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<?php |
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/** |
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* @author Gerard van Helden <[email protected]> |
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* @copyright Zicht Online <http://zicht.nl> |
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*/ |
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namespace Zicht\Tool\Script; |
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/** |
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* Wraps a list of tokens into an convenience class for matching and iterating the tokens |
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*/ |
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class TokenStream |
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{ |
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protected $ptr = 0; |
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/** |
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* Create the tokenstream with the specified list of tokens. |
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* |
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* @param Token[] $tokenList |
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* @param bool $skipWhitespace |
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*/ |
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public function __construct($tokenList, $skipWhitespace = true) |
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{ |
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if ($skipWhitespace) { |
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$callback = function (Token $token) { |
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return !$token->match(Token::WHITESPACE); |
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}; |
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$this->tokenList = array_values(array_filter($tokenList, $callback)); |
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} else { |
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$this->tokenList = $tokenList; |
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} |
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} |
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/** |
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* Advances the internal pointer |
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* |
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* @return void |
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*/ |
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public function next() |
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{ |
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$this->ptr++; |
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} |
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/** |
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* Checks if there is a next token |
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* |
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* @return bool |
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*/ |
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public function hasNext() |
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{ |
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return $this->ptr < count($this->tokenList) - 1; |
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} |
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/** |
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* Checks if there is a current token |
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* |
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* @return bool |
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*/ |
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public function valid() |
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{ |
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return $this->ptr < count($this->tokenList); |
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} |
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/** |
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* Returns the current token |
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* |
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* @return Token |
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* @throws \UnexpectedValueException |
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*/ |
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public function current() |
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{ |
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if (!isset($this->tokenList[$this->ptr])) { |
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throw new \UnexpectedValueException("Unexpected input at offset {$this->ptr}, unexpected end of stream"); |
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} |
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return $this->tokenList[$this->ptr]; |
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} |
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/** |
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* Returns the pointer in the stream |
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* |
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* @return int |
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*/ |
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public function key() |
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{ |
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return $this->ptr; |
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} |
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/** |
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* Checks if the current token matches the specified type and/or value |
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* |
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* @param string $type |
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* @param string $value |
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* @return boolean |
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*/ |
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public function match($type, $value = null) |
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{ |
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return $this->current()->match($type, $value); |
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} |
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/** |
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* Asserts the current token matches the specified value and/or type. Throws an exception if it doesn't |
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* |
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* @param string $type |
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* @param string $value |
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* @return Token |
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* |
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* @throws \UnexpectedValueException |
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*/ |
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public function expect($type, $value = null) |
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{ |
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if (!$this->match($type, $value)) { |
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$msg = "Unexpected token {$this->current()->type} '{$this->current()->value}', expected {$type}"; |
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throw new \UnexpectedValueException($msg); |
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} |
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$current = $this->current(); |
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$this->next(); |
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return $current; |
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} |
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} |
zicht /
z
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: