344 lines
7.8 KiB
PHP
344 lines
7.8 KiB
PHP
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<?php
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/**
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* Class WP_SQLite_Query_Rewriter
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*
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* @package wp-sqlite-integration
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*/
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/**
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* The query rewriter class.
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*/
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class WP_SQLite_Query_Rewriter {
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/**
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* An array of input token objects.
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*
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* @var WP_SQLite_Token[]
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*/
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public $input_tokens = array();
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/**
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* An array of output token objects.
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*
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* @var WP_SQLite_Token[]
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*/
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public $output_tokens = array();
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/**
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* The current index.
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*
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* @var int
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*/
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public $index = -1;
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/**
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* The maximum index.
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*
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* @var int
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*/
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public $max = -1;
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/**
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* The call stack.
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*
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* @var array
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*/
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public $call_stack = array();
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/**
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* The current depth.
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*
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* @var int
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*/
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public $depth = 0;
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/**
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* The current token.
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*
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* @var WP_SQLite_Token
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*/
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private $token;
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/**
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* The last function call.
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*
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* @var WP_SQLite_Token
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*/
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private $last_function_call;
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/**
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* Constructor.
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*
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* @param WP_SQLite_Token[] $input_tokens Array of token objects.
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*/
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public function __construct( $input_tokens ) {
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$this->input_tokens = $input_tokens;
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$this->max = count( $input_tokens );
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}
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/**
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* Returns the updated query.
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*
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* @return string
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*/
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public function get_updated_query() {
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$query = '';
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foreach ( $this->output_tokens as $token ) {
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$query .= $token->token;
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}
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return $query;
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}
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/**
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* Add a token to the output.
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*
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* @param WP_SQLite_Token $token Token object.
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*/
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public function add( $token ) {
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if ( $token ) {
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$this->output_tokens[] = $token;
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}
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}
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/**
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* Add multiple tokens to the output.
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*
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* @param WP_SQLite_Token[] $tokens Array of token objects.
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*/
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public function add_many( $tokens ) {
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$this->output_tokens = array_merge( $this->output_tokens, $tokens );
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}
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/**
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* Replaces all tokens.
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*
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* @param WP_SQLite_Token[] $tokens Array of token objects.
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*/
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public function replace_all( $tokens ) {
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$this->output_tokens = $tokens;
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}
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/**
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* Peek at the next tokens and return one that matches the given criteria.
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*
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* @param array $query Optional. Search query.
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* [
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* 'type' => string|null, // Token type.
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* 'flags' => int|null, // Token flags.
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* 'values' => string|null, // Token values.
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* ].
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*
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* @return WP_SQLite_Token
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*/
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public function peek( $query = array() ) {
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$type = isset( $query['type'] ) ? $query['type'] : null;
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$flags = isset( $query['flags'] ) ? $query['flags'] : null;
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$values = isset( $query['value'] )
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? ( is_array( $query['value'] ) ? $query['value'] : array( $query['value'] ) )
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: null;
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$i = $this->index;
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while ( ++$i < $this->max ) {
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if ( $this->input_tokens[ $i ]->matches( $type, $flags, $values ) ) {
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return $this->input_tokens[ $i ];
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}
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}
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}
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/**
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* Move forward and return the next tokens that match the given criteria.
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*
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* @param int $nth The nth token to return.
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*
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* @return WP_SQLite_Token
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*/
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public function peek_nth( $nth ) {
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$found = 0;
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for ( $i = $this->index + 1;$i < $this->max;$i++ ) {
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$token = $this->input_tokens[ $i ];
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if ( ! $token->is_semantically_void() ) {
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++$found;
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}
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if ( $found === $nth ) {
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return $this->input_tokens[ $i ];
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}
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}
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}
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/**
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* Consume all the tokens.
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*
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* @param array $query Search query.
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*
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* @return void
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*/
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public function consume_all( $query = array() ) {
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while ( $this->consume( $query ) ) {
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// Do nothing.
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}
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}
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/**
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* Consume the next tokens and return one that matches the given criteria.
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*
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* @param array $query Search query.
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* [
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* 'type' => null, // Optional. Token type.
