feat: add arg placeholder (apache#420)

Co-authored-by: gamife <[email protected]>

src/ast/value.rs

@@ -56,6 +56,8 @@ pub enum Value {
     },
     /// `NULL` value
     Null,
+    /// `?` or `$` Prepared statement arg placeholder
+    Placeholder(String),
 }
 
 impl fmt::Display for Value {
@@ -108,6 +110,7 @@ impl fmt::Display for Value {
                 Ok(())
             }
             Value::Null => write!(f, "NULL"),
+            Value::Placeholder(v) => write!(f, "{}", v),
         }
     }
 }

src/parser.rs

@@ -445,6 +445,10 @@ impl<'a> Parser<'a> {
                 self.expect_token(&Token::RParen)?;
                 Ok(expr)
             }
+            Token::Placeholder(_) => {
+                self.prev_token();
+                Ok(Expr::Value(self.parse_value()?))
+            }
             unexpected => self.expected("an expression:", unexpected),
         }?;
 
@@ -1966,6 +1970,7 @@ impl<'a> Parser<'a> {
             Token::SingleQuotedString(ref s) => Ok(Value::SingleQuotedString(s.to_string())),
             Token::NationalStringLiteral(ref s) => Ok(Value::NationalStringLiteral(s.to_string())),
             Token::HexStringLiteral(ref s) => Ok(Value::HexStringLiteral(s.to_string())),
+            Token::Placeholder(ref s) => Ok(Value::Placeholder(s.to_string())),
             unexpected => self.expected("a value", unexpected),
         }
     }

src/tokenizer.rs

@@ -124,6 +124,8 @@ pub enum Token {
     PGSquareRoot,
     /// `||/` , a cube root math operator in PostgreSQL
     PGCubeRoot,
+    /// `?` or `$` , a prepared statement arg placeholder
+    Placeholder(String),
 }
 
 impl fmt::Display for Token {
@@ -176,6 +178,7 @@ impl fmt::Display for Token {
             Token::ShiftRight => f.write_str(">>"),
             Token::PGSquareRoot => f.write_str("|/"),
             Token::PGCubeRoot => f.write_str("||/"),
+            Token::Placeholder(ref s) => write!(f, "{}", s),
         }
     }
 }
@@ -304,6 +307,7 @@ impl<'a> Tokenizer<'a> {
                 Token::Word(w) if w.quote_style != None => self.col += w.value.len() as u64 + 2,
                 Token::Number(s, _) => self.col += s.len() as u64,
                 Token::SingleQuotedString(s) => self.col += s.len() as u64,
+                Token::Placeholder(s) => self.col += s.len() as u64,
                 _ => self.col += 1,
             }
 
@@ -550,6 +554,15 @@ impl<'a> Tokenizer<'a> {
                 '~' => self.consume_and_return(chars, Token::Tilde),
                 '#' => self.consume_and_return(chars, Token::Sharp),
                 '@' => self.consume_and_return(chars, Token::AtSign),
+                '?' => self.consume_and_return(chars, Token::Placeholder(String::from("?"))),
+                '$' => {
+                    chars.next();
+                    let s = peeking_take_while(
+                        chars,
+                        |ch| matches!(ch, '0'..='9' | 'A'..='Z' | 'a'..='z'),
+                    );
+                    Ok(Some(Token::Placeholder(String::from("$") + &s)))
+                }
                 other => self.consume_and_return(chars, Token::Char(other)),
             },
             None => Ok(None),
@@ -616,7 +629,7 @@ impl<'a> Tokenizer<'a> {
                                 'r' => s.push('\r'),
                                 't' => s.push('\t'),
                                 'Z' => s.push('\x1a'),
-                                x => s.push(x)
+                                x => s.push(x),
                             }
                         }
                     }

tests/sqlparser_common.rs

@@ -24,8 +24,12 @@ use test_utils::{all_dialects, expr_from_projection, join, number, only, table,
 
 use matches::assert_matches;
 use sqlparser::ast::*;
-use sqlparser::dialect::{keywords::ALL_KEYWORDS, SQLiteDialect};
+use sqlparser::dialect::{
+    keywords::ALL_KEYWORDS, AnsiDialect, GenericDialect, MsSqlDialect, PostgreSqlDialect,
+    SQLiteDialect, SnowflakeDialect,
+};
 use sqlparser::parser::{Parser, ParserError};
+use sqlparser::test_utils::TestedDialects;
 
 #[test]
 fn parse_insert_values() {
@@ -2715,10 +2719,10 @@ fn parse_scalar_subqueries() {
     assert_matches!(
         verified_expr(sql),
         Expr::BinaryOp {
-        op: BinaryOperator::Plus, ..
-        //left: box Subquery { .. },
-        //right: box Subquery { .. },
-    }
+            op: BinaryOperator::Plus,
+            .. //left: box Subquery { .. },
+               //right: box Subquery { .. },
+        }
     );
 }
 
@@ -3557,6 +3561,42 @@ fn parse_rolling_window() {
     );
 }
 
+#[test]
+fn test_placeholder() {
+    let sql = "SELECT * FROM student WHERE id = ?";
+    let ast = verified_only_select(sql);
+    assert_eq!(
+        ast.selection,
+        Some(Expr::BinaryOp {
+            left: Box::new(Expr::Identifier(Ident::new("id"))),
+            op: BinaryOperator::Eq,
+            right: Box::new(Expr::Value(Value::Placeholder("?".into())))
+        })
+    );
+
+    let dialects = TestedDialects {
+        dialects: vec![
+            Box::new(GenericDialect {}),
+            Box::new(PostgreSqlDialect {}),
+            Box::new(MsSqlDialect {}),
+            Box::new(AnsiDialect {}),
+            Box::new(SnowflakeDialect {}),
+            // Note: `$` is the starting word for the HiveDialect identifier
+            // Box::new(sqlparser::dialect::HiveDialect {}),
+        ],
+    };
+    let sql = "SELECT * FROM student WHERE id = $Id1";
+    let ast = dialects.verified_only_select(sql);
+    assert_eq!(
+        ast.selection,
+        Some(Expr::BinaryOp {
+            left: Box::new(Expr::Identifier(Ident::new("id"))),
+            op: BinaryOperator::Eq,
+            right: Box::new(Expr::Value(Value::Placeholder("$Id1".into())))
+        })
+    );
+}
+
 fn parse_sql_statements(sql: &str) -> Result<Vec<Statement>, ParserError> {
     all_dialects().parse_sql_statements(sql)
 }