearch -glob $newpaths ${p}/*]
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# Cannot use "in", we need the position for the message.
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if {$pos >= 0} {
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return -code error \
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"$p is ancestor of existing module path [lindex $newpaths $pos]."
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}
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# Now look for existing paths which are ancestors of the new
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# one. This reverse question forces us to loop over the
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# existing paths, as each element is the pattern, not the new
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# path :(
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foreach ep $newpaths {
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if {[string match ${ep}/* $p]} {
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return -code error \
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"$p is subdirectory of existing module path $ep."
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}
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}
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set newpaths [linsert $newpaths 0 $p]
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}
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# The validation of the input is complete and successful, and
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# everything in newpaths is either an old path, or added. We can
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# now extend the official list of paths, a simple assignment is
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# sufficient.
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set paths $newpaths
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return
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}
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proc ::tcl::tm::remove {path args} {
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# PART OF THE ::tcl::tm::path ENSEMBLE
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#
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# Removes the path from the list of module paths. The command is
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# silently ignored if the path is not on the list.
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variable paths
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foreach p [linsert $args 0 $path] {
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set pos [lsearch -exact $paths $p]
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if {$pos >= 0} {
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set paths [lreplace $paths $pos $pos]
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}
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}
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}
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proc ::tcl::tm::list {} {
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# PART OF THE ::tcl::tm::path ENSEMBLE
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variable paths
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return $paths
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}
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# ::tcl::tm::UnknownHandler --
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#
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# Unknown handler for Tcl Modules, i.e. packages in module form.
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#
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# Arguments
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# original - Original [package unknown] procedure.
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# name - Name of desired package.
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# version - Version of desired package. Can be the
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# empty string.
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# exact - Either -exact or ommitted.
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#
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# Name, version, and exact are used to determine
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# satisfaction. The original is called iff no satisfaction was
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# achieved. The name is also used to compute the directory to
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# target in the search.
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#
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# Results
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# None.
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#
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# Sideeffects
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# May populate the package ifneeded database with additional
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# provide scripts.
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proc ::tcl::tm::UnknownHandler {original name args} {
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# Import the list of paths to search for packages in module form.
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# Import the pattern used to check package names in detail.
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variable paths
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variable pkgpattern
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# Without paths to search we can do nothing. (Except falling back
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# to the regular search).
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if {[llength $paths]} {
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set pkgpath [string map {:: /} $name]
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set pkgroot [file dirname $pkgpath]
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if {$pkgroot eq "."} {
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set pkgroot ""
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}
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# We don't remember a copy of the paths while looping. Tcl
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# Modules are unable to change the list while we are searching
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# for them. This also simplifies the loop, as we cannot get
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# additional directories while iterating over the list. A
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# simple foreach is sufficient.
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set satisfied 0
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foreach path $paths {
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if {![interp issafe] && ![file exists $path]} {
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continue
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}
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set currentsearchpath [file join $path $pkgroot]
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if {![interp issafe] && ![file exists $currentsearchpath]} {
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continue
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}
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set strip [llength [file split $path]]
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# We can't use glob in safe interps, so enclose the following
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# in a catch statement, where we get the module files out
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# of the subdirectories. In other words, Tcl Modules are
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# not-functional in such an interpreter. This is the same
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# as for the command "tclPkgUnknown", i.e. the search for
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# regular packages.
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catch {
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# We always look for _all_ possible modules in the current
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# path, to get the max result out of the glob.
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foreach file [glob -nocomplain -directory $currentsearchpath *.tm] {
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set pkgfilename [join [lrange [file split $file] $strip end] ::]
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if {![regexp -- $pkgpattern $pkgfilename --> pkgname pkgversion]} {
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# Ignore everything not matching our pattern
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# for package names.
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continue
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}
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if {[catch {package vcompare $pkgversion 0}]} {
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# Ignore everything where the version part is
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# not acceptable to "package vcompare".
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continue
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}
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if {[package ifneeded $pkgname $pkgversion] ne {}} {
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# There's already a provide script registered for
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# this version of this package. Since all units of
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# code claiming to be the same version of the same
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# package ought to be identical, just stick with
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# the one we already have.
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continue
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}
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# We have found a candidate, generate a "provide
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# script" for it, and remember it. Note that we
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# are using ::list to do this; locally [list]
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# means something else without the namespace
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# specifier.
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# NOTE. When making changes to the format of the
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# provide command generated below CHECK that the
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# 'LOCATE' procedure in core file
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# 'platform/shell.tcl' still understands it, or,
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# if not, update its implementation appropriately.
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#
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# Right now LOCATE's implementation assumes that
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# the path of the package file is the last element
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# in the list.
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package ifneeded $pkgname $pkgversion \
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"[::list package provide $pkgname $pkgversion];[::list source -encoding utf-8 $file]"
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# We abort in this unknown handler only if we got
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# a satisfying candidate for the requested
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# package. Otherwise we still have to fallback to
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# the regular package search to complete the
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# processing.
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if {($pkgname eq $name)
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&& [package vsatisfies $pkgversion {*}$args]} {
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set satisfied 1
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# We do not abort the loop, and keep adding
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# provide scripts for every candidate in the
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# directory, just remember to not fall back to
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# the regular search anymore.
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}
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}
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}
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}
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if {$satisfied} {
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return
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}
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}
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# Fallback to previous command, if existing. See comment above
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# about ::list...
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if {[llength $original]} {
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uplevel 1 $original [::linsert $args 0 $name]
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}
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}
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# ::tcl::tm::Defaults --
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#
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# Determines the default search paths.
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#
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# Arguments
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# None
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#
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# Results
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# None.
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#
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# Sideeffects
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# May add paths to the list of defaults.
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proc ::tcl::tm::Defaults {} {
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global env tcl_platform
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lassign [split [info tclversion] .] major minor
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set exe [file normalize [info nameofexecutable]]
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# Note that we're using [::list], not [list] because [list] means
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# something other than [::list] in this namespace.
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roots [::list \
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[file dirname [info library]] \
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[file join [file dirname [file dirname $exe]] lib] \
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]
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if {$tcl_platform(platform) eq "windows"} {
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set sep ";"
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} else {
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set sep ":"
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}
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for {set n $minor} {$n >= 0} {incr n -1} {
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foreach ev [::list \
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TCL${major}.${n}_TM_PATH \
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TCL${major}_${n}_TM_PATH \
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] {
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if {![info exists env($ev)]} continue
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foreach p [split $env($ev) $sep] {
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path add $p
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}
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}
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}
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return
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}
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# ::tcl::tm::roots --
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#
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# Public API to the module path. See specification.
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#
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# Arguments
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# paths - List of 'root' paths to derive search paths from.
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#
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# Results
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# No result.
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#
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# Sideeffects
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# Calls 'path add' to paths to the list of module search paths.
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proc ::tcl::tm::roots {paths} {
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lassign [split [package present Tcl] .] major minor
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foreach pa $paths {
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set p [file join $pa tcl$major]
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for {set n $minor} {$n >= 0} {incr n -1} {
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set px [file join $p ${major}.${n}]
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if {![interp issafe]} { set px [file normalize $px] }
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path add $px
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}
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set px [file join $p site-tcl]
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if {![interp issafe]} { set px [file normalize $px] }
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path add $px
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}
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return
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}
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# Initialization. Set up the default paths, then insert the new
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# handler into the chain.
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if {![interp issafe]} { ::tcl::tm::Defaults }
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