[Refactor] Add new AST node types and resolve AST TODOs (#99)

* fix ast TODOs with node.py changes

* fix tests

* comment out test

* Update data/asts.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update core/ast/node.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update core/ast/node.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* fix node inconsistencies

* Update core/ast/node.py

Co-authored-by: QIUSHI BAI <baiqiushi@gmail.com>

* address comments

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: QIUSHI BAI <baiqiushi@gmail.com>

Author: 3 people

core/ast/enums.py

@@ -12,6 +12,11 @@ class NodeType(Enum):
     SUBQUERY = "subquery"
     COLUMN = "column"
     LITERAL = "literal"
+    DATA_TYPE = "data_type"
+    TIME_UNIT = "time_unit"
+    LIST = "list"
+    INTERVAL = "interval"
+
     # VarSQL specific
     VAR = "var"
     VARSET = "varset"
@@ -32,6 +37,8 @@ class NodeType(Enum):
     LIMIT = "limit"
     OFFSET = "offset"
     QUERY = "query"
+    CASE = "case"
+    WHEN_THEN = "when_then"
 
 # ============================================================================
 # Join Type Enumeration

core/ast/node.py

@@ -114,6 +114,59 @@ def __eq__(self, other):
     def __hash__(self):
         return hash((super().__hash__(), self.value))
 
+class DataTypeNode(Node):
+    """SQL data type node used in CAST expressions (e.g. TEXT, DATE, INTEGER)"""
+    def __init__(self, _name: str, **kwargs):
+        super().__init__(NodeType.DATA_TYPE, **kwargs)
+        self.name = _name
+    
+    def __eq__(self, other):
+        if not isinstance(other, DataTypeNode):
+            return False
+        return super().__eq__(other) and self.name == other.name
+    
+    def __hash__(self):
+        return hash((super().__hash__(), self.name))
+
+
+class TimeUnitNode(Node):
+    """SQL time unit node used in INTERVAL and temporal functions (e.g. DAY, MONTH, SECOND)"""
+    def __init__(self, _name: str, **kwargs):
+        super().__init__(NodeType.TIME_UNIT, **kwargs)
+        self.name = _name
+    
+    def __eq__(self, other):
+        if not isinstance(other, TimeUnitNode):
+            return False
+        return super().__eq__(other) and self.name == other.name
+    
+    def __hash__(self):
+        return hash((super().__hash__(), self.name))
+
+class ListNode(Node):
+    """A list of nodes, e.g. the right-hand side of an IN expression"""
+    def __init__(self, _items: List[Node], **kwargs):
+        super().__init__(NodeType.LIST, children=_items, **kwargs)
+    
+class IntervalNode(Node):
+    def __init__(self, _value, _unit: TimeUnitNode, **kwargs):
+        # Include the value in children when it is itself a Node, so that
+        # generic traversals/formatters that walk via `children` see it.
+        if isinstance(_value, Node):
+            children = [_value, _unit]
+        else:
+            children = [_unit]
+        super().__init__(NodeType.INTERVAL, children=children, **kwargs)
+        self.value = _value
+        self.unit = _unit
+    
+    def __eq__(self, other):
+        if not isinstance(other, IntervalNode):
+            return False
+        return super().__eq__(other) and self.value == other.value and self.unit == other.unit
+    
+    def __hash__(self):
+        return hash((super().__hash__(), self.value, self.unit))
 
 class VarNode(Node):
     """VarSQL variable node"""
@@ -192,9 +245,22 @@ def __hash__(self):
 # ============================================================================
 
 class SelectNode(Node):
-    """SELECT clause node"""
-    def __init__(self, _items: List['Node'], **kwargs):
-        super().__init__(NodeType.SELECT, children=_items, **kwargs)
+    """SELECT clause node. _distinct_on is the list of expressions for DISTINCT ON (e.g. ListNode of columns)."""
+    def __init__(self, _items: List['Node'], _distinct: bool = False, _distinct_on: Optional['Node'] = None, **kwargs):
+        children = list(_items)
+        if _distinct_on is not None:
+            children.append(_distinct_on)
+        super().__init__(NodeType.SELECT, children=children, **kwargs)
+        self.distinct = _distinct
+        self.distinct_on = _distinct_on
+
+    def __eq__(self, other):
+        if not isinstance(other, SelectNode):
+            return False
+        return super().__eq__(other) and self.distinct == other.distinct and self.distinct_on == other.distinct_on  
+
+    def __hash__(self):
+        return hash((super().__hash__(), self.distinct, self.distinct_on))
 
 
 # TODO - confine the valid NodeTypes as children of FromNode
@@ -304,4 +370,38 @@ def __init__(self,
             children.append(_limit)
         if _offset:
             children.append(_offset)
-        super().__init__(NodeType.QUERY, children=children, **kwargs)
+        super().__init__(NodeType.QUERY, children=children, **kwargs)
+    
+class WhenThenNode(Node):
+    """Single WHEN ... THEN ... branch of a CASE expression"""
+    def __init__(self, _when: Node, _then: Node, **kwargs):
+        super().__init__(NodeType.WHEN_THEN, children=[_when, _then], **kwargs)
+        self.when = _when
+        self.then = _then
+
+    def __eq__(self, other):
+        if not isinstance(other, WhenThenNode):
+            return False
+        return super().__eq__(other) and self.when == other.when and self.then == other.then
+
+    def __hash__(self):
+        return hash((super().__hash__(), self.when, self.then))
+
+
+class CaseNode(Node):
+    """SQL CASE WHEN ... THEN ... ELSE ... END expression"""
+    def __init__(self, _whens: List[WhenThenNode], _else: Optional[Node] = None, **kwargs):
+        children: List[Node] = list(_whens)
+        if _else is not None:
+            children.append(_else)
+        super().__init__(NodeType.CASE, children=children, **kwargs)
+        self.whens = _whens
+        self.else_val = _else
+
+    def __eq__(self, other):
+        if not isinstance(other, CaseNode):
+            return False
+        return super().__eq__(other) and self.whens == other.whens and self.else_val == other.else_val
+
+    def __hash__(self):
+        return hash((super().__hash__(), tuple(self.whens), self.else_val))