Parsing a file with Tcl - tcl

Question

I have a file in here which has multiple set statements. However I want to extract the lines of my interest. Can the following code help
set in [open filename r]
seek $in 0 start
while{ [gets $in line ] != -1} {
regexp (line to be extracted)
}

Answer 1

Other solution:
Instead of using gets I prefer using read function to read the whole contents of the file and then process those line by line. So we are in complete control of operation on file by having it as list of lines
set fileName [lindex $argv 0]
catch {set fptr [open $fileName r]} ;
set contents [read -nonewline $fptr] ;#Read the file contents
close $fptr ;#Close the file since it has been read now
set splitCont [split $contents "\n"] ;#Split the files contents on new line
foreach ele $splitCont {
if {[regexp {^set +(\S+) +(.*)} $ele -> name value]} {
puts "The name \"$name\" maps to the value \"$value\""
}
}
How to run this code:
say above code is saved in test.tcl
Then
tclsh test.tcl FileName
FileName is full path of file unless the file is in the same directory where the program is.

Answer 2

First, you don't need to seek to the beginning straight after opening a file for reading; that's where it starts.
Second, the pattern for reading a file is this:
set f [open $filename]
while {[gets $f line] > -1} {
# Process lines
if {[regexp {^set +(\S+) +(.*)} $line -> name value]} {
puts "The name \"$name\" maps to the value \"$value\""
}
}
close $f
OK, that's a very simple RE in the middle there (and for more complicated files you'll need several) but that's the general pattern. Note that, as usual for Tcl, the space after the while command word is important, as is the space between the while expression and the while body. For specific help with what RE to use for particular types of input data, ask further questions here on Stack Overflow.

Answer 3

Yet another solution:
as it looks like the source is a TCL script, create a new safe interpreter using interp which only has the set command exposed (and any others you need), hide all other commands and replace unknown to just skip anything unrecognised. source the input in this interpreter

Answer 4

Here is yet another solution: use the file scanning feature of Tclx. Please look up Tclx for more info. I like this solution for that you can have several scanmatch blocks.
package require Tclx
# Open a file, skip error checking for simplicity
set inputFile [open sample.tcl r]
# Scan the file
set scanHandle [scancontext create]
scanmatch $scanHandle {^\s*set} {
lassign $matchInfo(line) setCmd varName varValue; # parse the line
puts "$varName = $varValue"
}
scanfile $scanHandle $inputFile
close $inputFile
Yet another solution: use the grep command from the fileutil package:
package require fileutil
puts [lindex $argv 0]
set matchedLines [fileutil::grep {^\s*set} [lindex $argv 0]]
foreach line $matchedLines {
# Each line is in format: filename:line, for example
# sample.tcl:set foo bar
set varName [lindex $line 1]
set varValue [lindex $line 2]
puts "$varName = $varValue"
}

Answer 5

I've read your comments so far, and if I understand you correctly your input data file has 6 (or 9, depending which comment) data fields per line, separated by spaces. You want to use a regexp to parse them into 6 (or 9) arrays or lists, one per data field.
If so, I'd try something like this (using lists):
set f [open $filename]
while {[gets $f line] > -1} {
# Process lines
if {[regexp {(\S+) (\S+) (\S+) (\S+) (\S+) (\S+)} $line -> name source drain gate bulk inst]} {
lappend nameL $name
lappend sourceL $source
lappend drainL $drain
lappend gateL $gate
lappend bulkL $bulk
lappend instL $inst
}
}
close $f
Now you should have a set of 6 lists, one per field, with one entry in the list for each item in your input file. To access the i-th name, for example, you grab $nameL[$i].
If (as I suspect) your main goal is to get the parameters of the device whose name is "foo", you'd use a structure like this:
set name "foo"
set i [lsearch $nameL $name]
if {$i != -1} {
set source $sourceL[$i]
} else {
puts "item $name not found."
set source ''
# or set to 0, or whatever "not found" marker you like
}

Answer 6

set File [ open $fileName r ]
while { [ gets $File line ] >= 0 } {
regex {(set) ([a-zA-Z0-0]+) (.*)} $line str1 str2 str3 str4
#str2 contains "set";
#str3 contains variable to be set;
#str4 contains the value to be set;
close $File
}