"""
sqlobject.sqlbuilder
--------------------

:author: Ian Bicking <ianb@colorstudy.com>

Builds SQL expressions from normal Python expressions.

Disclaimer
----------

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

Instructions
------------

To begin a SQL expression, you must use some sort of SQL object -- a
field, table, or SQL statement (``SELECT``, ``INSERT``, etc.)  You can
then use normal operators, with the exception of: `and`, `or`, `not`,
and `in`.  You can use the `AND`, `OR`, `NOT`, and `IN` functions
instead, or you can also use `&`, `|`, and `~` for `and`, `or`, and
`not` respectively (however -- the precidence for these operators
doesn't work as you would want, so you must use many parenthesis).

To create a sql field, table, or constant/function, use the namespaces
`table`, `const`, and `func`.  For instance, ``table.address`` refers
to the ``address`` table, and ``table.address.state`` refers to the
``state`` field in the address table.  ``const.NULL`` is the ``NULL``
SQL constant, and ``func.NOW()`` is the ``NOW()`` function call
(`const` and `func` are actually identicle, but the two names are
provided for clarity).  Once you create this object, expressions
formed with it will produce SQL statements.

The ``sqlrepr(obj)`` function gets the SQL representation of these
objects, as well as the proper SQL representation of basic Python
types (None==NULL).

There are a number of DB-specific SQL features that this does not
implement.  There are a bunch of normal ANSI features also not present
-- particularly left joins, among others.  You may wish to only use
this to generate ``WHERE`` clauses.

See the bottom of this module for some examples, and run it (i.e.
``python sql.py``) to see the results of those examples.

"""

########################################
## Constants
########################################

class VersionError(Exception):
    pass
class NoDefault:
    pass

True, False = (1==1), (0==1)

import re, fnmatch
import operator
import threading
import types

from converters import sqlrepr, registerConverter, TRUE, FALSE

safeSQLRE = re.compile(r'^[a-zA-Z_][a-zA-Z0-9_\.]*$')
def sqlIdentifier(obj):
    # some db drivers return unicode column names 
    return isinstance(obj, types.StringTypes) and bool(safeSQLRE.search(obj.strip()))


def execute(expr, executor):
    if hasattr(expr, 'execute'):
        return expr.execute(executor)
    else:
        return expr

########################################
## Expression generation
########################################

class SQLExpression:
    def __add__(self, other):
        return SQLOp("+", self, other)
    def __radd__(self, other):
        return SQLOp("+", other, self)
    def __sub__(self, other):
        return SQLOp("-", self, other)
    def __rsub__(self, other):
        return SQLOp("-", other, self)
    def __mul__(self, other):
        return SQLOp("*", self, other)
    def __rmul__(self, other):
        return SQLOp("*", other, self)
    def __div__(self, other):
        return SQLOp("/", self, other)
    def __rdiv__(self, other):
        return SQLOp("/", other, self)
    def __pos__(self):
        return SQLPrefix("+", self)
    def __neg__(self):
        return SQLPrefix("-", self)
    def __pow__(self, other):
        return SQLConstant("POW")(self, other)
    def __rpow__(self, other):
        return SQLConstant("POW")(other, self)
    def __abs__(self):
        return SQLConstant("ABS")(self)
    def __mod__(self, other):
        return SQLConstant("MOD")(self, other)
    def __rmod__(self, other):
        return SQLConstant("MOD")(other, self)

    def __lt__(self, other):
        return SQLOp("<", self, other)
    def __le__(self, other):
        return SQLOp("<=", self, other)
    def __gt__(self, other):
        return SQLOp(">", self, other)
    def __ge__(self, other):
        return SQLOp(">=", self, other)
    def __eq__(self, other):
        if other is None:
            return ISNULL(self)
        else:
            return SQLOp("=", self, other)
    def __ne__(self, other):
        if other is None:
            return ISNOTNULL(self)
        else:
            return SQLOp("<>", self, other)

