MorpheusParser.php

<?php
/*
    Note: some parts based on the Spyc YAML parser at http://code.google.com/p/spyc/
 */
class MorpheusParser {
    private $Form = array();
    
    /* Pseudo Global Variables shared by several methods */
    private $group_cursor  = 0;
    private $field_name    = '';
    private $CURRENT_STATE = 'START';

    private function getFile($input) {
        if (!empty($input) and file_exists($input)) {
            return file($input);
        }
    }

    private function isComment ($line) {
        if (!$line) {
            return false;
        }

        if ($line[0] == '#') {
            return true;
        }

        return false;
    }

    private function isBlankLine($line) {
        return $line === '';
    }

    private function parseAttributes($line) {
        $result  = array();
        $attribs = explode(' ', $line);
        foreach ($attribs as $attrib) {
            $current = explode('=', $attrib);
            $result[array_shift($current)] = array_shift($current);
        }

        return $result;
    }

    private function addForm($line) {
        $params        = explode(' ', $line);
        $params_number = count($params);
        if ($params_number < 2) {
            throw new Exception('"form:" directive requires, at least, one line
                                  with two parameters separated by a space.');
        }

        $this->Form['layout'] = array_shift($params);
        $this->Form['method'] = array_shift($params);
        if ($params_number === 3) {
            $this->Form['action'] = array_shift($params);
        }
    }

    private function addFormAttributes($line) {
        if (!$this->isBlankLine($line)) {
            $this->Form['attrib'] = $this->parseAttributes($line);
        }
    }

    private function isAttributeLine($line) {
        return strpos($line, '=') !== false;
    }

    private function isFieldStart($line) {
        $pos = strpos($line, ':');
        if ($pos !== false and $line !== 'group:' and $line !== 'form:') {
            return $pos;
        }

        return false;
    }

    private function addGroup($line) {
        if (empty($line)) {
            throw new Exception('"legend" cannot be empty when adding a group.');
        }

        $this->Form['groups'] = array();
        $this->Form['groups'][$this->group_cursor]['legend'] = $line;
        $this->Form['groups'][$this->group_cursor]['fields'] = array();
    }

    private function addGroupAttributes($line) {
        $return = $this->isAttributeLine($line);
        if ($return) {
             $this->Form['groups'][$this->group_cursor]['attrib'] = $this->parseAttributes($line);
        }

        return $return;
    }

    private function setFieldName($line) {
        $pos  = strpos($line, ':');
        $name = substr($line, 0, $pos);
        $this->Form['groups'][$this->group_cursor]['fields'][$name]['name'] = $name;

        $this->field_name = $name;
    }

    private function addFieldParams($line) {
        $params        = explode(' ', $line);
        $params_number = count($params);
        if ($params_number != 2) {
            throw new Exception('"field:" directive requires exactly two parameters: TYPE and LABEL.');
        }

        $this->Form['groups'][$this->group_cursor]['fields'][$this->field_name]['type'] = array_shift($params);
        $this->Form['groups'][$this->group_cursor]['fields'][$this->field_name]['label'] = array_shift($params);
    }

    private function addFieldValidations($line) {
        $params = explode(' ', $line);
        $validations = array();
        foreach ($params as $validation) {
            $validations[] = $validation;
        }

        $this->Form['groups'][$this->group_cursor]['fields'][$this->field_name]['validations'] = $validations;
    }

    private function addFieldAttributes($line) {
        $return = $this->isAttributeLine($line);
        if ($return) {
            $this->Form['groups'][$this->group_cursor]['fields'][$this->field_name]['attrib'] = $this->parseAttributes($line);
        }

        return $return;
    }

    private function automatonStartCheck($line) {
        if ($line == 'form:') {
            $this->CURRENT_STATE = 'FORM';
        } else if ($line == 'group:') {
            $this->CURRENT_STATE = 'GROUP';
        } else if ($this->isFieldStart($line)) {
            $this->setFieldName($line);
            $this->CURRENT_STATE = 'FIELD_PARAMS';
        }
    }

    private function automaton($line) {
        switch ($this->CURRENT_STATE) {
            case 'START':
                $this->automatonStartCheck($line);
                break;

            case 'FORM':
                $this->addForm($line);
                $this->CURRENT_STATE = 'FORM_ATTRIBS';
                break;

            case 'FORM_ATTRIBS':
                $this->addFormAttributes($line);
                $this->CURRENT_STATE = 'START';
                break;
                
            case 'GROUP':
                $this->addGroup($line);
                $this->CURRENT_STATE = 'GROUP_ATTRIBS';
                break;

            case 'GROUP_ATTRIBS':
                if ($this->addGroupAttributes($line)) {
                    $this->CURRENT_STATE = 'FIELD';
                    break;                    
                }
            case 'FIELD':
                $this->setFieldName($line);
                $this->CURRENT_STATE = 'FIELD_PARAMS';
                break;

            case 'FIELD_PARAMS':
                $this->addFieldParams($line);
                $this->CURRENT_STATE = 'VALIDATIONS';
                break;

            case 'VALIDATIONS':
                $this->addFieldValidations($line);
                $this->CURRENT_STATE = 'FIELD_ATTRIBS';
                break;

            case 'FIELD_ATTRIBS':
                if ($this->addFieldAttributes($line)) {
                    $this->CURRENT_STATE = 'START';
                } else {
                    $this->automatonStartCheck($line);
                }
                break;
        }
    }

    private function isDataLine($line) {
        return !($this->isComment($line) or $this->isBlankLine($line));
    }

    private function parse($file) {
        $lines = $this->getFile($file);
        $lines = array_map('trim', $lines);

        for ($i = 0; $i < count($lines); $i++) {
            if ($this->isDataLine($lines[$i])) {
                $this->automaton($lines[$i]);
            }
        }

        return $this->Form;
    }

    public static function load($file) {
        $parser = new MorpheusParser();
        return $parser->parse($file);
    }
}