refactor(markdown-parser): promote pre-marker indent to explicit CST by jfmcdowell · Pull Request #9224 · biomejs/biome

jfmcdowell · 2026-02-24T12:23:52Z

Note

AI Assistance Disclosure: This PR was developed with assistance from Claude Code.

Summary

Add MdQuoteIndent and MdQuoteIndentList to the grammar, following the MdHash/MdHashList wrapper pattern for repeating over raw tokens.
Change MdQuotePrefix.pre_marker_indent from a single optional token slot to MdQuoteIndentList, so each space before > gets its own MdQuoteIndent node.
Register MD_QUOTE_INDENT and MD_QUOTE_INDENT_LIST in markdown_kinds_src.rs.
Replace skip_line_indent(3) in emit_quote_prefix_tokens with an explicit loop that emits MdQuoteIndentList > MdQuoteIndent nodes with MD_QUOTE_PRE_MARKER_INDENT tokens.
Add FormatNodeRule stubs for MdQuoteIndent and FormatRule for MdQuoteIndentList.
Add test cases for 1-space, 2-space, 3-space, tab, and nested pre-marker indentation.
Update all blockquote parser snapshots to reflect the new CST shape.

This is the follow-up to #9219, completing Phase 1 parser-side work. Pre-marker indentation (0-3 spaces before >) was the last remaining skipped trivia in blockquote parsing. Each indent space is now a real CST node visible to the formatter harness.

No user-facing behavior change. Parsed semantics are preserved; only the internal CST representation changes.

Test Plan

cargo test -p biome_markdown_parser — 66 tests pass (65 existing + 1 new)
cargo insta test -p biome_markdown_parser
rg -n "pre_marker_indent: MdQuoteIndentList|MD_QUOTE_INDENT_LIST|MD_QUOTE_INDENT" crates/biome_markdown_parser/tests/md_test_suite/**/*.snap — verifies snapshots contain explicit pre-marker indent nodes
Tab pre-marker indent correctly rejected (tab = 4 columns > 3 max, parsed as indented code block)

Docs

N/A — internal structural change, no new user-facing features.

…nodes Replace skip_line_indent(3) in emit_quote_prefix_tokens with explicit MdQuoteIndentList > MdQuoteIndent node emission, following the MdHash/MdHashList pattern. Each space before '>' is now a real CST node visible to the formatter harness instead of skipped trivia. Grammar: add MdQuoteIndent, MdQuoteIndentList; change MdQuotePrefix pre_marker_indent from optional token to list field.

changeset-bot · 2026-02-24T12:23:59Z

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coderabbitai · 2026-02-24T12:34:34Z

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between cb74be5 and 6cf94b3.

📒 Files selected for processing (2)

crates/biome_markdown_parser/src/syntax/mod.rs
crates/biome_markdown_parser/src/syntax/quote.rs

Walkthrough

The PR introduces explicit handling of quote pre‑marker indentation across parser, codegen and formatter. The parser adds MAX_BLOCK_PREFIX_INDENT and new token kinds (MD_QUOTE_PRE_MARKER_INDENT, MD_QUOTE_INDENT, MD_QUOTE_INDENT_LIST) and emits bounded indentation tokens. Codegen adds MdQuoteIndent and MdQuoteIndentList nodes. The formatter gains modules and crate‑scoped formatters (FormatMdQuoteIndent, FormatMdQuoteIndentList) plus AsFormat/IntoFormat/FormatRule wiring and tests for varied pre‑marker indent patterns.

Possibly related PRs

feat(formatter): set up boiletplate for markdown formatter #8962: Prior work that introduced generated formatter wiring and trait impl patterns this change extends.
fix(markdown-parser): promote blockquote prefix markers from skipped trivia to explicit CST nodes #9219: Related changes to quote‑prefix/indent handling that add or adjust quote‑related CST/token types and formatter hooks.
feat(parser/markdown): parser implementation #8525: Earlier modifications to quote parsing/tokenisation that touch the same block‑quote prefix logic and tokens.

Suggested reviewers

ematipico
dyc3

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarises the main change: promoting pre-marker indent to explicit CST nodes in the markdown parser.
Description check	✅ Passed	The description is comprehensive and directly related to the changeset, detailing grammar changes, parser updates, and test coverage.

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ematipico

Great work! I left a couple of comments. I'll merge once you add the comment I asked for

ematipico · 2026-02-24T14:29:39Z

crates/biome_markdown_parser/src/syntax/quote.rs

+        if text.is_empty() || !text.chars().all(|c| c == ' ' || c == '\t') {
+            break;
+        }
+        let indent: usize = text.chars().map(|c| if c == '\t' { 4 } else { 1 }).sum();
+        if consumed + indent > 3 {
+            break;
+        }


You might want to add some comments that explain this logic, mostly because there are some magic numbers that don't give enough context of the business logic

I’ll address the review comments here and replace the semantic/spec magic numbers that are in scope for this PR.

