- basic framework for generic functions, [ticket:615]

- changed the various "literal" generation functions to use an anonymous
bind parameter.  not much changes here except their labels now look
like ":param_1", ":param_2" instead of ":literal"
- from_obj keyword argument to select() can be a scalar or a list.

3 files changed, 135 insertions, 32 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index d94d3fef6..ea7c1b734 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -8,15 +8,10 @@
 
 import string, re
 from sqlalchemy import schema, engine, util, exceptions
-from sqlalchemy.sql import operators, visitors
+from sqlalchemy.sql import operators, visitors, functions
 from sqlalchemy.sql import util as sql_util
 from sqlalchemy.sql import expression as sql
 
-ANSI_FUNCS = util.Set([
-    'CURRENT_DATE', 'CURRENT_TIME', 'CURRENT_TIMESTAMP',
-    'CURRENT_USER', 'LOCALTIME', 'LOCALTIMESTAMP',
-    'SESSION_USER', 'USER'])
-
 RESERVED_WORDS = util.Set([
     'all', 'analyse', 'analyze', 'and', 'any', 'array',
     'as', 'asc', 'asymmetric', 'authorization', 'between',
@@ -87,6 +82,18 @@ OPERATORS =  {
     operators.isnot : 'IS NOT'
 }
 
+FUNCTIONS = {
+    functions.coalesce : 'coalesce%(expr)s',
+    functions.current_date: 'CURRENT_DATE', 
+    functions.current_time: 'CURRENT_TIME', 
+    functions.current_timestamp: 'CURRENT_TIMESTAMP',
+    functions.current_user: 'CURRENT_USER', 
+    functions.localtime: 'LOCALTIME', 
+    functions.localtimestamp: 'LOCALTIMESTAMP',
+    functions.session_user :'SESSION_USER', 
+    functions.user: 'USER'
+}
+
 class DefaultCompiler(engine.Compiled):
     """Default implementation of Compiled.
 
@@ -97,6 +104,7 @@ class DefaultCompiler(engine.Compiled):
     __traverse_options__ = {'column_collections':False, 'entry':True}
 
     operators = OPERATORS
+    functions = FUNCTIONS
     
     def __init__(self, dialect, statement, column_keys=None, inline=False, **kwargs):
         """Construct a new ``DefaultCompiler`` object.
@@ -215,7 +223,7 @@ class DefaultCompiler(engine.Compiled):
         labelname = self._truncated_identifier("colident", label.name)
         
         if result_map is not None:
-            result_map[labelname] = (label.name, (label, label.obj), label.obj.type)
+            result_map[labelname.lower()] = (label.name, (label, label.obj), label.obj.type)
             
         return " ".join([self.process(label.obj), self.operator_string(operators.as_), self.preparer.format_label(label, labelname)])
         
@@ -231,7 +239,7 @@ class DefaultCompiler(engine.Compiled):
             name = column.name
 
         if result_map is not None:
-            result_map[name] = (name, (column, ), column.type)
+            result_map[name.lower()] = (name, (column, ), column.type)
         
         if column._is_oid:
             n = self.dialect.oid_column_name(column)
@@ -270,7 +278,7 @@ class DefaultCompiler(engine.Compiled):
     def visit_textclause(self, textclause, **kwargs):
         if textclause.typemap is not None:
             for colname, type_ in textclause.typemap.iteritems():
-                self.result_map[colname] = (colname, None, type_)
+                self.result_map[colname.lower()] = (colname, None, type_)
                 
         def do_bindparam(m):
             name = m.group(1)
@@ -297,9 +305,6 @@ class DefaultCompiler(engine.Compiled):
             sep = " " + self.operator_string(clauselist.operator) + " "
         return sep.join([s for s in [self.process(c) for c in clauselist.clauses] if s is not None])
 
-    def apply_function_parens(self, func):
-        return func.name.upper() not in ANSI_FUNCS or len(func.clauses) > 0
-
     def visit_calculatedclause(self, clause, **kwargs):
         return self.process(clause.clause_expr)
 
@@ -308,12 +313,20 @@ class DefaultCompiler(engine.Compiled):
 
     def visit_function(self, func, result_map=None, **kwargs):
         if result_map is not None:
-            result_map[func.name] = (func.name, None, func.type)
+            result_map[func.name.lower()] = (func.name, None, func.type)
+
+        name = self.function_string(func)
             
