Support SHOW $foo (where foo is TABLES, SOURCES, VIEWS, or SINKS)

Author: umanwizard

src/ast/mod.rs

@@ -457,6 +457,15 @@ pub enum Statement {
     /// ```
     /// Limitations: doesn't support `LIKE`,  `WHERE` or `SHOW COLUMNS FROM mytable FROM mydb;`
     ShowColumns { table_name: ObjectName },
+    /// SHOW <object>S
+    ///
+    /// ```sql
+    /// SHOW TABLES;
+    /// SHOW VIEWS;
+    /// SHOW SOURCES;
+    /// SHOW SINKS;
+    /// ```
+    Show { object_type: ObjectType },
 }
 
 impl fmt::Display for Statement {
@@ -662,6 +671,19 @@ impl fmt::Display for Statement {
                 write!(f, "ROLLBACK{}", if *chain { " AND CHAIN" } else { "" },)
             }
             Statement::Peek { name } => write!(f, "PEEK {}", name),
+            Statement::Show { object_type } => {
+                use ObjectType::*;
+                write!(
+                    f,
+                    "SHOW {}",
+                    match object_type {
+                        Table => "TABLES",
+                        View => "VIEWS",
+                        Source => "SOURCES",
+                        Sink => "SINKS",
+                    }
+                )
+            }
             Statement::ShowColumns { table_name } => write!(f, "SHOW COLUMNS FROM {}", table_name),
             Statement::Tail { name } => write!(f, "TAIL {}", name),
         }
@@ -781,7 +803,7 @@ impl FromStr for FileFormat {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Copy)]
 pub enum ObjectType {
     Table,
     View,

src/ast/visit.rs

@@ -469,6 +469,8 @@ pub trait Visit<'ast> {
         visit_show_columns(self, name)
     }
 
+    fn visit_show(&mut self, _object_type: ObjectType) {}
+
     fn visit_tail(&mut self, name: &'ast ObjectName) {
         visit_tail(self, name)
     }
@@ -546,6 +548,7 @@ pub fn visit_statement<'ast, V: Visit<'ast> + ?Sized>(visitor: &mut V, statement
         Statement::Peek { name } => {
             visitor.visit_peek(name);
         }
+        Statement::Show { object_type } => visitor.visit_show(*object_type),
         Statement::ShowColumns { table_name } => visitor.visit_show_columns(table_name),
         Statement::Tail { name } => {
             visitor.visit_tail(name);

src/dialect/keywords.rs

@@ -341,9 +341,11 @@ define_keywords!(
     SHOW,
     SIMILAR,
     SINK,
+    SINKS,
     SMALLINT,
     SOME,
     SOURCE,
+    SOURCES,
     SPECIFIC,
     SPECIFICTYPE,
     SQL,
@@ -367,6 +369,7 @@ define_keywords!(
     SYSTEM_TIME,
     SYSTEM_USER,
     TABLE,
+    TABLES,
     TABLESAMPLE,
     TAIL,
     TEXT,
@@ -410,6 +413,7 @@ define_keywords!(
     VARYING,
     VERSIONING,
     VIEW,
+    VIEWS,
     WHEN,
     WHENEVER,
     WHERE,

src/parser.rs

@@ -1668,7 +1668,13 @@ impl Parser {
         if self.parse_keyword("COLUMNS") {
             self.parse_show_columns()
         } else {
-            self.expected("COLUMNS", self.peek_token())
+            self.parse_show_objects().ok_or_else(|| {
+                self.expected::<()>(
+                    "One of {COLUMNS, TABLES, VIEWS, SOURCES, SINKS}",
+                    self.peek_token(),
+                )
+                .unwrap_err()
+            })
         }
     }
 
@@ -1683,6 +1689,22 @@ impl Parser {
         })
     }
 
+    fn parse_show_objects(&mut self) -> Option<Statement> {
+        let object_type = self
+            .parse_one_of_keywords(&["SOURCES", "VIEWS", "SINKS", "TABLES"])
+            .map(|s| match s {
+                "SOURCES" => ObjectType::Source,
+                "VIEWS" => ObjectType::View,
+                "SINKS" => ObjectType::Sink,
+                "TABLES" => ObjectType::Table,
+                val => panic!(
+                    "`parse_one_of_keywords` returned an impossible value: {}",
+                    val
+                ),
+            })?;
+        Some(Statement::Show { object_type })
+    }
+
     pub fn parse_table_and_joins(&mut self) -> Result<TableWithJoins, ParserError> {
         let relation = self.parse_table_factor()?;
 

tests/sqlparser_common.rs

@@ -1481,6 +1481,21 @@ fn parse_show_columns() {
     }
 }
 
+#[test]
+fn parse_show_objects() {
+    let trials = [
+        ("SOURCES", ObjectType::Source),
+        ("VIEWS", ObjectType::View),
+        ("TABLES", ObjectType::Table),
+        ("SINKS", ObjectType::Sink),
+    ];
+
+    for (s, ot) in &trials {
+        let sql = format!("SHOW {}", s);
+        assert_eq!(verified_stmt(&sql), Statement::Show { object_type: *ot })
+    }
+}
+
 #[test]
 fn parse_simple_case_expr() {
     // ANSI calls a CASE expression with an operand "<simple case>"