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Postgres FD Implementation
Commit 559a2874 authored by Thomas G. Lockhart's avatar Thomas G. Lockhart
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Use exclusive states for parsing quoted strings. 

Implement extended comments ("/* ... */") using exclusive states.
Modify definitions of operators to remove some restrictions on characters
 and character order.
parent 1370a087
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Showing with 106 additions and 56 deletions
src/backend/parser/scan.l
View file @ 559a2874
......@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/scan.l,v 1.14 1997/08/20 01:50:06 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/scan.l,v 1.15 1997/09/01 05:51:52 thomas Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -59,7 +59,42 @@ void unput(char);
#endif /* FLEX_SCANNER */
extern YYSTYPE yylval;
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.
* <xc> is an exclusive condition to allow embedded C-style comments.
* When in an exclusive condition, only those rules defined for that condition apply.
* So, when in condition <xc>, only strings which would terminate the "extended comment"
* trigger any action other than "ignore".
* The "extended comment" syntax closely resembles allowable operator syntax.
* Therefore, be sure to match _any_ candidate comment, including those with appended
* operator-like symbols. - thomas 1997-07-14
*/
/* define an exclusive condition to allow extended C-style comments - tgl 1997-07-12 */
%x xc
/* define an exclusive condition for quoted strings - tgl 1997-07-30 */
%x xq
/* We used to allow double-quoted strings, but SQL doesn't so we won't either */
quote '
xqstart {quote}
xqstop {quote}
xqdouble {quote}{quote}
xqinside [^\']*
xqliteral [\\].
xcline [\/][\*].*[\*][\/]{space}*\n*
xcstart [\/][\*]{op_and_self}*
xcstop {op_and_self}*[\*][\/]({space}*|\n)
xcinside [^*]*
xcstar [^/]
digit [0-9]
letter [_A-Za-z]
......@@ -69,15 +104,15 @@ sysfunc SYS_{letter}{letter_or_digit}*
identifier {letter}{letter_or_digit}*
typecast "::"
self [,()\[\].;$\:\+\-\*\/\<\>\=\|]
selfm {self}[\-][\.0-9]
op_and_self [\~\!\@\#\%\^\&\|\`\?\$\:\+\-\*\/\<\>\=]
op_and_self2 [\~\!\@\#\%\^\&\|\`\?\$\:\*\/\<\>\=]
op_only [\~\!\@\#\%\^\&\`\?]
operator ({op_and_self}{op_and_self2}+)|{op_only}+
/* we used to allow double-quoted strings, but SQL doesn't */
/* so we won't either*/
quote '
operator {op_and_self}+
operatorm {op_and_self}+[\-][\.0-9]
integer -?{digit}+
real -?{digit}+\.{digit}+([Ee][-+]?{digit}+)?
......@@ -97,10 +132,57 @@ other .
{comment} { /* ignore */ }
"::" { return TYPECAST; }
/* allow extended comments using C-style delimiters - tgl 1997-07-12 */
{xcline} { /* ignore */ }
<xc>{xcstar} |
{xcstart} { BEGIN(xc); }
<xc>{xcstop} { BEGIN(INITIAL); }
<xc>{xcinside} { /* ignore */ }
{xqstart} {
BEGIN(xq);
llen = 0;
*literal = '\0';
}
<xq>{xqstop} {
BEGIN(INITIAL);
yylval.str = pstrdup(scanstr(literal));
return (SCONST);
}
<xq>{xqdouble} |
<xq>{xqinside} {
if ((llen+yyleng) > (MAX_PARSE_BUFFER - 1)) {
elog(WARN,"quoted string parse buffer of %d chars exceeded",MAX_PARSE_BUFFER);
/* not reached */
}
memcpy(literal+llen, yytext, yyleng+1);
llen += yyleng;
}
<xq>{xqliteral} {
if ((llen+yyleng-1) > (MAX_PARSE_BUFFER - 1)) {
elog(WARN,"quoted string parse buffer of %d chars exceeded",MAX_PARSE_BUFFER);
/* not reached */
}
memcpy(literal+llen, yytext+1, yyleng);
llen += yyleng-1;
}
{typecast} { return TYPECAST; }
{selfm} {
yyless(yyleng-2);
return (yytext[0]);
}
{self} { return (yytext[0]); }
{operatorm} {
yyless(yyleng-2);
yylval.str = pstrdup((char*)yytext);
return (Op);
}
{operator} {
if (strcmp((char*)yytext,"!=") == 0)
yylval.str = pstrdup("<>"); /* compatability */
......@@ -124,49 +206,6 @@ other .
CheckFloat8Val(yylval.dval);
return (FCONST);
}
{quote} {
char literal[MAX_PARSE_BUFFER];
int i = 0;
int c = 0;
/* quote_seen can be either \ or ' because
we handle both cases of \' and '' for
quoting quotes*/
int quote_seen = 0;
while (i < MAX_PARSE_BUFFER - 1) {
c = input();
if (quote_seen != 0) {
if (quote_seen == '\'' &&
c != '\'') {
/* a non-quote follows a single quote */
/* so we've hit the end of the literal */
if (c != '\0' && c != EOF)
unput(c); /* put back the extra char we read*/
i = i - 1;
break; /* break out of the while loop */
}
/* if we reach here, we're still in */
/* the string literal */
literal[i++] = c;
quote_seen = 0;
continue;
}
if (c == '\0' || c == EOF) {
elog(WARN,"unterminated quoted string literal");
/* not reached */
}
literal[i++] = c;
if (c == '\'' || c == '\\')
quote_seen = c;
}
if ( i == MAX_PARSE_BUFFER - 1) {
elog (WARN, "unterminated quote string. parse buffer of %d chars exceeded", MAX_PARSE_BUFFER);
/* not reached */
}
literal[i] = '\0';
yylval.str = pstrdup(scanstr(literal));
return (SCONST);
}
{identifier} {
int i;
ScanKeyword *keyword;
......@@ -177,10 +216,16 @@ other .
keyword = ScanKeywordLookup((char*)yytext);
if (keyword != NULL) {
if ( keyword->value == DEFAULT )
if ( keyword->value == DEFAULT ) {
DefaultStartPosition = CurScanPosition () + yyleng + 1;
else if ( keyword->value == CHECK )
printf( "default offset is %d\n", DefaultStartPosition);
} else if ( keyword->value == CHECK ) {
CheckStartPosition = CurScanPosition () + yyleng + 1;
printf( "check offset is %d\n", CheckStartPosition);
};
return (keyword->value);
} else {
yylval.str = pstrdup((char*)yytext);
......@@ -282,7 +327,12 @@ myinput(char* buf, int max)
int
CurScanPosition(void)
{
printf( "current position is %d\n", yy_c_buf_p - yy_current_buffer->yy_ch_buf - yyleng);
return (parseCh - parseString - yyleng - 1);
#if FALSE
return (yy_c_buf_p - yy_current_buffer->yy_ch_buf - yyleng);
#endif
}
#endif /* FLEX_SCANNER */
......
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