-        if not self.apply_function_parens(func):
-            return ".".join(func.packagenames + [func.name])
+        if callable(name):
+            return name(*[self.process(x) for x in func.clause_expr])
         else:
-            return ".".join(func.packagenames + [func.name]) + (not func.group and " " or "") + self.process(func.clause_expr)
+            return ".".join(func.packagenames + [name]) % {'expr':self.function_argspec(func)}
+    
+    def function_argspec(self, func):
+        return self.process(func.clause_expr)
+        
+    def function_string(self, func):
+        return self.functions.get(func.__class__, func.name + "%(expr)s")
 
     def visit_compound_select(self, cs, asfrom=False, parens=True, **kwargs):
         stack_entry = {'select':cs}
@@ -358,10 +371,11 @@ class DefaultCompiler(engine.Compiled):
         
     def operator_string(self, operator):
         return self.operators.get(operator, str(operator))
-
+    
     def visit_bindparam(self, bindparam, **kwargs):
-        # apply truncation to the ultimate generated name
-
+        # TODO: remove this whole "unique" thing, just use regular
+        # anonymous params to implement.  params used for inserts/updates
+        # etc. should no longer be "unique".
         if bindparam.unique:
             count = 1
             key = bindparam.key
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index c21b102c7..6ad29218f 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -26,10 +26,11 @@ to stay the same in future releases.
 """
 
 import re
+import datetime
 from sqlalchemy import util, exceptions
 from sqlalchemy.sql import operators, visitors
 from sqlalchemy import types as sqltypes
-
+functions = None
 
 __all__ = [
     'Alias', 'ClauseElement', 
@@ -596,7 +597,7 @@ def literal(value, type_=None):
       bind-parameter translation for this literal.
     """
 
-    return _BindParamClause('literal', value, type_=type_, unique=True)
+    return _BindParamClause(None, value, type_=type_, unique=True)
 
 def label(name, obj):
     """Return a [sqlalchemy.sql.expression#_Label] object for the given [sqlalchemy.sql.expression#ColumnElement].
@@ -766,6 +767,14 @@ class _FunctionGenerator(object):
     def __call__(self, *c, **kwargs):
         o = self.opts.copy()
         o.update(kwargs)
+        if len(self.__names) == 1:
+            global functions
+            if functions is None:
+                from sqlalchemy.sql import functions
+            func = getattr(functions, self.__names[-1].lower(), None)
+            if func is not None:
+                return func(*c, **o)
+                
         return _Function(self.__names[-1], packagenames=self.__names[0:-1], *c, **o)
 
 func = _FunctionGenerator()
@@ -798,7 +807,7 @@ def _literal_as_column(element):
     else:
         return element
 
-def _literal_as_binds(element, name='literal', type_=None):
+def _literal_as_binds(element, name=None, type_=None):
     if isinstance(element, Operators):
         return element.expression_element()
     elif _is_literal(element):
@@ -1344,7 +1353,7 @@ class _CompareMixin(ColumnOperators):
         return lambda other: self.__operate(operator, other)
 
     def _bind_param(self, obj):
-        return _BindParamClause('literal', obj, type_=self.type, unique=True)
+        return _BindParamClause(None, obj, type_=self.type, unique=True)
 
     def _check_literal(self, other):
         if isinstance(other, _BindParamClause) and isinstance(other.type, sqltypes.NullType):
@@ -1762,6 +1771,10 @@ class _BindParamClause(ClauseElement, _CompareMixin):
         unicode : sqltypes.NCHAR,
         int : sqltypes.Integer,
         float : sqltypes.Numeric,
+        datetime.date : sqltypes.Date,
+        datetime.datetime : sqltypes.DateTime,
+        datetime.time : sqltypes.Time,
+        datetime.timedelta : sqltypes.Interval,
         type(None):sqltypes.NullType
     }
 
