Table layout library for command line.

• string and integer cell content
• left and right cell content alignment
• strong arity checks
• very high-level code (no loops used!)

Create a table of user names and their IDs from /etc/passwd.

#include <stdlib.h>
#include <pwd.h>
#include <m_list.h>

int
main(void)
{
  struct passwd* pwd;
  struct tabl t;
  struct m_list values;

  tabl_init(&t);
  tabl_add_column(&t, "UID", TABL_CONTENT_DECIMAL, TABL_ALIGN_RIGHT);
  tabl_add_column(&t, "Name", TABL_CONTENT_STRING, TABL_ALIGN_LEFT);

  m_list_init(&values);
  while ((pwd = getpwent()) != NULL) {
    m_list_clear(&values);
    m_list_append(&values, M_LIST_COPY_DEEP, &pwd->pw_uid, sizeof(uid_t));
    m_list_append(&values, M_LIST_COPY_DEEP, pwd->pw_name, strlen(pwd->pw_name)+1);
    tabl_add_row(&t, &values);
  }
  endpwent();

  tabl_render(&t);
  return EXIT_SUCCESS;
}

Compile & run:

$ clang -o passwd passwd.c -ltabl
$ ./passwd
  UID Name
    0 root
    8 news
    9 man
   22 sshd
   25 smmsp
   26 mailnull
   68 pop
   78 auditdistd
   80 www
  845 hast
65534 nobody

The usage of libtabl is completely linear. The whole workflow has four steps: initialisation, column creation, row insertion and rendering of the table. The order of tasks must be preserved.

Use the tabl_init(struct tabl* t) function to initialise a already allocated table.

Each column is specified by the name displayed in the header, the content of the data in the column and the alignment of the data. To append a new column to the table, use the tabl_add_column(struct tabl* t, const char* name, uint8_t content, uint8_t align). Appending a new column after already appending some rows will result in an runtime error.

Content can be one of the following:

• TABL_CONTENT_STRING which expect the data to be a NULL-terminated string
• TABL_CONTENT_DECIMAL which expect a single int of data that will be printed in the decimal format

Alignment can be one of the following:

• TABL_ALIGN_LEFT align content to the left
• TABL_ALIGN_RIGHT align content to the right

Each row is represented as a separate m_list. As a security measure, the number of columns and number of elements in the row is compared, to ensure the arity consistence. To append a row, use the tabl_add_row(struct tabl* t, struct m_list* row) function.

To render the finished table onto the stdout, use the tabl_render(struct tabl* t) function.

• FreeBSD 10.0 with Clang 3.3

If a platform does not appear to be in the previous list, it does not mean that libtabl will not work in such environment. It only means that nobody tested it - you are encouraged to do so and report either success or failure.

• m_list

$ ninja

2-clause BSD license. For more information please consult the license file. In the case that you need a different license, feel free to contact me.

Daniel Lovasko (lovasko@freebsd.org)