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#1 UVL

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Posted 24 May 2006 - 12:25 PM

I've recently began my long journey into mastering php, and along the way I started skinning and modding phpBB as a way to get deeper into php and build my skills.

As I dug through the code, I noticed that phpBB uses what I assume to be a custom class which allows for you to make script calls from the html template files by simply outlining the "script name" in curly brackets.

Ex. {SCRIPT_NAME}

This provides a wealth of power in the way the scripts are used inside of the template html.

What I want to learn, is how to use that code from phpBB, or at least how they made it work, so I can use that to power my own sites. It would allow for building a foundation application that could be reused for various clients, with just customized html templates for each client.

I've included the entire template.php, which I believe is the brain behind the operation, however I'm still too fresh into php to really make heads or tails of it.

I'm hoping someone here can explain this and help me grasp this so I can get my head wrapped around it, or hopefully could explain another way to get this same effect, but allow it to be reusable for any site I create.

Template.php (from phpBB):
class Template {
    var $classname = "Template";

    // variable that holds all the data we'll be substituting into
    // the compiled templates.
    // ...
    // This will end up being a multi-dimensional array like this:
    // $this->_tpldata[block.][iteration#][child.][iteration#][child2.][iteration#][variablename] == value
    // if it's a root-level variable, it'll be like this:
    // $this->_tpldata[.][0][varname] == value
    var $_tpldata = array();

    // Hash of filenames for each template handle.
    var $files = array();

    // Root template directory.
    var $root = "";

    // this will hash handle names to the compiled code for that handle.
    var $compiled_code = array();

    // This will hold the uncompiled code for that handle.
    var $uncompiled_code = array();

    /**
     * Constructor. Simply sets the root dir.
     *
     */
    function Template($root = ".")
    {
        $this->set_rootdir($root);
    }

    /**
     * Destroys this template object. Should be called when you're done with it, in order
     * to clear out the template data so you can load/parse a new template set.
     */
    function destroy()
    {
        $this->_tpldata = array();
    }

    /**
     * Sets the template root directory for this Template object.
     */
    function set_rootdir($dir)
    {
        if (!is_dir($dir))
        {
            return false;
        }

        $this->root = $dir;
        return true;
    }

    /**
     * Sets the template filenames for handles. $filename_array
     * should be a hash of handle => filename pairs.
     */
    function set_filenames($filename_array)
    {
        if (!is_array($filename_array))
        {
            return false;
        }

        reset($filename_array);
        while(list($handle, $filename) = each($filename_array))
        {
            $this->files[$handle] = $this->make_filename($filename);
        }

        return true;
    }


    /**
     * Load the file for the handle, compile the file,
     * and run the compiled code. This will print out
     * the results of executing the template.
     */
    function pparse($handle)
    {
        if (!$this->loadfile($handle))
        {
            die("Template->pparse(): Couldn't load template file for handle $handle");
        }

        // actually compile the template now.
        if (!isset($this->compiled_code[$handle]) || empty($this->compiled_code[$handle]))
        {
            // Actually compile the code now.
            $this->compiled_code[$handle] = $this->compile($this->uncompiled_code[$handle]);
        }

        // Run the compiled code.
        eval($this->compiled_code[$handle]);
        return true;
    }

    /**
     * Inserts the uncompiled code for $handle as the
     * value of $varname in the root-level. This can be used
     * to effectively include a template in the middle of another
     * template.
     * Note that all desired assignments to the variables in $handle should be done
     * BEFORE calling this function.
     */
    function assign_var_from_handle($varname, $handle)
    {
        if (!$this->loadfile($handle))
        {
            die("Template->assign_var_from_handle(): Couldn't load template file for handle $handle");
        }

        // Compile it, with the "no echo statements" option on.
        $_str = "";
        $code = $this->compile($this->uncompiled_code[$handle], true, '_str');

