Add support for parsing MDX ESM, expressions

This commit adds support for hooks that lets a user integrate another
parser with `micromark-rs`, to parse ESM and expressions according to
a particular grammar (such as a programming language, typically
JavaScript).

For an example integrating with SWC, see `tests/test_utils/mod.rs`.

The integration occurs with two functions passed in `options`:
`mdx_expression_parse` and `mdx_esm_parse`.
The can signal back to micromark when they are successful,
whether there is an error at the end (in which case micromark will
try to parse more), or whether there is a syntax error (in which case
micromark will crash).

1 files changed, 47 insertions, 0 deletions

diff --git a/tests/mdx_swc.rs b/tests/mdx_swc.rs
new file mode 100644
index 0000000..c9a2a61
--- /dev/null
+++ b/tests/mdx_swc.rs
@@ -0,0 +1,47 @@
+extern crate micromark;
+mod test_utils;
+use micromark::{micromark_with_options, Constructs, Options};
+use pretty_assertions::assert_eq;
+use test_utils::{parse_esm, parse_expression};
+
+#[test]
+fn mdx_swc() -> Result<(), String> {
+    let mdx = Options {
+        constructs: Constructs::mdx(),
+        mdx_esm_parse: Some(Box::new(parse_esm)),
+        mdx_expression_parse: Some(Box::new(parse_expression)),
+        ..Options::default()
+    };
+
+    assert_eq!(
+        micromark_with_options("{'}'}", &mdx)?,
+        "",
+        "should support JavaScript-aware flow expressions w/ `mdx_expression_parse`"
+    );
+
+    assert_eq!(
+        micromark_with_options("a {'}'} b", &mdx)?,
+        "<p>a  b</p>",
+        "should support JavaScript-aware text expressions w/ `mdx_expression_parse`"
+    );
+
+    assert_eq!(
+        micromark_with_options("<a {...a/*}*/} />", &mdx)?,
+        "",
+        "should support JavaScript-aware attribute expressions w/ `mdx_expression_parse`"
+    );
+
+    assert_eq!(
+        micromark_with_options("<a b={'}'} />", &mdx)?,
+        "",
+        "should support JavaScript-aware attribute value expressions w/ `mdx_expression_parse`"
+    );
+
+    assert_eq!(
+        micromark_with_options("import a from 'b'\n\nexport {a}\n\n# c", &mdx)?,
+        "<h1>c</h1>",
+        "should support JavaScript-aware ESM w/ `mdx_esm_parse`"
+    );
+
+    Ok(())
+}