sql_digest_stream.h

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  it under the terms of the GNU General Public License, version 2.0,
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#ifndef SQL_DIGEST_STREAM_H
#define SQL_DIGEST_STREAM_H
 
#include "sql/sql_digest.h"
 
union Lexer_yystype;
 
/**
  State data storage for @c digest_start, @c digest_add_token.
  This structure extends the @c sql_digest_storage structure
  with temporary state used only during parsing.
*/
struct sql_digest_state {
  /**
    Index, in the digest token array, of the last peekable position.
    Reduce rules used in the digest computation can not
    apply to tokens seen before an identifier,
    because an identifier uses a variable length storage.
    Likewise, peek code can not backtrack before
    a by numeric column token, because of the extra value stored.
    Fortunately, once an id or a by numeric column token is stored,
    no additional rule will reduce this further,
    so there is never a need to backtrack in the digest stream
    on variable length records.
    @sa digest_add_token
  */
  int m_last_peekable_index;
  sql_digest_storage m_digest_storage;
 
  inline void reset(unsigned char *token_array, uint length) {
    m_last_peekable_index = 0;
    m_digest_storage.reset(token_array, length);
  }
 
  inline bool is_empty() { return m_digest_storage.is_empty(); }
};
typedef struct sql_digest_state sql_digest_state;
 
sql_digest_state *digest_add_token(sql_digest_state *state, uint token,
                                   Lexer_yystype *yylval);
 
sql_digest_state *digest_reduce_token(sql_digest_state *state, uint token_left,
                                      uint token_right);
 
sql_digest_state *digest_adjust_by_numeric_column_token(sql_digest_state *state,
                                                        ulonglong value);
 
#endif