Visually align TSV using tabs - csv

Question

I have a text file with fields, separated by some number of consequent tabs (so that the fields are all visually aligned). I'd like to add a lot of new fields to it from another (not aligned, pure tsv) file, while keeping everything aligned. A lot of values contain spaces in them, so only tabs (with assumed width of 8) can be used for alignment, because I want to be able to parse the file later by splitting each line on any number of consequent tabs. This means that I can't use tools like column or tsv-pretty as they use spaces for alignment. Is there a tool or a short script I can use to achieve what I want?
Example:
File 1:
AA BB CCC
AAAA BBB CCC
AA BBBB CC
File 2:
DD EE FF
DDDD EE FFFF
DD EEEE FF
Result:
AA BB CCC
AAAA BBB CCC
AA BBBB CC
DD EE FF
DDDD EE FFFF
DD EEEE FF

Answer 1

Visual alignment is for human consumption don't save the file in that format, rather when you need to view the file use column to format it for you.
First need to get rid of the extra tabs in your first file and combine the files
$ cat <(tr -s '\t' <file1) file2 > file12
which will have the aligned columns by the delimiter (tab). Now you can use column -ts$'\t' file12 whenever you want to view the file which will align the columns for you.
This assumes you don't have missing fields.

Answer 2

I asked this question in hope that there's an existing tool or a simple awk/perl one-liner that can do what I want. Looks like there isn't, so I wrote a simple tool in Go that worked for my input. It doesn't handle a lot of things that a good tsv parser should (like escaping) but maybe it'll still be useful for someone else:
package main
import (
"bufio"
"fmt"
"math"
"os"
"strings"
)
const tabWidth = 8
func tsvAlign(filenames []string) (err error) {
var lines [][]string
for _, filename := range filenames {
file, err := os.Open(filename)
if err != nil {
return err
}
defer file.Close()
scanner := bufio.NewScanner(file)
for scanner.Scan() {
lines = append(lines, strings.FieldsFunc(scanner.Text(), func(c rune) bool { return c == '\t' }))
}
}
maxFieldWidths := make([]int, len(lines[0])-1, len(lines[0])-1)
for i := 0; i < len(lines[0])-1; i++ {
for _, line := range lines {
if len(line[i]) > maxFieldWidths[i] {
maxFieldWidths[i] = len(line[i])
}
}
}
for _, line := range lines {
for i, field := range line[:len(line)-1] {
padding := int(math.Ceil(float64(maxFieldWidths[i]+tabWidth-maxFieldWidths[i]%tabWidth)/8 - float64(len(field))/8))
fmt.Print(field, strings.Repeat("\t", padding))
}
fmt.Println(line[len(line)-1])
}
return err
}
func main() {
if len(os.Args) < 2 {
fmt.Fprintln(os.Stderr, "ERROR: No arguments provided")
return
}
err := tsvAlign(os.Args[1:])
if err != nil {
fmt.Fprintln(os.Stderr, "ERROR: ", err)
}
}