    def __and__(self, other):
        return SQLOp("AND", self, other)
    def __rand__(self, other):
        return SQLOp("AND", other, self)
    def __or__(self, other):
        return SQLOp("OR", self, other)
    def __ror__(self, other):
        return SQLOp("OR", other, self)
    def __invert__(self):
        return SQLPrefix("NOT", self)

    def __call__(self, *args):
        return SQLCall(self, args)

    def __repr__(self):
        try:
            return self.__sqlrepr__(None)
        except AssertionError:
            return '<%s %s>' % (
                self.__class__.__name__, hex(id(self))[2:])

    def __str__(self):
        return repr(self)

    def __cmp__(self, other):
        raise VersionError, "Python 2.1+ required"
    def __rcmp__(self, other):
        raise VersionError, "Python 2.1+ required"

    def startswith(self, s):
        return STARTSWITH(self, s)
    def endswith(self, s):
        return ENDSWITH(self, s)
    def contains(self, s):
        return CONTAINSSTRING(self, s)

    def components(self):
        return []

    def tablesUsed(self):
        return self.tablesUsedDict().keys()
    def tablesUsedDict(self):
        tables = {}
        for table in self.tablesUsedImmediate():
            tables[str(table)] = 1
        for component in self.components():
            tables.update(tablesUsedDict(component))
        return tables
    def tablesUsedImmediate(self):
        return []

#######################################
# Converter for SQLExpression instances
#######################################

def SQLExprConverter(value, db):
    return value.__sqlrepr__()

registerConverter(SQLExpression, SQLExprConverter)

def tablesUsedDict(obj):
    if hasattr(obj, "tablesUsedDict"):
        return obj.tablesUsedDict()
    else:
        return {}

operatorMap = {
    "+": operator.add,
    "/": operator.div,
    "-": operator.sub,
    "*": operator.mul,
    "<": operator.lt,
    "<=": operator.le,
    "=": operator.eq,
    "!=": operator.ne,
    ">=": operator.ge,
    ">": operator.gt,
    "IN": operator.contains,
    "IS": operator.eq,
    }

class SQLOp(SQLExpression):
    def __init__(self, op, expr1, expr2):
        self.op = op.upper()
        self.expr1 = expr1
        self.expr2 = expr2
    def __sqlrepr__(self, db):
        s1 = sqlrepr(self.expr1, db)
        s2 = sqlrepr(self.expr2, db)
        if s1[0] != '(' and s1 != 'NULL':
            s1 = '(' + s1 + ')'
        if s2[0] != '(' and s2 != 'NULL':
            s2 = '(' + s2 + ')'
        return "(%s %s %s)" % (s1, self.op, s2)
    def components(self):
        return [self.expr1, self.expr2]
    def execute(self, executor):
        if self.op == "AND":
            return execute(self.expr1, executor) \
                   and execute(self.expr2, executor)
        elif self.op == "OR":
            return execute(self.expr1, executor) \
                   or execute(self.expr2, executor)
        else:
            return operatorMap[self.op.upper()](execute(self.expr1, executor),
                                                execute(self.expr2, executor))

registerConverter(SQLOp, SQLExprConverter)

class SQLCall(SQLExpression):
    def __init__(self, expr, args):
        self.expr = expr
        self.args = args
    def __sqlrepr__(self, db):
        return "%s%s" % (sqlrepr(self.expr, db), sqlrepr(self.args, db))
    def components(self):
        return [self.expr] + list(self.args)
    def execute(self, executor):
        raise ValueError, "I don't yet know how to locally execute functions"

registerConverter(SQLCall, SQLExprConverter)

class SQLPrefix(SQLExpression):
    def __init__(self, prefix, expr):
        self.prefix = prefix
        self.expr = expr
    def __sqlrepr__(self, db):
        return "%s %s" % (self.prefix, sqlrepr(self.expr, db))
    def components(self):
        return [self.expr]
    def execute(self, executor):
        expr = execute(self.expr, executor)
        if prefix == "+":
            return expr
        elif prefix == "-":
            return -expr
        elif prefix.upper() == "NOT":
            return not expr

registerConverter(SQLPrefix, SQLExprConverter)

class SQLConstant(SQLExpression):
    def __init__(self, const):
        self.const = const
    def __sqlrepr__(self, db):
        return self.const
    def execute(self, executor):
        raise ValueError, "I don't yet know how to execute SQL constants"

registerConverter(SQLConstant, SQLExprConverter)

class SQLTrueClauseClass(SQLExpression):
    def __sqlrepr__(self, db):
        return "1 = 1"
    def execute(self, executor):
        return 1

