add trino DESCRIBE statement support

pegjs/trino.pegjs

@@ -21,6 +21,7 @@
 
     'DELETE': true,
     'DESC': true,
+    'DESCRIBE': true,
     'DISTINCT': true,
     'DROP': true,
 
@@ -254,6 +255,7 @@ cmd_stmt
   / set_stmt
   / lock_stmt
   / show_stmt
+  / desc_stmt
   / deallocate_stmt
 
 create_stmt
@@ -1988,6 +1990,25 @@ show_stmt
     }
   }
 
+desc_stmt
+  = KW_DESCRIBE __ t:table_name {
+    /*
+      export interface desc_stmt_node {
+        type: 'describe';
+        table: table_name;
+      }
+      => AstStatement<desc_stmt_node>
+    */
+    return {
+      tableList: Array.from(tableList),
+      columnList: columnListTableAlias(columnList),
+      ast: {
+        type: 'describe',
+        table: t
+      }
+    };
+  }
+
 deallocate_stmt
   = KW_DEALLOCATE __ p:('PREPARE'i)? __ i:(ident_name / KW_ALL) {
     return {
@@ -4348,6 +4369,7 @@ KW_OFFSET   = "OFFSET"i     !ident_start { return 'OFFSET' }
 
 KW_ASC      = "ASC"i        !ident_start { return 'ASC'; }
 KW_DESC     = "DESC"i       !ident_start { return 'DESC'; }
+KW_DESCRIBE = "DESCRIBE"i   !ident_start { return 'DESCRIBE'; }
 
 KW_ALL      = "ALL"i        !ident_start { return 'ALL'; }
 KW_DISTINCT = "DISTINCT"i   !ident_start { return 'DISTINCT';}

src/command.js

@@ -46,7 +46,8 @@ function commonCmdToSQL(stmt) {
 function descToSQL(stmt) {
   const { type, table } = stmt
   const action = toUpper(type)
-  return `${action} ${identifierToSql(table)}`
+  const tableName = typeof table === 'string' ? identifierToSql(table) : tableToSQL(table)
+  return `${action} ${tableName}`
 }
 
 function executeToSQL(stmt) {

src/sql.js

@@ -1,6 +1,6 @@
 import { unionToSQL, multipleToSQL } from './union'
 
-const supportedTypes = ['analyze', 'attach', 'select', 'deallocate', 'delete', 'exec', 'update', 'insert', 'drop', 'rename', 'truncate', 'call', 'desc', 'use', 'alter', 'set', 'create', 'lock', 'unlock', 'declare', 'show', 'replace', 'if', 'grant', 'revoke', 'proc', 'raise', 'execute', 'transaction', 'explain', 'comment', 'load_data']
+const supportedTypes = ['analyze', 'attach', 'select', 'deallocate', 'delete', 'exec', 'update', 'insert', 'drop', 'rename', 'truncate', 'call', 'desc', 'describe', 'use', 'alter', 'set', 'create', 'lock', 'unlock', 'declare', 'show', 'replace', 'if', 'grant', 'revoke', 'proc', 'raise', 'execute', 'transaction', 'explain', 'comment', 'load_data']
 
 function checkSupported(expr) {
   const ast = expr && expr.ast ? expr.ast : expr

src/union.js

@@ -57,6 +57,7 @@ const typeToSQLFn = {
   rename      : renameToSQL,
   call        : callToSQL,
   desc        : descToSQL,
+  describe    : descToSQL,
   set         : setVarToSQL,
   lock        : lockUnlockToSQL,
   unlock      : lockUnlockToSQL,

test/trino.spec.js

@@ -101,13 +101,21 @@ describe('trino', () => {
     {
       title: 'ROW expression',
       sql: [
-        'SELECT ROW(12 AS x, 122 y) FROM t',
+        "SELECT ROW(12 AS x, 122 y) FROM t",
         'SELECT ROW(12 AS "x", 122 AS "y") FROM "t"'
-      ]
-    }
-  ]
-  SQL_LIST.forEach(sqlInfo => {
-    const { title, sql } = sqlInfo
+      ],
+    },
+    {
+      title: "DESCRIBE statement",
+      sql: ["DESCRIBE my_table", 'DESCRIBE "my_table"'],
+    },
+    {
+      title: "DESCRIBE statement with fully qualified name",
+      sql: ['DESCRIBE my_catalog.my_schema.my_table', 'DESCRIBE "my_catalog"."my_schema"."my_table"'],
+    },
+  ];
+  SQL_LIST.forEach((sqlInfo) => {
+    const { title, sql } = sqlInfo;
     it(`should support ${title}`, () => {
       expect(getParsedSql(sql[0], opt)).to.equal(sql[1])
     })