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Commitf3a9d75

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Finish cleaning up backend's handling of /* ... */ and -- comments,
per pghackers discussion around 20-Feb. Also add specific error messagesfor unterminated comments and unterminated quoted strings. These thingsare nonissues for input coming from psql, but they do matter for inputcoming from other front ends.
1 parent370186e commitf3a9d75

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-19
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‎src/backend/parser/scan.l‎

Lines changed: 55 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $Header: /cvsroot/pgsql/src/backend/parser/scan.l,v 1.65 2000/02/21 18:47:02 tgl Exp $
12+
* $Header: /cvsroot/pgsql/src/backend/parser/scan.l,v 1.66 2000/03/11 05:14:06 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -133,22 +133,24 @@ xdstop{dquote}
133133
xdinside[^"]+
134134

135135
/* C-style comments
136-
* Ignored by the scanner and parser.
137136
*
138137
* The "extended comment" syntax closely resembles allowable operator syntax.
139138
* The tricky part here is to get lex to recognize a string starting with
140139
* slash-star as a comment, when interpreting it as an operator would produce
141-
* a longer match --- remember lex will prefer a longer match! So, we have
142-
* to provide a special rule for xcline (a complete comment that could
143-
* otherwise look like an operator), as well as append {op_and_self}* to
144-
* xcstart so that it matches at least as much as {operator} would.
145-
* Then the tie-breaker (first matching rule of same length) wins.
146-
* There is still a problem if someone writes, eg, slash-star-star-slash-plus.
147-
* It'll be taken as an xcstart, rather than xcline and an operator as one
148-
* could wish. I don't see any way around that given lex's behavior;
149-
* that someone will just have to write a space after the comment.
140+
* a longer match --- remember lex will prefer a longer match! Also, if we
141+
* have something like plus-slash-star, lex will think this is a 3-character
142+
* operator whereas we want to see it as a + operator and a comment start.
143+
* The solution is two-fold:
144+
* 1. append {op_and_self}* to xcstart so that it matches as much text as
145+
* {operator} would. Then the tie-breaker (first matching rule of same
146+
* length) ensures xcstart wins. We put back the extra stuff with yyless()
147+
* in case it contains a star-slash that should terminate the comment.
148+
* 2. In the operator rule, check for slash-star within the operator, and
149+
* if found throw it back with yyless(). This handles the plus-slash-star
150+
* problem.
151+
* SQL92-style comments, which start with dash-dash, have similar interactions
152+
* with the operator rule.
150153
*/
151-
xcline\/\*{op_and_self}*\*\/
152154
xcstart\/\*{op_and_self}*
153155
xcstop\*+\/
154156
xcinside([^*]+)|(\*+[^/])
@@ -161,6 +163,7 @@ identifier{letter}{letter_or_digit}*
161163

162164
typecast"::"
163165

166+
/* NB: if you change "self", fix the copy in the operator rule too! */
164167
self[,()\[\].;$\:\+\-\*\/\%\^\<\>\=\|]
165168
op_and_self[\~\!\@\#\^\&\|\`\?\$\:\+\-\*\/\%\<\>\=]
166169
operator{op_and_self}+
@@ -218,27 +221,30 @@ other.
218221
*
219222
* Quoted strings must allow some special characters such as single-quote
220223
* and newline.
221-
* Embedded single-quotes are implemented both in theSQL/92-standard
224+
* Embedded single-quotes are implemented both in theSQL92-standard
222225
* style of two adjacent single quotes "''" and in the Postgres/Java style
223226
* of escaped-quote "\'".
224227
* Other embedded escaped characters are matched explicitly and the leading
225228
* backslash is dropped from the string. - thomas 1997-09-24
226-
* Note that xcline must appear before xcstart, which must appear before
227-
* operator, as explained above! Also whitespace (comment) must appear
228-
* before operator.
229+
* Note that xcstart must appear before operator, as explained above!
230+
* Also whitespace (comment) must appear before operator.
229231
*/
230232

231233
%%
232234
{whitespace}{/* ignore */ }
233235

234-
{xcline}{/* ignore */ }
235-
236-
{xcstart}{BEGIN(xc); }
236+
{xcstart}{
237+
BEGIN(xc);
238+
/* Put back any characters past slash-star; see above */
239+
yyless(2);
240+
}
237241

238242
<xc>{xcstop}{BEGIN(INITIAL); }
239243

240244
<xc>{xcinside}{/* ignore */ }
241245

246+
<xc><<EOF>>{elog(ERROR,"Unterminated /* comment"); }
247+
242248
{xbstart}{
243249
BEGIN(xb);
244250
startlit();
@@ -262,6 +268,7 @@ other.
262268
<xb>{xbcat}{
263269
/* ignore */
264270
}
271+
<xb><<EOF>>{elog(ERROR,"Unterminated binary integer"); }
265272

266273
{xhstart}{
267274
BEGIN(xh);
@@ -278,6 +285,7 @@ other.
278285
literalbuf);
279286
return ICONST;
280287
}
288+
<xh><<EOF>>{elog(ERROR,"Unterminated hexadecimal integer"); }
281289

282290
{xqstart}{
283291
BEGIN(xq);
@@ -296,6 +304,7 @@ other.
296304
<xq>{xqcat}{
297305
/* ignore */
298306
}
307+
<xq><<EOF>>{elog(ERROR,"Unterminated quoted string"); }
299308

300309

301310
{xdstart}{
@@ -310,12 +319,39 @@ other.
310319
<xd>{xdinside}{
311320
addlit(yytext, yyleng);
312321
}
322+
<xd><<EOF>>{elog(ERROR,"Unterminated quoted identifier"); }
313323

314324
{typecast}{return TYPECAST; }
315325

316326
{self}{return yytext[0]; }
317327

318328
{operator}{
329+
/* Check for embedded slash-star or dash-dash */
330+
char *slashstar =strstr((char*)yytext,"/*");
331+
char *dashdash =strstr((char*)yytext,"--");
332+
333+
if (slashstar && dashdash)
334+
{
335+
if (slashstar > dashdash)
336+
slashstar = dashdash;
337+
}
338+
elseif (!slashstar)
339+
slashstar = dashdash;
340+
341+
if (slashstar)
342+
{
343+
int nchars = slashstar - ((char*)yytext);
344+
yyless(nchars);
345+
/* If what we have left is only one char, and it's
346+
* one of the characters matching "self", then
347+
* return it as a character token the same way
348+
* that the "self" rule would have.
349+
*/
350+
if (nchars ==1 &&
351+
strchr(",()[].;$:+-*/%^<>=|", yytext[0]))
352+
return yytext[0];
353+
}
354+
319355
if (strcmp((char*)yytext,"!=") ==0)
320356
yylval.str =pstrdup("<>");/* compatibility */
321357
else

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