405 lines
11 KiB
PHP
405 lines
11 KiB
PHP
<?php
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/**
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* Block Serialization Parser
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*
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* @package WordPress
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*/
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/**
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* Class WP_Block_Parser
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*
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* Parses a document and constructs a list of parsed block objects
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*
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* @since 5.0.0
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* @since 4.0.0 returns arrays not objects, all attributes are arrays
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*/
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class WP_Block_Parser {
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/**
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* Input document being parsed
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*
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* @example "Pre-text\n<!-- wp:paragraph -->This is inside a block!<!-- /wp:paragraph -->"
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*
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* @since 5.0.0
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* @var string
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*/
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public $document;
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/**
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* Tracks parsing progress through document
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*
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* @since 5.0.0
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* @var int
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*/
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public $offset;
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/**
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* List of parsed blocks
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*
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* @since 5.0.0
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* @var WP_Block_Parser_Block[]
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*/
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public $output;
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/**
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* Stack of partially-parsed structures in memory during parse
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*
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* @since 5.0.0
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* @var WP_Block_Parser_Frame[]
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*/
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public $stack;
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/**
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* Parses a document and returns a list of block structures
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*
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* When encountering an invalid parse will return a best-effort
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* parse. In contrast to the specification parser this does not
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* return an error on invalid inputs.
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*
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* @since 5.0.0
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*
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* @param string $document Input document being parsed.
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* @return array[]
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*/
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public function parse( $document ) {
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$this->document = $document;
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$this->offset = 0;
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$this->output = array();
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$this->stack = array();
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while ( $this->proceed() ) {
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continue;
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}
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return $this->output;
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}
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/**
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* Processes the next token from the input document
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* and returns whether to proceed eating more tokens
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*
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* This is the "next step" function that essentially
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* takes a token as its input and decides what to do
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* with that token before descending deeper into a
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* nested block tree or continuing along the document
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* or breaking out of a level of nesting.
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*
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* @internal
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* @since 5.0.0
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* @return bool
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*/
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public function proceed() {
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$next_token = $this->next_token();
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list( $token_type, $block_name, $attrs, $start_offset, $token_length ) = $next_token;
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$stack_depth = count( $this->stack );
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// we may have some HTML soup before the next block.
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$leading_html_start = $start_offset > $this->offset ? $this->offset : null;
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switch ( $token_type ) {
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case 'no-more-tokens':
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// if not in a block then flush output.
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if ( 0 === $stack_depth ) {
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$this->add_freeform();
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return false;
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}
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/*
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* Otherwise we have a problem
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* This is an error
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*
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* we have options
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* - treat it all as freeform text
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* - assume an implicit closer (easiest when not nesting)
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*/
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// for the easy case we'll assume an implicit closer.
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if ( 1 === $stack_depth ) {
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$this->add_block_from_stack();
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return false;
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}
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/*
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* for the nested case where it's more difficult we'll
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* have to assume that multiple closers are missing
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* and so we'll collapse the whole stack piecewise
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*/
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while ( 0 < count( $this->stack ) ) {
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$this->add_block_from_stack();
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}
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return false;
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case 'void-block':
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/*
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* easy case is if we stumbled upon a void block
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* in the top-level of the document
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*/
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if ( 0 === $stack_depth ) {
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if ( isset( $leading_html_start ) ) {
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$this->output[] = (array) $this->freeform(
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substr(
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$this->document,
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$leading_html_start,
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$start_offset - $leading_html_start
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)
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);
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}
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$this->output[] = (array) new WP_Block_Parser_Block( $block_name, $attrs, array(), '', array() );
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$this->offset = $start_offset + $token_length;
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return true;
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}
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// otherwise we found an inner block.
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$this->add_inner_block(
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new WP_Block_Parser_Block( $block_name, $attrs, array(), '', array() ),
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$start_offset,
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$token_length
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);
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$this->offset = $start_offset + $token_length;
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return true;
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case 'block-opener':
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// track all newly-opened blocks on the stack.