@@ -1997,11 +2010,12 @@ class _Function(_CalculatedClause, FromClause):
     def __init__(self, name, *clauses, **kwargs):
         self.packagenames = kwargs.get('packagenames', None) or []
         self.oid_column = None
-        kwargs['operator'] = operators.comma_op
-        _CalculatedClause.__init__(self, name, **kwargs)
-        for c in clauses:
-            self.append(c)
-
+        self.name = name
+        self._bind = kwargs.get('bind', None)
+        args = [_literal_as_binds(c, self.name) for c in clauses]
+        self.clause_expr = ClauseList(operator=operators.comma_op, group_contents=True, *args).self_group()
+        self.type = sqltypes.to_instance(kwargs.get('type_', None))
+        
     key = property(lambda self:self.name)
     columns = property(lambda self:[self])
 
@@ -2012,9 +2026,6 @@ class _Function(_CalculatedClause, FromClause):
     def get_children(self, **kwargs):
         return _CalculatedClause.get_children(self, **kwargs)
 
-    def append(self, clause):
-        self.clauses.append(_literal_as_binds(clause, self.name))
-
 
 class _Cast(ColumnElement):
 
@@ -2984,7 +2995,7 @@ class Select(_SelectBaseMixin, FromClause):
         if from_obj:
             self._froms = util.Set([
                 _is_literal(f) and _TextFromClause(f) or f
-                for f in from_obj
+                for f in util.to_list(from_obj)
             ])
         else:
             self._froms = util.Set()
diff --git a/lib/sqlalchemy/sql/functions.py b/lib/sqlalchemy/sql/functions.py
new file mode 100644
index 000000000..d39032b91
--- /dev/null
+++ b/lib/sqlalchemy/sql/functions.py
@@ -0,0 +1,78 @@
+from sqlalchemy import types as sqltypes
+from sqlalchemy.sql.expression import _Function, _literal_as_binds, ClauseList, _FigureVisitName
+from sqlalchemy.sql import operators
+
+class _GenericMeta(_FigureVisitName):
+    def __init__(cls, clsname, bases, dict):
+        cls.__visit_name__ = 'function'
+        type.__init__(cls, clsname, bases, dict)
+       
+    def __call__(self, *args, **kwargs):
+        args = [_literal_as_binds(c) for c in args]
+        return type.__call__(self, *args, **kwargs)
+        
+class GenericFunction(_Function):
+    __metaclass__ = _GenericMeta
+
+    def __init__(self, type_=None, group=True, args=(), **kwargs):
+        self.packagenames = []
+        self.oid_column = None
+        self.name = self.__class__.__name__
+        self._bind = kwargs.get('bind', None)
+        if group:
+            self.clause_expr = ClauseList(operator=operators.comma_op, group_contents=True, *args).self_group()
+        else:
+            self.clause_expr = ClauseList(operator=operators.comma_op, group_contents=True, *args)
+        self.type = sqltypes.to_instance(type_ or getattr(self, '__return_type__', None))
+        
+class AnsiFunction(GenericFunction):
+    def __init__(self, **kwargs):
+        GenericFunction.__init__(self, **kwargs)
+
+        
+class coalesce(GenericFunction):
+    def __init__(self, *args, **kwargs):
+        kwargs.setdefault('type_', _type_from_args(args))
+        GenericFunction.__init__(self, args=args, **kwargs)
+
+class concat(GenericFunction):
+    __return_type__ = sqltypes.String
+    def __init__(self, *args, **kwargs):
+        GenericFunction.__init__(self, args=args, **kwargs)
+
+class char_length(GenericFunction):
+    __return_type__ = sqltypes.Integer
+
+    def __init__(self, arg, **kwargs):
+        GenericFunction.__init__(self, args=[arg], **kwargs)
+        
+class current_date(AnsiFunction):
+    __return_type__ = sqltypes.Date
+        
+class current_time(AnsiFunction):
+    __return_type__ = sqltypes.Time
+
+class current_timestamp(AnsiFunction):
+    __return_type__ = sqltypes.DateTime
+
+class current_user(AnsiFunction):
+    __return_type__ = sqltypes.String
+
+class localtime(AnsiFunction):
+    __return_type__ = sqltypes.DateTime
+
+class localtimestamp(AnsiFunction):
+    __return_type__ = sqltypes.DateTime
+
+class session_user(AnsiFunction):
+    __return_type__ = sqltypes.String
+
+class user(AnsiFunction):
+    __return_type__ = sqltypes.String
+
+def _type_from_args(args):
+    for a in args:
+        if not isinstance(a.type, sqltypes.NullType):
+            return a.type
+    else:
+        return sqltypes.NullType
\ No newline at end of file