git.m6w6.name Git - m6w6/pq-gateway/blob - lib/pq/Query/Expr.php

   1 <?php
   2
   3 namespace pq\Query;
   4
   5 class Expr
   6 {
   7         /**
   8          * @var string
   9          */
  10         protected $expression;
  11
  12         /**
  13          * @var \pq\Query\Expr
  14          */
  15         protected $next;
  16
  17         /**
  18          * @param string $e the expression or a format string followed by arguments
  19          * @param string ...
  20          */
  21         function __construct($e, $arg = null) {
  22                 if (func_num_args() > 1) {
  23                         $e = call_user_func_array("sprintf", func_get_args());
  24                 }
  25                 $this->expression = trim($e);
  26         }
  27
  28         /**
  29          * Get the string expression
  30          * @return string
  31          */
  32         function __toString() {
  33                 $string = $this->expression;
  34                 if ($this->next) {
  35                         $string .= " " . $this->next;
  36                 }
  37                 return (string) $string;
  38         }
  39
  40         /**
  41          * Check for NULL
  42          * @return bool
  43          */
  44         function isNull() {
  45                 return !strcasecmp($this->expression, "null");
  46         }
  47
  48         /**
  49          * Append an expresssion
  50          * @param \pq\Query\Expr $next
  51          * @return \pq\Query\Expr $this
  52          * @throws \UnexpectedValueException if any expr is NULL
  53          */
  54         function add(Expr $next) {
  55                 if ($this->isNull() || $next->isNull()) {
  56                         throw new \UnexpectedValueException("Cannot add anything to NULL");
  57                 }
  58                 for ($that = $this; $that->next; $that = $that->next);
  59                 $that->next = $next;
  60                 return $this;
  61         }
  62 }