parse.php

<?php
/**
 * IPPcode22 parser
 * @author Aleksandr Verevkin (xverev00), VUT FIT IPP 2021/2022
 */

// setting to show errors on stderr
ini_set('display_errors', 'stderr');

/**
 * Class with utilities
 */
final class Utils
{
    // errors
    const PARAM_ERR = 10;
    const HEADER_ERR = 21;
    const OPCODE_ERR = 22;
    const LEX_SYN_ERR = 23;

    /**
     * Print error message and exit program with given return code
     *
     * @param int $err error code
     * @param string $msg error message
     */
    function error(int $err, string $msg) {
        fwrite(STDERR, "Error: " . $msg . "\n");
        exit($err);
    }

    /**
     * Check if symbol is variable or constant representation
     *
     * @param string $operand symbol to be checked
     * @param DOMDocument $xml output XML document
     * @param int $arg_num number of argument
     * @return DOMElement new argument element
     */
    function check_symb(string $operand, DOMDocument $xml, int $arg_num) : DOMElement {
        $type = explode("@", $operand, 2);
        if ($type[0] == "GF" || $type[0] == "LF" || $type[0] == "TF") {
            $arg = $xml->createElement("arg$arg_num", htmlspecialchars($operand));
            $arg->setAttribute("type", "var");
        } else {
            $arg = $xml->createElement("arg$arg_num", htmlspecialchars($type[1]));
            $arg->setAttribute("type", $type[0]);
        }
        return $arg;
    }

    /**
     * Check if given program arguments are supported
     *
     * @param int $argc count of given arguments
     * @param array $argv array of given arguments
     */
    function check_args(int $argc, array $argv) {
        switch ($argc) {
            // program don't have additional arguments
            case 1:
                break;
            // program has 1 argument
            case 2:
                // check if it's --help argument
                if ($argv[1] == "--help") {
                    echo HELP;
                    exit;
                    // else return error
                } else {
                    $this->error(UTILS::PARAM_ERR, "unknown parameter");
                }
            // program has more than 1 additional arguments -> error
            default:
                $this->error(UTILS::PARAM_ERR, "wrong amount of parameters");
        }
    }
}
// help message
const HELP = <<<EOD
            usage: php8.1 parse.php < file [--help]

            The script of filter type reads the source code in IPPcode22, 
            checks the lexical and syntactic correctness of the code and 
            prints to standard output XML representation of the program. 

            options:
              --help        prints short help message\n
EOD;
// regex representation of identifiers
const SPEC_CHAR = "_\-$&%*!?";
const HEADER = "%^\.IPPcode22$%i";
const FRAMES = "(GF|LF|TF)";
const NIL = "(nil@nil)";
const BOOL = "(bool@(true|false))";
const DECIMAL = "([0-9]+)";
const OCTAL = "(0[oO]?[0-7]+)";
const HEXADECIMAL = "(0[xX][0-9a-fA-F]+)";
const INT = "(int@(\+|\-)?(" . DECIMAL . "|" . OCTAL . "|" . HEXADECIMAL . "))";
const STRING = "((string)@((\\\\[0-9]{3})|[^\s\#\\\\])*)";
const TYPE = "~^(bool|int|string)$~";
const CONSTANT = "(" . NIL . "|" . BOOL . "|" . INT . "|" . STRING . ")";
const IDENTIFIER_SOLO = "([A-Za-z" . SPEC_CHAR . "][0-9A-Za-z" . SPEC_CHAR . "]*)";
const IDENTIFIER = "~^" . IDENTIFIER_SOLO . "$~";
const VARIABLE_SOLO = "(" . FRAMES . "@" . IDENTIFIER_SOLO . ")";
const VARIABLE = "~^" . VARIABLE_SOLO . "$~";
const SYMBOL = "~^(" . CONSTANT . "|" . VARIABLE_SOLO . ")$~";
// create Utils instance for latter use
$utils = new Utils();
// check arguments
$utils->check_args($argc, $argv);
// create output xml document
$xml = new DOMDocument("1.0", "UTF-8");
$xml->formatOutput = true;
// create header element
$xml_program = $xml->createElement("program");
$xml_program = $xml->appendChild($xml_program);
$xml_lang = $xml->createAttribute("language");
$xml_lang->value = "IPPcode22";
$xml_program->appendChild($xml_lang);

