iffyio commented on code in PR #1513:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/1513#discussion_r1846854663
##########
src/parser/mod.rs:
##########
@@ -1009,6 +1009,180 @@ impl<'a> Parser<'a> {
Ok(Statement::NOTIFY { channel, payload })
}
+ fn parse_expr_prefix_by_reserved_word(
+ &mut self,
+ w: &Word,
+ ) -> Result<Option<Expr>, ParserError> {
+ match w.keyword {
+ Keyword::TRUE | Keyword::FALSE if
self.dialect.supports_boolean_literals() => {
+ self.prev_token();
+ Ok(Some(Expr::Value(self.parse_value()?)))
+ }
+ Keyword::NULL => {
+ self.prev_token();
+ Ok(Some(Expr::Value(self.parse_value()?)))
+ }
+ Keyword::CURRENT_CATALOG
+ | Keyword::CURRENT_USER
+ | Keyword::SESSION_USER
+ | Keyword::USER
+ if dialect_of!(self is PostgreSqlDialect | GenericDialect) =>
+ {
+ Ok(Some(Expr::Function(Function {
+ name: ObjectName(vec![w.to_ident()]),
+ parameters: FunctionArguments::None,
+ args: FunctionArguments::None,
+ null_treatment: None,
+ filter: None,
+ over: None,
+ within_group: vec![],
+ })))
+ }
+ Keyword::CURRENT_TIMESTAMP
+ | Keyword::CURRENT_TIME
+ | Keyword::CURRENT_DATE
+ | Keyword::LOCALTIME
+ | Keyword::LOCALTIMESTAMP => {
+
Ok(Some(self.parse_time_functions(ObjectName(vec![w.to_ident()]))?))
+ }
+ Keyword::CASE => Ok(Some(self.parse_case_expr()?)),
+ Keyword::CONVERT => Ok(Some(self.parse_convert_expr(false)?)),
+ Keyword::TRY_CONVERT if self.dialect.supports_try_convert() =>
Ok(Some(self.parse_convert_expr(true)?)),
+ Keyword::CAST => Ok(Some(self.parse_cast_expr(CastKind::Cast)?)),
+ Keyword::TRY_CAST =>
Ok(Some(self.parse_cast_expr(CastKind::TryCast)?)),
+ Keyword::SAFE_CAST =>
Ok(Some(self.parse_cast_expr(CastKind::SafeCast)?)),
+ Keyword::EXISTS
+ // Support parsing Databricks has a function named `exists`.
+ if !dialect_of!(self is DatabricksDialect)
+ || matches!(
+ self.peek_nth_token(1).token,
+ Token::Word(Word {
+ keyword: Keyword::SELECT | Keyword::WITH,
+ ..
+ })
+ ) =>
+ {
+ Ok(Some(self.parse_exists_expr(false)?))
+ }
+ Keyword::EXTRACT => Ok(Some(self.parse_extract_expr()?)),
+ Keyword::CEIL => Ok(Some(self.parse_ceil_floor_expr(true)?)),
+ Keyword::FLOOR => Ok(Some(self.parse_ceil_floor_expr(false)?)),
+ Keyword::POSITION if self.peek_token().token == Token::LParen => {
+ Ok(Some(self.parse_position_expr(w.to_ident())?))
+ }
+ Keyword::SUBSTRING => Ok(Some(self.parse_substring_expr()?)),
+ Keyword::OVERLAY => Ok(Some(self.parse_overlay_expr()?)),
+ Keyword::TRIM => Ok(Some(self.parse_trim_expr()?)),
+ Keyword::INTERVAL => Ok(Some(self.parse_interval()?)),
+ // Treat ARRAY[1,2,3] as an array [1,2,3], otherwise try as
subquery or a function call
+ Keyword::ARRAY if self.peek_token() == Token::LBracket => {
+ self.expect_token(&Token::LBracket)?;
+ Ok(Some(self.parse_array_expr(true)?))
