Re: help with bison - Mailing list pgsql-hackers

Thomas Lockhart wrote:>> The other day there was a discussion around the fact that X'ffff'>> will get converted into an
integerconstant... ... while SQL99>> says that this syntax *should* be used to specify a "binary>> string". It looks
likethe hex-to-integer magic actually occurs in>> the lexer, and then the integer value of 65535 is passed to the
parser>>as an ICONST. I'm wondering if changing the lexer to make this a 
 
conversion>> to a properly escaped bytea input string, and passing it to the>> parser as a string constant would speed
thingsup?>>> What else is described as a "binary string" in the spec? I would> have guessed that this would map to a
bitfield type (and maybe even> had looked it up at one time).>> Is B'00010001' also described as a "binary string"
also,or is it> more explicitly tied to bit fields?>> - Thomas
 

In SQL99, Section "5.3 <literal>", I see this:
  <national character string literal> ::=     N <quote> [ <character representation>... ] <quote>     [ { <separator>
<quote>[ <character representation>... ]     <quote> }... ]  <bit string literal> ::=     B <quote> [ <bit>... ]
<quote>    [ { <separator> <quote> [ <bit>... ] <quote> }... ]  <hex string literal> ::=     X <quote> [ <hexit>... ]
<quote>    [ { <separator> <quote> [ <hexit>... ] <quote> }... ]  <binary string literal> ::=     X <quote> [ { <hexit>
<hexit>}... ] <quote>     [ { <separator> <quote> [ { <hexit> <hexit> }... ] <quote> }... ]  <bit> ::=     0 | 1
<hexit>::=     <digit> | A | B | C | D | E | F | a | b | c | d | e | f
 

and further down:
  11) The declared type of a <bit string literal> is fixed-length      bit string. The length of a <bit string literal>
isthe number      of bits that it contains.  12) The declared type of a <hex string literal> is fixed-length bit
string.Each <hexit> appearing in the literal is equivalent to      a quartet of bits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A,
B,C, D, E,      and F are interpreted as 0000, 0001, 0010, 0011, 0100, 0101,      0110, 0111, 1000, 1001, 1010, 1011,
1100,1101, 1110, and 1111,      respectively. The <hexit>s a, b, c, d, e, and f have respectively      the same values
asthe <hexit>s A, B, C, D, E, and F.  13) The declared type of a <binary string literal> is binary string.      Each
<hexit>appearing in the literal is equivalent to a quartet      of bits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E,
andF are      interpreted as 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111,      1000, 1001, 1010, 1011, 1100, 1101,
1110,and 1111, respectively.      The <hexit>s a, b, c, d, e, and f have respectively the same      values as the
<hexit>sA, B, C, D, E, and F.
 

So, as Peter pointed out, X'ffff' can be interpreted as a binary string 
*or* a bit string, but ISTM B'1111' is explicitly tied to a bit string.

Joe