        // evaluate the variable assignment.
        eval($code);
        // assign the value of the generated variable to the given varname.
        $this->assign_var($varname, $_str);

        return true;
    }

    /**
     * Block-level variable assignment. Adds a new block iteration with the given
     * variable assignments. Note that this should only be called once per block
     * iteration.
     */
    function assign_block_vars($blockname, $vararray)
    {
        if (strstr($blockname, '.'))
        {
            // Nested block.
            $blocks = explode('.', $blockname);
            $blockcount = sizeof($blocks) - 1;
            $str = '$this->_tpldata';
            for ($i = 0; $i < $blockcount; $i++)
            {
                $str .= '[\'' . $blocks[$i] . '.\']';
                eval('$lastiteration = sizeof(' . $str . ') - 1;');
                $str .= '[' . $lastiteration . ']';
            }
            // Now we add the block that we're actually assigning to.
            // We're adding a new iteration to this block with the given
            // variable assignments.
            $str .= '[\'' . $blocks[$blockcount] . '.\'][] = $vararray;';

            // Now we evaluate this assignment we've built up.
            eval($str);
        }
        else
        {
            // Top-level block.
            // Add a new iteration to this block with the variable assignments
            // we were given.
            $this->_tpldata[$blockname . '.'][] = $vararray;
        }

        return true;
    }

    /**
     * Root-level variable assignment. Adds to current assignments, overriding
     * any existing variable assignment with the same name.
     */
    function assign_vars($vararray)
    {
        reset ($vararray);
        while (list($key, $val) = each($vararray))
        {
            $this->_tpldata['.'][0][$key] = $val;
        }

        return true;
    }

    /**
     * Root-level variable assignment. Adds to current assignments, overriding
     * any existing variable assignment with the same name.
     */
    function assign_var($varname, $varval)
    {
        $this->_tpldata['.'][0][$varname] = $varval;

        return true;
    }


    /**
     * Generates a full path+filename for the given filename, which can either
     * be an absolute name, or a name relative to the rootdir for this Template
     * object.
     */
    function make_filename($filename)
    {
        // Check if it's an absolute or relative path.
        if (substr($filename, 0, 1) != '/')
        {
               $filename = ($rp_filename = phpbb_realpath($this->root . '/' . $filename)) ? $rp_filename : $filename;
        }

        if (!file_exists($filename))
        {
            die("Template->make_filename(): Error - file $filename does not exist");
        }

        return $filename;
    }


    /**
     * If not already done, load the file for the given handle and populate
     * the uncompiled_code[] hash with its code. Do not compile.
     */
    function loadfile($handle)
    {
        // If the file for this handle is already loaded and compiled, do nothing.
        if (isset($this->uncompiled_code[$handle]) && !empty($this->uncompiled_code[$handle]))
        {
            return true;
        }

        // If we don't have a file assigned to this handle, die.
        if (!isset($this->files[$handle]))
        {
            die("Template->loadfile(): No file specified for handle $handle");
        }

        $filename = $this->files[$handle];

        $str = implode("", @file($filename));
        if (empty($str))
        {
            die("Template->loadfile(): File $filename for handle $handle is empty");
        }

        $this->uncompiled_code[$handle] = $str;

        return true;
    }



    /**
     * Compiles the given string of code, and returns
     * the result in a string.
     * If "do_not_echo" is true, the returned code will not be directly
     * executable, but can be used as part of a variable assignment
     * for use in assign_code_from_handle().
     */
    function compile($code, $do_not_echo = false, $retvar = '')
    {
        // replace \ with \\ and then ' with \'.
        $code = str_replace('\\', '\\\\', $code);
        $code = str_replace('\'', '\\\'', $code);

        // change template varrefs into PHP varrefs

        // This one will handle varrefs WITH namespaces
        $varrefs = array();
        preg_match_all('#\{(([a-z0-9\-_]+?\.)+?)([a-z0-9\-_]+?)\}#is', $code, $varrefs);
        $varcount = sizeof($varrefs[1]);
        for ($i = 0; $i < $varcount; $i++)
        {
            $namespace = $varrefs[1][$i];
            $varname = $varrefs[3][$i];
            $new = $this->generate_block_varref($namespace, $varname);

            $code = str_replace($varrefs[0][$i], $new, $code);
        }

        // This will handle the remaining root-level varrefs
        $code = preg_replace('#\{([a-z0-9\-_]*?)\}#is', '\' . ( ( isset($this->_tpldata[\'.\'][0][\'\1\']) ) ? $this->_tpldata[\'.\'][0][\'\1\'] : \'\' ) . \'', $code);

        // Break it up into lines.
        $code_lines = explode("\n", $code);

        $block_nesting_level = 0;
        $block_names = array();
        $block_names[0] = ".";