$ln = 0;
$header = false;
// go through input file, line by line
while ($line = fgets(STDIN)) {
    # cut line from possible comments
    $line = trim(explode("#", $line)[0]);
    if ($line == "") {
        continue;
    }
    // check input for .ippcode22 header
    if (!$header) {
        if(preg_match(HEADER, $line)) {
            $header = true;
            continue;
        } else {
            $utils->error(UTILS::HEADER_ERR, "input file should start with '.IPPcode22' header");
        }
    }
    // split line into an operand and operands
    $line_args = preg_split("/\s+/", $line);
    $ln++;
    $xmlInstruction = $xml->createElement("instruction");
    $xmlInstruction->setAttribute("order", $ln);
    $xmlInstruction->setAttribute("opcode", strtoupper($line_args[0]));
    // check first line argument on operand
    switch (strtoupper($line_args[0])) {
        // no operands
        case "CREATEFRAME":
        case "PUSHFRAME":
        case "POPFRAME":
        case "RETURN":
        case "BREAK":
            if (count($line_args) != 1) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            break;
        // <var>
        case "DEFVAR":
        case "POPS":
            if (count($line_args) != 2) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(VARIABLE, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "variable identifier");
            }
            $arg1 = $xml->createElement("arg1", htmlspecialchars($line_args[1]));
            $arg1->setAttribute("type", "var");
            $xmlInstruction->appendChild($arg1);
            break;
        // <label>
        case "CALL":
        case "LABEL":
        case "JUMP":
            if (count($line_args) != 2) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(IDENTIFIER, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "label identifier");
            }
            $arg1 = $xml->createElement("arg1", htmlspecialchars($line_args[1]));
            $arg1->setAttribute("type", "label");
            $xmlInstruction->appendChild($arg1);
            break;
        // <symb>
        case "PUSHS":
        case "WRITE":
        case "EXIT":
        case "DPRINT":
            if (count($line_args) != 2) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(SYMBOL, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "symbol identifier");
            }
            $arg1 = $utils->check_symb($line_args[1], $xml, 1);
            $xmlInstruction->appendChild($arg1);
            break;
        // <var> <symb>
        case "MOVE":
        case "INT2CHAR":
        case "STRLEN":
        case "TYPE":
        case "NOT":
            if (count($line_args) != 3) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(VARIABLE, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "variable identifier");
            }
            if (!preg_match(SYMBOL, $line_args[2])) {
                $utils->error(UTILS::LEX_SYN_ERR, "symbol identifier");
            }
            $arg1 = $xml->createElement("arg1", htmlspecialchars($line_args[1]));
            $arg1->setAttribute("type", "var");
            $arg2 = $utils->check_symb($line_args[2], $xml, 2);
            $xmlInstruction->appendChild($arg1);
            $xmlInstruction->appendChild($arg2);
            break;
        // <var> <type>
        case "READ":
            if (count($line_args) != 3) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(VARIABLE, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "variable identifier");
            }
            if (!preg_match(TYPE, $line_args[2])) {
                $utils->error(UTILS::LEX_SYN_ERR, "type identifier");
            }
            $arg1 = $xml->createElement("arg1", htmlspecialchars($line_args[1]));
            $arg1->setAttribute("type", "var");
            $arg2 = $xml->createElement("arg2", htmlspecialchars($line_args[2]));
            $arg2->setAttribute("type", "type");
            $xmlInstruction->appendChild($arg1);
            $xmlInstruction->appendChild($arg2);
            break;
        // <var> <symb1> <symb2>
        case "ADD":
        case "SUB":
        case "MUL":
        case "IDIV":
        case "LT":
        case "GT":
        case "EQ":
        case "AND":
        case "OR":
        case "STRI2INT":
        case "CONCAT":
        case "GETCHAR":
        case "SETCHAR":
            if (count($line_args) != 4) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(VARIABLE, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "variable identifier");
            }
            if (!preg_match(SYMBOL, $line_args[2])) {
                $utils->error(UTILS::LEX_SYN_ERR, "symbol identifier");
            }
            if (!preg_match(SYMBOL, $line_args[3])) {
                $utils->error(UTILS::LEX_SYN_ERR, "symbol identifier");
            }
            $arg1 = $xml->createElement("arg1", htmlspecialchars($line_args[1]));
            $arg1->setAttribute("type", "var");
            $arg2 = $utils->check_symb($line_args[2], $xml, 2);
            $arg3 = $utils->check_symb($line_args[3], $xml, 3);
            $xmlInstruction->appendChild($arg1);
            $xmlInstruction->appendChild($arg2);
            $xmlInstruction->appendChild($arg3);
            break;
        // <label> <symb1> <symb2>
        case "JUMPIFEQ":
        case "JUMPIFNEQ":
            if (count($line_args) != 4) {
                $utils->error(UTILS::LEX_SYN_ERR, "wrong amount of operands");
            }
            if (!preg_match(IDENTIFIER, $line_args[1])) {
                $utils->error(UTILS::LEX_SYN_ERR, "label identifier");
            }
            if (!preg_match(SYMBOL, $line_args[2])) {
                $utils->error(UTILS::LEX_SYN_ERR, "symbol identifier");
            }
            if (!preg_match(SYMBOL, $line_args[3])) {
                $utils->error(UTILS::LEX_SYN_ERR, "symbol identifier");
            }
            $arg1 = $xml->createElement("arg1", htmlspecialchars($line_args[1]));
            $arg1->setAttribute("type", "label");
            $arg2 = $utils->check_symb($line_args[2], $xml, 2);
            $arg3 = $utils->check_symb($line_args[3], $xml, 3);
            $xmlInstruction->appendChild($arg1);
            $xmlInstruction->appendChild($arg2);
            $xmlInstruction->appendChild($arg3);
            break;
        default:
            $utils->error(UTILS::OPCODE_ERR, "unknown opcode");
    }
    $xml_program->appendChild($xmlInstruction);
}
echo $xml->saveXML();
exit;