Parser

Character-by-character string parsing library.

Contents

• Features
• Requirements
• Usage
  • Creating a parser
  • Parser properties
  • Parser method overview
  • Example INI parser implementation
• Character types
  • Customizing character types

Features

• line number tracking (can be disabled for performance)
• supports CR, LF and CRLF line endings
• verbose exceptions
• many methods to navigate and operate the parser
  • forward / backward peeking and seeking
  • forward / backward character consumption
  • state stack
• character types
• expectations

Requirements

• PHP 7.1+

Usage

Creating a parser

Create a new parser instance with string input.

The parser begins at the first character.

<?php

use Kuria\Parser\Parser;

$input = 'foo bar baz';

$parser = new Parser($input);

Parser properties

The parser has several public properties that can be used to inspect its current state:

• $parser->i - current position
• $parser->char - current character (or NULL at the end of input)
• $parser->lastChar - last character (or NULL at the start of input)
• $parser->line - current line (or NULL if line tracking is disabled)
• $parser->end - end of input indicator (TRUE at the end, FALSE otherwise)
• $parser->vars - user-defined variables attached to the current state

Warning

All of the public properties (with the exception of $parser->vars) are read-only and must not be modified directly by the calling code.

Use the built-in parser methods to mutate the parser state. See Parser method overview.

Parser method overview

Refer to doc comments of the respective methods for more information.

Also see Character types.

Static methods

• getCharType($char): int - determine character type
• getCharTypeName($charType): string - get human-readable character type name

Instance methods

• getInput(): string - get the input string
• setInput($input): void - replace the input string (this also resets the parser)
• getLength(): int - get length of the input string
• isTrackingLineNumbers(): bool - see if line number tracking is enabled
• type(): int - get type of the current character
• is(...$types): bool - check whether the current character is of one of the specified types
• atNewline(): bool - see if the parser is at the start of a newline sequence
• eat(): ?string - go to the next character and return the current one (returns NULL at the end)
• spit(): ?string - go to the previous character and return the current one (returns NULL at the beginning)
• shift(): ?string - go to the next character and return it (returns NULL at the end)
• unshift(): ?string - go to the previous character and return it (returns NULL at the beginning)
• peek($offset, $absolute = false): ?string - get character at the given offset or absolute position (does not affect state)
• seek($offset, $absolute = false): void - alter current position
• reset(): void - reset states, vars and rewind to the beginning
• rewind(): void - rewind to the beginning
• eatChar($char): ?string - consume specific character and return the next character
• tryEatChar(): bool - attempt to consume specific character and return success state
• eatType($type): string - consume all characters of the specified type
• eatTypes($typeMap): string - consume all characters of the specified types
• eatWs(): string - consume whitespace, if any
• eatUntil($delimiterMap, $skipDelimiter = true, $allowEnd = false): string - consume all characters until the specified delimiters
• eatUntilEol($skip = true): string - consume all character until end of line or input
• eatEol(): string - consume end of line sequence
• eatRest(): string - consume reamaining characters
• getChunk($start, $end): string - get chunk of the input (does not affect state)
• detectEol(): ?string - find and return the next end of line sequence (does not affect state)
• countStates(): int - get number of stored states
• pushState(): void - store the current state
• revertState(): void - revert to the last stored state and pop it
• popState(): void - pop the last stored state without reverting to it
• clearStates(): void - throw away all stored states
• expectEnd(): void - ensure that the parser is at the end
• expectNotEnd(): void - ensure that the parser is not at the end
• expectChar($expectedChar): void - ensure that the current character matches the expectation
• expectCharType($expectedType): void - ensure that the current character is of the given type

Example INI parser implementation

<?php

use Kuria\Parser\Parser;

/**
 * INI parser (example)
 */
class IniParser
{
    /**
     * Parse an INI string
     */
    public function parse(string $string): array
    {
        // create parser
        $parser = new Parser($string);

        // prepare variables
        $data = [];
        $currentSection = null;

        // parse
        while (!$parser->end) {
            // skip whitespace
            $parser->eatWs();
            if ($parser->end) {
                break;
            }

            // parse the current thing
            if ($parser->char === '[') {
                // a section
                $currentSection = $this->parseSection($parser);
            } elseif ($parser->char === ';') {
                // a comment
                $this->skipComment($parser);
            } else {
                // a key=value pair
                [$key, $value] = $this->parseKeyValue($parser);

                // add to output
                if ($currentSection === null) {
                    $data[$key] = $value;
                } else {
                    $data[$currentSection][$key] = $value;
                }
            }
        }

        return $data;
    }

    /**
     * Parse a section and return its name
     */
    private function parseSection(Parser $parser): string
    {
        // we should be at the [ character now, eat it
        $parser->eatChar('[');