        // Second: prepend echo ', append ' . "\n"; to each line.
        $line_count = sizeof($code_lines);
        for ($i = 0; $i < $line_count; $i++)
        {
            $code_lines[$i] = chop($code_lines[$i]);
            if (preg_match('#<!-- BEGIN (.*?) -->#', $code_lines[$i], $m))
            {
                $n[0] = $m[0];
                $n[1] = $m[1];

                // Added: dougk_ff7-Keeps templates from bombing if begin is on the same line as end.. I think. :)
                if ( preg_match('#<!-- END (.*?) -->#', $code_lines[$i], $n) )
                {
                    $block_nesting_level++;
                    $block_names[$block_nesting_level] = $m[1];
                    if ($block_nesting_level < 2)
                    {
                        // Block is not nested.
                        $code_lines[$i] = '$_' . $n[1] . '_count = ( isset($this->_tpldata[\'' . $n[1] . '.\']) ) ?  sizeof($this->_tpldata[\'' . $n[1] . '.\']) : 0;';
                        $code_lines[$i] .= "\n" . 'for ($_' . $n[1] . '_i = 0; $_' . $n[1] . '_i < $_' . $n[1] . '_count; $_' . $n[1] . '_i++)';
                        $code_lines[$i] .= "\n" . '{';
                    }
                    else
                    {
                        // This block is nested.

                        // Generate a namespace string for this block.
                        $namespace = implode('.', $block_names);
                        // strip leading period from root level..
                        $namespace = substr($namespace, 2);
                        // Get a reference to the data array for this block that depends on the
                        // current indices of all parent blocks.
                        $varref = $this->generate_block_data_ref($namespace, false);
                        // Create the for loop code to iterate over this block.
                        $code_lines[$i] = '$_' . $n[1] . '_count = ( isset(' . $varref . ') ) ? sizeof(' . $varref . ') : 0;';
                        $code_lines[$i] .= "\n" . 'for ($_' . $n[1] . '_i = 0; $_' . $n[1] . '_i < $_' . $n[1] . '_count; $_' . $n[1] . '_i++)';
                        $code_lines[$i] .= "\n" . '{';
                    }

                    // We have the end of a block.
                    unset($block_names[$block_nesting_level]);
                    $block_nesting_level--;
                    $code_lines[$i] .= '} // END ' . $n[1];
                    $m[0] = $n[0];
                    $m[1] = $n[1];
                }
                else
                {
                    // We have the start of a block.
                    $block_nesting_level++;
                    $block_names[$block_nesting_level] = $m[1];
                    if ($block_nesting_level < 2)
                    {
                        // Block is not nested.
                        $code_lines[$i] = '$_' . $m[1] . '_count = ( isset($this->_tpldata[\'' . $m[1] . '.\']) ) ? sizeof($this->_tpldata[\'' . $m[1] . '.\']) : 0;';
                        $code_lines[$i] .= "\n" . 'for ($_' . $m[1] . '_i = 0; $_' . $m[1] . '_i < $_' . $m[1] . '_count; $_' . $m[1] . '_i++)';
                        $code_lines[$i] .= "\n" . '{';
                    }
                    else
                    {
                        // This block is nested.

                        // Generate a namespace string for this block.
                        $namespace = implode('.', $block_names);
                        // strip leading period from root level..
                        $namespace = substr($namespace, 2);
                        // Get a reference to the data array for this block that depends on the
                        // current indices of all parent blocks.
                        $varref = $this->generate_block_data_ref($namespace, false);
                        // Create the for loop code to iterate over this block.
                        $code_lines[$i] = '$_' . $m[1] . '_count = ( isset(' . $varref . ') ) ? sizeof(' . $varref . ') : 0;';
                        $code_lines[$i] .= "\n" . 'for ($_' . $m[1] . '_i = 0; $_' . $m[1] . '_i < $_' . $m[1] . '_count; $_' . $m[1] . '_i++)';
                        $code_lines[$i] .= "\n" . '{';
                    }
                }
            }
            else if (preg_match('#<!-- END (.*?) -->#', $code_lines[$i], $m))
            {
                // We have the end of a block.
                unset($block_names[$block_nesting_level]);
                $block_nesting_level--;
                $code_lines[$i] = '} // END ' . $m[1];
            }
            else
            {
                // We have an ordinary line of code.
                if (!$do_not_echo)
                {
                    $code_lines[$i] = 'echo \'' . $code_lines[$i] . '\' . "\\n";';
                }
                else
                {
                    $code_lines[$i] = '$' . $retvar . '.= \'' . $code_lines[$i] . '\' . "\\n";'; 
                }
            }
        }