+ }
+ Keyword::ARRAY
+ if self.peek_token() == Token::LParen
+ && !dialect_of!(self is ClickHouseDialect |
DatabricksDialect) =>
+ {
+ self.expect_token(&Token::LParen)?;
+ let query = self.parse_query()?;
+ self.expect_token(&Token::RParen)?;
+ Ok(Some(Expr::Function(Function {
+ name: ObjectName(vec![w.to_ident()]),
+ parameters: FunctionArguments::None,
+ args: FunctionArguments::Subquery(query),
+ filter: None,
+ null_treatment: None,
+ over: None,
+ within_group: vec![],
+ })))
+ }
+ Keyword::NOT => Ok(Some(self.parse_not()?)),
+ Keyword::MATCH if dialect_of!(self is MySqlDialect |
GenericDialect) => {
+ Ok(Some(self.parse_match_against()?))
+ }
+ Keyword::STRUCT if dialect_of!(self is BigQueryDialect |
GenericDialect) => {
+ self.prev_token();
+ Ok(Some(self.parse_bigquery_struct_literal()?))
+ }
+ Keyword::PRIOR if matches!(self.state, ParserState::ConnectBy) => {
+ let expr =
self.parse_subexpr(self.dialect.prec_value(Precedence::PlusMinus))?;
+ Ok(Some(Expr::Prior(Box::new(expr))))
+ }
+ Keyword::MAP if self.peek_token() == Token::LBrace &&
self.dialect.support_map_literal_syntax() => {
+ Ok(Some(self.parse_duckdb_map_literal()?))
+ }
+ _ => Ok(None)
+ }
+ }
+
+ fn parse_expr_prefix_by_nonreserved_word(&mut self, w: &Word) ->
Result<Expr, ParserError> {
Review Comment:
```suggestion
fn parse_expr_prefix_by_unreserved_word(&mut self, w: &Word) ->
Result<Expr, ParserError> {
```
Also could we add a short description to both this and
`parse_expr_prefix_by_reserved_word` highlighting what they do? it would make
it easier for folks that come across, what the difference is without further
digging into the code
##########
src/parser/mod.rs:
##########
@@ -1057,176 +1231,33 @@ impl<'a> Parser<'a> {
let next_token = self.next_token();
let expr = match next_token.token {
- Token::Word(w) => match w.keyword {
- Keyword::TRUE | Keyword::FALSE if
self.dialect.supports_boolean_literals() => {
- self.prev_token();
- Ok(Expr::Value(self.parse_value()?))
- }
- Keyword::NULL => {
- self.prev_token();
- Ok(Expr::Value(self.parse_value()?))
- }
- Keyword::CURRENT_CATALOG
- | Keyword::CURRENT_USER
- | Keyword::SESSION_USER
- | Keyword::USER
- if dialect_of!(self is PostgreSqlDialect | GenericDialect)
=>
- {
- Ok(Expr::Function(Function {
- name: ObjectName(vec![w.to_ident()]),
- parameters: FunctionArguments::None,
- args: FunctionArguments::None,
- null_treatment: None,
- filter: None,
- over: None,
- within_group: vec![],
- }))
- }
- Keyword::CURRENT_TIMESTAMP
- | Keyword::CURRENT_TIME
- | Keyword::CURRENT_DATE
- | Keyword::LOCALTIME
- | Keyword::LOCALTIMESTAMP => {
- self.parse_time_functions(ObjectName(vec![w.to_ident()]))
- }
- Keyword::CASE => self.parse_case_expr(),
- Keyword::CONVERT => self.parse_convert_expr(false),
- Keyword::TRY_CONVERT if self.dialect.supports_try_convert() =>
self.parse_convert_expr(true),
- Keyword::CAST => self.parse_cast_expr(CastKind::Cast),
- Keyword::TRY_CAST => self.parse_cast_expr(CastKind::TryCast),
- Keyword::SAFE_CAST => self.parse_cast_expr(CastKind::SafeCast),
- Keyword::EXISTS
- // Support parsing Databricks has a function named
`exists`.
- if !dialect_of!(self is DatabricksDialect)
- || matches!(
- self.peek_nth_token(1).token,
- Token::Word(Word {
- keyword: Keyword::SELECT | Keyword::WITH,
- ..