SQLTrueClause = SQLTrueClauseClass()

registerConverter(SQLTrueClauseClass, SQLExprConverter)

########################################
## Namespaces
########################################

class Field(SQLExpression):
    def __init__(self, tableName, fieldName):
        self.tableName = tableName
        self.fieldName = fieldName
    def __sqlrepr__(self, db):
        return self.tableName + "." + self.fieldName
    def tablesUsedImmediate(self):
        return [self.tableName]
    def execute(self, executor):
        return executor.field(self.tableName, self.fieldName)

class SQLObjectField(Field):
    def __init__(self, tableName, fieldName, original):
        self.original = original
        Field.__init__(self, tableName, fieldName)

registerConverter(SQLObjectField, SQLExprConverter)


class UnicodeField(SQLObjectField):
    def __init__(self, tableName, fieldName, original, column):
        SQLObjectField.__init__(self, tableName, fieldName, original)
        self.column = column
    def __eq__(self, other):
        if other is None:
            return ISNULL(self)
        if isinstance(other, unicode):
            other = other.encode(self.column.dbEncoding)
        return SQLOp('=', self, other)
    def __ne__(self, other):
        if other is None:
            return ISNOTNULL(self)
        if isinstance(other, unicode):
            other = other.encode(self.column.dbEncoding)
        return SQLOp('<>', self, other)

registerConverter(UnicodeField, SQLExprConverter)


class Table(SQLExpression):
    FieldClass = Field

    def __init__(self, tableName):
        self.tableName = tableName
    def __getattr__(self, attr):
        if attr.startswith('__'):
            raise AttributeError
        return self.FieldClass(self.tableName, attr)
    def __sqlrepr__(self, db):
        return str(self.tableName)
    def execute(self, executor):
        raise ValueError, "Tables don't have values"

class SQLObjectTable(Table):
    FieldClass = SQLObjectField
    UnicodeFieldClass = UnicodeField

    def __init__(self, soClass):
        self.soClass = soClass
        assert soClass.sqlmeta.table, (
            "Bad table name in class %r: %r"
            % (soClass, soClass.sqlmeta.table))
        Table.__init__(self, soClass.sqlmeta.table)

    def __getattr__(self, attr):
        if attr.startswith('__'):
            raise AttributeError
        if attr == 'id':
            return self.FieldClass(self.tableName, self.soClass.sqlmeta.idName, attr)
        elif attr not in self.soClass.sqlmeta.columns:
            raise AttributeError("%s instance has no attribute '%s'" % (self.soClass.__name__, attr))
        else:
            column = self.soClass.sqlmeta.columns[attr]
            if hasattr(column, "dbEncoding"):
                return self.UnicodeFieldClass(self.tableName, column.dbName,
                    attr, column)
            else:
                return self.FieldClass(self.tableName, column.dbName, attr)

class TableSpace:
    TableClass = Table

    def __getattr__(self, attr):
        if attr.startswith('__'):
            raise AttributeError
        return self.TableClass(attr)

class ConstantSpace:
    def __getattr__(self, attr):
        if attr.startswith('__'):
            raise AttributeError
        return SQLConstant(attr)


