mirror of
https://gerrit.wikimedia.org/r/mediawiki/extensions/AbuseFilter.git
synced 2024-11-28 07:50:24 +00:00
612 lines
14 KiB
PHP
612 lines
14 KiB
PHP
<?php
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/**
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* A version of the abuse filter parser that separates parsing the filter and
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* evaluating it into different passes, allowing the parse tree to be cached.
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*
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* @file
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*/
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/**
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* A parser that transforms the text of the filter into a parse tree.
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*/
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class AFPTreeParser {
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// The tokenized representation of the filter parsed.
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public $mTokens;
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// Current token handled by the parser and its position.
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public $mCur, $mPos;
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const CACHE_VERSION = 2;
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/**
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* Create a new instance
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*/
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public function __construct() {
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$this->resetState();
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}
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public function resetState() {
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$this->mTokens = [];
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$this->mPos = 0;
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}
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/**
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* Advances the parser to the next token in the filter code.
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*/
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protected function move() {
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list( $this->mCur, $this->mPos ) = $this->mTokens[$this->mPos];
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}
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/**
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* getState() function allows parser state to be rollbacked to several tokens
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* back.
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*
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* @return AFPParserState
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*/
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protected function getState() {
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return new AFPParserState( $this->mCur, $this->mPos );
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}
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/**
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* setState() function allows parser state to be rollbacked to several tokens
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* back.
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*
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* @param AFPParserState $state
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*/
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protected function setState( AFPParserState $state ) {
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$this->mCur = $state->token;
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$this->mPos = $state->pos;
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}
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/**
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* Parse the supplied filter source code into a tree.
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*
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* @param string $code
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* @throws AFPUserVisibleException
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* @return AFPTreeNode|null
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*/
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public function parse( $code ) {
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$this->mTokens = AbuseFilterTokenizer::tokenize( $code );
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$this->mPos = 0;
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return $this->doLevelEntry();
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}
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/* Levels */
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/**
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* Handles unexpected characters after the expression.
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* @return AFPTreeNode|null
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* @throws AFPUserVisibleException
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*/
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protected function doLevelEntry() {
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$result = $this->doLevelSemicolon();
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if ( $this->mCur->type != AFPToken::TNONE ) {
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throw new AFPUserVisibleException(
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'unexpectedatend',
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$this->mPos, [ $this->mCur->type ]
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);
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}
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return $result;
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}
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/**
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* Handles the semicolon operator.
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*
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* @return AFPTreeNode|null
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*/
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protected function doLevelSemicolon() {
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$statements = [];
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do {
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$this->move();
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$position = $this->mPos;
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if ( $this->mCur->type == AFPToken::TNONE ) {
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break;
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}
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// Allow empty statements.
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if ( $this->mCur->type == AFPToken::TSTATEMENTSEPARATOR ) {
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continue;
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}
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$statements[] = $this->doLevelSet();
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$position = $this->mPos;
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} while ( $this->mCur->type == AFPToken::TSTATEMENTSEPARATOR );
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// Flatten the tree if possible.
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if ( count( $statements ) == 0 ) {
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return null;
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} elseif ( count( $statements ) == 1 ) {
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return $statements[0];
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} else {
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return new AFPTreeNode( AFPTreeNode::SEMICOLON, $statements, $position );
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}
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}
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/**
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* Handles variable assignment.
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*
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* @return AFPTreeNode
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* @throws AFPUserVisibleException
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*/
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protected function doLevelSet() {
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if ( $this->mCur->type == AFPToken::TID ) {
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$varname = $this->mCur->value;
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// Speculatively parse the assignment statement assuming it can
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// potentially be an assignment, but roll back if it isn't.
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$initialState = $this->getState();
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$this->move();
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if ( $this->mCur->type == AFPToken::TOP && $this->mCur->value == ':=' ) {
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$position = $this->mPos;
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$this->move();
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$value = $this->doLevelSet();
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return new AFPTreeNode( AFPTreeNode::ASSIGNMENT, [ $varname, $value ], $position );
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}
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if ( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == '[' ) {
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$this->move();
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if ( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == ']' ) {
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$index = 'append';
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} else {
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// Parse index offset.
