对编译原理有兴趣的入

include 'ttrie.php';

class Rule extends TTrie {
  public $rule = array();
  public $savematch = 0;

  function __construct($s='') {
    $this->set( array(
        ' ' => 'Separated',
        "\r\n" => 'set_rule',
        "\n" => 'set_rule',
        "\t" => 'Separated',
        '->' => 'Separated',
        '→' => 'Separated',
        '|' => 'set_parallel_rule',
        ));
    $this->match($s);
    if($this->rule[0][0] == $this->rule[0][1]) {
        if(count($this->rule[0]) == 2) $this->rule[0][0] .= "'";
        else array_unshift($this->rule, array($this->rule[0][0]."'", $this->rule[0][0]));
    }else {
        $c = $this->rule[0][0];
        $n = 0;
        foreach($this->rule as $r) if($r[0] == $c) $n++;
        if($n > 1) array_unshift($this->rule, array($this->rule[0][0]."'", $this->rule[0][0]));
    }
  }
  function Separated() {
  }
  function set_rule() {
    $this->rule[] = $this->buffer;
    $this->buffer = array();
  }
  function set_parallel_rule() {
    $t = $this->buffer[0];
    $this->set_rule();
    $this->buffer[] = $t;
  }
}


class Grammar {
  var $closure = array();
  var $first = array();
  var $follow = array();
  var $rule = array();
  var $identifier = array();
  var $leay = array();
  var $forecast = array();
  var $stack = array();
  var $ll = 'LL(0)';
  var $lr = 'LR(0)';

  function __construct($s='') {
    $p = new Rule($s);
    $this->rule = $p->rule;
    $this->set_grammar();
  }

  function set_grammar() {
    foreach($this->rule as $rule) {
        if(! in_array($rule[0], $this->identifier)) $this->identifier[] = $rule[0];
    }
    foreach($this->rule as $rule) {
        foreach($rule as $v)
            if(! in_array($v, $this->identifier) && ! in_array($v, $this->leay))
                $this->leay[] = $v;
    }
    $this->set_first();
    $this->set_follow();
    $this->set_closure();
    $this->set_select();
    $this->set_forecast();
  }
  function set_first() {
    foreach($this->rule as $rule) $this->first[$rule[0]] = array();
    //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
    foreach($this->rule as $v) {
        if(in_array($v[1], $this->leay)) $this->first[$v[0]][] = $v[1];
    }
    //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
    do {
        $t = serialize($this->first);
        foreach($this->rule as $rule) {
            for($i=1; $iidentifier)) {
                    $this->first[$rule[0]] = array_unique(array_merge($this->first[$rule[0]], $this->first[$v]));
                    if(! in_array('//m.sbmmt.com/m/faq/#', $this->first[$v])) break;
                }else break;
            }
        }
    }while($t != serialize($this->first));
  }
  function set_follow() {
    foreach($this->rule as $rule) $this->follow[$rule[0]] = array();
    //直接收取 形如 …Ua… 的，把a直接收入到Follow(U)中
    foreach($this->rule as $rule) {
        for($i=1; $iidentifier) && in_array($rule[$i+1], $this->leay))
                $this->follow[$rule[$i]][] = $rule[$i+1];
        }
        if(in_array($rule[$i], $this->identifier)) $this->follow[$rule[$i]][] = '//m.sbmmt.com/m/faq/#';
    }
    foreach($this->follow as &$v) if(! $v) $v[] = '//m.sbmmt.com/m/faq/#';
    //直接收取 形如 …UP…(P是非终结符)的，把First(P)中非ε收入到Follow(U)中
    foreach($this->rule as $rule) {
        for($i=1; $iidentifier) && in_array($rule[$i+1], $this->identifier)) {
                $this->follow[$rule[$i]] = array_unique(array_merge($this->follow[$rule[$i]], array_diff($this->first[$rule[$i+1]], array('//m.sbmmt.com/m/faq/#'))));
            }
        }
    }
    //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
    do {
        $t = serialize($this->follow);
        foreach($this->rule as $rule) {
            $s = $rule[0];
            $d = end($rule);
            if(in_array($d, $this->leay)) continue;
            $p = prev($rule);
            if(in_array($p, $this->leay)) $this->follow[$d] = array_unique(array_merge($this->follow[$d], $this->follow[$s]));
            elseif(in_array('//m.sbmmt.com/m/faq/#', $this->follow[$d])) $this->follow[$p] = array_unique(array_merge($this->follow[$p], $this->follow[$s]));
        }
    }while($t != serialize($this->follow));
  }
  function set_closure() {
    $shift = array();
    $this->closure[0][] = array('offs' => 1, 'rule' => 0);
    for($i=0 ; $i < count($this->closure); $i++) {
        $cnt = count($this->closure);
        //构造闭包 closure
        $ex = array();
        $j = 0;
        $tmp = array();
        do {
            $size = count($this->closure[$i]);
            for($j=0; $jclosure[$i]); $j++) {
                $dfa = $this->closure[$i][$j];
                $rule = $this->rule[$dfa['rule']];
                if(isset($rule[$dfa['offs']])) {
                    $ch = $ex[] = $rule[$dfa['offs']];
                }
                foreach($this->rule as $r=>$rule) {
                    if(in_array($rule[0], $ex)) {
                        $t = array('offs' => 1, 'rule' => $r);
                        if(!isset($tmp[$r][1])) $this->closure[$i][] = $t;
                        $tmp[$r][1] = 1;
                    }
                }
            }
        }while(count($this->closure[$i]) != $size); //直到不再增大

