Fix and enhance en/em dash translation

asciidoc.conf

@@ -52,6 +52,7 @@ lsquo=‘
 rsquo=’
 ldquo=“
 rdquo=”
+compat-mode=
 
 [titles]
 subs=specialcharacters,quotes,replacements,macros,attributes,replacements2
@@ -124,6 +125,22 @@ monospacedwords=
 (\w)--(\w)=\1—\2
 \\--(?!-)=--
 
+ifndef::compat-mode[]
+# --- Spaced and unspaced em dashes (entity reference —).
+# Space on both sides is translated to thin space characters.
+(^--- )=— 
+(\n--- )|( --- )|( ---\n)= — 
+(\w)---(\w)=\1—\2
+\\---(?!-)=---
+
+# -- Spaced and unspaced en dashes (entity reference –).
+# Space on both sides is translated to thin space characters.
+(^-- )=– 
+(\n-- )|( -- )|( --\n)= – 
+(\w)--(\w)=\1–\2
+\\--(?!-)=--
+endif::compat-mode[]
+
 # Replace vertical typewriter apostrophe with punctuation apostrophe.
 (\w)'(\w)=\1’\2
 (\w)\\'(\w)=\1'\2

latex.conf

@@ -70,7 +70,10 @@ _=\_{}
 # Line break.
 (?m)^(.*)\s\+$=\1 !..backslash..!newline!..braceleft..!!..braceright..!
 
-# -- Spaced em dashes (entity reference —)
+# --- Spaced em dashes (entity reference —)
+(^|[^-\\])---($|[^-])=\1---\2
+
+# -- Spaced en dashes (entity reference –)
 (^|[^-\\])--($|[^-])=\1--\2