- })
- ) =>
- {
- self.parse_exists_expr(false)
- }
- Keyword::EXTRACT => self.parse_extract_expr(),
- Keyword::CEIL => self.parse_ceil_floor_expr(true),
- Keyword::FLOOR => self.parse_ceil_floor_expr(false),
- Keyword::POSITION if self.peek_token().token == Token::LParen
=> {
- self.parse_position_expr(w.to_ident())
- }
- Keyword::SUBSTRING => self.parse_substring_expr(),
- Keyword::OVERLAY => self.parse_overlay_expr(),
- Keyword::TRIM => self.parse_trim_expr(),
- Keyword::INTERVAL => self.parse_interval(),
- // Treat ARRAY[1,2,3] as an array [1,2,3], otherwise try as
subquery or a function call
- Keyword::ARRAY if self.peek_token() == Token::LBracket => {
- self.expect_token(&Token::LBracket)?;
- self.parse_array_expr(true)
- }
- Keyword::ARRAY
- if self.peek_token() == Token::LParen
- && !dialect_of!(self is ClickHouseDialect |
DatabricksDialect) =>
- {
- self.expect_token(&Token::LParen)?;
- let query = self.parse_query()?;
- self.expect_token(&Token::RParen)?;
- Ok(Expr::Function(Function {
- name: ObjectName(vec![w.to_ident()]),
- parameters: FunctionArguments::None,
- args: FunctionArguments::Subquery(query),
- filter: None,
- null_treatment: None,
- over: None,
- within_group: vec![],
- }))
- }
- Keyword::NOT => self.parse_not(),
- Keyword::MATCH if dialect_of!(self is MySqlDialect |
GenericDialect) => {
- self.parse_match_against()
- }
- Keyword::STRUCT if dialect_of!(self is BigQueryDialect |
GenericDialect) => {
- self.prev_token();
- self.parse_bigquery_struct_literal()
- }
- Keyword::PRIOR if matches!(self.state, ParserState::ConnectBy)
=> {
- let expr =
self.parse_subexpr(self.dialect.prec_value(Precedence::PlusMinus))?;
- Ok(Expr::Prior(Box::new(expr)))
- }
- Keyword::MAP if self.peek_token() == Token::LBrace &&
self.dialect.support_map_literal_syntax() => {
- self.parse_duckdb_map_literal()
- }
- // Here `w` is a word, check if it's a part of a multipart
- // identifier, a function call, or a simple identifier:
- _ => match self.peek_token().token {
- Token::LParen | Token::Period => {
- let mut id_parts: Vec<Ident> = vec![w.to_ident()];
- let mut ends_with_wildcard = false;
- while self.consume_token(&Token::Period) {
- let next_token = self.next_token();
- match next_token.token {
- Token::Word(w) => id_parts.push(w.to_ident()),
- Token::Mul => {
- // Postgres explicitly allows
funcnm(tablenm.*) and the
- // function array_agg traverses this
control flow
- if dialect_of!(self is PostgreSqlDialect) {
- ends_with_wildcard = true;
- break;
- } else {
- return self
- .expected("an identifier after
'.'", next_token);
- }
- }
- Token::SingleQuotedString(s) => {
- id_parts.push(Ident::with_quote('\'', s))
- }
- _ => {
- return self
- .expected("an identifier or a '*'
after '.'", next_token);
- }
- }
- }
-
- if ends_with_wildcard {
- Ok(Expr::QualifiedWildcard(ObjectName(id_parts)))
- } else if self.consume_token(&Token::LParen) {
- if dialect_of!(self is SnowflakeDialect |
MsSqlDialect)
- && self.consume_tokens(&[Token::Plus,
Token::RParen])
- {
- Ok(Expr::OuterJoin(Box::new(
- match <[Ident; 1]>::try_from(id_parts) {
- Ok([ident]) => Expr::Identifier(ident),
- Err(parts) =>
Expr::CompoundIdentifier(parts),
- },
- )))
- } else {
- self.prev_token();
- self.parse_function(ObjectName(id_parts))
+ Token::Word(w) => {
+ // Save the parser index so we can rollback
+ let index_before = self.index;
+ // We first try to parse the word as the prefix of an
expression.