        //判断状态转向 go
        $out = array();
        foreach($this->closure[$i] as $k=>$dfa) {
            $rule = $this->rule[$dfa['rule']];
            if(isset($rule[$dfa['offs']])) {
                $t = "$dfa[rule],$dfa[offs]";
                $ch = $rule[$dfa['offs']];
                $this->closure[$i][$k]['char'] = $ch;
                if(isset($out[$ch])) $shift[$t] = $out[$ch];
                if(isset($shift[$t])) {
                    $this->closure[$i][$k]['target'] = $shift[$t];
                    $dfa['offs']++;
                    if(!$this->in_closure($dfa, $this->closure[$shift[$t]])) $this->closure[$shift[$t]][] = $dfa;

                } else {
                    $cnt = count($this->closure);
                    $this->closure[$i][$k]['target'] = $cnt;
                    $shift[$t] = $cnt;
                    $dfa['offs']++;
                    $this->closure[count($this->closure)][] = $dfa;
                    $out[$ch] = $cnt;
                }
            }
        }

        //构造状态转换表
        foreach($this->closure[$i] as $k=>$dfa) {
            if(isset($dfa['target'])) {
                $v = $dfa['char'];
                if(in_array($v, $this->identifier)) $this->goto[$i][$v] = $dfa['target'];
                else {
                    $this->action[$i][$v][] = "S$dfa[target]";
                    $this->request[$i][$v] = $dfa['rule'];
                }
            } else {
                $ch = $this->rule[$dfa['rule']][0];
                foreach($this->follow[$ch] as $v) {
                    $this->action[$i][$v][] = "r$dfa[rule]";
                    $this->request[$i][$v] = $dfa['rule'];
                }
            }
        }
        foreach($this->action[$i] as $c=>$v) {
            $v = array_unique($v);
            if(count($v) > 1) $this->lr = 'SLR(1)';
            $this->action[$i][$c] = $v;
        }
    }
  }

  function in_closure($t, $s) {
    foreach($s as $r) if($t['offs'] == $r['offs'] && $t['rule'] == $r['rule']) return true;
    return false;
    return in_array(serialize($t), array_map('serialize', $s));
  }
  function set_select() {
    foreach($this->rule as $i=>$rule) {
        $y = array($rule[1]);
        if(in_array($y[0], $this->leay)) {
            if($y[0] != '//m.sbmmt.com/m/faq/#') {
                $this->select[$i] = $y;
                continue;
            }
        }else $y = $this->first[$rule[1]];
        $x = $this->follow[$rule[0]];
        //SELECT(X->Y)=(FIRST(Y)-{ε})并FOLLOW(X)
        $this->select[$i] = array_unique( array_merge(array_diff($y, array('//m.sbmmt.com/m/faq/#')), $x) );
    }
  }
  /**
   * 构造预测分析表
   **/
  function set_forecast() {
    foreach($this->select as $i=>$r) {
        $c = $this->rule[$i][0];
        $v = array_reverse(array_slice($this->rule[$i], 1));
        foreach($r as $k) {
            $this->forecast[$c][$k][] = $v;
        }
    }
    //检查冲突
    foreach($this->forecast as $c=>$r) {
        foreach($r as $k) {
            if(count($k) > 1) {
                $this->ll = 'LL(1)';
            }
        }
    }
  }

 

                 
              
              
        
            
      
      
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