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<?php |
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namespace App; |
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use App\Exception\ParseError; |
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use App\Node\BinaryOperator; |
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use App\Node\FunctionCall; |
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use App\Node\Integer; |
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use App\Node\Real; |
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use App\Node\UnaryOperator; |
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use App\Node\Visitable; |
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class Parser |
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{ |
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/** |
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* @var Lexer |
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*/ |
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private $lexer; |
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/** |
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* @var Token |
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*/ |
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private $currentToken; |
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/** |
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* Parser constructor. |
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* @param Lexer $lexer |
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* @throws Exception\LexerException |
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* @throws Exception\UnknownIdentifier |
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*/ |
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public function __construct( |
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Lexer $lexer |
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) |
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{ |
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$this->lexer = $lexer; |
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$this->currentToken = $this->lexer->getNextToken(); |
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} |
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/** |
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* @param string $tokenType |
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* @throws Exception\LexerException |
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* @throws ParseError |
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* @throws Exception\UnknownIdentifier |
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*/ |
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private function eat(string $tokenType): void |
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{ |
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if ($this->currentToken->type === $tokenType) { |
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$this->currentToken = $this->lexer->getNextToken(); |
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} else { |
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throw new ParseError('Wrong token type'); |
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} |
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} |
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/** |
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* @return Visitable |
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* @throws Exception\LexerException |
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* @throws ParseError |
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* @throws Exception\UnknownIdentifier |
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*/ |
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public function factor(): Visitable |
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{ |
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$token = $this->currentToken; |
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if ($token->type === Token::PLUS) { |
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$this->eat(Token::PLUS); |
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return new UnaryOperator($token, $this->factor()); |
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} |
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if ($token->type === Token::MINUS) { |
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$this->eat(Token::MINUS); |
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return new UnaryOperator($token, $this->factor()); |
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} |
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if ($token->type === Token::INT) { |
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$this->eat(Token::INT); |
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return new Integer((int)$token->value); |
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} |
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if ($token->type === Token::REAL) { |
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$this->eat(Token::REAL); |
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return new Real((float)$token->value); |
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} |
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if ($token->type === Token::FUNCTION_CALL) { |
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$this->eat(Token::FUNCTION_CALL); |
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$this->eat(Token::LPAREN); |
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$args = []; |
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while (true) { |
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$args[] = $this->expr(); |
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if ($this->currentToken->type === Token::COMMA) { |
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$this->eat(Token::COMMA); |
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} else { |
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break; |
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} |
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} |
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$this->eat(Token::RPAREN); |
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return new FunctionCall($token, $args); |
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} |
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if ($token->type === Token::LPAREN) { |
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$this->eat(Token::LPAREN); |
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$node = $this->expr(); |
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$this->eat(Token::RPAREN); |
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return $node; |
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} |
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throw new ParseError('Unknown factor type'); |
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} |
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/** |
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* @return Visitable |
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* @throws Exception\LexerException |
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* @throws ParseError |
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* @throws Exception\UnknownIdentifier |
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*/ |
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public function term(): Visitable |
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{ |
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$node = $this->factor(); |
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while (in_array($this->currentToken->type, [Token::MUL, Token::REALDIV, Token::POWER], true)) { |
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/** @var Token $operator */ |
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$operator = $this->currentToken; |
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/** @psalm-suppress PossiblyNullArgument */ |
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$this->eat($this->currentToken->type); |
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$node = new BinaryOperator($node, $operator, $this->factor()); |
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} |
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return $node; |
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} |
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/** |
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* @return Visitable |
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* @throws Exception\LexerException |
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* @throws ParseError |
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* @throws Exception\UnknownIdentifier |
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*/ |
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private function expr(): Visitable |
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{ |
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$node = $this->term(); |
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while (in_array($this->currentToken->type, [Token::PLUS, Token::MINUS], true)) { |
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/** @var Token $operator */ |
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$operator = $this->currentToken; |
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/** @psalm-suppress PossiblyNullArgument */ |
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$this->eat($this->currentToken->type); |
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$node = new BinaryOperator($node, $operator, $this->term()); |
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} |
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return $node; |
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} |
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/** |
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* @return Visitable |
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* @throws Exception\LexerException |
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* @throws ParseError |
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* @throws Exception\UnknownIdentifier |
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*/ |
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public function parse(): Visitable |
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{ |
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return $this->expr(); |
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} |
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} |
drumser /
arithmetic-parser