+ // For example, the word INTERVAL in: SELECT INTERVAL '7' DAY
+ match self.parse_expr_prefix_by_reserved_word(&w) {
+ // No expression prefix associated with this word
+ Ok(None) =>
Ok(self.parse_expr_prefix_by_nonreserved_word(&w)?),
+ // This word indicated an expression prefix and parsing
was successful
+ Ok(Some(expr)) => Ok(expr),
+ // This word indicated an expression prefix but parsing
failed. Two options:
+ // 1. Malformed statement
+ // 2. The dialect may allow this word as identifier as
well as indicating an expression
Review Comment:
The comments are indeed helpful to follow thanks! Thinking here we could
clarify 2. even further with the `SELECT MAX(interval) from tbl` example?
##########
src/parser/mod.rs:
##########
@@ -1057,176 +1231,33 @@ impl<'a> Parser<'a> {
let next_token = self.next_token();
let expr = match next_token.token {
- Token::Word(w) => match w.keyword {
- Keyword::TRUE | Keyword::FALSE if
self.dialect.supports_boolean_literals() => {
- self.prev_token();
- Ok(Expr::Value(self.parse_value()?))
- }
- Keyword::NULL => {
- self.prev_token();
- Ok(Expr::Value(self.parse_value()?))
- }
- Keyword::CURRENT_CATALOG
- | Keyword::CURRENT_USER
- | Keyword::SESSION_USER
- | Keyword::USER
- if dialect_of!(self is PostgreSqlDialect | GenericDialect)
=>
- {
- Ok(Expr::Function(Function {
- name: ObjectName(vec![w.to_ident()]),
- parameters: FunctionArguments::None,
- args: FunctionArguments::None,
- null_treatment: None,
- filter: None,
- over: None,
- within_group: vec![],
- }))
- }
- Keyword::CURRENT_TIMESTAMP
- | Keyword::CURRENT_TIME
- | Keyword::CURRENT_DATE
- | Keyword::LOCALTIME
- | Keyword::LOCALTIMESTAMP => {
- self.parse_time_functions(ObjectName(vec![w.to_ident()]))
- }
- Keyword::CASE => self.parse_case_expr(),
- Keyword::CONVERT => self.parse_convert_expr(false),
- Keyword::TRY_CONVERT if self.dialect.supports_try_convert() =>
self.parse_convert_expr(true),
- Keyword::CAST => self.parse_cast_expr(CastKind::Cast),
- Keyword::TRY_CAST => self.parse_cast_expr(CastKind::TryCast),
- Keyword::SAFE_CAST => self.parse_cast_expr(CastKind::SafeCast),
- Keyword::EXISTS
- // Support parsing Databricks has a function named
`exists`.
- if !dialect_of!(self is DatabricksDialect)
- || matches!(
- self.peek_nth_token(1).token,
- Token::Word(Word {
- keyword: Keyword::SELECT | Keyword::WITH,
- ..
