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Add comments and move a few declaration blocks to help readability.

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No functional changes this time!
This commit is contained in:
Thomas G. Lockhart
1997-11-30 23:05:39 +00:00
parent b12ba5f695
commit 361f9e7f8d
2 changed files with 241 additions and 215 deletions
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84
src/backend/parser/scan.l
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/scan.l,v 1.30 1997/11/20 23:22:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/scan.l,v 1.31 1997/11/30 23:05:36 thomas Exp $
*
*-------------------------------------------------------------------------
*/
@@ -60,37 +60,55 @@ int llen;
char literal[MAX_PARSE_BUFFER];
%}
/* OK, here is a short description of lex/flex rules behavior.
* The longest pattern which matches an input string is always chosen.
* For equal-length patterns, the first occurring in the rules list is chosen.
* INITIAL is the starting condition, to which all non-conditional rules apply.
* When in an exclusive condition, only those rules defined for that condition apply.
*
* Exclusive states change parsing rules while the state is active.
* There are exclusive states for quoted strings, extended comments,
* and to eliminate parsing troubles for numeric strings.
* Exclusive states:
* <xb> binary numeric string - thomas 1997-11-16
* <xh> hexadecimal numeric string - thomas 1997-11-16
* <xc> extended C-style comments - tgl 1997-07-12
* <xq> quoted strings - tgl 1997-07-30
* <xm> numeric strings with embedded minus sign - tgl 1997-09-05
* <xd> delimited identifiers (double-quoted identifiers) - tgl 1997-10-27
*
* The "extended comment" syntax closely resembles allowable operator syntax.
* So, when in condition <xc>, only strings which would terminate the
* "extended comment" trigger any action other than "ignore".
* Be sure to match _any_ candidate comment, including those with appended
* operator-like symbols. - thomas 1997-07-14
*/
/* OK, here is a short description of lex/flex rules behavior.
* The longest pattern which matches an input string is always chosen.
* For equal-length patterns, the first occurring in the rules list is chosen.
* INITIAL is the starting condition, to which all non-conditional rules apply.
* When in an exclusive condition, only those rules defined for that condition apply.
*
* Exclusive states change parsing rules while the state is active.
* There are exclusive states for quoted strings, extended comments,
* and to eliminate parsing troubles for numeric strings.
* Exclusive states:
* <xb> binary numeric string - thomas 1997-11-16
* <xc> extended C-style comments - tgl 1997-07-12
* <xd> delimited identifiers (double-quoted identifiers) - tgl 1997-10-27
* <xh> hexadecimal numeric string - thomas 1997-11-16
* <xm> numeric strings with embedded minus sign - tgl 1997-09-05
* <xq> quoted strings - tgl 1997-07-30
*
* The "extended comment" syntax closely resembles allowable operator syntax.
* So, when in condition <xc>, only strings which would terminate the
* "extended comment" trigger any action other than "ignore".
* Be sure to match _any_ candidate comment, including those with appended
* operator-like symbols. - thomas 1997-07-14
*/
%x xb
%x xc
%x xd
%x xh
%x xq
%x xm
%x xq
/* Binary number
*/
xbstart [bB]{quote}
xbstop {quote}
xbinside [^']*
xbcat {quote}{space}*\n{space}*{quote}
/* Hexadecimal number
*/
xhstart [xX]{quote}
xhstop {quote}
xhinside [^']*
xhcat {quote}{space}*\n{space}*{quote}
/* Extended quote
* xqdouble implements SQL92 embedded quote
* xqcat allows strings to cross input lines
*/
quote '
xqstart {quote}
xqstop {quote}
@@ -100,21 +118,17 @@ xqembedded "\\'"
xqliteral [\\](.|\n)
xqcat {quote}{space}*\n{space}*{quote}
xbstart [bB]{quote}
xbstop {quote}
xbinside [^']*
xbcat {quote}{space}*\n{space}*{quote}
xhstart [xX]{quote}
xhstop {quote}
xhinside [^']*
xhcat {quote}{space}*\n{space}*{quote}
/* Delimited quote
* Allows embedded spaces and other special characters into identifiers.
*/
dquote \"
xdstart {dquote}
xdstop {dquote}
xdinside [^"]*
/* Comments
* Ignored by the scanner and parser.
*/
xcline [\/][\*].*[\*][\/]{space}*\n*
xcstart [\/][\*]{op_and_self}*
xcstop {op_and_self}*[\*][\/]({space}*|\n)