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$this->setState( $initialState );
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$this->move();
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$index = $this->doLevelSemicolon();
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if ( !( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == ']' ) ) {
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throw new AFPUserVisibleException( 'expectednotfound', $this->mPos,
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[ ']', $this->mCur->type, $this->mCur->value ] );
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}
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}
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$this->move();
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if ( $this->mCur->type == AFPToken::TOP && $this->mCur->value == ':=' ) {
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$position = $this->mPos;
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$this->move();
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$value = $this->doLevelSet();
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if ( $index === 'append' ) {
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return new AFPTreeNode(
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AFPTreeNode::LIST_APPEND, [ $varname, $value ], $position );
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} else {
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return new AFPTreeNode(
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AFPTreeNode::INDEX_ASSIGNMENT,
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[ $varname, $index, $value ],
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$position
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);
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}
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}
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}
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// If we reached this point, we did not find an assignment. Roll back
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// and assume this was just a literal.
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$this->setState( $initialState );
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}
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return $this->doLevelConditions();
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}
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/**
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* Handles ternary operator and if-then-else-end.
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*
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* @return AFPTreeNode
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* @throws AFPUserVisibleException
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*/
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protected function doLevelConditions() {
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if ( $this->mCur->type == AFPToken::TKEYWORD && $this->mCur->value == 'if' ) {
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$position = $this->mPos;
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$this->move();
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$condition = $this->doLevelBoolOps();
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if ( !( $this->mCur->type == AFPToken::TKEYWORD && $this->mCur->value == 'then' ) ) {
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throw new AFPUserVisibleException( 'expectednotfound',
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$this->mPos,
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[
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'then',
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$this->mCur->type,
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$this->mCur->value
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]
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);
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}
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$this->move();
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$valueIfTrue = $this->doLevelConditions();
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if ( !( $this->mCur->type == AFPToken::TKEYWORD && $this->mCur->value == 'else' ) ) {
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throw new AFPUserVisibleException( 'expectednotfound',
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$this->mPos,
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[
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'else',
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$this->mCur->type,
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$this->mCur->value
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]
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);
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}
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$this->move();
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$valueIfFalse = $this->doLevelConditions();
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if ( !( $this->mCur->type == AFPToken::TKEYWORD && $this->mCur->value == 'end' ) ) {
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throw new AFPUserVisibleException( 'expectednotfound',
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$this->mPos,
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[
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'end',
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$this->mCur->type,
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$this->mCur->value
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]
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);
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}
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$this->move();
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return new AFPTreeNode(
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AFPTreeNode::CONDITIONAL,
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[ $condition, $valueIfTrue, $valueIfFalse ],
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$position
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);
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}
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$condition = $this->doLevelBoolOps();
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if ( $this->mCur->type == AFPToken::TOP && $this->mCur->value == '?' ) {
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$position = $this->mPos;
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$this->move();
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$valueIfTrue = $this->doLevelConditions();
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if ( !( $this->mCur->type == AFPToken::TOP && $this->mCur->value == ':' ) ) {
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throw new AFPUserVisibleException( 'expectednotfound',
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$this->mPos,
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[
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':',
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$this->mCur->type,
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$this->mCur->value
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]
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);
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}
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$this->move();
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$valueIfFalse = $this->doLevelConditions();
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return new AFPTreeNode(
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AFPTreeNode::CONDITIONAL,
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[ $condition, $valueIfTrue, $valueIfFalse ],
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$position
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);
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}
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return $condition;
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}
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/**
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* Handles logic operators.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelBoolOps() {
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$leftOperand = $this->doLevelCompares();
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$ops = [ '&', '|', '^' ];
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while ( $this->mCur->type == AFPToken::TOP && in_array( $this->mCur->value, $ops ) ) {
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$op = $this->mCur->value;
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$position = $this->mPos;
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$this->move();
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$rightOperand = $this->doLevelCompares();
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$leftOperand = new AFPTreeNode(
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AFPTreeNode::LOGIC,
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[ $op, $leftOperand, $rightOperand ],
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$position
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);
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}
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return $leftOperand;
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}
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/**
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* Handles comparison operators.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelCompares() {
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$leftOperand = $this->doLevelSumRels();
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$ops = [ '==', '===', '!=', '!==', '<', '>', '<=', '>=', '=' ];