        // eat everything until ]
        $sectionName = $parser->eatUntil(']');

        return $sectionName;
    }

    /**
     * Skip a commented-out line
     */
    private function skipComment(Parser $parser): void
    {
        // we should be at the ; character now, eat it
        $parser->eatChar(';');

        // eat everything until the end of line
        $parser->eatUntilEol();
    }

    /**
     * Parse a key=value pair
     */
    private function parseKeyValue(Parser $parser): array
    {
        // we should be at the first character of the key
        // eat characters until = is found
        $key = $parser->eatUntil('=');

        // eat everything until the end of line
        // that is our value
        $value = trim($parser->eatUntilEol());

        return [$key, $value];
    }
}

Using the parser

<?php

$iniParser = new IniParser();

$iniString = <<<INI
; An example comment
name=Foo
type=Bar

[options]
size=150x100
onload=
INI;

$data = $iniParser->parse($iniString);

print_r($data);

Output:

Array
(
    [name] => Foo
    [type] => Bar
    [options] => Array
        (
            [size] => 150x100
            [onload] =>
        )

)

Character types

The table below lists the default character types.

These types are available as constants on the Parser class:

• Parser::C_NONE - no character (NULL)
• Parser::C_WS - whitespace (tab, linefeed, vertical tab, form feed, carriage return and space)
• Parser::C_NUM - numeric character (0-9)
• Parser::C_STR - string character (a-z, A-Z, _ and any 8-bit char)
• Parser::C_CTRL - control character (ASCII 127 and ASCII < 32 except whitespace)
• Parser::C_SPECIAL - !"#$%&'()*+,-./:;<=>?@[\\]^\`{|}~