########################################
## Table aliases
########################################

class AliasField(Field):
    as_string = '' # set it to "AS" if your database requires it

    def __init__(self, tableName, fieldName, alias):
        Field.__init__(self, tableName, fieldName)
        self.alias = alias

    def __sqlrepr__(self, db):
        return self.alias + "." + self.fieldName

    def tablesUsedImmediate(self):
        return ["%s %s %s" % (self.tableName, self.as_string, self.alias)]

class AliasTable(Table):
    FieldClass = AliasField

    _alias_lock = threading.Lock()
    _alias_counter = 0

    def __init__(self, table, alias=None):
        if hasattr(table, "sqlmeta"):
            tableName = table.sqlmeta.table
        else:
            tableName = table
            table = None
        Table.__init__(self, tableName)
        self.table = table
        if alias is None:
            self._alias_lock.acquire()
            try:
                AliasTable._alias_counter += 1
                alias = "%s_alias%d" % (tableName, AliasTable._alias_counter)
            finally:
                self._alias_lock.release()
        self.alias = alias

    def __getattr__(self, attr):
        if attr.startswith('__'):
            raise AttributeError
        if self.table:
            attr = getattr(self.table.q, attr).fieldName
        return self.FieldClass(self.tableName, attr, self.alias)

class Alias:
    def __init__(self, table, alias=None):
        self.q = AliasTable(table, alias)


########################################
## SQL Statements
########################################

class Select(SQLExpression):
    def __init__(self, items, where=NoDefault, groupBy=NoDefault,
                 having=NoDefault, orderBy=NoDefault, limit=NoDefault, join=NoDefault):
        if type(items) is not type([]) and type(items) is not type(()):
            items = [items]
        self.items = items
        self.whereClause = where
        self.groupBy = groupBy
        self.having = having
        self.orderBy = orderBy
        self.limit = limit
        self.join  = join

    def __sqlrepr__(self, db):
        select = "SELECT %s" % ", ".join([sqlrepr(v, db) for v in self.items])

        join = []
        if self.join is not NoDefault:
            if isinstance(self.join, SQLJoin):
                join.append(self.join)
            else:
                join.extend(self.join)
        tables = {}
        things = list(self.items)
        if self.whereClause is not NoDefault:
            things.append(self.whereClause)
        for thing in things:
            if isinstance(thing, SQLExpression):
                tables.update(tablesUsedDict(thing))
        for j in join:
            if j.table1 in tables: del tables[j.table1]
            if j.table2 in tables: del tables[j.table2]
        tables = tables.keys()
        if tables:
            select += " FROM %s" % ", ".join(tables)
        elif join:
            select += " FROM "
        for j in join:
            if tables and j.table1:
                sep = ", "
            else:
                sep = " "
            select += sep + sqlrepr(j, db)

        if self.whereClause is not NoDefault:
            select += " WHERE %s" % sqlrepr(self.whereClause, db)
        if self.groupBy is not NoDefault:
            groupBy = sqlrepr(self.groupBy, db)
            if isinstance(self.groupBy, list) or isinstance(self.groupBy, tuple):
                groupBy = groupBy[1:-1] # Remove parens
            select += " GROUP BY %s" % groupBy
        if self.having is not NoDefault:
            select += " HAVING %s" % sqlrepr(self.having, db)
        if self.orderBy is not NoDefault:
            orderBy = sqlrepr(self.orderBy, db)
            if isinstance(self.orderBy, list) or isinstance(self.orderBy, tuple):
                orderBy = orderBy[1:-1] # Remove parens
            select += " ORDER BY %s" % orderBy
        if self.limit is not NoDefault:
            select += " LIMIT %s" % sqlrepr(self.limit, db)
        return select

registerConverter(Select, SQLExprConverter)

class Insert(SQLExpression):
    def __init__(self, table, valueList=None, values=None, template=NoDefault):
        self.template = template
        self.table = table
        if valueList:
            if values:
                raise TypeError, "You may only give valueList *or* values"
            self.valueList = valueList
        else:
            self.valueList = [values]
    def __sqlrepr__(self, db):
        if not self.valueList:
            return ''
        insert = "INSERT INTO %s" % self.table
        allowNonDict = True
        template = self.template
        if template is NoDefault and type(self.valueList[0]) is type({}):
            template = self.valueList[0].keys()
            allowNonDict = False
        if template is not NoDefault:
            insert += " (%s)" % ", ".join(template)
        insert += " VALUES "
        listToJoin = []
        listToJoin_app = listToJoin.append
        for value in self.valueList:
            if type(value) is type({}):
                if template is NoDefault:
                    raise TypeError, "You can't mix non-dictionaries with dictionaries in an INSERT if you don't provide a template (%s)" % repr(value)
                value = dictToList(template, value)
            elif not allowNonDict:
                raise TypeError, "You can't mix non-dictionaries with dictionaries in an INSERT if you don't provide a template (%s)" % repr(value)
            listToJoin_app("(%s)" % ", ".join([sqlrepr(v, db) for v in value]))
        insert = "%s%s" % (insert, ", ".join(listToJoin))
        return insert

