Fix nested brace counting in MDX expressions

[rlch]

Remove parser check that prevented brace counting when external parser is configured. The original logic skipped counting opening braces in gnostic mode, causing expressions like {{ x: 1 }} to exit prematurely at the first closing brace.

Tokenizer must count all braces to find expression boundaries before the external parser validates syntax.

Fixes:

• Nested object literals: {{ x: 1 }}
• Nested function calls: func({ x: g({ y: 2 }) })
• JSX attribute expressions with nested objects

Tests added for nested object literal scenarios.

[wooorm]

The idea is that if you have mdx_expression_parse, then you want something different than counting, because it doesn’t work, and instead accept/crash from mdx_expression_parse based on what language you expect.
Otherwise, why is mdx_expression_parse there?

So, why is mdx_expression_parse there? Why don’t you use the existing methods, from there, to signal back whether things are as expected or not?

[wooorm]

It also looks like you want JS in there, which is exactly what is supported here? Why not use that?

markdown-rs/tests/test_utils/swc.rs

Lines 149 to 156 in 1506572

	pub fn parse_expression(value: &str, kind: &MdxExpressionKind) -> MdxSignal {
	let result = parse_expression_core(value, kind);
	match result {
	Err((span, message)) => swc_error_to_signal(span, &message, value.len()),
	Ok(_) => MdxSignal::Ok,
	}
	}