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tokenizer: support Mustache token #38

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Merged
merged 1 commit into from
Sep 19, 2025
Merged

tokenizer: support Mustache token #38

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43 changes: 42 additions & 1 deletion src/tokenizer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,8 @@ pub enum Token {
UnicodeStringLiteral(String),
/// Hexadecimal string literal: i.e.: X'deadbeef'
HexStringLiteral(String),
/// Interpolated text using Mustache-style syntax, e.g. {{FooBar}}.
Mustache(String),
/// Comma
Comma,
/// Whitespace (space, tab, etc)
Expand Down Expand Up @@ -303,6 +305,7 @@ impl fmt::Display for Token {
Token::DoubleQuotedRawStringLiteral(ref s) => write!(f, "R\"{s}\""),
Token::TripleSingleQuotedRawStringLiteral(ref s) => write!(f, "R'''{s}'''"),
Token::TripleDoubleQuotedRawStringLiteral(ref s) => write!(f, "R\"\"\"{s}\"\"\""),
Token::Mustache(ref s) => write!(f, "{{{s}}}"),
Token::Comma => f.write_str(","),
Token::Whitespace(ws) => write!(f, "{ws}"),
Token::DoubleEq => f.write_str("=="),
Expand Down Expand Up @@ -1599,7 +1602,45 @@ impl<'a> Tokenizer<'a> {
_ => Ok(Some(Token::Caret)),
}
}
'{' => self.consume_and_return(chars, Token::LBrace),
'{' => {
chars.next(); // consume the '{'
if let Some('{') = chars.peek() {
chars.next(); // consume the second '{'

let mut s = String::new();
let mut is_terminated = false;
let mut prev: Option<char> = None;

while let Some(&ch) = chars.peek() {
if prev == Some('}') {
if ch == '}' {
chars.next();
is_terminated = true;
break;
} else {
s.push('}');
s.push(ch);
}
} else if ch != '}' {
s.push(ch);
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The mustache format check is done elsewhere by regular expression, should we add another case for ch == '\n'?

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I'm not sure what regular expression you're referring to. I can't think of any particular reason to block multi-line {{ }} other than it doesn't appear to currently work in the product.

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That makes sense, you have more context than I do here. The regular expression I'm referring to pulls out the template keys for replacement. I was thinking this could be a good place to throw an error since it's easy to detect multiline mustaches, but we can likely just as easily detect a missing template key in this case.

}

prev = Some(ch);
chars.next();
}

if chars.peek().is_none() && !is_terminated {
self.tokenizer_error(
chars.location(),
"Unterminated mustache interpolation",
)
} else {
Ok(Some(Token::Mustache(s)))
}
} else {
Ok(Some(Token::LBrace))
}
}
'}' => self.consume_and_return(chars, Token::RBrace),
'#' if dialect_of!(self is SnowflakeDialect | BigQueryDialect | MySqlDialect | HiveDialect) =>
{
Expand Down