influxql: add LIST USERS statement

QUERIES.md

@@ -108,6 +108,9 @@ LIST FIELD KEYS FROM cpu
 -- but you can't do this
 LIST FIELD VALUES
 -- we don't index field values, so this query should be invalid.
+
+-- list all users
+LIST USERS
 ```
 
 Note that `FROM` and `WHERE` are optional clauses in all of the list series queries.

influxql/INFLUXQL.md

@@ -123,6 +123,7 @@ statement           = alter_retention_policy_stmt |
                       list_series_stmt |
                       list_tag_key_stmt |
                       list_tag_value_stmt |
+                      list_users_stmt |
                       revoke_stmt |
                       select_stmt .
 ```
@@ -307,6 +308,19 @@ list_retention_policies = "LIST RETENTION POLICIES" db_name .
 LIST RETENTION POLICIES mydb;
 ```
 
+### LIST USERS
+
+```
+list_users_stmt = "LIST USERES" .
+```
+
+#### Example:
+
+```sql
+-- list all users
+LIST USERS;
+```
+
 ## Clauses
 
 ```

influxql/ast.go

@@ -68,6 +68,7 @@ func (_ *ListMeasurementsStatement) node()      {}
 func (_ *ListSeriesStatement) node()            {}
 func (_ *ListTagKeysStatement) node()           {}
 func (_ *ListTagValuesStatement) node()         {}
+func (_ *ListUsersStatement) node()             {}
 func (_ *RevokeStatement) node()                {}
 func (_ *SelectStatement) node()                {}
 
@@ -140,6 +141,7 @@ func (_ *ListRetentionPoliciesStatement) stmt() {}
 func (_ *ListSeriesStatement) stmt()            {}
 func (_ *ListTagKeysStatement) stmt()           {}
 func (_ *ListTagValuesStatement) stmt()         {}
+func (_ *ListUsersStatement) stmt()             {}
 func (_ *RevokeStatement) stmt()                {}
 func (_ *SelectStatement) stmt()                {}
 
@@ -897,6 +899,14 @@ func (s *ListTagValuesStatement) String() string {
 	return buf.String()
 }
 
+// ListUsersStatement represents a command for listing users.
+type ListUsersStatement struct{}
+
+// String retuns a string representation of the ListUsersStatement.
+func (s *ListUsersStatement) String() string {
+	return "LIST USERS"
+}
+
 // ListFieldKeyStatement represents a command for listing field keys.
 type ListFieldKeysStatement struct {
 	// Data source that fields are extracted from.