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* 'flags' => null, // Optional. Token flags.
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* 'values' => null, // Optional. Token values.
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* ].
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*
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* @return WP_SQLite_Token|null
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*/
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public function consume( $query = array() ) {
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$tokens = $this->move_forward( $query );
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$this->output_tokens = array_merge( $this->output_tokens, $tokens );
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return $this->token;
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}
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/**
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* Drop the last consumed token and return it.
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*
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* @return WP_SQLite_Token|null
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*/
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public function drop_last() {
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return array_pop( $this->output_tokens );
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}
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/**
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* Skip over the next tokens and return one that matches the given criteria.
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*
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* @param array $query Search query.
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* [
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* 'type' => null, // Optional. Token type.
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* 'flags' => null, // Optional. Token flags.
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* 'values' => null, // Optional. Token values.
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* ].
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*
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* @return WP_SQLite_Token|null
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*/
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public function skip( $query = array() ) {
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$this->skip_and_return_all( $query );
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return $this->token;
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}
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/**
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* Skip over the next tokens until one matches the given criteria,
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* and return all the skipped tokens.
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*
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* @param array $query Search query.
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* [
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* 'type' => null, // Optional. Token type.
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* 'flags' => null, // Optional. Token flags.
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* 'values' => null, // Optional. Token values.
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* ].
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*
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* @return WP_SQLite_Token[]
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*/
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public function skip_and_return_all( $query = array() ) {
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$tokens = $this->move_forward( $query );
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/*
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* When skipping over whitespaces, make sure to consume
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* at least one to avoid SQL syntax errors.
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*/
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foreach ( $tokens as $token ) {
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if ( $token->matches( WP_SQLite_Token::TYPE_WHITESPACE ) ) {
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$this->add( $token );
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break;
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}
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}
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return $tokens;
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}
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/**
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* Returns the next tokens that match the given criteria.
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*
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* @param array $query Search query.
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* [
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* 'type' => string|null, // Optional. Token type.
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* 'flags' => int|null, // Optional. Token flags.
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* 'values' => string|null, // Optional. Token values.
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* ].
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*
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* @return array
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*/
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private function move_forward( $query = array() ) {
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$type = isset( $query['type'] ) ? $query['type'] : null;
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$flags = isset( $query['flags'] ) ? $query['flags'] : null;
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$values = isset( $query['value'] )
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? ( is_array( $query['value'] ) ? $query['value'] : array( $query['value'] ) )
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: null;
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$depth = isset( $query['depth'] ) ? $query['depth'] : null;
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$buffered = array();
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while ( true ) {
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if ( ++$this->index >= $this->max ) {
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$this->token = null;
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$this->call_stack = array();
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break;
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}
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$this->token = $this->input_tokens[ $this->index ];
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$this->update_call_stack();
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$buffered[] = $this->token;
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if (
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( null === $depth || $this->depth === $depth )
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&& $this->token->matches( $type, $flags, $values )
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) {
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break;
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}
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}
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return $buffered;
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}
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/**
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* Returns the last call stack element.
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*
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* @return array|null
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*/
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public function last_call_stack_element() {
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return count( $this->call_stack ) ? $this->call_stack[ count( $this->call_stack ) - 1 ] : null;
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}
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/**
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* Updates the call stack.
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*
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* @return void
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*/
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private function update_call_stack() {
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if ( $this->token->flags & WP_SQLite_Token::FLAG_KEYWORD_FUNCTION ) {
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$this->last_function_call = $this->token->value;
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}
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if ( WP_SQLite_Token::TYPE_OPERATOR === $this->token->type ) {
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switch ( $this->token->value ) {
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case '(':
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if ( $this->last_function_call ) {
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array_push(
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$this->call_stack,
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array(
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'function' => $this->last_function_call,
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'depth' => $this->depth,
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)
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);
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$this->last_function_call = null;
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}
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++$this->depth;
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break;
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case ')':
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--$this->depth;
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$call_parent = $this->last_call_stack_element();
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if (
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$call_parent &&
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$call_parent['depth'] === $this->depth
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) {
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array_pop( $this->call_stack );
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}
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break;
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}
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}
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}
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}
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