For the broader cleanup, I’ll open a follow-up PR to standardize the remaining semantic constants across the markdown parser in one pass, since that ended up being larger than expected.

ematipico · 2026-02-24T14:31:18Z

crates/biome_markdown_parser/src/syntax/quote.rs

+        p.bump_remap(MD_QUOTE_PRE_MARKER_INDENT);
+        indent_m.complete(p, MD_QUOTE_INDENT);
+    }
+    indent_list_m.complete(p, MD_QUOTE_INDENT_LIST);


Is there a particular reason why we don't use ParseList for this? Just curious

My thinking: this is a tiny bounded scan (<= 3 cols per CommonMark’s 0–3 indent before >), immediately followed by > validation, so a direct loop felt simpler than ParseNodeList. It also keeps this path strictly no-recovery/no-diagnostic.

Happy to switch to ParseNodeList if you prefer consistency.

No, I think it's fine for now. Maybe can you leave a comment explaning the reasoning

coderabbitai

Actionable comments posted: 1

♻️ Duplicate comments (1)

crates/biome_markdown_parser/src/syntax/quote.rs (1)
139-162: Comments and reasoning look good — past feedback addressed.

The bounded scan is well-documented, the tab-expansion logic matches the existing pattern in fenced_code_block.rs and parser.rs, and the rationale for not using ParseNodeList is clearly stated. The always-emitted (possibly empty) MD_QUOTE_INDENT_LIST is consistent with how other list nodes work in biome.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@crates/biome_markdown_parser/src/syntax/quote.rs` around lines 139 - 162, No
change required: the bounded scan in quote handling is correct — keep the
tab-expansion logic and the always-emitted MD_QUOTE_INDENT_LIST as-is; verify
the existing symbols indent_list_m, indent_m, TAB_STOP_SPACES and
MAX_BLOCK_PREFIX_INDENT remain used exactly as shown and leave the
MD_QUOTE_PRE_MARKER_INDENT remap and completion to MD_QUOTE_INDENT untouched.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/biome_markdown_parser/src/syntax/quote.rs`:
- Around line 44-46: Define a new constant named MAX_BLOCK_PREFIX_INDENT in the
constants section of the syntax module (next to INDENT_CODE_BLOCK_SPACES and
TAB_STOP_SPACES) with visibility pub(crate), type usize, and value 3 so imports
of MAX_BLOCK_PREFIX_INDENT in quote.rs and other files resolve; ensure the
constant is declared alongside the existing constants in mod.rs.

---

Duplicate comments:
In `@crates/biome_markdown_parser/src/syntax/quote.rs`:
- Around line 139-162: No change required: the bounded scan in quote handling is
correct — keep the tab-expansion logic and the always-emitted
MD_QUOTE_INDENT_LIST as-is; verify the existing symbols indent_list_m, indent_m,
TAB_STOP_SPACES and MAX_BLOCK_PREFIX_INDENT remain used exactly as shown and
leave the MD_QUOTE_PRE_MARKER_INDENT remap and completion to MD_QUOTE_INDENT
untouched.

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📥 Commits

Reviewing files that changed from the base of the PR and between 86ff35c and cb74be5.

📒 Files selected for processing (1)

crates/biome_markdown_parser/src/syntax/quote.rs

crates/biome_markdown_parser/src/syntax/quote.rs

…ndent loop

github-actions bot added A-Parser Area: parser A-Formatter Area: formatter A-Tooling Area: internal tools labels Feb 24, 2026

ematipico approved these changes Feb 24, 2026

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crates/biome_markdown_parser/src/syntax/quote.rs Show resolved Hide resolved

refactor(markdown-parser): add comments explaining magic numbers in i…

6cf94b3

…ndent loop

jfmcdowell force-pushed the refactor/md-parser-pre-marker-indent branch from cb74be5 to 6cf94b3 Compare February 24, 2026 16:51

jfmcdowell requested a review from ematipico February 24, 2026 17:24

jfmcdowell mentioned this pull request Feb 24, 2026

refactor(markdown-parser): extract magic numbers to named constants #9228

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ematipico approved these changes Feb 27, 2026

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ematipico merged commit ce67318 into biomejs:main Feb 27, 2026
14 checks passed

This was referenced Feb 27, 2026

refactor(markdown-parser): replace remaining magic numbers with named constants #9264

Merged

refactor(markdown-parser): promote list structural tokens from skipped trivia to explicit CST nodes #9274

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refactor(markdown-parser): promote pre-marker indent to explicit CST#9224

refactor(markdown-parser): promote pre-marker indent to explicit CST#9224
ematipico merged 2 commits intobiomejs:mainfrom
jfmcdowell:refactor/md-parser-pre-marker-indent

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jfmcdowell commented Feb 24, 2026

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