registerConverter(Insert, SQLExprConverter)

def dictToList(template, dict):
    list = []
    for key in template:
        list.append(dict[key])
    if len(dict.keys()) > len(template):
        raise TypeError, "Extra entries in dictionary that aren't asked for in template (template=%s, dict=%s)" % (repr(template), repr(dict))
    return list

class Update(SQLExpression):
    def __init__(self, table, values, template=NoDefault, where=NoDefault):
        self.table = table
        self.values = values
        self.template = template
        self.whereClause = where
    def __sqlrepr__(self, db):
        update = "%s %s" % (self.sqlName(), self.table)
        update += " SET"
        first = True
        if self.template is not NoDefault:
            for i in range(len(self.template)):
                if first:
                    first = False
                else:
                    update += ","
                update += " %s=%s" % (self.template[i], sqlrepr(self.values[i], db))
        else:
            for key, value in self.values.items():
                if first:
                    first = False
                else:
                    update += ","
                update += " %s=%s" % (key, sqlrepr(value, db))
        if self.whereClause is not NoDefault:
            update += " WHERE %s" % sqlrepr(self.whereClause, db)
        return update
    def sqlName(self):
        return "UPDATE"

registerConverter(Update, SQLExprConverter)

class Delete(SQLExpression):
    """To be safe, this will signal an error if there is no where clause,
    unless you pass in where=None to the constructor."""
    def __init__(self, table, where=NoDefault):
        self.table = table
        if where is NoDefault:
            raise TypeError, "You must give a where clause or pass in None to indicate no where clause"
        self.whereClause = where
    def __sqlrepr__(self, db):
        whereClause = self.whereClause
        if whereClause is None:
            return "DELETE FROM %s" % self.table
        if isinstance(whereClause, SQLExpression):
            whereClause = sqlrepr(whereClause, db)
        return "DELETE FROM %s WHERE %s" % (self.table, whereClause)

registerConverter(Delete, SQLExprConverter)

class Replace(Update):
    def sqlName(self):
        return "REPLACE"

registerConverter(Replace, SQLExprConverter)

########################################
## SQL Builtins
########################################

class DESC(SQLExpression):

    def __init__(self, expr):
        self.expr = expr

    def __sqlrepr__(self, db):
        if isinstance(self.expr, DESC):
            return sqlrepr(self.expr.expr, db)
        return '%s DESC' % sqlrepr(self.expr, db)

def AND(*ops):
    if not ops:
        return None
    op1 = ops[0]
    ops = ops[1:]
    if ops:
        return SQLOp("AND", op1, AND(*ops))
    else:
        return op1

def OR(*ops):
    if not ops:
        return None
    op1 = ops[0]
    ops = ops[1:]
    if ops:
        return SQLOp("OR", op1, OR(*ops))
    else:
        return op1

def NOT(op):
    return SQLPrefix("NOT", op)

def _IN(item, list):
    return SQLOp("IN", item, list)

def IN(item, list):
    if isinstance(list, Select):
        return INSubquery(item, list)
    else:
        return _IN(item, list)

def NOTIN(item, list):
    if isinstance(list, Select):
        return NOTINSubquery(item, list)
    else:
        return NOT(_IN(item, list))

def STARTSWITH(expr, pattern):
    return SQLOp("LIKE", expr, _LikeQuoted(pattern) + '%')

def ENDSWITH(expr, pattern):
    return SQLOp("LIKE", expr, '%' + _LikeQuoted(pattern))

def CONTAINSSTRING(expr, pattern):
    return SQLOp("LIKE", expr, '%' + _LikeQuoted(pattern) + '%')

def ISNULL(expr):
    return SQLOp("IS", expr, None)

def ISNOTNULL(expr):
    return SQLOp("IS NOT", expr, None)

class _LikeQuoted:
    # It assumes prefix and postfix are strings; usually just a percent sign.

