HE 2015-10-08:
lsearch determines which values in a list match a pattern. I want to determine which patterns in a list match a value.
Here is my solution:
mode specifies the type of pattern, and is is one of:
value is a string to apply each pattern to.
patList is a list of patterns.
searchPatList returns the index of the the first pattern in patList that matches value, or -1 if no pattern matches.
proc searchPatList {mode value patList} {
set n 0
switch -exact -- $mode {
-exact {
foreach el $patList {
if {$el eq $value} {
return $n
}
incr n
}
return -1
}
-glob {
foreach el $patList {
if {[string match $el $value]} {
return $n
}
incr n
}
return -1
}
-regexp {
foreach el $patList {
if {[regexp -- $el $value]} {
return $n
}
incr n
}
return -1
}
default {
error "Unknown mode '$mode'!"
}
}
return
}And the examples:
set patList [list \
{test 3.4.1} \
{dummy} \
{^test *[0-9.]*$} \
{test *} \
]
searchPatList -exact {test 3.4.1} $patList
0
searchPatList -exact {test 3.4.2} $patList
-1
searchPatList -exact {dummy} $patList
1
searchPatList -glob {test 3.4.1} $patList
0
searchPatList -glob {test 3.4.2} $patList
3
searchPatList -glob {dummy} $patList
1
searchPatList -regexp {test 3.4.1} $patList
0
searchPatList -regexp {test 3.4.2} $patList
2
searchPatList -regexp {dummy} $patList
1
searchPatList -default {dummy} $patList
Unknown mode '-default'!PYK 2015-10-08:
$patList mixes patterns which are clearly intended to be used with some particular command, yet searchPatList only operates in one mode at a time, making the overall design a bit over-engineered. This type of situation just might be the right place to use if without bracing the expressions:
set matchers {
{{test 3.4.1} eq [lindex @val@]}
{0 && [lindex @val@]}
{[string match {^test *[0-9.]*$} @val@]}
{[string match {test *} @val@]}
}
foreach matcher $matchers {
if [string map [list @val@ [list $val]] $matcher] {
puts [list matched $matcher]
break
}
}The advantages of this approach are that patterns and their associated commands appear together, and arbitrary matching algorithms can be introduced as needed. The [lindex @val@] bit serves merely as an identity function, which is one way to properly quote a value being inserted into an expr template. Note also the use of [list $val] which is the right way to escape a value being interpolated into a Tcl script template.
HE 2015-10-08: Hello PYK Thank you for the suggestion. Even if your approach doesn't match the quest written in the first line. Perhaps I doesn't explain enough what I want to archive. I want a procedure, which like lsearch provide the index of the matching list item or -1 in case of no match. But instead of a list of values which are checked against a single pattern, I have a single value and a list of pattern. Like lsearch the kind of pattern is defined by an option.
With this information, you also understand, that patList is not a list of different kind of pattern. Even if I use in the test cases the same pattern for all three modes.
The result of my procedure is a number which can be used with if as it can be done with lsearch. The results of the example shows exactly what I want to get as a result. For sure some could extend the procedure to add option which deliver additional different result sets as it could be done with lsearch. But this is nothing I need as I wrote the searchPatList.
There is also a security issue in case the pattern list comes from outside the tcl script like a configuration file or the Tk GUI. I use a win64 system and add the pattern '{exec more deda}' to matchers. The external program 'more' is executed. If I add this pattern to patList and use it with searchPatList the external program 'more# is not executed. Think what happen with with other programs which could format your HD or do other harm.
HE 2015-10-08: Hello pooryorick you removed the option -- behind the switch instruction. There is nothing wrong with -- and there are a lot of persons which like to use it to prevent possible future errors. Even if it is not needed in a special case.
Please accept that other person have a different opinion how to write code then yourself. Therefore, I changed it back and ask you not to change the code again. Let this wiki a place where diversity of writing tcl is possible.
Thanks.