<?php
/**
* The Forminator_Calculator_Parser_Tokenizer class.
*
* @package Forminator
*/
/**
* Class Forminator_Calculator_Tokenizer
*/
class Forminator_Calculator_Parser_Tokenizer {
/**
* Input
*
* @var string
*/
public $input = '';
/**
* Current position
*
* @var int
*/
public $current_position = 0;
/**
* Forminator_Calculator_Parser_Tokenizer constructor
*
* @param mixed $input Input.
*/
public function __construct( $input = null ) {
$this->input = $input;
}
/**
* Tokenize
*
* @return Forminator_Calculator_Parser_Token[]
*/
public function tokenize() {
$this->reset();
$tokens = array();
$token = $this->read_token();
while ( $token ) {
$tokens[] = $token;
$token = $this->read_token();
}
return $tokens;
}
/**
* Read token
*
* @return Forminator_Calculator_Parser_Token|null
*/
protected function read_token() {
$this->step_over_whitespace();
$char = $this->read_current();
if ( null === $char ) {
return null;
}
if ( $this->is_letter( $char ) ) {
$value = $this->read_word();
$type = Forminator_Calculator_Parser_Token::TYPE_WORD;
} elseif ( $this->is_digit( $char ) || $this->is_period( $char ) ) {
$value = $this->read_number();
$type = Forminator_Calculator_Parser_Token::TYPE_NUMBER;
} else {
$value = $this->read_char();
$type = Forminator_Calculator_Parser_Token::TYPE_CHAR;
}
$token = new Forminator_Calculator_Parser_Token( $type, $value, $this->get_current_position() );
return $token;
}
/**
* Returns true, if a given character is a letter (a-z and A-Z).
*
* @param string $char A single character.
*
* @return bool
*/
protected function is_letter( $char ) {
if ( null === $char ) {
return false;
}
// Notice: ord(null) will return 0.
// ord() does not work with utf-8 characters.
$ascii = ord( $char );
/**
* ASCII codes: 65 = 'A', 90 = 'Z', 97 = 'a', 122 = 'z'--
*/
return ( ( $ascii >= 65 && $ascii <= 90 ) || ( $ascii >= 97 && $ascii <= 122 ) );
}
/**
* Returns true, if a given character is a digit (0-9).
*
* @param string|null $char A single character.
*
* @return bool
*/
protected function is_digit( $char ) {
if ( null === $char ) {
return false;
}
// Notice: ord(null) will return 0.
// ord() does not work with utf-8 characters.
$ascii = ord( $char );
/**
* ASCII codes: 48 = '0', 57 = '9'
*/
return ( $ascii >= 48 && $ascii <= 57 );
}
/**
* Returns true, if a given character is a period ('.').
*
* @param string|null $char A single character.
*
* @return bool
*/
protected function is_period( $char ) {
return ( '.' === $char );
}
/**
* Returns true, if a given character is whitespace.
* Notice: A null char is not seen as whitespace.
*
* @param string|null $char Character.
* @return bool
*/
protected function is_whitespace( $char ) {
return in_array( $char, array( ' ', "\t", "\n" ), true );
}
/**
* Moves the pointer to the next char that is not whitespace.
* Might be a null char, might not move the pointer at all.
*
* @return void
*/
protected function step_over_whitespace() {
while ( $this->is_whitespace( $this->read_current() ) ) {
$this->read_next();
}
}
/**
* Reads a word. Assumes that the cursor of the input stream
* currently is positioned at the beginning of a word.
*
* @return string
*/
protected function read_word() {
$word = '';
$char = $this->read_current();
// Try to read the word.
while ( null !== $char ) {
if ( $this->is_letter( $char ) ) {
$word .= $char;
} else {
break;
}
// Just move the cursor to the next position.
$char = $this->read_next();
}
return $word;
}
/**
* Reads a number (as a string). Assumes that the cursor
* of the input stream currently is positioned at the
* beginning of a number.
*
* @return string
* @throws Forminator_Calculator_Exception When there is an Calculator error.
*/
protected function read_number() {
$number = '';
$found_period = false;
// Try to read the number.
// Notice: It does not matter if the number only consists of a single period.
// or if it ends with a period.
$char = $this->read_current();
while ( null !== $char ) {
if ( $this->is_period( $char ) || $this->is_digit( $char ) ) {
if ( $this->is_period( $char ) ) {
if ( $found_period ) {
throw new Forminator_Calculator_Exception( 'Error: A number cannot have more than one period' );
}
$found_period = true;
}
$number .= $char;
} else {
break;
}
// read next.
$char = $this->read_next();
}
return $number;
}
/**
* Reads a single char. Assumes that the cursor of the input stream
* currently is positioned at a char (not on null).
*
* @return string
*/
protected function read_char() {
$char = $this->read_current();
// Just move the cursor to the next position.
$this->read_next();
return $char;
}
/**
* Move the the cursor to the next position.
* Will always move the cursor, even if the end of the string has been passed.
*
* @return string|null
*/
public function read_next() {
++$this->current_position;
return $this->read_current();
}
/**
* Returns the current character.
*
* @return string|null
*/
public function read_current() {
$char = null;
if ( $this->has_current() && ! empty( $this->input ) ) {
$char = $this->input[ $this->current_position ];
}
return $char;
}
/**
* Returns true if there is a character at the current position
*
* @return bool
*/
public function has_current() {
return ( $this->current_position < strlen( $this->input ) );
}
/**
* Resets the position of the cursor to the beginning of the string.
*
* @return void
*/
public function reset() {
$this->current_position = 0;
}
/**
* Getter for the cursor position
*
* @return int
*/
public function get_current_position() {
return $this->current_position;
}
}