Fixes #121

This aims to prevent extending UserDefinedFunction for UDFs whose translation
is very simple (e.g. different name in SQL, different argument order, etc).

Fixes #115

when ending the query with an EOF.

This commit reverts commit 89418d13.

The reverted commit will be applied in another branch (probably 'adql-2.1') as
it is part of the next release of ADQL-Lib.

- Now, `ADQLParserFactory.createParser(...)` should be used to create a parser
- Only the new function `LOWER` is supported for the moment
- Not yet possible to manage the optional features _(next dev to come)_
=> 1st step for ADQL-Lib v2.0

- TAP adapted so that using the last stable version of the ADQL language
  (i.e. 2.0 for the moment)
  - but not yet possible to set the ADQL version to use in the configuration
    file

This new function - ADQLParser.tryQuickFix(...) - fixes the most common issues
with ADQL queries:

- replace Unicode confusable characters by their ASCII/UTF-8 version,
- double-quote SQL reserved words/terms (e.g. `public`, `year`, `date`),
- double-quote ADQL function names used a column name/alias (e.g. `distance`,
  `min`, `avg`),
- double-quote invalid regular identifiers (e.g. `_RAJ2000`, `2mass`).

The last point is far from being perfect but should work at least for
identifiers starting with a digit or an underscore, or an identifier including
one of the following character: `?`, `!`, `$`, `@`, `#`, `{`, `}`, `[`, `]`,
`~`, `^` and '`'.

It should also been noted that double-quoting a column/table name will make it
case-sensitive. Then, it is possible that the query does not pass even after the
double-quote operation ; the case would have to be checked by the user.

Finally, there is no attempt to fix column and table names (i.e. case
sensitivity and/or typos) using tables/columns list/metadata. That could be a
possible evolution of this function or an additional feature to implement in the
parser.

_This commit fixes the GitHub issue #97 ._

tables.

Since commit 3d96c9d9 aliases put on a table
without double quotes are put in lower case and then double quoted. This
modification was not effective for ORDER BY's column identifiers.

The previous commit broke some JUnit tests. It was indeed not any more possible
to prefix a column with the fully qualified table name
(e.g. `"aSchema"."aTable"`) if the table was automatically aliased. If an alias
is set on a table, this table should be referenced only by this alias. The
previous commit was not able to replace fully qualified table names with their
corresponding alias....and doing that would probably introduce other unexpected
parsing/checking behaviors.

So, it is better to keep this part of the parsing as simple as now. Just for few
DB error messages showing real database names (and only if they are different
from the ADQL ones), it does not worth _yet_ making the parsing more complex.

_This commit ends the issue #108 ._

(i.e. not a subquery).

The idea is to avoid ambiguous error messages coming from the database when
raising an error on a table or column name having different DB and ADQL names.

This commit sets by default an alias on each table reference. This default
alias is the ADQL table name as it is used in the ADQL query.

_This commit fixes the GitHub issue #108 ._

As @vforchi said:

> The ANSI standard `||` is supported only by Oracle and Postgres: MySQL uses
> `CONCAT` and SQLServer uses `+`.

_This commit resolves the issue #70 ._

* The parsing did not allow unsigned numerics and SQL SET functions as
  specified in the ADQL 2.0 grammar

* It was even forbidden to put a column whose the type is not String.

* The translation of a concatenation expression was always prefixed by the
  ADQLList's name: CONCAT_STR. Of course, no database likes that...

Regarding this last point, this commit fixes the GitHub issue #54

This commit fixes the Github issue #58

if the alias is not delimited in ADQL.

This commit fixes the GitHub issue #56

are translated: the table part (if a reference to an aliased table) should be
as declared in the DBTable (especially now that we have DBTableAlias to deal
nicely with table aliases).

this table is declared with an alias. Instead, the table alias must be used.

Note: This problem occurred only when ADQLParser was used with a DBChecker.

This commit fixes the GitHub issue #53

A delimited identifier is any sequence of characters between a pair of
double quotes. For instance: "123 I am a delimited identifier!".

It is of course possible to have double quotes inside this kind of identifier,
but they have to be doubled in order to not be mistaken with the end of the
identifier. For instance: "Cool ""identifier""".

However, this escape option was not taken into account by the ADQL library,
though the same mechanism was already in place for string contants.

reserved word is encountered instead of a column/table/schema name/alias.

On the contrary to the previous commit, this time a list of SQL reserved words
has been added into the ADQL grammar. In this way, the parser will ensure that
no word of this list is used in an ADQL query. The raised error is then enriched
of an HINT message stating that this word is part of SQL, is not supported
by ADQL and must be written between double quotes if used as an identifier.

The list of SQL reserved words comes from the ADQL-2.0 standard, after removal
of all potentially used ADQL words, in order to avoid a conflict with the
already existing tokens in the ADQL grammar.

reserved word is encountered instead of a column/table/schema name/alias.

No list of ADQL reserved words has been added into the ADQL grammar.

However, the ADQL grammar has been slightly changed in order to provide a more
precise location of the REAL wrong part of the query.

Before this commit, if an ADQL reserved word (e.g. 'point') was encountered
outside of its normal syntax (e.g. 'point' no followed by an opening
parenthesis), the next token was highlighted instead of this one. Hence a
confusing error message.

For instance, the following ADQL query:

```sql
SELECT point
FROM aTable
```

returned the following error message:

> Encountered "FROM". Was expecting: "("

Now, it will return the following one:

> Encountered "point". Was expecting one of: "*" <QUANTIFIER> "TOP" [...]
> (HINT: "point" is a reserved ADQL word. To use it as a column/table/schema name/alias, write it between double quotes.)