    # @@: I'm not sure what the quoting rules really are for all the
    # databases

    def __init__(self, expr):
        self.expr = expr
        self.prefix = ''
        self.postfix = ''

    def __radd__(self, s):
        self.prefix = s + self.prefix
        return self

    def __add__(self, s):
        self.postfix += s
        return self

    def __sqlrepr__(self, db):
        s = self.expr
        if isinstance(s, SQLExpression):
            values = []
            if self.prefix:
                values.append("'%s'" % self.prefix)
            s = _quote_percent(sqlrepr(s, db), db)
            values.append(s)
            if self.postfix:
                values.append("'%s'" % self.postfix)
            if db == "mysql":
                return "CONCAT(%s)" % ", ".join(values)
            else:
                return " || ".join(values)
        else: # assuming s is a string
            s = _quote_percent(s, db)
            return "'%s%s%s'" % (self.prefix, s, self.postfix)

def _quote_percent(s, db):
    if db in ('postgres', 'mysql'):
        s = s.replace('%', '\\%')
    else:
        s = s.replace('%', '%%')
    return s

########################################
## SQL JOINs
########################################

class SQLJoin(SQLExpression):
    def __init__(self, table1, table2, op=','):
        if table1 and type(table1) <> str:
            if isinstance(table1, Alias):
                table1 = "%s %s %s" % (table1.q.tableName, AliasField.as_string, table1.q.alias)
            else:
                table1 = table1.sqlmeta.table
        if type(table2) <> str:
            if isinstance(table2, Alias):
                table2 = "%s %s %s" % (table2.q.tableName, AliasField.as_string, table2.q.alias)
            else:
                table2 = table2.sqlmeta.table
        self.table1 = table1
        self.table2 = table2
        self.op = op

    def __sqlrepr__(self, db):
        if self.table1:
            return "%s%s %s" % (self.table1, self.op, self.table2)
        else:
            return "%s %s" % (self.op, self.table2)

registerConverter(SQLJoin, SQLExprConverter)

def JOIN(table1, table2):
    return SQLJoin(table1, table2, " JOIN")

def INNERJOIN(table1, table2):
    return SQLJoin(table1, table2, " INNER JOIN")

def CROSSJOIN(table1, table2):
    return SQLJoin(table1, table2, " CROSS JOIN")

def STRAIGHTJOIN(table1, table2):
    return SQLJoin(table1, table2, " STRAIGHT JOIN")

def LEFTJOIN(table1, table2):
    return SQLJoin(table1, table2, " LEFT JOIN")

def LEFTOUTERJOIN(table1, table2):
    return SQLJoin(table1, table2, " LEFT OUTER JOIN")

def NATURALJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL JOIN")

def NATURALLEFTJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL LEFT JOIN")

def NATURALLEFTOUTERJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL LEFT OUTER JOIN")

def RIGHTJOIN(table1, table2):
    return SQLJoin(table1, table2, " RIGHT JOIN")

def RIGHTOUTERJOIN(table1, table2):
    return SQLJoin(table1, table2, " RIGHT OUTER JOIN")

def NATURALRIGHTJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL RIGHT JOIN")

def NATURALRIGHTOUTERJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL RIGHT OUTER JOIN")

def FULLJOIN(table1, table2):
    return SQLJoin(table1, table2, " FULL JOIN")

def FULLOUTERJOIN(table1, table2):
    return SQLJoin(table1, table2, " FULL OUTER JOIN")

def NATURALFULLJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL FULL JOIN")

def NATURALFULLOUTERJOIN(table1, table2):
    return SQLJoin(table1, table2, " NATURAL FULL OUTER JOIN")

