PHP: Lexer examples

Lexer examples

Example #1 Tokenize comma separated integer list

<?php

use Parle\Token;
use Parle\Lexer;
use Parle\LexerException;

/* name => id */
$token = array(
        "COMMA" => 1,
        "CRLF" => 2,
        "DECIMAL" => 3,
);
/* id => name */
$tokenIdToName = array_flip($token);

$lex = new Lexer;
$lex->push("[\x2c]", $token["COMMA"]);
$lex->push("[\r][\n]", $token["CRLF"]);
$lex->push("[\d]+", $token["DECIMAL"]);
$lex->build();

$in = "0,1,2\r\n3,42,5\r\n6,77,8\r\n";

$lex->consume($in);

do {
        $lex->advance();
        $tok = $lex->getToken();

        if (Token::UNKNOWN == $tok->id) {
                throw new LexerException("Unknown token '{$tok->value}' at offset {$lex->marker}.");
        }

        echo "TOKEN: ", $tokenIdToName[$tok->id], PHP_EOL;
} while (Token::EOI != $tok->id);

Example #2 Tokenize assign statement

<?php

use Parle\{Token, Lexer};

$lex = new Lexer;

$lex->push("\$[a-zA-Z_][a-zA-Z0-9_]*", 1);
$lex->push("=", 2);
$lex->push("\d+", 3);
$lex->push(";", 4);

$lex->build();

$lex->consume('$x = 42; $y = 24;');

do {
    $lex->advance();
    $tok = $lex->getToken();
    var_dump($tok);
} while (Token::EOI != $tok->id);

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