This error message highlights exactly the source of the problem and even provide
to the user a clear explanation of why the query did not parse and how it could
be solved.

The idea is to get rid of special characters such as '-', '+' , '(', ...

This commit resolves a part of the Pull Request #14

and HashMap more generic by returning resp. a List and Map instead.

This commit resolves a part of the Pull Request #14

In the resulting SQL query, if there are an alias on the joined tables, these
aliases must be used in the ON clause (instead of the full table name).

For instance, the following ADQL query:

```sql
  SELECT *
  FROM tableA AS a NATURAL JOIN tableB AS b;
```

should be translated into the following SQL:

```sql
  SELECT *
  FROM tableA AS a
    INNER JOIN tableB AS b
      ON a.id = b.id
```

This commit complete the resolution of the Pull Request #16
(more details about the issue can be got in there)

In MS-SQLServer, the following functions return a value of the same
type as the given argument:
  - abs
  - ceiling
  - degrees
  - floor
  - radians
  - round.

Since ADQL requires that these functions return a DOUBLE
(i.e. a float in MS-SQLServer), it must be ensured that the given
argument is a float.

This commit partially fixes the Pull Request #16

when an incorrect character that can not be interpreted by
the JavaCC Token Manager is encountered.

Actually, the TokenMgrError thrown by JavaCC is caught by all
ADQLParser.parseQuery(...) functions, wrapped inside a ParseException
which is finally thrown instead of the TokenMgrError. In this way,
ADQL-Lib users just have to care about a single Throwable:
ParseException.

Besides the error message has been slightly modified from:

> Lexical error at line 1, column 10.  Encountered: "\u00e9" (233), after : \"\"

to:

> Incorrect character encountered at l.1, c.10: \"\\u00e9\" ('é'), after : \"\"

Thus, the error is more user-friendly, more easy to understand by users.
Additionally, the incorrect character is displayed, as before, in its unicode
expression, but also in its character form (instead of an integer value that
nobody can really understand).

This commit fixes the GitHub issue #17

On the contrary to other DBMS, MySQL supports schemas, but as databases.
Which means that JDBCConnection gets from the JDBC driver that MySQL does
not support schemas and so it tries to access TAP_SCHEMA tables with a
'TAP_SCHEMA_' prefix instead of 'TAP_SCHEMA.' one. Since MySQL does
behave like it supports schemas, JDBCConnection.supportsSchema must be
set to 'true' if the DBMS is MySQL.

Besides, since no schemas are returned by the JDBC driver
(cf DatabaseMetadata.listSchema(...)), the function
JDBCConnection.isSchemaExisting(String, DatabaseMetaData) must always assume
that the specified schema exists if the DBMS is MySQL. This is particularly
important when the existence of 'TAP_UPLOAD' must be checked, because if the
function returns 'false' the library will attempt to create the database/schema
'TAP_UPLOAD' and will obviously fail due to a lack of permissions. Of course,
it means that the TAP implementor must create manually the schema/database
'TAP_UPLOAD' him-/her-self.

The second particularity of MySQL is the quote character for identifiers.
It is a back-quote (`) instead of a double quote ("). To reflect this
difference, JDBCTranslator.appendIdentifier(...) has been overwritten in a new
JDBCTranslator extension: MySQLTranslator.

The translation of all SQL types and mathematical functions have been adapted to
MySQL according to the online documentation. Few tests have been done locally
with a tiny database. This seems to work but further testing should be
performed in order to ensure the stability of this implementation.

This infinite loop occured only when the replacement object is just
a wrapping of the matching object ; after replacement, the new object was
inspected for matching objects.

Example: infinite loop if we want to wrap all foo(...) functions with
         the function ROUND in the following query:
    SELECT foo(foo(123)) FROM myTable
	     Expected result:
    SELECT ROUND(foo(ROUND(foo(123)))) FROM myTable
	     But generated result was:
    SELECT ROUND(ROUND(ROUND(......foo(foo(123))))) FROM myTable

See the test case TestDBChecker.testClauseADQLWithNameNull() for more details.

since the commit 8e2fa9ff.

(005fc622). The position of a TokenMgrError
was not there anymore.

(https://github.com/gmantele/taplib/commit/7a70c6038cef460ab169682bed391bb5ae1de1e9)

It was not possible to use a GROUP BY with a qualified column name.
So finally, now, a GROUP BY is a ClauseADQL<ADQLColumn> instead of
a ClauseADQL<ColumnReference>. Indeed, according to the ADQL's BNF,
GROUP BY items are only columns as they would appear in the SELECT
clause (i.e. qualified or not, delimited or not). On the other
hand an ORDER BY accepts ONLY column index or non-qualified column
name/alias.

The class ColumnReference is kept for backward compatibility (or in
case the next version of the ADQL grammar make items of GROUP BY and
ORDER BY of the same type: index or qualified column). Besides, this
class is still inherited for the ORDER BY clause items
(see adql.query.ADQLOrder).

a qualified column name should be allowed, but still no column index should be.

This error has been raised on the issue #32 by Zarquan.

Two classes have been modified after compilation:
    - ADQLParser - a simple cast for one of the automatically generated
                   constructor.
    - ParseException - the token position has been stored for better
                       syntax error messages.
A note has been added at the top comment for both files to highlight
the modified parts and how to restore them after re-generation.