From 2c97732432014df61eb676cbd8fdd25424f99d6c Mon Sep 17 00:00:00 2001
From: Tab Atkins-Bittner <jackalmage@gmail.com>
Date: Wed, 15 Nov 2023 12:39:22 -0800
Subject: [PATCH] Allow for nodes to *decrement* the line count as well, if
 they print to more lines than they occupied in the source.

---
 bikeshed/InputSource.py | 20 ++++++++++++++------
 bikeshed/constants.py   |  1 +
 bikeshed/h/parser.py    | 12 ++++++++----
 3 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/bikeshed/InputSource.py b/bikeshed/InputSource.py
index 29b67941aa..346a7fe99c 100644
--- a/bikeshed/InputSource.py
+++ b/bikeshed/InputSource.py
@@ -28,19 +28,27 @@ def lines(self) -> list[line.Line]:
         offset = 0
         for i, text in enumerate(self.rawLines, 1):
             lineNo = i + offset
-            # The early HTML parser runs before Markdown,
-            # and in some cases removes linebreaks that were present
-            # in the source. When properly invoked, it inserts
-            # a special PUA char for each of these omitted linebreaks,
-            # so I can remove them here and properly increment the
-            # line number.
+            # The early HTML parser can change how nodes print,
+            # so they occupy a different number of lines than they
+            # had in the source. Markdown parser needs to know
+            # the correct source lines, tho, so when this happens,
+            # the nodes will insert special PUA chars to indicate that.
+            # I can remove them here and properly adjust the line number.
             # Current known causes of this:
             # * line-ending -- turned into em dashes
             # * multi-line start tags
+            # * multi-line markdown code spans;
+            #     - the text loses its newlines
+            #     - the original text goes into an attribute on the start
+            #       tag now
             ilcc = constants.incrementLineCountChar
+            dlcc = constants.decrementLineCountChar
             if ilcc in text:
                 offset += text.count(ilcc)
                 text = text.replace(ilcc, "")
+            if dlcc in text:
+                offset -= text.count(dlcc)
+                text = text.replace(dlcc, "")
 
             ret.append(line.Line(lineNo, text))
 
diff --git a/bikeshed/constants.py b/bikeshed/constants.py
index 08e5a37f73..98fae99b96 100644
--- a/bikeshed/constants.py
+++ b/bikeshed/constants.py
@@ -11,4 +11,5 @@
 macroStartChar = "\uebbb"
 macroEndChar = "\uebbc"
 incrementLineCountChar = "\uebbd"
+decrementLineCountChar = "\uebbf"
 bsComment = "<!--\uebbe-->"
diff --git a/bikeshed/h/parser.py b/bikeshed/h/parser.py
index 7f55eff9cb..c1f6982682 100644
--- a/bikeshed/h/parser.py
+++ b/bikeshed/h/parser.py
@@ -277,6 +277,7 @@ def initialDocumentParse(text: str, config: ParseConfig, startLine: int = 1) ->
 def strFromNodes(nodes: t.Iterable[ParserNode], withIlcc: bool = False) -> str:
     strs = []
     ilcc = constants.incrementLineCountChar
+    dlcc = constants.decrementLineCountChar
     for node in nodes:
         if isinstance(node, Comment):
             # Serialize comments as a standardized, recognizable sequence
@@ -287,10 +288,13 @@ def strFromNodes(nodes: t.Iterable[ParserNode], withIlcc: bool = False) -> str:
             continue
         s = str(node)
         if withIlcc:
-            numLines = s.count("\n")
-            diffLineNo = node.endLine - node.line
-            if diffLineNo > numLines:
-                s += ilcc * (diffLineNo - numLines)
+            outputExtraLines = s.count("\n")
+            sourceExtraLines = node.endLine - node.line
+            diff = sourceExtraLines - outputExtraLines
+            if diff > 0:
+                s += ilcc * diff
+            elif diff < 0:
+                s += dlcc * -diff
         strs.append(s)
     return "".join(strs)