alamb commented on code in PR #1847:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/1847#discussion_r2085270580
##########
src/ast/mod.rs:
##########
@@ -628,7 +634,12 @@ pub struct CaseWhen {
impl fmt::Display for CaseWhen {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- write!(f, "WHEN {} THEN {}", self.condition, self.result)
+ f.write_str("WHEN ")?;
+ self.condition.fmt(f)?;
+ f.write_str(" THEN")?;
+ SpaceOrNewline.fmt(f)?;
Review Comment:
that is pretty cool
I wonder about how you will connect this back to your original goal of
preserving the original whitespace.
Perhaps eventually this could be passed the original span 🤔
##########
src/lib.rs:
##########
@@ -64,6 +64,27 @@
//! // The original SQL text can be generated from the AST
//! assert_eq!(ast[0].to_string(), sql);
//! ```
+//!
+//! # Pretty Printing
+//!
+//! SQL statements can be pretty-printed with proper indentation and line
breaks using the alternate flag (`{:#}`):
Review Comment:
❤️
##########
tests/pretty_print.rs:
##########
@@ -0,0 +1,157 @@
+use sqlparser::dialect::GenericDialect;
+use sqlparser::parser::Parser;
+
+fn prettify(sql: &str) -> String {
+ let ast = Parser::parse_sql(&GenericDialect {}, sql).unwrap();
+ format!("{:#}", ast[0])
+}
+
+#[test]
+fn test_pretty_print_select() {
+ assert_eq!(
Review Comment:
this is great
##########
src/display_utils.rs:
##########
@@ -0,0 +1,133 @@
+//! Utilities for formatting SQL AST nodes with pretty printing support.
+//!
+//! The module provides formatters that implement the `Display` trait with
support
+//! for both regular (`{}`) and pretty (`{:#}`) formatting modes. Pretty
printing
+//! adds proper indentation and line breaks to make SQL statements more
readable.
+
+use core::fmt::{self, Display, Write};
+
+/// A wrapper around a value that adds an indent to the value when displayed
with {:#}.
+pub(crate) struct Indent<T>(pub T);
Review Comment:
since it is crate private we can change it later, but I think it would
likely be helpful eventually to make the indent configurable (for embedded
subqueries, for example)
##########
src/ast/mod.rs:
##########
@@ -4204,6 +4236,28 @@ impl fmt::Display for RaisErrorOption {
}
impl fmt::Display for Statement {
+ /// Formats a SQL statement with support for pretty printing.
+ ///
+ /// When using the alternate flag (`{:#}`), the statement will be
formatted with proper
+ /// indentation and line breaks. For example:
+ ///
+ /// ```
+ /// # use sqlparser::dialect::GenericDialect;
+ /// # use sqlparser::parser::Parser;
+ /// let sql = "SELECT a, b FROM table_1";
+ /// let ast = Parser::parse_sql(&GenericDialect, sql).unwrap();
+ ///
+ /// // Regular formatting
+ /// assert_eq!(format!("{}", ast[0]), "SELECT a, b FROM table_1");
Review Comment:
this is awesome
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