对编译原理有兴趣的进解决方法

include 'ttrie.php';<br><br>class Rule extends TTrie {<br>  public $rule = array();<br>  public $savematch = 0;<br><br>  function __construct($s='') {<br>
$this->set( array(<br>
' ' => 'Separated',<br>
"\r\n" => 'set_rule',<br>
"\n" => 'set_rule',<br>
"\t" => 'Separated',<br>
'->' => 'Separated',<br>
'→' => 'Separated',<br>
'|' => 'set_parallel_rule',<br>
));<br>
$this->match($s);<br>
if($this->rule[0][0] == $this->rule[0][1]) {<br>
if(count($this->rule[0]) == 2) $this->rule[0][0] .= "'";<br>
else array_unshift($this->rule, array($this->rule[0][0]."'", $this->rule[0][0]));<br>
}else {<br>
$c = $this->rule[0][0];<br>
$n = 0;<br>
foreach($this->rule as $r) if($r[0] == $c) $n++;<br>
if($n > 1) array_unshift($this->rule, array($this->rule[0][0]."'", $this->rule[0][0]));<br>
}<br>  }<br>  function Separated() {<br>  }<br>  function set_rule() {<br>
$this->rule[] = $this->buffer;<br>
$this->buffer = array();<br>  }<br>  function set_parallel_rule() {<br>
$t = $this->buffer[0];<br>
$this->set_rule();<br>
$this->buffer[] = $t;<br>  }<br>}<br><br><br>class Grammar {<br>  var $closure = array();<br>  var $first = array();<br>  var $follow = array();<br>  var $rule = array();<br>  var $identifier = array();<br>  var $leay = array();<br>  var $forecast = array();<br>  var $stack = array();<br>  var $ll = 'LL(0)';<br>  var $lr = 'LR(0)';<br><br>  function __construct($s='') {<br>
$p = new Rule($s);<br>
$this->rule = $p->rule;<br>
$this->set_grammar();<br>  }<br><br>  function set_grammar() {<br>
foreach($this->rule as $rule) {<br>
if(! in_array($rule[0], $this->identifier)) $this->identifier[] = $rule[0];<br>
}<br>
foreach($this->rule as $rule) {<br>
foreach($rule as $v)<br>
if(! in_array($v, $this->identifier) && ! in_array($v, $this->leay))<br>
$this->leay[] = $v;<br>
}<br>
$this->set_first();<br>
$this->set_follow();<br>
$this->set_closure();<br>
$this->set_select();<br>
$this->set_forecast();<br>  }<br>  function set_first() {<br>
foreach($this->rule as $rule) $this->first[$rule[0]] = array();<br>
//直接收取 形如U->a…的产生式（其中a是终结符），把a收入到First(U)中<br>
foreach($this->rule as $v) {<br>
if(in_array($v[1], $this->leay)) $this->first[$v[0]][] = $v[1];<br>
}<br>
//反复传递 形入U->P1P2P3…Pn的产生式（其中P是非终结符），应先把First(P1)中的全部内容传送到First(U)中,如果P1中有ε，把First(P2)中的内容传送到First(U)中,类推直到Pi中无ε<br>
do {<br>
$t = serialize($this->first);<br>
foreach($this->rule as $rule) {<br>
for($i=1; $i<count($rule); $i++)="" {<br="">
$v = $rule[$i];<br>
if(in_array($v, $this->identifier)) {<br>
$this->first[$rule[0]] = array_unique(array_merge($this->first[$rule[0]], $this->first[$v]));<br>
if(! in_array('#', $this->first[$v])) break;<br>
}else break;<br>
}<br>
}<br>
}while($t != serialize($this->first));<br>  }<br>  function set_follow() {<br>
foreach($this->rule as $rule) $this->follow[$rule[0]] = array();<br>
//直接收取 形如 …Ua… 的，把a直接收入到Follow(U)中<br>
foreach($this->rule as $rule) {<br>
for($i=1; $i<count($rule)-1; $i++)="" {<br="">
if(in_array($rule[$i], $this->identifier) && in_array($rule[$i+1], $this->leay))<br>
$this->follow[$rule[$i]][] = $rule[$i+1];<br>
}<br>
if(in_array($rule[$i], $this->identifier)) $this->follow[$rule[$i]][] = '#';<br>
}<br>
foreach($this->follow as &$v) if(! $v) $v[] = '#';<br>
//直接收取 形如 …UP…(P是非终结符)的，把First(P)中非ε收入到Follow(U)中<br>
foreach($this->rule as $rule) {<br>
for($i=1; $i<count($rule)-1; $i++)="" {<br="">
if(in_array($rule[$i], $this->identifier) && in_array($rule[$i+1], $this->identifier)) {<br>
$this->follow[$rule[$i]] = array_unique(array_merge($this->follow[$rule[$i]], array_diff($this->first[$rule[$i+1]], array('#'))));<br>
}<br>
}<br>
}<br>
//反复传递 形如U－>aP的(P是非终结符)或U->aPQ(P,Q为非终结符且Q中含ε)，应把Follow(U)中的全部内容传送到Follow(P)中<br>
do {<br>
$t = serialize($this->follow);<br>
foreach($this->rule as $rule) {<br>
$s = $rule[0];<br>
$d = end($rule);<br>
if(in_array($d, $this->leay)) continue;                    </count($rule)-1;></count($rule)-1;></count($rule);>