src/op5/ninja_sdk/parsegen/LalrState.php

   1 <?php
   2
   3 class LalrState {
   4         private $items; /* kernel */
   5         private $grammar;
   6
   7         public function __construct( $items, $grammar ) {
   8                 if( !is_array( $items ) )
   9                         $items = array( $items );
  10
  11                 $this->items = $items;
  12                 $this->grammar = $grammar;
  13         }
  14
  15         public function next_symbols() {
  16                 $symbols = array();
  17                 foreach( $this->closure() as $item ) {
  18                         $next = $item->next();
  19                         if( $next !== false && !in_array( $next, $symbols ) ) {
  20                                 $symbols[] = $next;
  21                         }
  22                 }
  23                 return $symbols;
  24         }
  25
  26         public function take( $symbol ) {
  27                 $next_items = array();
  28                 foreach( $this->closure() as $item ) {
  29                         $next_item = $item->take( $symbol );
  30                         if( $next_item !== false ) {
  31                                 $next_items[] = $next_item;
  32                         }
  33                 }
  34                 return new self( $next_items, $this->grammar );
  35         }
  36
  37         public function closure() {
  38                 $items = $this->items;
  39
  40                 /* Don't use foreach. $items can grow in the loop, and the new items needs to be handled too */
  41                 for( $i = 0; $i<count($items); $i++ ) {
  42                         $cur_item = $items[$i];
  43                         $next_symbol = $cur_item->next();
  44                         if( $next_symbol === false ) {
  45
  46                         } else {
  47                                 foreach( $this->grammar->productions( $next_symbol ) as $new_item ) {
  48                                         $add = true;
  49                                         foreach( $items as $test_item ) {
  50                                                 if( $test_item->equals($new_item) ) {
  51                                                         $add = false;
  52                                                 }
  53                                         }
  54                                         if( $add ) {
  55                                                 $items[] = $new_item;
  56                                         }
  57                                 }
  58                         }
  59                 }
  60                 return $items;
  61         }
  62
  63         public function errors() {
  64                 $items = $this->items;
  65
  66                 $errors = array();
  67                 /* Don't use foreach. $items can grow in the loop, and the new items needs to be handled too */
  68                 for( $i = 0; $i<count($items); $i++ ) {
  69                         $cur_item = $items[$i];
  70                         $next_symbol = $cur_item->next();
  71                         $rule = $this->grammar->errors($next_symbol);
  72                         if($rule) {
  73                                 foreach( $rule->follow() as $follow ) {
  74                                         $errors[$follow] = $rule;
  75                                 }
  76                         }
  77                 }
  78                 return $errors;
  79         }
  80
  81         public function __toString() {
  82                 $outp = "";
  83                 foreach( $this->closure() as $item ) {
  84                         $outp .= "$item\n";
  85                 }
  86                 return $outp;
  87         }
  88
  89         public function equals( $state ) {
  90                 if( count( $this->items ) != count( $state->items ) ) {
  91                         return false;
  92                 }
  93                 foreach( $this->items as $itema ) {
  94                         $exists = false;
  95                         foreach( $state->items as $itemb ) {
  96                                 if( $itema->equals( $itemb ) ) {
  97                                         $exists = true;
  98                                 }
  99                         }
 100                         if( $exists == false )
 101                                 return false;
 102                 }
 103                 return true;
 104         }
 105 }