        // Bring it back into a single string of lines of code.
        $code = implode("\n", $code_lines);
        return $code;

    }


    /**
     * Generates a reference to the given variable inside the given (possibly nested)
     * block namespace. This is a string of the form:
     * ' . $this->_tpldata['parent'][$_parent_i]['$child1'][$_child1_i]['$child2'][$_child2_i]...['varname'] . '
     * It's ready to be inserted into an "echo" line in one of the templates.
     * NOTE: expects a trailing "." on the namespace.
     */
    function generate_block_varref($namespace, $varname)
    {
        // Strip the trailing period.
        $namespace = substr($namespace, 0, strlen($namespace) - 1);

        // Get a reference to the data block for this namespace.
        $varref = $this->generate_block_data_ref($namespace, true);
        // Prepend the necessary code to stick this in an echo line.

        // Append the variable reference.
        $varref .= '[\'' . $varname . '\']';

        $varref = '\' . ( ( isset(' . $varref . ') ) ? ' . $varref . ' : \'\' ) . \'';

        return $varref;

    }


    /**
     * Generates a reference to the array of data values for the given
     * (possibly nested) block namespace. This is a string of the form:
     * $this->_tpldata['parent'][$_parent_i]['$child1'][$_child1_i]['$child2'][$_child2_i]...['$childN']
     *
     * If $include_last_iterator is true, then [$_childN_i] will be appended to the form shown above.
     * NOTE: does not expect a trailing "." on the blockname.
     */
    function generate_block_data_ref($blockname, $include_last_iterator)
    {
        // Get an array of the blocks involved.
        $blocks = explode(".", $blockname);
        $blockcount = sizeof($blocks) - 1;
        $varref = '$this->_tpldata';
        // Build up the string with everything but the last child.
        for ($i = 0; $i < $blockcount; $i++)
        {
            $varref .= '[\'' . $blocks[$i] . '.\'][$_' . $blocks[$i] . '_i]';
        }
        // Add the block reference for the last child.
        $varref .= '[\'' . $blocks[$blockcount] . '.\']';
        // Add the iterator for the last child if requried.
        if ($include_last_iterator)
        {
            $varref .= '[$_' . $blocks[$blockcount] . '_i]';
        }

        return $varref;
    }

}

?>




#2 trq

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Posted 24 May 2006 - 01:48 PM

There are literally hundreds of template systems built for / in php. Why not pick one with documentation?

#3 UVL

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Posted 24 May 2006 - 03:20 PM

It helps me learn.

And in the words of your signature link...

I'm not a luser...I'm trying to understand how to write my own template system [img src=\"style_emoticons/[#EMO_DIR#]/laugh.gif\" style=\"vertical-align:middle\" emoid=\":laugh:\" border=\"0\" alt=\"laugh.gif\" /]


Ok, I'm officially stuck.

I got the {SCRIPT_NAME} working in the html templates based on a modified version of the template.php

However, I am recieving this error:

Fatal error: Call to a member function assign_vars() on a non-object in on line 24

This is referring to the code I have set up that declares the {SCRIPT_NAMES} which is something like:

Code:

$script = print "this"; 

   $Macro->assign_vars(array( 
      'SCRIPT_NAME' => $script 
      )); 

I believe the issue exists in the "assign_vars" function call...however that function is readily available in the script itself as such:

    function assign_vars($vararray)
    {
        reset ($vararray);
        while (list($key, $val) = each($vararray))
        {
            $this->_htmldata['.'][0][$key] = $val;
        }

        return true;
    }

The really strange thing is, it passes the variable $script into the html file through the {SCRIPT_NAME} and prints "this" nicely.

Directly after that however it gives me the ugly error and breaks all programming.

#4 jstgermain

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Posted 24 May 2006 - 03:30 PM

it would be a lot easier to pick one with documentation untill you learn, or get a book to help build you to that level
Justin St. Germain

#5 UVL

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Posted 24 May 2006 - 03:32 PM

well...i've got it working, kinda...

I don't want to stop now.




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