BIND 10 #2372: define State class for MasterLexer, base part

[BIND 10 Development]

#2372: define State class for MasterLexer, base part
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                   Reporter:         |                 Owner:  UnAssigned
  jinmei                             |                Status:  new
                       Type:  task   |             Milestone:  New Tasks
                   Priority:         |            Resolution:
  medium                             |             Sensitive:  0
                  Component:         |           Sub-Project:  DNS
  libdns++                           |  Estimated Difficulty:  0
                   Keywords:         |           Total Hours:  0
            Defect Severity:  N/A    |
Feature Depending on Ticket:         |
  loadzone-ng                        |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Description changed by jinmei:

Old description:

> Subtask of #2368.  See #2371.  This defines the state class
> of `MasterLexer`.
>
> It's essentially private to `MasterLexer`, but we want to test them
> directly, so define it as semi-public, in the master_lexer_internal
> namespace.
>
> For the state transition, first understand the overall logic flow
> of BIND 9's isc_lex_gettoken().  Attached drawing may also help.
>
> This is the base class of the state.  We'll have the following
> derived classes.
>
> {{{#!cpp
> class master_lexer_internal::State {
>     // correspond specific state and derived class.
>     enum ID { Start, CRLF, String, QuotedString, Number, EatLine, Done };
>
>     // Handle the current state, and return next state.  'Done' class
>     // throws.
>     virtual State* handle(MasterLexer& lexer) const = 0;
>
>     // Return whether state transition is completed.  By default false,
>     // only 'Done' class returns true.
>     virtual bool isCompleted() const { return (false); }
>
>     // We use singleton instances.  This returns pre-generated instance.
>     static State* getInstance(ID id);
> };
> }}}
>
> In this ticket, we define the base class and Start, CRLF, EatLine, and
> Done classes.  For details of the state transition, see
> isc_lex_gettoken().  Sample implementation of Start is like this:
>
> {{{#!cpp
> class MasterLexer::Start : public MasterLexerState {
>     virtual void handle(MasterLexer& lexer) const {
>         const int c = lexer.source->getNextChar();
>         if (lexer.isCommentStart(lexer, c, this)) {
>             return (State::getInstance(EAT_LINE));
>         }
>         if (c == EOF) {
>             lexer.last_was_eol_ = false;
>             return (State::getInstance(DONE));
>         }
>         if (c == '\r') {
>             return (State::getInstance(CRLF));
>         }
>         if (isdigit(c)) {
>             lexer.last_was_eol_ = false;
>             return (State::getInstance(NUMBER));
>         }
>         // and so on
>     }
> };
> }}}

New description:

 Subtask of #2368.  See #2371.  This defines the state class
 of `MasterLexer`.  To test this, we'll probably need to introduce a
 base class of `MasterLexer` or template (that way, this task is
 mostly dependency free).

 It's essentially private to `MasterLexer`, but we want to test them
 directly, so define it as semi-public, in the master_lexer_internal
 namespace.

 For the state transition, first understand the overall logic flow
 of BIND 9's isc_lex_gettoken().  Attached drawing may also help.

 This is the base class of the state.  We'll have the following
 derived classes.

 {{{#!cpp
 class master_lexer_internal::State {
     // correspond specific state and derived class.
     enum ID { Start, CRLF, String, QuotedString, Number, EatLine, Done };

     // Handle the current state, and return next state.  'Done' class
     // throws.
     virtual State* handle(MasterLexer& lexer) const = 0;

     // Return whether state transition is completed.  By default false,
     // only 'Done' class returns true.
     virtual bool isCompleted() const { return (false); }

     // We use singleton instances.  This returns pre-generated instance.
     static State* getInstance(ID id);
 };
 }}}

 In this ticket, we define the base class and Start, CRLF, EatLine, and
 Done classes.  For details of the state transition, see
 isc_lex_gettoken().  Sample implementation of Start is like this:

 {{{#!cpp
 class MasterLexer::Start : public MasterLexerState {
     virtual void handle(MasterLexer& lexer) const {
         const int c = lexer.source->getNextChar();
         if (lexer.isCommentStart(lexer, c, this)) {
             return (State::getInstance(EAT_LINE));
         }
         if (c == EOF) {
             lexer.last_was_eol_ = false;
             return (State::getInstance(DONE));
         }
         if (c == '\r') {
             return (State::getInstance(CRLF));
         }
         if (isdigit(c)) {
             lexer.last_was_eol_ = false;
             return (State::getInstance(NUMBER));
         }
         // and so on
     }
 };
 }}}

--

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Ticket URL: <http://bind10.isc.org/ticket/2372#comment:1>
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