feat: support comments between concise mode line attributes

Allow `//` and `/*...*/` comment lines between comma-prefixed line
attributes in concise mode. The comments are scanned over (not emitted)
and no longer terminate the open tag.

Fixes #203

Author: DylanPiercey

.changeset/quick-comments-attrs.md

@@ -0,0 +1,5 @@
+---
+"htmljs-parser": minor
+---
+
+Support comments between concise mode line attributes.

src/__tests__/fixtures/attr-comma-multiline-comment-trailing/__snapshots__/attr-comma-multiline-comment-trailing.expected.txt

@@ -0,0 +1,12 @@
+1╭─ div
+ ╰─ ╰─ tagName "div"
+2╭─   ,foo=bar
+ │     │  │╰─ attrValue.value "bar"
+ │     │  ╰─ attrValue "=bar"
+ ╰─    ╰─ attrName "foo"
+3╭─   // trailing comment
+ │  │ │ ╰─ comment.value " trailing comment"
+ │  │ ╰─ comment "// trailing comment"
+ ╰─ ╰─ openTagEnd
+4╭─ 
+ ╰─ ╰─ closeTagEnd(div)

src/__tests__/fixtures/attr-comma-multiline-comment-trailing/input.marko

@@ -0,0 +1,3 @@
+div
+  ,foo=bar
+  // trailing comment

src/__tests__/fixtures/attr-comma-multiline-comments/__snapshots__/attr-comma-multiline-comments.expected.txt

@@ -0,0 +1,19 @@
+1╭─ div
+ ╰─ ╰─ tagName "div"
+2╭─   ,foo=bar
+ │     │  │╰─ attrValue.value "bar"
+ │     │  ╰─ attrValue "=bar"
+ ╰─    ╰─ attrName "foo"
+3├─   // comment
+4╭─   ,bar=baz
+ │     │  │╰─ attrValue.value "baz"
+ │     │  ╰─ attrValue "=baz"
+ ╰─    ╰─ attrName "bar"
+5├─   /* block */
+6╭─   ,qux=qux
+ │     │  │╰─ attrValue.value "qux"
+ │     │  ╰─ attrValue "=qux"
+ ╰─    ╰─ attrName "qux"
+7╭─ 
+ │  ├─ openTagEnd
+ ╰─ ╰─ closeTagEnd(div)

src/__tests__/fixtures/attr-comma-multiline-comments/input.marko

@@ -0,0 +1,6 @@
+div
+  ,foo=bar
+  // comment
+  ,bar=baz
+  /* block */
+  ,qux=qux

src/states/OPEN_TAG.ts

@@ -1,5 +1,6 @@
 import {
   isIndentCode,
+  isLineCode,
   isWhitespaceCode,
   matchesCloseAngleBracket,
   matchesCloseParen,
@@ -105,13 +106,40 @@ export const OPEN_TAG: StateDefinition<OpenTagMeta> = {
             : 1;
 
         if (this.isConcise && tag.stage !== TAG_STAGE.ATTR_GROUP) {
-          if (this.consumeWhitespaceIfBefore(",")) {
-            this.pos++; // skip ,
+          let cur = this.pos;
+          while (cur < maxPos) {
+            const peek = data.charCodeAt(cur);
+            if (isWhitespaceCode(peek)) {
+              cur++;
+            } else if (
+              peek === CODE.FORWARD_SLASH &&
+              data.charCodeAt(cur + 1) === CODE.FORWARD_SLASH
+            ) {
+              // line comment
+              cur += 2;
+              while (cur < maxPos && !isLineCode(data.charCodeAt(cur))) cur++;
+            } else if (
+              peek === CODE.FORWARD_SLASH &&
+              data.charCodeAt(cur + 1) === CODE.ASTERISK
+            ) {
+              // block comment
+              const end = data.indexOf("*/", cur + 2);
+              if (end === -1) break;
+              cur = end + 2;
+            } else {
+              break;
+            }
+          }
+
+          // comma continues the open tag with another line attribute
+          if (data.charCodeAt(cur) === CODE.COMMA) {
+            this.pos = cur + 1;
             this.consumeWhitespace();
             continue;
           }
+
           this.exitState();
-          return; // parent handles newline
+          return;
         }
 
         this.pos += len;