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while ( $this->mCur->type == AFPToken::TOP && in_array( $this->mCur->value, $ops ) ) {
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$op = $this->mCur->value;
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$position = $this->mPos;
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$this->move();
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$rightOperand = $this->doLevelSumRels();
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$leftOperand = new AFPTreeNode(
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AFPTreeNode::COMPARE,
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[ $op, $leftOperand, $rightOperand ],
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$position
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);
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}
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return $leftOperand;
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}
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/**
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* Handle addition and subtraction.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelSumRels() {
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$leftOperand = $this->doLevelMulRels();
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$ops = [ '+', '-' ];
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while ( $this->mCur->type == AFPToken::TOP && in_array( $this->mCur->value, $ops ) ) {
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$op = $this->mCur->value;
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$position = $this->mPos;
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$this->move();
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$rightOperand = $this->doLevelMulRels();
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$leftOperand = new AFPTreeNode(
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AFPTreeNode::SUM_REL,
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[ $op, $leftOperand, $rightOperand ],
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$position
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);
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}
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return $leftOperand;
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}
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/**
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* Handles multiplication and division.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelMulRels() {
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$leftOperand = $this->doLevelPow();
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$ops = [ '*', '/', '%' ];
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while ( $this->mCur->type == AFPToken::TOP && in_array( $this->mCur->value, $ops ) ) {
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$op = $this->mCur->value;
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$position = $this->mPos;
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$this->move();
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$rightOperand = $this->doLevelPow();
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$leftOperand = new AFPTreeNode(
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AFPTreeNode::MUL_REL,
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[ $op, $leftOperand, $rightOperand ],
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$position
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);
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}
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return $leftOperand;
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}
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/**
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* Handles exponentiation.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelPow() {
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$base = $this->doLevelBoolInvert();
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while ( $this->mCur->type == AFPToken::TOP && $this->mCur->value == '**' ) {
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$position = $this->mPos;
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$this->move();
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$exponent = $this->doLevelBoolInvert();
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$base = new AFPTreeNode( AFPTreeNode::POW, [ $base, $exponent ], $position );
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}
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return $base;
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}
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/**
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* Handles boolean inversion.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelBoolInvert() {
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if ( $this->mCur->type == AFPToken::TOP && $this->mCur->value == '!' ) {
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$position = $this->mPos;
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$this->move();
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$argument = $this->doLevelKeywordOperators();
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return new AFPTreeNode( AFPTreeNode::BOOL_INVERT, [ $argument ], $position );
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}
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return $this->doLevelKeywordOperators();
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}
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/**
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* Handles keyword operators.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelKeywordOperators() {
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$leftOperand = $this->doLevelUnarys();
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$keyword = strtolower( $this->mCur->value );
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if ( $this->mCur->type == AFPToken::TKEYWORD &&
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in_array( $keyword, array_keys( AbuseFilterParser::$mKeywords ) )
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) {
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$position = $this->mPos;
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$this->move();
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$rightOperand = $this->doLevelUnarys();
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return new AFPTreeNode(
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AFPTreeNode::KEYWORD_OPERATOR,
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[ $keyword, $leftOperand, $rightOperand ],
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$position
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);
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}
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return $leftOperand;
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}
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/**
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* Handles unary operators.
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*
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* @return AFPTreeNode
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*/
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protected function doLevelUnarys() {
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$op = $this->mCur->value;
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if ( $this->mCur->type == AFPToken::TOP && ( $op == "+" || $op == "-" ) ) {
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$position = $this->mPos;
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$this->move();
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$argument = $this->doLevelListElements();
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return new AFPTreeNode( AFPTreeNode::UNARY, [ $op, $argument ], $position );
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}
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return $this->doLevelListElements();
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}
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/**
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* Handles accessing a list element by an offset.
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*
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* @return AFPTreeNode
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* @throws AFPUserVisibleException
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*/
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protected function doLevelListElements() {
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$list = $this->doLevelParenthesis();
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while ( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == '[' ) {
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$position = $this->mPos;
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$index = $this->doLevelSemicolon();
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$list = new AFPTreeNode( AFPTreeNode::LIST_INDEX, [ $list, $index ], $position );
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if ( !( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == ']' ) ) {
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throw new AFPUserVisibleException( 'expectednotfound', $this->mPos,
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[ ']', $this->mCur->type, $this->mCur->value ] );
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}
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$this->move();
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}
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return $list;
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}
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/**
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* Handles parenthesis.
