feat: markdown 增量解析

packages/client/ui-primitives/src/markdown/parse.ts

@@ -0,0 +1,41 @@
+/**
+ * The markdown renderer's two mdast grammars, one per rendering arm. Both are
+ * built from the same micromark extensions, so block boundaries and inline
+ * semantics are identical wherever a document (or a document tail) is parsed:
+ * the incremental streaming path, the settled path, and the plain-text
+ * projection all agree on where blocks start and end.
+ */
+
+import type { Root } from 'mdast'
+import { fromMarkdown } from 'mdast-util-from-markdown'
+import { gfmFromMarkdown } from 'mdast-util-gfm'
+import { mathFromMarkdown } from 'mdast-util-math'
+import { gfm } from 'micromark-extension-gfm'
+import { math } from 'micromark-extension-math'
+import { mathCompatibility } from './mathCompatibility.ts'
+
+/**
+ * Parse GFM markdown (the streaming arm's grammar: no math, so incomplete
+ * TeX never flashes KaTeX errors mid-stream).
+ * @param text - Markdown source.
+ * @returns The mdast root.
+ */
+export function parseGfm(text: string): Root {
+  return fromMarkdown(text, {
+    extensions: [gfm()],
+    mdastExtensions: [gfmFromMarkdown()],
+  })
+}
+
+/**
+ * Parse GFM markdown plus TeX math with the compatibility delimiters
+ * (the settled arm's grammar).
+ * @param text - Markdown source.
+ * @returns The mdast root.
+ */
+export function parseGfmWithMath(text: string): Root {
+  return fromMarkdown(text, {
+    extensions: [gfm(), mathCompatibility(), math()],
+    mdastExtensions: [gfmFromMarkdown(), mathFromMarkdown()],
+  })
+}