PHP配列をS式へ変換する

sexp_encode.php

<?php
/*
 * $ php sexp_encode.php | gosh -E"begin (write (read)) (write (read))" -E"exit"
 */

// TODO: symbolエスケープ?

function sexp_str_escape($str) {
  return addcslashes($str, "\"\\\n\r\f\t\0");
}

function is_vector($hash) {
  $i = 0;
  foreach ($hash as $key => $val) {
    if (!is_int($key)) return false;
    if (!$i === (int)$key) return false;
    $i++;
  }
  return true;
}

function sexp_encode($v, $sdelim="\t", $pdelim = "\t") {
  if (is_string($v)) {
    return '"'.sexp_str_escape($v).'"';
  } else if (is_array($v)) {
    $s = '';
    if (is_vector($v)) {
      foreach ($v as $key => $val) {
        $s = $s . sexp_encode($val) . $sdelim;
      }
      $s = rtrim($s) . $pdelim;
    } else {
      foreach ($v as $key => $val) {
        $s = $s . "($pdelim|".$key."|$sdelim".sexp_encode($val)."$pdelim)$pdelim";
      }
    }
    return "($pdelim$s)";
  } else {
    return $v;
  }
  return '';
}

$hoge = array(1,2,3);
$fuga = array();
$fuga['foo'] = 'bar';
$fuga[')('] = 'x		x


x';
$fuga['boo'] = ')(babaa"';
$fuga['hoge'] = $hoge;
//echo sexp_encode($fuga);
echo sexp_encode(array("a","b","c"), " ", "");