limit the numbers of regsub commands to delete spaces, end of line or carriage return in list-CodePudding

My list :

set myList "{ 
                {key value} {key1 value1}
                {
                    {key2 value2} {key3 value3}
                }
            }"

Desired output :

{{key value} {key1 value1} {{key2 value2} {key3 value3}}}

What I’ve tried so far:

set myList  [string trim $myList]
set newList [string map {\n "" \t " "} $myList]

regsub -all {^\{\s \{} $newList "{{"  newList ; # start of list
regsub -all {\}\s \}$} $newList "}}"  newList ; # end of list
regsub -all {\}\s \{}  $newList "} {" newList ; # middle of list
regsub -all {\{\s \{}  $newList "{{"  newList ; # middle of list again
regsub -all {\}\s \}}  $newList "}}"  newList ; # middle of list again and again

It works , but I've used many regsub command. Is it possible to limit them ? or a different approach, without regsub...

CodePudding user response：

First off, doing it with regsub in 8.6 requires two, where one of them is decidedly ugly (using lookaheads):

regsub -all {(\{)\s (?=[{}])|(\})\s (?=\})} [regsub -all {(\})\s (?=\{)} $myList {\1 }] {\1\2}

In 8.7, you can do it with one using the -command option (because you need the different substituent in some cases) but the RE itself will be uglier.

You can do it without regsub, but only if you know how deep you want to normalize (i.e., what the logical structure is); in your case, twice is enough:

lmap item $myList {
    lmap subitem $item {
        list {*}$subitem
    }
}

The command list {*}$thing is rather like concat $thing except that it is a proper list-native. concat isn't (and we have the test cases to prove it).

CodePudding user response：

This removes leading/trailing whitespace from each line and also newlines

regsub -all -line {(^\s )|(\s $)|\n} $myList ""
# => {{key value} {key1 value1}{{key2 value2} {key3 value3}}}

It does remove the space between sublists though.

regsub -all -line {(^\s )|(\s $)|\n} $myList "" flattened
regsub -all {\}\{} $flattened "} {"
# => {{key value} {key1 value1} {{key2 value2} {key3 value3}}}