class SQLJoinConditional(SQLJoin):
    """Conditional JOIN"""
    def __init__(self, table1, table2, op, on_condition=None, using_columns=None):
        """For condition you must give on_condition or using_columns but not both

            on_condition can be a string or SQLExpression, for example
                Table1.q.col1 == Table2.q.col2
            using_columns can be a string or a list of columns, e.g.
                (Table1.q.col1, Table2.q.col2)
        """
        if not on_condition and not using_columns:
            raise TypeError, "You must give ON condition or USING columns"
        if on_condition and using_columns:
            raise TypeError, "You must give ON condition or USING columns but not both"
        SQLJoin.__init__(self, table1, table2, op)
        self.on_condition = on_condition
        self.using_columns = using_columns

    def __sqlrepr__(self, db):
        if self.on_condition:
            on_condition = self.on_condition
            if hasattr(on_condition, "__sqlrepr__"):
                on_condition = sqlrepr(on_condition, db)
            join = "%s %s ON %s" % (self.op, self.table2, on_condition)
            if self.table1:
                join = "%s %s" % (self.table1, join)
            return join
        elif self.using_columns:
            using_columns = []
            for col in self.using_columns:
                if hasattr(col, "__sqlrepr__"):
                    col = sqlrepr(col, db)
                using_columns.append(col)
            using_columns = ", ".join(using_columns)
            join = "%s %s USING (%s)" % (self.op, self.table2, using_columns)
            if self.table1:
                join = "%s %s" % (self.table1, join)
            return join
        else:
            RuntimeError, "Impossible error"

registerConverter(SQLJoinConditional, SQLExprConverter)

def INNERJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "INNER JOIN", on_condition, using_columns)

def LEFTJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "LEFT JOIN", on_condition, using_columns)

def LEFTOUTERJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "LEFT OUTER JOIN", on_condition, using_columns)

def RIGHTJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "RIGHT JOIN", on_condition, using_columns)

def RIGHTOUTERJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "RIGHT OUTER JOIN", on_condition, using_columns)

def FULLJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "FULL JOIN", on_condition, using_columns)

def FULLOUTERJOINConditional(table1, table2, on_condition=None, using_columns=None):
    return SQLJoinConditional(table1, table2, "FULL OUTER JOIN", on_condition, using_columns)

class SQLJoinOn(SQLJoinConditional):
    """Conditional JOIN ON"""
    def __init__(self, table1, table2, op, on_condition):
        SQLJoinConditional.__init__(self, table1, table2, op, on_condition)

registerConverter(SQLJoinOn, SQLExprConverter)

class SQLJoinUsing(SQLJoinConditional):
    """Conditional JOIN USING"""
    def __init__(self, table1, table2, op, using_columns):
        SQLJoinConditional.__init__(self, table1, table2, op, None, using_columns)

registerConverter(SQLJoinUsing, SQLExprConverter)

def INNERJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "INNER JOIN", on_condition)

def LEFTJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "LEFT JOIN", on_condition)

def LEFTOUTERJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "LEFT OUTER JOIN", on_condition)

def RIGHTJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "RIGHT JOIN", on_condition)

def RIGHTOUTERJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "RIGHT OUTER JOIN", on_condition)

def FULLJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "FULL JOIN", on_condition)

def FULLOUTERJOINOn(table1, table2, on_condition):
    return SQLJoinOn(table1, table2, "FULL OUTER JOIN", on_condition)

def INNERJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "INNER JOIN", using_columns)

def LEFTJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "LEFT JOIN", using_columns)

def LEFTOUTERJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "LEFT OUTER JOIN", using_columns)

def RIGHTJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "RIGHT JOIN", using_columns)

def RIGHTOUTERJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "RIGHT OUTER JOIN", using_columns)

def FULLJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "FULL JOIN", using_columns)

def FULLOUTERJOINUsing(table1, table2, using_columns):
    return SQLJoinUsing(table1, table2, "FULL OUTER JOIN", using_columns)