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array_push(
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$this->stack,
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new WP_Block_Parser_Frame(
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new WP_Block_Parser_Block( $block_name, $attrs, array(), '', array() ),
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$start_offset,
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$token_length,
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$start_offset + $token_length,
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$leading_html_start
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)
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);
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$this->offset = $start_offset + $token_length;
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return true;
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case 'block-closer':
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/*
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* if we're missing an opener we're in trouble
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* This is an error
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*/
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if ( 0 === $stack_depth ) {
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/*
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* we have options
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* - assume an implicit opener
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* - assume _this_ is the opener
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* - give up and close out the document
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*/
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$this->add_freeform();
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return false;
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}
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// if we're not nesting then this is easy - close the block.
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if ( 1 === $stack_depth ) {
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$this->add_block_from_stack( $start_offset );
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$this->offset = $start_offset + $token_length;
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return true;
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}
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/*
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* otherwise we're nested and we have to close out the current
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* block and add it as a new innerBlock to the parent
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*/
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$stack_top = array_pop( $this->stack );
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$html = substr( $this->document, $stack_top->prev_offset, $start_offset - $stack_top->prev_offset );
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$stack_top->block->innerHTML .= $html;
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$stack_top->block->innerContent[] = $html;
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$stack_top->prev_offset = $start_offset + $token_length;
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$this->add_inner_block(
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$stack_top->block,
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$stack_top->token_start,
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$stack_top->token_length,
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$start_offset + $token_length
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);
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$this->offset = $start_offset + $token_length;
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return true;
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default:
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// This is an error.
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$this->add_freeform();
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return false;
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}
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}
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/**
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* Scans the document from where we last left off
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* and finds the next valid token to parse if it exists
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*
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* Returns the type of the find: kind of find, block information, attributes
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*
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* @internal
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* @since 5.0.0
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* @since 4.6.1 fixed a bug in attribute parsing which caused catastrophic backtracking on invalid block comments
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* @return array
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*/
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public function next_token() {
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$matches = null;
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/*
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* aye the magic
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* we're using a single RegExp to tokenize the block comment delimiters
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* we're also using a trick here because the only difference between a
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* block opener and a block closer is the leading `/` before `wp:` (and
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* a closer has no attributes). we can trap them both and process the
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* match back in PHP to see which one it was.
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*/
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$has_match = preg_match(
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'/<!--\s+(?P<closer>\/)?wp:(?P<namespace>[a-z][a-z0-9_-]*\/)?(?P<name>[a-z][a-z0-9_-]*)\s+(?P<attrs>{(?:(?:[^}]+|}+(?=})|(?!}\s+\/?-->).)*+)?}\s+)?(?P<void>\/)?-->/s',
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$this->document,
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$matches,
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PREG_OFFSET_CAPTURE,
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$this->offset
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);
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// if we get here we probably have catastrophic backtracking or out-of-memory in the PCRE.
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if ( false === $has_match ) {
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return array( 'no-more-tokens', null, null, null, null );
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}
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// we have no more tokens.
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if ( 0 === $has_match ) {
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return array( 'no-more-tokens', null, null, null, null );
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}
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list( $match, $started_at ) = $matches[0];
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$length = strlen( $match );
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$is_closer = isset( $matches['closer'] ) && -1 !== $matches['closer'][1];
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$is_void = isset( $matches['void'] ) && -1 !== $matches['void'][1];
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$namespace = $matches['namespace'];
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$namespace = ( isset( $namespace ) && -1 !== $namespace[1] ) ? $namespace[0] : 'core/';
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$name = $namespace . $matches['name'][0];
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$has_attrs = isset( $matches['attrs'] ) && -1 !== $matches['attrs'][1];
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/*
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* Fun fact! It's not trivial in PHP to create "an empty associative array" since all arrays
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* are associative arrays. If we use `array()` we get a JSON `[]`
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*/
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$attrs = $has_attrs
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? json_decode( $matches['attrs'][0], /* as-associative */ true )
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: array();
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/*
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* This state isn't allowed
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* This is an error
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*/
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if ( $is_closer && ( $is_void || $has_attrs ) ) {
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// we can ignore them since they don't hurt anything.