- })
- ) =>
- {
- self.parse_exists_expr(false)
- }
- Keyword::EXTRACT => self.parse_extract_expr(),
- Keyword::CEIL => self.parse_ceil_floor_expr(true),
- Keyword::FLOOR => self.parse_ceil_floor_expr(false),
- Keyword::POSITION if self.peek_token().token == Token::LParen
=> {
- self.parse_position_expr(w.to_ident())
- }
- Keyword::SUBSTRING => self.parse_substring_expr(),
- Keyword::OVERLAY => self.parse_overlay_expr(),
- Keyword::TRIM => self.parse_trim_expr(),
- Keyword::INTERVAL => self.parse_interval(),
- // Treat ARRAY[1,2,3] as an array [1,2,3], otherwise try as
subquery or a function call
- Keyword::ARRAY if self.peek_token() == Token::LBracket => {
- self.expect_token(&Token::LBracket)?;
- self.parse_array_expr(true)
- }
- Keyword::ARRAY
- if self.peek_token() == Token::LParen
- && !dialect_of!(self is ClickHouseDialect |
DatabricksDialect) =>
- {
- self.expect_token(&Token::LParen)?;
- let query = self.parse_query()?;
- self.expect_token(&Token::RParen)?;
- Ok(Expr::Function(Function {
- name: ObjectName(vec![w.to_ident()]),
- parameters: FunctionArguments::None,
- args: FunctionArguments::Subquery(query),
- filter: None,
- null_treatment: None,
- over: None,
- within_group: vec![],
- }))
- }
- Keyword::NOT => self.parse_not(),
- Keyword::MATCH if dialect_of!(self is MySqlDialect |
GenericDialect) => {
- self.parse_match_against()
- }
- Keyword::STRUCT if dialect_of!(self is BigQueryDialect |
GenericDialect) => {
- self.prev_token();
- self.parse_bigquery_struct_literal()
- }
- Keyword::PRIOR if matches!(self.state, ParserState::ConnectBy)
=> {
- let expr =
self.parse_subexpr(self.dialect.prec_value(Precedence::PlusMinus))?;
- Ok(Expr::Prior(Box::new(expr)))
- }
- Keyword::MAP if self.peek_token() == Token::LBrace &&
self.dialect.support_map_literal_syntax() => {
- self.parse_duckdb_map_literal()
- }
- // Here `w` is a word, check if it's a part of a multipart
- // identifier, a function call, or a simple identifier:
- _ => match self.peek_token().token {
- Token::LParen | Token::Period => {
- let mut id_parts: Vec<Ident> = vec![w.to_ident()];
- let mut ends_with_wildcard = false;
- while self.consume_token(&Token::Period) {
- let next_token = self.next_token();
- match next_token.token {
- Token::Word(w) => id_parts.push(w.to_ident()),
- Token::Mul => {
- // Postgres explicitly allows
funcnm(tablenm.*) and the
- // function array_agg traverses this
control flow
- if dialect_of!(self is PostgreSqlDialect) {
- ends_with_wildcard = true;
- break;
- } else {
- return self
- .expected("an identifier after
'.'", next_token);
- }
- }
- Token::SingleQuotedString(s) => {
- id_parts.push(Ident::with_quote('\'', s))
- }
- _ => {
- return self
- .expected("an identifier or a '*'
after '.'", next_token);
- }
- }
- }
-
- if ends_with_wildcard {
- Ok(Expr::QualifiedWildcard(ObjectName(id_parts)))
- } else if self.consume_token(&Token::LParen) {
- if dialect_of!(self is SnowflakeDialect |
MsSqlDialect)
- && self.consume_tokens(&[Token::Plus,
Token::RParen])
- {
- Ok(Expr::OuterJoin(Box::new(
- match <[Ident; 1]>::try_from(id_parts) {
- Ok([ident]) => Expr::Identifier(ident),
- Err(parts) =>
Expr::CompoundIdentifier(parts),
- },
- )))
- } else {
- self.prev_token();
- self.parse_function(ObjectName(id_parts))
+ Token::Word(w) => {
+ // Save the parser index so we can rollback
+ let index_before = self.index;
+ // We first try to parse the word as the prefix of an
expression.
+ // For example, the word INTERVAL in: SELECT INTERVAL '7' DAY
+ match self.parse_expr_prefix_by_reserved_word(&w) {
+ // No expression prefix associated with this word
+ Ok(None) =>
Ok(self.parse_expr_prefix_by_nonreserved_word(&w)?),
+ // This word indicated an expression prefix and parsing
was successful
+ Ok(Some(expr)) => Ok(expr),
+ // This word indicated an expression prefix but parsing
failed. Two options:
+ // 1. Malformed statement
+ // 2. The dialect may allow this word as identifier as
well as indicating an expression
+ Err(e) => {
+ let index_after_error = self.index;
+ if !self.dialect.is_reserved_for_identifier(w.keyword)
{
+ // Rollback before trying to parse using a
different approach
+ self.index = index_before;
Review Comment:
I'm thinking ideally we're somehow reusing maybe_parse for the logic, feels
like we're duplicating that behavior for this custom use case with the manual
stashing of indexes which makes it a bit harder to track the logic's correctness
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