influxql/parser.go

@@ -89,36 +89,39 @@ func (p *Parser) ParseStatement() (Statement, error) {
 // This function assumes the LIST token has already been consumed.
 func (p *Parser) parseListStatement() (Statement, error) {
 	tok, pos, lit := p.scanIgnoreWhitespace()
-	if tok == SERIES {
-		return p.parseListSeriesStatement()
-	} else if tok == CONTINUOUS {
+	switch tok {
+	case CONTINUOUS:
 		return p.parseListContinuousQueriesStatement()
-	} else if tok == DATABASES {
+	case DATABASES:
 		return p.parseListDatabasesStatement()
-	} else if tok == MEASUREMENTS {
-		return p.parseListMeasurementsStatement()
-	} else if tok == TAG {
-		if tok, pos, lit := p.scanIgnoreWhitespace(); tok == KEYS {
-			return p.parseListTagKeysStatement()
-		} else if tok == VALUES {
-			return p.parseListTagValuesStatement()
-		} else {
-			return nil, newParseError(tokstr(tok, lit), []string{"KEYS", "VALUES"}, pos)
-		}
-	} else if tok == FIELD {
-		if tok, pos, lit := p.scanIgnoreWhitespace(); tok == KEYS {
+	case FIELD:
+		tok, pos, lit := p.scanIgnoreWhitespace()
+		if tok == KEYS {
 			return p.parseListFieldKeysStatement()
 		} else if tok == VALUES {
 			return p.parseListFieldValuesStatement()
-		} else {
-			return nil, newParseError(tokstr(tok, lit), []string{"KEYS", "VALUES"}, pos)
 		}
-	} else if tok == RETENTION {
-		if tok, pos, lit := p.scanIgnoreWhitespace(); tok == POLICIES {
+		return nil, newParseError(tokstr(tok, lit), []string{"KEYS", "VALUES"}, pos)
+	case MEASUREMENTS:
+		return p.parseListMeasurementsStatement()
+	case RETENTION:
+		tok, pos, lit := p.scanIgnoreWhitespace()
+		if tok == POLICIES {
 			return p.parseListRetentionPoliciesStatement()
-		} else {
-			return nil, newParseError(tokstr(tok, lit), []string{"POLICIES"}, pos)
 		}
+		return nil, newParseError(tokstr(tok, lit), []string{"POLICIES"}, pos)
+	case SERIES:
+		return p.parseListSeriesStatement()
+	case TAG:
+		tok, pos, lit := p.scanIgnoreWhitespace()
+		if tok == KEYS {
+			return p.parseListTagKeysStatement()
+		} else if tok == VALUES {
+			return p.parseListTagValuesStatement()
+		}
+		return nil, newParseError(tokstr(tok, lit), []string{"KEYS", "VALUES"}, pos)
+	case USERS:
+		return p.parseListUsersStatement()
 	}
 
 	return nil, newParseError(tokstr(tok, lit), []string{"SERIES", "CONTINUOUS", "MEASUREMENTS", "TAG", "FIELD", "RETENTION"}, pos)
@@ -747,6 +750,12 @@ func (p *Parser) parseListTagValuesStatement() (*ListTagValuesStatement, error)
 	return stmt, nil
 }
 
+// parseListUsersStatement parses a string and returns a ListUsersStatement.
+// This function assumes the "LIST USERS" tokens have been consumed.
+func (p *Parser) parseListUsersStatement() (*ListUsersStatement, error) {
+	return &ListUsersStatement{}, nil
+}
+
 // parseListFieldKeysStatement parses a string and returns a ListSeriesStatement.
 // This function assumes the "LIST FIELD KEYS" tokens have already been consumed.
 func (p *Parser) parseListFieldKeysStatement() (*ListFieldKeysStatement, error) {

influxql/parser_test.go

@@ -241,6 +241,12 @@ func TestParser_ParseStatement(t *testing.T) {
 			},
 		},
 
+		// LIST USERS
+		{
+			s:    `LIST USERS`,
+			stmt: &influxql.ListUsersStatement{},
+		},
+
 		// LIST FIELD KEYS
 		{
 			s: `LIST FIELD KEYS FROM src WHERE region = 'uswest' ORDER BY ASC, field1, field2 DESC LIMIT 10`,

influxql/scanner_test.go

@@ -144,6 +144,7 @@ func TestScanner_Scan(t *testing.T) {
 		{s: `TAG`, tok: influxql.TAG},
 		{s: `TO`, tok: influxql.TO},
 		{s: `USER`, tok: influxql.USER},
+		{s: `USERS`, tok: influxql.USERS},
 		{s: `VALUES`, tok: influxql.VALUES},
 		{s: `WHERE`, tok: influxql.WHERE},
 		{s: `WITH`, tok: influxql.WITH},

influxql/token.go

@@ -99,6 +99,7 @@ const (
 	TAG
 	TO
 	USER
+	USERS
 	VALUES
 	WHERE
 	WITH
@@ -187,6 +188,7 @@ var tokens = [...]string{
 	TAG:          "TAG",
 	TO:           "TO",
 	USER:         "USER",
+	USERS:        "USERS",
 	VALUES:       "VALUES",
 	WHERE:        "WHERE",
 	WITH:         "WITH",