sqlite-database-integration / wp-includes / sqlite / class-wp-sqlite-query-rewriter.php

class-wp-sqlite-query-rewriter.php in SQLite Database Integration 2.2.21, at wp-includes/sqlite/class-wp-sqlite-query-rewriter.php

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1	<?php
2	/**
3	* Class WP_SQLite_Query_Rewriter
4	*
5	* @package wp-sqlite-integration
6	*/
7
8	/**
9	* The query rewriter class.
10	*/
11	class WP_SQLite_Query_Rewriter {
12
13	/**
14	* An array of input token objects.
15	*
16	* @var WP_SQLite_Token[]
17	*/
18	public $input_tokens = array();
19
20	/**
21	* An array of output token objects.
22	*
23	* @var WP_SQLite_Token[]
24	*/
25	public $output_tokens = array();
26
27	/**
28	* The current index.
29	*
30	* @var int
31	*/
32	public $index = -1;
33
34	/**
35	* The maximum index.
36	*
37	* @var int
38	*/
39	public $max = -1;
40
41	/**
42	* The call stack.
43	*
44	* @var array
45	*/
46	public $call_stack = array();
47
48	/**
49	* The current depth.
50	*
51	* @var int
52	*/
53	public $depth = 0;
54
55	/**
56	* The current token.
57	*
58	* @var WP_SQLite_Token
59	*/
60	private $token;
61
62	/**
63	* The last function call.
64	*
65	* @var WP_SQLite_Token
66	*/
67	private $last_function_call;
68
69	/**
70	* Constructor.
71	*
72	* @param WP_SQLite_Token[] $input_tokens Array of token objects.
73	*/
74	public function __construct( $input_tokens ) {
75	$this->input_tokens = $input_tokens;
76	$this->max = count( $input_tokens );
77	}
78
79	/**
80	* Returns the updated query.
81	*
82	* @return string
83	*/
84	public function get_updated_query() {
85	$query = '';
86	foreach ( $this->output_tokens as $token ) {
87	$query .= $token->token;
88	}
89	return $query;
90	}
91
92	/**
93	* Add a token to the output.
94	*
95	* @param WP_SQLite_Token $token Token object.
96	*/
97	public function add( $token ) {
98	if ( $token ) {
99	$this->output_tokens[] = $token;
100	}
101	}
102
103	/**
104	* Add multiple tokens to the output.
105	*
106	* @param WP_SQLite_Token[] $tokens Array of token objects.
107	*/
108	public function add_many( $tokens ) {
109	$this->output_tokens = array_merge( $this->output_tokens, $tokens );
110	}
111
112	/**
113	* Replaces all tokens.
114	*
115	* @param WP_SQLite_Token[] $tokens Array of token objects.
116	*/
117	public function replace_all( $tokens ) {
118	$this->output_tokens = $tokens;
119	}
120
121	/**
122	* Peek at the next tokens and return one that matches the given criteria.
123	*
124	* @param array $query Optional. Search query.
125	* [
126	* 'type' => string\|null, // Token type.
127	* 'flags' => int\|null, // Token flags.
128	* 'values' => string\|null, // Token values.
129	* ].
130	*
131	* @return WP_SQLite_Token
132	*/
133	public function peek( $query = array() ) {
134	$type = isset( $query['type'] ) ? $query['type'] : null;
135	$flags = isset( $query['flags'] ) ? $query['flags'] : null;
136	$values = isset( $query['value'] )
137	? ( is_array( $query['value'] ) ? $query['value'] : array( $query['value'] ) )
138	: null;
139
140	$i = $this->index;
141	while ( ++$i < $this->max ) {
142	if ( $this->input_tokens[ $i ]->matches( $type, $flags, $values ) ) {
143	return $this->input_tokens[ $i ];
144	}
145	}
146	}
147
148	/**
149	* Move forward and return the next tokens that match the given criteria.
150	*
151	* @param int $nth The nth token to return.
152	*
153	* @return WP_SQLite_Token
154	*/
155	public function peek_nth( $nth ) {
156	$found = 0;
157	for ( $i = $this->index + 1;$i < $this->max;$i++ ) {
158	$token = $this->input_tokens[ $i ];
159	if ( ! $token->is_semantically_void() ) {
160	++$found;
161	}
162	if ( $found === $nth ) {
163	return $this->input_tokens[ $i ];
164	}
165	}
166	}
167
168	/**
169	* Consume all the tokens.
170	*
171	* @param array $query Search query.
172	*
173	* @return void
174	*/
175	public function consume_all( $query = array() ) {
176	while ( $this->consume( $query ) ) {
177	// Do nothing.
178	}
179	}
180
181	/**
182	* Consume the next tokens and return one that matches the given criteria.
