BIND 10 #2370: define MasterToken

[BIND 10 Development]

#2370: define MasterToken
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            Reporter:  jinmei        |                        Owner:
                Type:  task          |  UnAssigned
            Priority:  medium        |                       Status:  new
           Component:  libdns++      |                    Milestone:  New
           Sensitive:  0             |  Tasks
         Sub-Project:  DNS           |                     Keywords:
Estimated Difficulty:  0             |              Defect Severity:  N/A
         Total Hours:  0             |  Feature Depending on Ticket:
                                     |  loadzone-ng
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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 Subtask of #2368, (mostly) no dependency.

 This defines a simple class encapsulating tokens returned by
 `MasterLexer`.
 This is probably a subclass of `MasterLexer`.

 A sample definition is this:
 {{{#!cpp
 class MasterToken {
 public:
     enum TokenType {
         ERROR,                  // getToken failed
         STRING, NUMBER, QSTRING, EOL /* end of line */, EOF /* end of file
 */,
         INITIAL_WS /* space at the beginning of line */
     };

     Token(TokenType type);      // non value type
     Token(type, const char* str_beg, size_t str_len); // type STRING or
 QSTRING
     Token(uint32_t num);                               // type NUMBER

     const TokenType type;

     // Only if type is STRING or QSTRING , otherwise throw
     std::string getString() const; // convert region_ to std::string and
 return
     const StringRegion& getStringRegion() const { return (region_); }

     // Only if type is NUMBER, otherwise throw
     uint32_t getNumber() const { return (number_) };

     struct StringRegion {
         const char* beg;
         size_t len;
     };
 private:
     union {
         StringRegion region_;
         uint32_t number_;
     };
 };
 }}}

 For string, I suggest using a pair of const char* and size_t instead
 of creating std::string unless it's really needed, to avoid
 unnecessary copy.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2370>
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