SqlParser\Lexer::parseNumber PHP Метод

    public function parseNumber()
    {
        // A rudimentary state machine is being used to parse numbers due to
        // the various forms of their notation.
        //
        // Below are the states of the machines and the conditions to change
        // the state.
        //
        //      1 --------------------[ + or - ]-------------------> 1
        //      1 -------------------[ 0x or 0X ]------------------> 2
        //      1 --------------------[ 0 to 9 ]-------------------> 3
        //      1 -----------------------[ . ]---------------------> 4
        //      1 -----------------------[ b ]---------------------> 7
        //
        //      2 --------------------[ 0 to F ]-------------------> 2
        //
        //      3 --------------------[ 0 to 9 ]-------------------> 3
        //      3 -----------------------[ . ]---------------------> 4
        //      3 --------------------[ e or E ]-------------------> 5
        //
        //      4 --------------------[ 0 to 9 ]-------------------> 4
        //      4 --------------------[ e or E ]-------------------> 5
        //
        //      5 ---------------[ + or - or 0 to 9 ]--------------> 6
        //
        //      7 -----------------------[ ' ]---------------------> 8
        //
        //      8 --------------------[ 0 or 1 ]-------------------> 8
        //      8 -----------------------[ ' ]---------------------> 9
        //
        // State 1 may be reached by negative numbers.
        // State 2 is reached only by hex numbers.
        // State 4 is reached only by float numbers.
        // State 5 is reached only by numbers in approximate form.
        // State 7 is reached only by numbers in bit representation.
        //
        // Valid final states are: 2, 3, 4 and 6. Any parsing that finished in a
        // state other than these is invalid.
        $iBak = $this->last;
        $token = '';
        $flags = 0;
        $state = 1;
        for (; $this->last < $this->len; ++$this->last) {
            if ($state === 1) {
                if ($this->str[$this->last] === '-') {
                    $flags |= Token::FLAG_NUMBER_NEGATIVE;
                } elseif ($this->last + 1 < $this->len && $this->str[$this->last] === '0' && ($this->str[$this->last + 1] === 'x' || $this->str[$this->last + 1] === 'X')) {
                    $token .= $this->str[$this->last++];
                    $state = 2;
                } elseif ($this->str[$this->last] >= '0' && $this->str[$this->last] <= '9') {
                    $state = 3;
                } elseif ($this->str[$this->last] === '.') {
                    $state = 4;
                } elseif ($this->str[$this->last] === 'b') {
                    $state = 7;
                } elseif ($this->str[$this->last] !== '+') {
                    // `+` is a valid character in a number.
                    break;
                }
            } elseif ($state === 2) {
                $flags |= Token::FLAG_NUMBER_HEX;
                if (!($this->str[$this->last] >= '0' && $this->str[$this->last] <= '9' || $this->str[$this->last] >= 'A' && $this->str[$this->last] <= 'F' || $this->str[$this->last] >= 'a' && $this->str[$this->last] <= 'f')) {
                    break;
                }
            } elseif ($state === 3) {
                if ($this->str[$this->last] === '.') {
                    $state = 4;
                } elseif ($this->str[$this->last] === 'e' || $this->str[$this->last] === 'E') {
                    $state = 5;
                } elseif ($this->str[$this->last] < '0' || $this->str[$this->last] > '9') {
                    // Just digits and `.`, `e` and `E` are valid characters.
                    break;
                }
            } elseif ($state === 4) {
                $flags |= Token::FLAG_NUMBER_FLOAT;
                if ($this->str[$this->last] === 'e' || $this->str[$this->last] === 'E') {
                    $state = 5;
                } elseif ($this->str[$this->last] < '0' || $this->str[$this->last] > '9') {
                    // Just digits, `e` and `E` are valid characters.
                    break;
                }
            } elseif ($state === 5) {
                $flags |= Token::FLAG_NUMBER_APPROXIMATE;
                if ($this->str[$this->last] === '+' || $this->str[$this->last] === '-' || $this->str[$this->last] >= '0' && $this->str[$this->last] <= '9') {
                    $state = 6;
                } else {
                    break;
                }
            } elseif ($state === 6) {
                if ($this->str[$this->last] < '0' || $this->str[$this->last] > '9') {
                    // Just digits are valid characters.
                    break;
                }
            } elseif ($state === 7) {
                $flags |= Token::FLAG_NUMBER_BINARY;
                if ($this->str[$this->last] === '\'') {
                    $state = 8;
                } else {
                    break;
                }
            } elseif ($state === 8) {
                if ($this->str[$this->last] === '\'') {
                    $state = 9;
                } elseif ($this->str[$this->last] !== '0' && $this->str[$this->last] !== '1') {
                    break;
                }
            } elseif ($state === 9) {
                break;
            }
            $token .= $this->str[$this->last];
        }
        if ($state === 2 || $state === 3 || $token !== '.' && $state === 4 || $state === 6 || $state === 9) {
            --$this->last;
            return new Token($token, Token::TYPE_NUMBER, $flags);
        }
        $this->last = $iBak;
        return null;
    }