Rename main_root_node property to root in MatchContext

Co-authored-by: gramalingam <10075881+gramalingam@users.noreply.github.com>

Author: Copilot

docs/tutorial/rewriter/conditional_rewrite.md

@@ -61,7 +61,7 @@ The MatchContext provides the following read-only properties:
 
 - `model`: The entire ONNX model being matched
 - `graph_or_function`: The specific graph or function being matched
-- `main_root_node`: The primary root node of the matching subgraph
+- `root`: The root node of the matching subgraph
 - `output_values`: The output values of the matching subgraph
 - `nodes`: All nodes that are part of the matching subgraph
 
@@ -74,7 +74,7 @@ def advanced_condition_check(context, x, y, **_):
     """Example condition function using MatchContext."""
 
     # Access the main node of the pattern match
-    main_node = context.main_root_node
+    main_node = context.root
 
     # Check that the main_node does not have an attribute called "alpha"
     if "alpha" in main_node.attributes:

onnxscript/rewriter/_basics.py

@@ -344,28 +344,28 @@ class MatchContext:
     """A read-only context containing information about a pattern match.
     
     This class captures information about the context describing a match to a given pattern,
-    providing access to the model, graph/function, main root node, output values, and all
+    providing access to the model, graph/function, root node, output values, and all
     nodes of the matching subgraph.
     """
 
     def __init__(
         self,
         model: ir.Model,
         graph_or_function: ir.Graph | ir.Function,
-        main_root_node: ir.Node,
+        root: ir.Node,
         match_result: MatchResult,
     ) -> None:
         """Initialize the pattern match context.
         
         Args:
             model: The model being matched.
             graph_or_function: The graph or function being matched.
-            main_root_node: The main root node of the matching subgraph.
+            root: The root node of the matching subgraph.
             match_result: The match result containing matched nodes and outputs.
         """
         self._model = model
         self._graph_or_function = graph_or_function
-        self._main_root_node = main_root_node
+        self._root = root
         self._match_result = match_result
 
     @property
@@ -379,9 +379,9 @@ def graph_or_function(self) -> ir.Graph | ir.Function:
         return self._graph_or_function
 
     @property
-    def main_root_node(self) -> ir.Node:
-        """The main root node of the matching subgraph."""
-        return self._main_root_node
+    def root(self) -> ir.Node:
+        """The root node of the matching subgraph."""
+        return self._root
 
     @property
     def output_values(self) -> Sequence[ir.Value]:

onnxscript/rewriter/match_context_test.py

@@ -31,7 +31,7 @@ def condition_using_context(context, x, y):
             # Use context to check properties of the match
             self.assertIs(context.model, model)
             self.assertIs(context.graph_or_function, model.graph)
-            self.assertIs(context.main_root_node, model.graph[2])
+            self.assertIs(context.root, model.graph[2])
 
             # Verify that we can inspect the matched nodes
             self.assertEqual(len(context.nodes), 2)