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Date: Wed, 23 Jun 2010 11:06:07 -0400
Message-ID: <AANLkTimeeHeJFKVPiBtcnwiH05OVPhSgpCYT2xrtV35v@mail.gmail.com>
Subject: Re: INTEGER range ("-2147483648" is not accepted.)
From: Robert Haas <robertmhaas@gmail.com>
To: Mike Toews <mwtoews@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Thom Brown <thombrown@gmail.com>,
	David Fetter <david@fetter.org>,
	Satoshi Nagayasu <satoshi.nagayasu@gmail.com>, pgsql-docs@postgresql.org
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On Wed, Jun 23, 2010 at 10:29 AM, Mike Toews <mwtoews@gmail.com> wrote:
> On 22 June 2010 18:49, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Thom Brown <thombrown@gmail.com> writes:
>>> Is that the right behaviour though? =A0Shouldn't the signed value reach
>>> the cast step rather than the absolute value? =A0Or maybe Postgres coul=
d
>>> implicitly accept -12345::integer to be (-12345)::integer. =A0Is there =
a
>>> blocking reason as to why it must work this way?
>>
>> Yes. =A0There is no reason to assume that - means the same thing for eve=
ry
>> datatype. =A0In general, :: should (and does) bind tighter than *every*
>> operator, to ensure that the appropriately typed operator is applied.
>>
>
> Sorry for adding to the non-DOC drift, but why is - assumed to be a
> unary operator on an unsigned integer, rather than parsed as part of
> an integer? Integers have digits with an optional - or + prefix (not
> unary operators). E.g., ([+\-]?[0-9]+)

You can't assume that a dash followed by digits is always a negative
number.  Consider:

SELECT 10-4;

If you we interpret this as "10" followed by "-4", it's a syntax
error.  You have to treat it as a separate token and work out later
whether it's a binary operator or a prefix operator.

--=20
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company