https://github.com/krakphp/lex
Functional Lexing Library
https://github.com/krakphp/lex
Last synced: 11 months ago
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Functional Lexing Library
- Host: GitHub
- URL: https://github.com/krakphp/lex
- Owner: krakphp
- License: mit
- Created: 2016-04-25T22:30:47.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2020-05-30T20:18:26.000Z (about 6 years ago)
- Last Synced: 2025-07-19T06:40:48.302Z (11 months ago)
- Language: PHP
- Size: 7.81 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
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README
# Lex
Lex is a library for lexical analysis in PHP. Currently, only simple regular expression lexers are available; but considering that you shouldn't be lexing anything complex in php, this should be fine :).
## Installation
```
composer require krak/lex
```
## Usage
```php
TOK_INT,
'/\+/A' => TOK_PLUS,
'/\-/A' => TOK_MINUS,
'/\s+/A' => TOK_WS
]);
// decorator for skipping tokens, in this case, just throw away the whitespace tokens
$lex = skipLexer($lex, [TOK_WS]);
// lex the input and return an iterator of tokens
$toks = $lex('1 + 2 - 3');
foreach ($toks as $matched_tok) {
printf(
"Matched token '%s' with input '%s' at offset %d\n",
$matched_tok->token,
$matched_tok->match,
$matched_tok->offset
);
}
```
The following program would output
```
Matched token 'int' with input '1' at offset 0
Matched token 'plus' with input '+' at offset 2
Matched token 'int' with input '2' at offset 4
Matched token 'minus' with input '-' at offset 6
Matched token 'int' with input '3' at offset 8
```
## TokenStream
A token stream is a simple interface for consuming one token at a time. This is very useful for [Recursive Decent Parsers](https://en.wikipedia.org/wiki/Recursive_descent_parser)
```php
'a', '/b/A' => 'b']);
$lex = tokenStreamLexer($lex);
$stream = $lex('aba');
assert($stream->peek() == 'a');
assert($stream->getToken() == 'a');
assert($stream->getToken() == 'b');
assert($stream->getToken() == 'a');
assert($stream->isEmpty());
```
## API
### Lexers
Each lexer will accept a string input and then return an iterable of `MatchedToken`
#### lexer($token_map, $throw = true)
Main lexer which lexes the strings based off of the `$token_map`. `$throw` determines whether or not the lexer should throw an exception on unrecognized input.
#### skipLexer($lex, $tokens)
Lexer decorator which will skip any Matched Tokens in the set of the `$tokens` passed in.
#### tokenStreamLexer($lex)
Lexer decorator that will convert the output of the `$lex` into a `TokenStream`
#### mockLexer($tokens)
Returns `$tokens` as is.
### class MatchedToken
#### $match
Returns the text that was matched.
#### $token
Returns the token name that was matched.
#### $offset
Returns the string offset at which the match started.
### interface TokenStream extends \\IteratorAggregate
#### getToken()
Returns the current token and advances the internal pointer up by one.
#### peek()
Returns the current token but does *not* advance the internal pointer
#### isEmpty()
returns true if the token stream is empty, false if not.