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Reduce indentation in parse_prefix()

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This commit is contained in:
Nickolay Ponomarev 2019-04-27 18:38:12 +03:00
parent f82dc74e38
commit e7949d493c
1 changed files with 73 additions and 77 deletions
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150
src/sqlparser.rs
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@ -155,87 +155,83 @@ impl Parser {
/// Parse an expression prefix
pub fn parse_prefix(&mut self) -> Result<ASTNode, ParserError> {
match self.next_token() {
Some(t) => match t {
Token::SQLWord(w) => match w.keyword.as_ref() {
"TRUE" | "FALSE" | "NULL" => {
self.prev_token();
self.parse_sql_value()
}
"CASE" => self.parse_case_expression(),
"CAST" => self.parse_cast_expression(),
"NOT" => {
let p = self.get_precedence(&Token::make_keyword("NOT"))?;
Ok(ASTNode::SQLUnary {
operator: SQLOperator::Not,
expr: Box::new(self.parse_subexpr(p)?),
})
}
// Here `w` is a word, check if it's a part of a multi-part
// identifier, a function call, or a simple identifier:
_ => match self.peek_token() {
Some(Token::LParen) | Some(Token::Period) => {
let mut id_parts: Vec<SQLIdent> = vec![w.as_sql_ident()];
let mut ends_with_wildcard = false;
while self.consume_token(&Token::Period) {
match self.next_token() {
Some(Token::SQLWord(w)) => id_parts.push(w.as_sql_ident()),
Some(Token::Mult) => {
ends_with_wildcard = true;
break;
}
unexpected => {
return self.expected(
"an identifier or a '*' after '.'",
unexpected,
);
}
}
}
if ends_with_wildcard {
Ok(ASTNode::SQLQualifiedWildcard(id_parts))
} else if self.consume_token(&Token::LParen) {
self.prev_token();
self.parse_function(SQLObjectName(id_parts))
} else {
Ok(ASTNode::SQLCompoundIdentifier(id_parts))
}
}
_ => Ok(ASTNode::SQLIdentifier(w.as_sql_ident())),
},
}, // End of Token::SQLWord
Token::Mult => Ok(ASTNode::SQLWildcard),
tok @ Token::Minus | tok @ Token::Plus => {
let p = self.get_precedence(&tok)?;
let operator = if tok == Token::Plus {
SQLOperator::Plus
} else {
SQLOperator::Minus
};
Ok(ASTNode::SQLUnary {
operator,
expr: Box::new(self.parse_subexpr(p)?),
})
}
Token::Number(_)
| Token::SingleQuotedString(_)
| Token::NationalStringLiteral(_) => {
let tok = self
.next_token()
.ok_or_else(|| ParserError::ParserError("Unexpected EOF".to_string()))?;
match tok {
Token::SQLWord(w) => match w.keyword.as_ref() {
"TRUE" | "FALSE" | "NULL" => {
self.prev_token();
self.parse_sql_value()
}
Token::LParen => {
let expr = if self.parse_keyword("SELECT") || self.parse_keyword("WITH") {
self.prev_token();
ASTNode::SQLSubquery(Box::new(self.parse_query()?))
} else {
ASTNode::SQLNested(Box::new(self.parse_expr()?))
};
self.expect_token(&Token::RParen)?;
Ok(expr)
"CASE" => self.parse_case_expression(),
"CAST" => self.parse_cast_expression(),
"NOT" => {
let p = self.get_precedence(&Token::make_keyword("NOT"))?;
Ok(ASTNode::SQLUnary {
operator: SQLOperator::Not,
expr: Box::new(self.parse_subexpr(p)?),
})
}
_ => self.expected("an expression", Some(t)),
},
None => parser_err!("Prefix parser expected a keyword but hit EOF"),
// Here `w` is a word, check if it's a part of a multi-part
// identifier, a function call, or a simple identifier:
_ => match self.peek_token() {
Some(Token::LParen) | Some(Token::Period) => {
let mut id_parts: Vec<SQLIdent> = vec![w.as_sql_ident()];
let mut ends_with_wildcard = false;
while self.consume_token(&Token::Period) {
match self.next_token() {
Some(Token::SQLWord(w)) => id_parts.push(w.as_sql_ident()),
Some(Token::Mult) => {
ends_with_wildcard = true;
break;
}
unexpected => {
return self
.expected("an identifier or a '*' after '.'", unexpected);
}
}
}
if ends_with_wildcard {
Ok(ASTNode::SQLQualifiedWildcard(id_parts))
} else if self.consume_token(&Token::LParen) {
self.prev_token();
self.parse_function(SQLObjectName(id_parts))
} else {
Ok(ASTNode::SQLCompoundIdentifier(id_parts))
}
}
_ => Ok(ASTNode::SQLIdentifier(w.as_sql_ident())),
},
}, // End of Token::SQLWord
Token::Mult => Ok(ASTNode::SQLWildcard),
tok @ Token::Minus | tok @ Token::Plus => {
let p = self.get_precedence(&tok)?;
let operator = if tok == Token::Plus {
SQLOperator::Plus
} else {
SQLOperator::Minus
};
Ok(ASTNode::SQLUnary {
operator,
expr: Box::new(self.parse_subexpr(p)?),
})
}
Token::Number(_) | Token::SingleQuotedString(_) | Token::NationalStringLiteral(_) => {
self.prev_token();
self.parse_sql_value()
}
Token::LParen => {
let expr = if self.parse_keyword("SELECT") || self.parse_keyword("WITH") {
self.prev_token();
ASTNode::SQLSubquery(Box::new(self.parse_query()?))
} else {
ASTNode::SQLNested(Box::new(self.parse_expr()?))
};
self.expect_token(&Token::RParen)?;
Ok(expr)
}
unexpected => self.expected("an expression", Some(unexpected)),
}
}