Skip to content

Instantly share code, notes, and snippets.

@Opencontent

Opencontent/ParensParser.php

Forked from xeoncross/ParensParser.php
Last active June 16, 2020 06:06
Download ZIP

Revisions

  1. Opencontent revised this gist Dec 22, 2015. 1 changed file with 7 additions and 1 deletion.
    8 changes: 7 additions & 1 deletion ParensParser.php
    View file
    Original file line number Diff line number Diff line change
    @@ -4,6 +4,7 @@
    // http://stackoverflow.com/a/7917979/99923
    class ParensParser
    {
    protected $length = null;
    // something to keep track of parens nesting
    protected $stack = null;
    // current level
    @@ -13,6 +14,7 @@ class ParensParser
    protected $string = null;
    // current character offset in string
    protected $position = null;
    protected $lastPosition = 0;
    // start of text-buffer
    protected $buffer_start = null;

    @@ -51,6 +53,7 @@ public function parse($string)
    $this->current = array_pop($this->stack);
    // add just saved scope to current scope
    $this->current[] = $t;
    $this->lastPosition = $this->position + 1;
    break;
    /*
    case ' ':
    @@ -67,7 +70,10 @@ public function parse($string)
    }
    }
    }

    if ( $this->lastPosition+1 < $this->length )
    {
    $this->current[] = substr($this->string, $this->lastPosition, $this->length - $this->lastPosition);
    }
    return $this->current;
    }

  2. @xeoncross xeoncross created this gist Feb 4, 2013.
    90 changes: 90 additions & 0 deletions ParensParser.php
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,90 @@
    <?php

    // @rodneyrehm
    // http://stackoverflow.com/a/7917979/99923
    class ParensParser
    {
    // something to keep track of parens nesting
    protected $stack = null;
    // current level
    protected $current = null;

    // input string to parse
    protected $string = null;
    // current character offset in string
    protected $position = null;
    // start of text-buffer
    protected $buffer_start = null;

    public function parse($string)
    {
    if (!$string) {
    // no string, no data
    return array();
    }

    if ($string[0] == '(') {
    // killer outer parens, as they're unnecessary
    $string = substr($string, 1, -1);
    }

    $this->current = array();
    $this->stack = array();

    $this->string = $string;
    $this->length = strlen($this->string);
    // look at each character
    for ($this->position=0; $this->position < $this->length; $this->position++) {
    switch ($this->string[$this->position]) {
    case '(':
    $this->push();
    // push current scope to the stack an begin a new scope
    array_push($this->stack, $this->current);
    $this->current = array();
    break;

    case ')':
    $this->push();
    // save current scope
    $t = $this->current;
    // get the last scope from stack
    $this->current = array_pop($this->stack);
    // add just saved scope to current scope
    $this->current[] = $t;
    break;
    /*
    case ' ':
    // make each word its own token
    $this->push();
    break;
    */
    default:
    // remember the offset to do a string capture later
    // could've also done $buffer .= $string[$position]
    // but that would just be wasting resources…
    if ($this->buffer_start === null) {
    $this->buffer_start = $this->position;
    }
    }
    }

    return $this->current;
    }

    protected function push()
    {
    if ($this->buffer_start !== null) {
    // extract string from buffer start to current position
    $buffer = substr($this->string, $this->buffer_start, $this->position - $this->buffer_start);
    // clean buffer
    $this->buffer_start = null;
    // throw token into current scope
    $this->current[] = $buffer;
    }
    }
    }

    $string = '(TOP (S (NP (PRP I)) (VP (VBP love) (NP (NP (DT a) (JJ big) (NN bed)) (PP (IN of) (NP (NNS roses))))) (. .)))';
    $p = new ParensParser();
    $result = $p->parse($string);
    var_dump($result);