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*
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* @return AFPTreeNode
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* @throws AFPUserVisibleException
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*/
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protected function doLevelParenthesis() {
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if ( $this->mCur->type == AFPToken::TBRACE && $this->mCur->value == '(' ) {
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$result = $this->doLevelSemicolon();
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if ( !( $this->mCur->type == AFPToken::TBRACE && $this->mCur->value == ')' ) ) {
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throw new AFPUserVisibleException(
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'expectednotfound',
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$this->mPos,
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[ ')', $this->mCur->type, $this->mCur->value ]
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);
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}
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$this->move();
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return $result;
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}
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return $this->doLevelFunction();
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}
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/**
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* Handles function calls.
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*
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* @return AFPTreeNode
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* @throws AFPUserVisibleException
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*/
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protected function doLevelFunction() {
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if ( $this->mCur->type == AFPToken::TID &&
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isset( AbuseFilterParser::$mFunctions[$this->mCur->value] )
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) {
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$func = $this->mCur->value;
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$position = $this->mPos;
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$this->move();
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if ( $this->mCur->type != AFPToken::TBRACE || $this->mCur->value != '(' ) {
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throw new AFPUserVisibleException( 'expectednotfound',
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$this->mPos,
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[
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'(',
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$this->mCur->type,
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$this->mCur->value
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]
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);
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}
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$args = [];
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do {
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$args[] = $this->doLevelSemicolon();
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} while ( $this->mCur->type == AFPToken::TCOMMA );
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if ( $this->mCur->type != AFPToken::TBRACE || $this->mCur->value != ')' ) {
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throw new AFPUserVisibleException( 'expectednotfound',
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$this->mPos,
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[
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')',
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$this->mCur->type,
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$this->mCur->value
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]
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);
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}
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$this->move();
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array_unshift( $args, $func );
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return new AFPTreeNode( AFPTreeNode::FUNCTION_CALL, $args, $position );
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}
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return $this->doLevelAtom();
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}
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/**
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* Handle literals.
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* @return AFPTreeNode
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* @throws AFPUserVisibleException
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*/
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protected function doLevelAtom() {
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$tok = $this->mCur->value;
|
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switch ( $this->mCur->type ) {
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case AFPToken::TID:
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case AFPToken::TSTRING:
|
|
case AFPToken::TFLOAT:
|
|
case AFPToken::TINT:
|
|
$result = new AFPTreeNode( AFPTreeNode::ATOM, $this->mCur, $this->mPos );
|
|
break;
|
|
case AFPToken::TKEYWORD:
|
|
if ( in_array( $tok, [ "true", "false", "null" ] ) ) {
|
|
$result = new AFPTreeNode( AFPTreeNode::ATOM, $this->mCur, $this->mPos );
|
|
break;
|
|
}
|
|
|
|
throw new AFPUserVisibleException(
|
|
'unrecognisedkeyword',
|
|
$this->mPos,
|
|
[ $tok ]
|
|
);
|
|
/** @noinspection PhpMissingBreakStatementInspection */
|
|
case AFPToken::TSQUAREBRACKET:
|
|
if ( $this->mCur->value == '[' ) {
|
|
$list = [];
|
|
while ( true ) {
|
|
$this->move();
|
|
if ( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == ']' ) {
|
|
break;
|
|
}
|
|
|
|
$list[] = $this->doLevelSet();
|
|
|
|
if ( $this->mCur->type == AFPToken::TSQUAREBRACKET && $this->mCur->value == ']' ) {
|
|
break;
|
|
}
|
|
if ( $this->mCur->type != AFPToken::TCOMMA ) {
|
|
throw new AFPUserVisibleException(
|
|
'expectednotfound',
|
|
$this->mPos,
|
|
[ ', or ]', $this->mCur->type, $this->mCur->value ]
|
|
);
|
|
}
|
|
}
|
|
|
|
$result = new AFPTreeNode( AFPTreeNode::LIST_DEFINITION, $list, $this->mPos );
|
|
break;
|
|
}
|
|
|
|
// Fallthrough expected
|
|
default:
|
|
throw new AFPUserVisibleException(
|
|
'unexpectedtoken',
|
|
$this->mPos,
|
|
[
|
|
$this->mCur->type,
|
|
$this->mCur->value
|
|
]
|
|
);
|
|
}
|
|
|
|
$this->move();
|
|
return $result;
|
|
}
|
|
}
|