Merge pull request #20990 from github/tausbn/python-support-relaxed-exception-groups

Python: Add support for PEP-758 exception syntax

Author: yoff

python/extractor/tests/parser/exception_groups_new.expected

@@ -1,4 +1,4 @@
-Module: [1, 0] - [27, 0]
+Module: [1, 0] - [32, 0]
   body: [
     Try: [1, 0] - [1, 4]
       body: [
@@ -153,4 +153,28 @@ Module: [1, 0] - [27, 0]
           ]
       ]
       finalbody: []
+    Try: [28, 0] - [28, 4]
+      body: [
+        Pass: [29, 4] - [29, 8]
+      ]
+      orelse: []
+      handlers: [
+        ExceptGroupStmt: [30, 0] - [31, 8]
+          type:
+            Tuple: [30, 8] - [30, 12]
+              elts: [
+                Name: [30, 8] - [30, 9]
+                  variable: Variable('x', None)
+                  ctx: Load
+                Name: [30, 11] - [30, 12]
+                  variable: Variable('y', None)
+                  ctx: Load
+              ]
+              ctx: Load
+          name: None
+          body: [
+            Pass: [31, 4] - [31, 8]
+          ]
+      ]
+      finalbody: []
   ]

python/extractor/tests/parser/exception_groups_new.py

@@ -24,3 +24,8 @@
     pass
 except *foo as e:
     pass
+
+try:
+    pass
+except* x, y:
+    pass

python/extractor/tests/parser/exceptions_new.expected

@@ -0,0 +1,64 @@
+Module: [1, 0] - [9, 0]
+  body: [
+    Try: [1, 0] - [1, 4]
+      body: [
+        Pass: [2, 4] - [2, 8]
+      ]
+      orelse: []
+      handlers: [
+        ExceptStmt: [3, 0] - [3, 12]
+          type:
+            Tuple: [3, 7] - [3, 11]
+              elts: [
+                Name: [3, 7] - [3, 8]
+                  variable: Variable('a', None)
+                  ctx: Load
+                Name: [3, 10] - [3, 11]
+                  variable: Variable('b', None)
+                  ctx: Load
+              ]
+              ctx: Load
+          name: None
+          body: [
+            Pass: [4, 4] - [4, 8]
+          ]
+        ExceptStmt: [5, 0] - [5, 14]
+          type:
+            Tuple: [5, 8] - [5, 12]
+              elts: [
+                Name: [5, 8] - [5, 9]
+                  variable: Variable('c', None)
+                  ctx: Load
+                Name: [5, 11] - [5, 12]
+                  variable: Variable('d', None)
+                  ctx: Load
+              ]
+              ctx: Load
+              parenthesised: True
+          name: None
+          body: [
+            Pass: [6, 4] - [6, 8]
+          ]
+        ExceptStmt: [7, 0] - [7, 19]
+          type:
+            Tuple: [7, 8] - [7, 12]
+              elts: [
+                Name: [7, 8] - [7, 9]
+                  variable: Variable('e', None)
+                  ctx: Load
+                Name: [7, 11] - [7, 12]
+                  variable: Variable('f', None)
+                  ctx: Load
+              ]
+              ctx: Load
+              parenthesised: True
+          name:
+            Name: [7, 17] - [7, 18]
+              variable: Variable('g', None)
+              ctx: Store
+          body: [
+            Pass: [8, 4] - [8, 8]
+          ]
+      ]
+      finalbody: []
+  ]

python/extractor/tests/parser/exceptions_new.py

@@ -0,0 +1,8 @@
+try:
+    pass
+except a, b: # new, relaxed syntax
+    pass
+except (c, d): # old syntax
+    pass
+except (e, f) as g: # old syntax
+    pass

python/extractor/tsg-python/python.tsg

@@ -12,7 +12,7 @@
 (assignment !type) @assign
 { let @assign.node = (ast-node @assign "Assign") }
 
-[ (expression_list) (tuple) (tuple_pattern) (pattern_list) (index_expression_list) ] @tuple
+[ (expression_list) (tuple) (tuple_pattern) (pattern_list) (index_expression_list) (exception_list)] @tuple
 { let @tuple.node = (ast-node @tuple "Tuple") }
 
 (list_pattern) @list
@@ -3445,6 +3445,9 @@
     (tuple element: (_) @elt) @parent
 
     (tuple_pattern element: (_) @elt) @parent
+
+    ; An exception list, as in `except A, B, C: ...`
+    (exception_list element: (_) @elt) @parent
 ]
 {
     edge @parent.node -> @elt.node
@@ -3480,6 +3483,7 @@
     (parenthesized_expression inner: (_) @elt)
     (set element: (_) @elt)
     (match_sequence_pattern (_) @elt)
+    (exception_list element: (_) @elt)
 ] @seq
 {
     attr (@elt.node) _inherited_ctx = @seq.node

python/extractor/tsg-python/tsp/.gitattributes

@@ -0,0 +1,4 @@
+# Mark tree-sitter generated files
+src/grammar.json linguist-generated
+src/node-types.json linguist-generated
+src/parser.c linguist-generated

python/extractor/tsg-python/tsp/grammar.js

@@ -297,12 +297,21 @@ module.exports = grammar({
       )
     ),
 
+    exception_list: $ => seq(
+      field('element', $.expression),
+      repeat1(
+        seq(
+          ',',
+          field('element', $.expression))
+        )
+      ),
+
     except_clause: $ => seq(
       'except',
       optional(seq(
-        field('type', $.expression),
+        field('type', choice($.expression, $.exception_list)),
         optional(seq(
-          choice('as', ','),
+          'as',
           field('alias', $.expression)
         ))
       )),
@@ -314,7 +323,7 @@ module.exports = grammar({
       'except',
       '*',
       seq(
-        field('type', $.expression),
+        field('type', choice($.expression, $.exception_list)),
         optional(seq(
           'as',
           field('alias', $.expression)