#	Character	Type
NULL	none	C_NONE
0	0x00	C_CTRL
1	0x01	C_CTRL
2	0x02	C_CTRL
3	0x03	C_CTRL
4	0x04	C_CTRL
5	0x05	C_CTRL
6	0x06	C_CTRL
7	0x07	C_CTRL
8	0x08	C_CTRL
9	\t	C_WS
10	\n	C_WS
11	\v	C_WS
12	\f	C_WS
13	\r	C_WS
14	0x0e	C_CTRL
15	0x0f	C_CTRL
16	0x10	C_CTRL
17	0x11	C_CTRL
18	0x12	C_CTRL
19	0x13	C_CTRL
20	0x14	C_CTRL
21	0x15	C_CTRL
22	0x16	C_CTRL
23	0x17	C_CTRL
24	0x18	C_CTRL
25	0x19	C_CTRL
26	0x1a	C_CTRL
27	0x1b	C_CTRL
28	0x1c	C_CTRL
29	0x1d	C_CTRL
30	0x1e	C_CTRL
31	0x1f	C_CTRL
32	0x20	C_WS
33	!	C_SPECIAL
34	"	C_SPECIAL
35	#	C_SPECIAL
36	$	C_SPECIAL
37	%	C_SPECIAL
38	&	C_SPECIAL
39	'	C_SPECIAL
40	(	C_SPECIAL
41	)	C_SPECIAL
42	*	C_SPECIAL
43	+	C_SPECIAL
44	,	C_SPECIAL
45	-	C_SPECIAL
46	.	C_SPECIAL
47	/	C_SPECIAL
48	0	C_NUM
49	1	C_NUM
50	2	C_NUM
51	3	C_NUM
52	4	C_NUM
53	5	C_NUM
54	6	C_NUM
55	7	C_NUM
56	8	C_NUM
57	9	C_NUM
58	:	C_SPECIAL
59	;	C_SPECIAL
60	<	C_SPECIAL
61	=	C_SPECIAL
62	>	C_SPECIAL
63	?	C_SPECIAL
64	@	C_SPECIAL
65	A	C_STR
66	B	C_STR
67	C	C_STR
68	D	C_STR
69	E	C_STR
70	F	C_STR
71	G	C_STR
72	H	C_STR
73	I	C_STR
74	J	C_STR
75	K	C_STR
76	L	C_STR
77	M	C_STR
78	N	C_STR
79	O	C_STR
80	P	C_STR
81	Q	C_STR
82	R	C_STR
83	S	C_STR
84	T	C_STR
85	U	C_STR
86	V	C_STR
87	W	C_STR
88	X	C_STR
89	Y	C_STR
90	Z	C_STR
91	[	C_SPECIAL
92	\	C_SPECIAL
93	]	C_SPECIAL
94	^	C_SPECIAL
95	_	C_STR
96	`	C_SPECIAL
97	a	C_STR
98	b	C_STR
99	c	C_STR
100	d	C_STR
101	e	C_STR
102	f	C_STR
103	g	C_STR
104	h	C_STR
105	i	C_STR
106	j	C_STR
107	k	C_STR
108	l	C_STR
109	m	C_STR
110	n	C_STR
111	o	C_STR
112	p	C_STR
113	q	C_STR
114	r	C_STR
115	s	C_STR
116	t	C_STR
117	u	C_STR
118	v	C_STR
119	w	C_STR
120	x	C_STR
121	y	C_STR
122	z	C_STR
123	{	C_SPECIAL
124	|	C_SPECIAL
125	}	C_SPECIAL
126	~	C_SPECIAL
127	0x7f	C_CTRL
128	0x80	C_STR
129	0x81	C_STR
130	0x82	C_STR
131	0x83	C_STR
132	0x84	C_STR
133	0x85	C_STR
134	0x86	C_STR
135	0x87	C_STR
136	0x88	C_STR
137	0x89	C_STR
138	0x8a	C_STR
139	0x8b	C_STR
140	0x8c	C_STR
141	0x8d	C_STR
142	0x8e	C_STR
143	0x8f	C_STR
144	0x90	C_STR
145	0x91	C_STR
146	0x92	C_STR
147	0x93	C_STR
148	0x94	C_STR
149	0x95	C_STR
150	0x96	C_STR
151	0x97	C_STR
152	0x98	C_STR
153	0x99	C_STR
154	0x9a	C_STR
155	0x9b	C_STR
156	0x9c	C_STR
157	0x9d	C_STR
158	0x9e	C_STR
159	0x9f	C_STR
160	0xa0	C_STR
161	0xa1	C_STR
162	0xa2	C_STR
163	0xa3	C_STR
164	0xa4	C_STR
165	0xa5	C_STR
166	0xa6	C_STR
167	0xa7	C_STR
168	0xa8	C_STR
169	0xa9	C_STR
170	0xaa	C_STR
171	0xab	C_STR
172	0xac	C_STR
173	0xad	C_STR
174	0xae	C_STR
175	0xaf	C_STR
176	0xb0	C_STR
177	0xb1	C_STR
178	0xb2	C_STR
179	0xb3	C_STR
180	0xb4	C_STR
181	0xb5	C_STR
182	0xb6	C_STR
183	0xb7	C_STR
184	0xb8	C_STR
185	0xb9	C_STR
186	0xba	C_STR
187	0xbb	C_STR
188	0xbc	C_STR
189	0xbd	C_STR
190	0xbe	C_STR
191	0xbf	C_STR
192	0xc0	C_STR
193	0xc1	C_STR
194	0xc2	C_STR
195	0xc3	C_STR
196	0xc4	C_STR
197	0xc5	C_STR
198	0xc6	C_STR
199	0xc7	C_STR
200	0xc8	C_STR
201	0xc9	C_STR
202	0xca	C_STR
203	0xcb	C_STR
204	0xcc	C_STR
205	0xcd	C_STR
206	0xce	C_STR
207	0xcf	C_STR
208	0xd0	C_STR
209	0xd1	C_STR
210	0xd2	C_STR
211	0xd3	C_STR
212	0xd4	C_STR
213	0xd5	C_STR
214	0xd6	C_STR
215	0xd7	C_STR
216	0xd8	C_STR
217	0xd9	C_STR
218	0xda	C_STR
219	0xdb	C_STR
220	0xdc	C_STR
221	0xdd	C_STR
222	0xde	C_STR
223	0xdf	C_STR
224	0xe0	C_STR
225	0xe1	C_STR
226	0xe2	C_STR
227	0xe3	C_STR
228	0xe4	C_STR
229	0xe5	C_STR
230	0xe6	C_STR
231	0xe7	C_STR
232	0xe8	C_STR
233	0xe9	C_STR
234	0xea	C_STR
235	0xeb	C_STR
236	0xec	C_STR
237	0xed	C_STR
238	0xee	C_STR
239	0xef	C_STR
240	0xf0	C_STR
241	0xf1	C_STR
242	0xf2	C_STR
243	0xf3	C_STR
244	0xf4	C_STR
245	0xf5	C_STR
246	0xf6	C_STR
247	0xf7	C_STR
248	0xf8	C_STR
249	0xf9	C_STR
250	0xfa	C_STR
251	0xfb	C_STR
252	0xfc	C_STR
253	0xfd	C_STR
254	0xfe	C_STR
255	0xff	C_STR

Customizing character types

Character types can be customized by extending the base Parser class.

The following example changes "-" and "." from CHAR_SPECIAL to CHAR_STR and inherits everything else.

<?php

class CustomParser extends Parser
{
    const CHAR_TYPE_MAP = [
        '-' => self::C_STR,
        '.' => self::C_STR,
    ] + parent::CHAR_TYPE_MAP; // inherit everything else
}

// usage example
$parser = new CustomParser('foo-bar.baz');

var_dump($parser->eatType(CustomParser::C_STR));

Output:

string(11) "foo-bar.baz"