feat: add support for pattern matching

https://www.python.org/dev/peps/pep-0636/ Fixes #116
tree-sitter · Dec 3, 2021 · 2e38411 · 2e38411
1 parent 24b530c
commit 2e38411
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Showing 8 changed files with 29,853 additions and 27,450 deletions.
diff --git a/grammar.js b/grammar.js
@@ -38,6 +38,7 @@ module.exports = grammar({
     [$.tuple, $.tuple_pattern],
     [$.list, $.list_pattern],
     [$.with_item, $._collection_elements],
+    [$.named_expression, $.as_pattern],
   ],
 
   supertypes: $ => [
@@ -222,6 +223,7 @@ module.exports = grammar({
 
     _compound_statement: $ => choice(
       $.if_statement,
+      $.match_statement,
       $.for_statement,
       $.while_statement,
       $.try_statement,
@@ -253,6 +255,20 @@ module.exports = grammar({
       field('body', $._suite)
     ),
 
+    match_statement: $ => seq(
+      'match',
+      field('subject', $.expression),
+      ':',
+      repeat(field('alternative', $.case_clause)),
+    ),
+
+    case_clause: $ => seq(
+      'case',
+      field('pattern', $.expression),
+      ':',
+      field('consequence', $._suite)
+    ),
+
     for_statement: $ => seq(
       optional('async'),
       'for',
@@ -320,10 +336,6 @@ module.exports = grammar({
 
     with_item: $ => prec.dynamic(-1, seq(
       field('value', $.expression),
-      optional(seq(
-        'as',
-        field('alias', $.pattern)
-      ))
     )),
 
     function_definition: $ => seq(
@@ -522,6 +534,14 @@ module.exports = grammar({
       choice($.identifier, $.keyword_identifier, $.subscript, $.attribute)
     ),
 
+    // Extended patterns (patterns allowed in match statement are far more flexible than simple patterns
+
+    as_pattern: $ => prec.left(seq(
+      $.expression,
+      'as',
+      $.expression
+    )),
+
     // Expressions
 
     _expression_within_for_in_clause: $ => choice(
@@ -537,7 +557,8 @@ module.exports = grammar({
       $.lambda,
       $.primary_expression,
       $.conditional_expression,
-      $.named_expression
+      $.named_expression,
+      $.as_pattern
     ),
 
     primary_expression: $ => choice(

diff --git a/src/grammar.json b/src/grammar.json
@@ -745,6 +745,10 @@
           "type": "SYMBOL",
           "name": "if_statement"
         },
+        {
+          "type": "SYMBOL",
+          "name": "match_statement"
+        },
         {
           "type": "SYMBOL",
           "name": "for_statement"
@@ -881,6 +885,67 @@
         }
       ]
     },
+    "match_statement": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "match"
+        },
+        {
+          "type": "FIELD",
+          "name": "subject",
+          "content": {
+            "type": "SYMBOL",
+            "name": "expression"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ":"
+        },
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "FIELD",
+            "name": "alternative",
+            "content": {
+              "type": "SYMBOL",
+              "name": "case_clause"
+            }
+          }
+        }
+      ]
+    },
+    "case_clause": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "case"
+        },
+        {
+          "type": "FIELD",
+          "name": "pattern",
+          "content": {
+            "type": "SYMBOL",
+            "name": "expression"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": ":"
+        },
+        {
+          "type": "FIELD",
+          "name": "consequence",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_suite"
+          }
+        }
+      ]
+    },
     "for_statement": {
       "type": "SEQ",
       "members": [
@@ -1260,31 +1325,6 @@
               "type": "SYMBOL",
               "name": "expression"
             }
-          },
-          {
-            "type": "CHOICE",
-            "members": [
-              {
-                "type": "SEQ",
-                "members": [
-                  {
-                    "type": "STRING",
-                    "value": "as"
-                  },
-                  {
-                    "type": "FIELD",
-                    "name": "alias",
-                    "content": {
-                      "type": "SYMBOL",
-                      "name": "pattern"
-                    }
-                  }
-                ]
-              },
-              {
-                "type": "BLANK"
-              }
-            ]
           }
         ]
       }
@@ -2248,6 +2288,27 @@
         }
       ]
     },
+    "as_pattern": {
+      "type": "PREC_LEFT",
+      "value": 0,
+      "content": {
+        "type": "SEQ",
+        "members": [
+          {
+            "type": "SYMBOL",
+            "name": "expression"
+          },
+          {
+            "type": "STRING",
+            "value": "as"
+          },
+          {
+            "type": "SYMBOL",
+            "name": "expression"
+          }
+        ]
+      }
+    },
     "_expression_within_for_in_clause": {
       "type": "CHOICE",
       "members": [
@@ -2300,6 +2361,10 @@
         {
           "type": "SYMBOL",
           "name": "named_expression"
+        },
+        {
+          "type": "SYMBOL",
+          "name": "as_pattern"
         }
       ]
     },
@@ -4914,6 +4979,10 @@
     [
       "with_item",
       "_collection_elements"
+    ],
+    [
+      "named_expression",
+      "as_pattern"
     ]
   ],
   "precedences": [],

diff --git a/src/node-types.json b/src/node-types.json
@@ -23,6 +23,10 @@
         "type": "if_statement",
         "named": true
       },
+      {
+        "type": "match_statement",
+        "named": true
+      },
       {
         "type": "try_statement",
         "named": true
@@ -107,6 +111,10 @@
     "type": "expression",
     "named": true,
     "subtypes": [
+      {
+        "type": "as_pattern",
+        "named": true
+      },
       {
         "type": "await",
         "named": true
@@ -360,6 +368,21 @@
       ]
     }
   },
+  {
+    "type": "as_pattern",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": true,
+      "required": true,
+      "types": [
+        {
+          "type": "expression",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "assert_statement",
     "named": true,
@@ -754,6 +777,32 @@
       }
     }
   },
+  {
+    "type": "case_clause",
+    "named": true,
+    "fields": {
+      "consequence": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "block",
+            "named": true
+          }
+        ]
+      },
+      "pattern": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "expression",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
   {
     "type": "chevron",
     "named": true,
@@ -1791,6 +1840,32 @@
       ]
     }
   },
+  {
+    "type": "match_statement",
+    "named": true,
+    "fields": {
+      "alternative": {
+        "multiple": true,
+        "required": false,
+        "types": [
+          {
+            "type": "case_clause",
+            "named": true
+          }
+        ]
+      },
+      "subject": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "expression",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
   {
     "type": "module",
     "named": true,
@@ -2444,16 +2519,6 @@
     "type": "with_item",
     "named": true,
     "fields": {
-      "alias": {
-        "multiple": false,
-        "required": false,
-        "types": [
-          {
-            "type": "pattern",
-            "named": true
-          }
-        ]
-      },
       "value": {
         "multiple": false,
         "required": true,
@@ -2711,6 +2776,10 @@
     "type": "break",
     "named": false
   },
+  {
+    "type": "case",
+    "named": false
+  },
   {
     "type": "class",
     "named": false
@@ -2807,6 +2876,10 @@
     "type": "lambda",
     "named": false
   },
+  {
+    "type": "match",
+    "named": false
+  },
   {
     "type": "none",
     "named": true