Too much memory used in PHP?

[MrApples]

I made a parser which is using too much memory ( 38 megs ), how could I cut that down?

I must be doing something which is bad practice in PHP but I'm new to it.

PHP Code:

function fetch_bbcode_trigger_blocks(){
    return array(
        'If (All Conditions Are True)',
        'If - Conditions',
                ....
                Continues for about 10
    );
}
    
function fetch_bbcode_trigger_actions(){
    return array(
                       'Set',
            '---',    
            'Skip Remaining Actions',
                         ....
                         Continues for about 30  
    ); 
}
    
function fetch_bbcode_trigger_icons(){
    return array(
            'If (All Conditions Are True)' => 'if',
            'If - Conditions' => 'if',
                        ....
                        Continues for about 40
    );
}    

function NextLine($pos, $code){
    $nextl = ( strpos($code,'<br />',$pos) + 6 );
    if ( $nextl > 0 ){
        return $next1;
    } else {
        return -1;
    }
}

function IsBlockEnd($code, $len){
    $reglen = strlen($code);
    $newlen = ($reglen - strlen(ltrim($code,"\t ")));
    return ($newlen < $len);
}

function IsBlock($code){
    $type = 0;
    $blocks = fetch_bbcode_trigger_blocks();
    foreach ($blocks as $block){
        $spos = stripos($code,$block);
        if ( $spos ){
            return $block;
        }
    }
}

function IsAction($code){
    $type = 0;
    $actions = fetch_bbcode_trigger_actions();
    foreach ($actions as $action){
        $spos = stripos($code,$action);
        if ( $spos ){
            return $action;
        }
    }
}

function IsUnknown($code){
    if ( IsBlock($code) ){
        return false;
    } elseif ( IsAction($code) ){
        return false;
    } elseif ( strpos($code, '(') ){
        return false;
    }
    return true;
}

function handle_bbcode_trigger($code){
//v    global $vbulletin, $vbphrase, $stylevar, $show, $html_allowed;
        $trig = '';
        // Define Images and HTML
        $icons = fetch_bbcode_trigger_icons();
        $iempty = '<img height=\"16\" width=\"16\" src=\"/imgs/jass/empty.gif\" alt=\"\"/>';
        $iline = '<img height=\"16\" width=\"16\" src=\"/imgs/jass/line.gif\" alt=\"\"/>';
        $ijoin = 'join';
        $iblock = '<div><a href=\'#top\' onclick=\'return ExpandCollapseNode(this,\"/imgs/jass/joinbottomplus.gif\",\"/imgs/jass/joinbottomminus.gif\")\'><img src=\'/imgs/jass/joinbottomminus.gif\' alt=\'Collapse\' border=\'0\' /></a><img src=\"/imgs/jass/join.gif\" alt=\"\" />';
        $ibend = '<img src=\"/imgs/jass/joinbottom.gif\" alt=\"\"/>';
        // Start Predefines
        $cur = 0;
        $setblock = 0;
        $blocklevel = 0;
        $lastlen = 0;
        $nextline = NextLine(0,$code);
        $action = '';
        $start = '';
        $end = '';
        $icon = '';
        while ( $nextline != -1 || $cur < 2 ){
            $cur++;
            $line = substr($code, $pos, $nextline);
            $pos = $nextline;
            if ( $setblock != 0 ){
                $blocklevel = ($blocklevel + $setblock);
                $setblock = 0;            
            }
            if ( $blocklevel == 0 ){
                // Is this a trigger name?
                if (!$actiondefined){
                    if ( IsUnknown($line) ){
                        // Yis!
                        $setblock = 1;
                        $icon = 'base';
                    }
                }
            } else {
                if ( IsBlockEnd($line,$lastlen) ){
                    $setblock = -1;
                } elseif ( IsBlock($line) ){
                    $setblock = 1;
                    $icon = IsBlock($line);
                }
            }
            $lastlen = strlen($line);
            // We can clean it now. IsBlockEnd requires whitespaces and tabs.
            $line = ltrim($line,"\t ");
            if ( $setblock <= 0 ){
                // Its a function...
                $action = IsAction($line);
                if ( $action != '' ){
                    $icon = $action;
                    if ( $blocklevel == 0 ){
                        $actiondefined = 1;
                    }
                } else {
                    $icon = 'unknown';
                }
            }
            $level = $blocklevel;
            if ( $level > 0 ){
                while ( $level > 1 ){
                    if ( $blockhere[$level] == 0 ){
                        $start .= $iempty;
                    } else {
                        $start .= $iline;
                    }
                    $level--;
                }
                if ( $setblock > 0 ){
                    $start .= $iblock;
                } elseif ( $setblock < 0 ){
                    $start .= $ibend;
                } else {
                    $start .= $ijoin;
                }
            } elseif ( $setblock > 0 ){
                $start .= $iblock;
                $start .= $ijoin;
            } 
            if ( $setblock < 0 ){
                $end = '</span></div>';
            } else {
                $end = '</span>';
            }
            $start .= "<img height=\"16\" width=\"16\" src=\"/imgs/jass/" . $icons[$icon] . ".gif\" alt=\"\" />',";
            $start .= "<span>";
            $line = $start . $line;
            $line .= $end;
            $trig .= $line;
            $nextline = NextLine($pos, $code);
            $action = '';
            $start = '';
            $end = '';
            $icon = '';
        }
        $code = '';
        $replace = array (
            '<br>',
            '<br />',
        );
        $with = array (
            '',
            '',
        );
        $trig = str_replace($replace, $with, $trig);
    return $trig;
} 


If it applies the error happens at "$trig .= $line;"