183	*
184	* @param array $query Search query.
185	* [
186	* 'type' => null, // Optional. Token type.
187	* 'flags' => null, // Optional. Token flags.
188	* 'values' => null, // Optional. Token values.
189	* ].
190	*
191	* @return WP_SQLite_Token\|null
192	*/
193	public function consume( $query = array() ) {
194	$tokens = $this->move_forward( $query );
195	$this->output_tokens = array_merge( $this->output_tokens, $tokens );
196	return $this->token;
197	}
198
199	/**
200	* Drop the last consumed token and return it.
201	*
202	* @return WP_SQLite_Token\|null
203	*/
204	public function drop_last() {
205	return array_pop( $this->output_tokens );
206	}
207
208	/**
209	* Skip over the next tokens and return one that matches the given criteria.
210	*
211	* @param array $query Search query.
212	* [
213	* 'type' => null, // Optional. Token type.
214	* 'flags' => null, // Optional. Token flags.
215	* 'values' => null, // Optional. Token values.
216	* ].
217	*
218	* @return WP_SQLite_Token\|null
219	*/
220	public function skip( $query = array() ) {
221	$this->skip_and_return_all( $query );
222	return $this->token;
223	}
224
225	/**
226	* Skip over the next tokens until one matches the given criteria,
227	* and return all the skipped tokens.
228	*
229	* @param array $query Search query.
230	* [
231	* 'type' => null, // Optional. Token type.
232	* 'flags' => null, // Optional. Token flags.
233	* 'values' => null, // Optional. Token values.
234	* ].
235	*
236	* @return WP_SQLite_Token[]
237	*/
238	public function skip_and_return_all( $query = array() ) {
239	$tokens = $this->move_forward( $query );
240
241	/*
242	* When skipping over whitespaces, make sure to consume
243	* at least one to avoid SQL syntax errors.
244	*/
245	foreach ( $tokens as $token ) {
246	if ( $token->matches( WP_SQLite_Token::TYPE_WHITESPACE ) ) {
247	$this->add( $token );
248	break;
249	}
250	}
251
252	return $tokens;
253	}
254
255	/**
256	* Returns the next tokens that match the given criteria.
257	*
258	* @param array $query Search query.
259	* [
260	* 'type' => string\|null, // Optional. Token type.
261	* 'flags' => int\|null, // Optional. Token flags.
262	* 'values' => string\|null, // Optional. Token values.
263	* ].
264	*
265	* @return array
266	*/
267	private function move_forward( $query = array() ) {
268	$type = isset( $query['type'] ) ? $query['type'] : null;
269	$flags = isset( $query['flags'] ) ? $query['flags'] : null;
270	$values = isset( $query['value'] )
271	? ( is_array( $query['value'] ) ? $query['value'] : array( $query['value'] ) )
272	: null;
273	$depth = isset( $query['depth'] ) ? $query['depth'] : null;
274
275	$buffered = array();
276	while ( true ) {
277	if ( ++$this->index >= $this->max ) {
278	$this->token = null;
279	$this->call_stack = array();
280	break;
281	}
282	$this->token = $this->input_tokens[ $this->index ];
283	$this->update_call_stack();
284	$buffered[] = $this->token;
285	if (
286	( null === $depth \|\| $this->depth === $depth )
287	&& $this->token->matches( $type, $flags, $values )
288	) {
289	break;
290	}
291	}
292
293	return $buffered;
294	}
295
296	/**
297	* Returns the last call stack element.
298	*
299	* @return array\|null
300	*/
301	public function last_call_stack_element() {
302	return count( $this->call_stack ) ? $this->call_stack[ count( $this->call_stack ) - 1 ] : null;
303	}
304
305	/**
306	* Updates the call stack.
307	*
308	* @return void
309	*/
310	private function update_call_stack() {
311	if ( $this->token->flags & WP_SQLite_Token::FLAG_KEYWORD_FUNCTION ) {
312	$this->last_function_call = $this->token->value;
313	}
314	if ( WP_SQLite_Token::TYPE_OPERATOR === $this->token->type ) {
315	switch ( $this->token->value ) {
316	case '(':
317	if ( $this->last_function_call ) {
318	array_push(
319	$this->call_stack,
320	array(
321	'function' => $this->last_function_call,
322	'depth' => $this->depth,
323	)
324	);
325	$this->last_function_call = null;
326	}
327	++$this->depth;
328	break;
329
330	case ')':
331	--$this->depth;
332	$call_parent = $this->last_call_stack_element();
333	if (
334	$call_parent &&
335	$call_parent['depth'] === $this->depth
336	) {
337	array_pop( $this->call_stack );
338	}
339	break;
340	}
341	}
342	}
343	}
344