########################################
## Subqueries (subselects)
########################################

class OuterField(Field):
    def tablesUsedImmediate(self):
        return []

class OuterTable(Table):
    FieldClass = OuterField

    def __init__(self, table):
        if hasattr(table, "sqlmeta"):
            tableName = table.sqlmeta.table
        else:
            tableName = table
            table = None
        Table.__init__(self, tableName)
        self.table = table

class Outer:
    def __init__(self, table):
        self.q = OuterTable(table)


class LIKE(SQLExpression):
    op = "LIKE"

    def __init__(self, expr, string):
        self.expr = expr
        self.string = string
    def __sqlrepr__(self, db):
        return "(%s %s (%s))" % (sqlrepr(self.expr, db), self.op, sqlrepr(self.string, db))
    def components(self):
        return [self.expr, self.string]
    def execute(self, executor):
        if not hasattr(self, '_regex'):
            # @@: Crude, not entirely accurate
            dest = self.string
            dest = dest.replace("%%", "\001")
            dest = dest.replace("*", "\002")
            dest = dest.replace("%", "*")
            dest = dest.replace("\001", "%")
            dest = dest.replace("\002", "[*]")
            self._regex = re.compile(fnmatch.translate(dest), re.I)
        return self._regex.search(execute(self.expr, executor))

class RLIKE(LIKE):
    op = "RLIKE"

    def _get_op(self, db):
        if db in ('mysql', 'maxdb', 'firebird'):
            return "RLIKE"
        elif db == 'sqlite':
            return "REGEXP"
        elif db == 'postgres':
            return "~"
        else:
            return "LIKE"
    def __sqlrepr__(self, db):
        return "(%s %s (%s))" % (
            sqlrepr(self.expr, db), self._get_op(db), sqlrepr(self.string, db)
        )
    def execute(self, executor):
        self.op = self._get_op(self.db)
        return LIKE.execute(self, executor)


class INSubquery(SQLExpression):
    op = "IN"

    def __init__(self, item, subquery):
        self.item = item
        self.subquery = subquery
    def components(self):
        return [self.item]
    def __sqlrepr__(self, db):
        return "%s %s (%s)" % (sqlrepr(self.item, db), self.op, sqlrepr(self.subquery, db))

class NOTINSubquery(INSubquery):
    op = "NOT IN"


class Subquery(SQLExpression):
    def __init__(self, op, subquery):
        self.op = op
        self.subquery = subquery

    def __sqlrepr__(self, db):
        return "%s (%s)" % (self.op, sqlrepr(self.subquery, db))

def EXISTS(subquery):
    return Subquery("EXISTS", subquery)

def NOTEXISTS(subquery):
    return Subquery("NOT EXISTS", subquery)

def SOME(subquery):
    return Subquery("SOME", subquery)

def ANY(subquery):
    return Subquery("ANY", subquery)

def ALL(subquery):
    return Subquery("ALL", subquery)


########################################
## Global initializations
########################################

table = TableSpace()
const = ConstantSpace()
func = const

########################################
## Testing
########################################

if __name__ == "__main__":
    tests = """
>>> AND(table.address.name == "Ian Bicking", table.address.zip > 30000)
>>> table.address.name
>>> AND(LIKE(table.address.name, "this"), IN(table.address.zip, [100, 200, 300]))
>>> Select([table.address.name, table.address.state], where=LIKE(table.address.name, "%ian%"))
>>> Select([table.user.name], where=AND(table.user.state == table.states.abbrev))
>>> Insert(table.address, [{"name": "BOB", "address": "3049 N. 18th St."}, {"name": "TIM", "address": "409 S. 10th St."}])
>>> Insert(table.address, [("BOB", "3049 N. 18th St."), ("TIM", "409 S. 10th St.")], template=('name', 'address'))
>>> Delete(table.address, where="BOB"==table.address.name)
>>> Update(table.address, {"lastModified": const.NOW()})
>>> Replace(table.address, [("BOB", "3049 N. 18th St."), ("TIM", "409 S. 10th St.")], template=('name', 'address'))
"""
    for expr in tests.split('\n'):
        if not expr.strip(): continue
        if expr.startswith('>>> '):
            expr = expr[4:]