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}
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if ( $is_void ) {
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return array( 'void-block', $name, $attrs, $started_at, $length );
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}
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if ( $is_closer ) {
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return array( 'block-closer', $name, null, $started_at, $length );
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}
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return array( 'block-opener', $name, $attrs, $started_at, $length );
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}
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/**
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* Returns a new block object for freeform HTML
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*
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* @internal
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* @since 3.9.0
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*
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* @param string $inner_html HTML content of block.
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* @return WP_Block_Parser_Block freeform block object.
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*/
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public function freeform( $inner_html ) {
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return new WP_Block_Parser_Block( null, array(), array(), $inner_html, array( $inner_html ) );
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}
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/**
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* Pushes a length of text from the input document
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* to the output list as a freeform block.
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*
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* @internal
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* @since 5.0.0
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* @param null $length how many bytes of document text to output.
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*/
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public function add_freeform( $length = null ) {
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$length = $length ? $length : strlen( $this->document ) - $this->offset;
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if ( 0 === $length ) {
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return;
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}
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$this->output[] = (array) $this->freeform( substr( $this->document, $this->offset, $length ) );
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}
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/**
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* Given a block structure from memory pushes
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* a new block to the output list.
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*
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* @internal
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* @since 5.0.0
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* @param WP_Block_Parser_Block $block The block to add to the output.
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* @param int $token_start Byte offset into the document where the first token for the block starts.
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* @param int $token_length Byte length of entire block from start of opening token to end of closing token.
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* @param int|null $last_offset Last byte offset into document if continuing form earlier output.
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*/
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public function add_inner_block( WP_Block_Parser_Block $block, $token_start, $token_length, $last_offset = null ) {
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$parent = $this->stack[ count( $this->stack ) - 1 ];
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$parent->block->innerBlocks[] = (array) $block;
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$html = substr( $this->document, $parent->prev_offset, $token_start - $parent->prev_offset );
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if ( ! empty( $html ) ) {
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$parent->block->innerHTML .= $html;
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$parent->block->innerContent[] = $html;
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}
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$parent->block->innerContent[] = null;
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$parent->prev_offset = $last_offset ? $last_offset : $token_start + $token_length;
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}
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/**
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* Pushes the top block from the parsing stack to the output list.
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*
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* @internal
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* @since 5.0.0
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* @param int|null $end_offset byte offset into document for where we should stop sending text output as HTML.
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*/
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public function add_block_from_stack( $end_offset = null ) {
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$stack_top = array_pop( $this->stack );
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$prev_offset = $stack_top->prev_offset;
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$html = isset( $end_offset )
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? substr( $this->document, $prev_offset, $end_offset - $prev_offset )
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: substr( $this->document, $prev_offset );
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if ( ! empty( $html ) ) {
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$stack_top->block->innerHTML .= $html;
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$stack_top->block->innerContent[] = $html;
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}
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if ( isset( $stack_top->leading_html_start ) ) {
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$this->output[] = (array) $this->freeform(
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substr(
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$this->document,
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$stack_top->leading_html_start,
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$stack_top->token_start - $stack_top->leading_html_start
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)
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);
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}
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$this->output[] = (array) $stack_top->block;
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}
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}
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/**
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* WP_Block_Parser_Block class.
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*
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* Required for backward compatibility in WordPress Core.
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*/
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require_once __DIR__ . '/class-wp-block-parser-block.php';
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/**
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* WP_Block_Parser_Frame class.
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*
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* Required for backward compatibility in WordPress Core.
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*/
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require_once __DIR__ . '/class-wp-block-parser-frame.php';
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