Fold Token::{Keyword, Identifier, DoubleQuotedString} into one
Token::SQLWord, which has the necessary information (was it a
known keyword and/or was it quoted).
This lets the parser easily accept DoubleQuotedString (a quoted
identifier) everywhere it expects an Identifier in the same match
arm. (To complete support of quoted identifiers, or "delimited
identifiers" as the spec calls them, a TODO in parse_tablename()
ought to be addressed.)
As an aside, per <https://en.wikibooks.org/wiki/SQL_Dialects_Reference/Data_structure_definition/Delimited_identifiers>
sqlite seems to be the only one supporting 'identifier'
(which is rather hairy, since it can also be a string
literal), and `identifier` seems only to be supported by
MySQL. I didn't implement either one.
This also allows the use of `parse`/`expect_keyword` machinery
for non-reserved keywords: previously they relied on the keyword
being a Token::Keyword, which wasn't a Token::Identifier, and so
wasn't accepted as one.
Now whether a keyword can be used as an identifier can be decided
by the parser. (I didn't add a blacklist of "reserved" keywords,
so that any keyword which doesn't have a special meaning in the
parser could be used as an identifier. The list of keywords in
the dialect could be re-used for that purpose at a later stage.)
i.e. ASC/DESC/unspecified - so that we don't lose information about
source code.
Also don't take any keyword other than ASC/DESC or Comma to mean
'ascending'.
...as this syntax is not specific to the PostgreSQL dialect.
Also use verified() to assert that parsing + serializing results in the
original SQL string.
Its existence alongside SingleQuotedString simply doesn't make sense:
`'a string'` is a string literal, while `a string` is not a "value".
It's only used in postgresql-specific tab-separated-values parser to
store the string representation of a field's value. For that use-case
Option<String> looks like a more appropriate choice than Value.
...and parser support for the corresponding token, as "..." in SQL[*] is
not a literal string like we parse it - but a quoted identifier (which I
intend to implement later).
[*] in all the RBDMSes I know, except for sqlite which has complex rules
in the name of "compatibility": https://www.sqlite.org/lang_keywords.html
Mainly by replacing `assert_eq!(sql, ast.to_string())` with a call to
the recently introduced `verified()` helper or using `parses_to()` where
the expected serialization differs from the original SQL string.
There was one case (parse_implicit_join), where the inputs were different:
let sql = "SELECT * FROM t1,t2";
//vs
let sql = "SELECT * FROM t1, t2";
and since we don't test the whitespace handling in other tests, I just
used the canonical representation as input.
Before this missing keywords THEN/WHEN/AS would be parsed as if they
were in the text as the code didn't check the return value of
consume_token() - see upcoming commit.
There's no Token::Period in such situation, so fractional part (from sec) was silently truncated.
Can't uncomment the test yet, because parse_timestamp() is effectively
unused: the code added to parse_value() in 5abd9e7dec
was wrong as it attempted to handle unquoted date/time literals. One
part of it was commented out earlier, the other can't work as far as I
can see, as it tries to parse a Number token - `([0-9]|\.)+` - as a
timestamp, so I removed it as well.
1) Simplified the bit in parse_datatype()
2) Made sure it was covered by the test (the "public.year" bit)
2a) ...the rest of changes in the test are to fix incorrect variable
names: c_name/c_lat/c_lng were copy-pasted from a previous test.
3) Removed the branch from parse_pg_cast, which duplicated what
parse_data_type already handled (added in the same commit even
2007995938 )
