From 90d5b0125fb943eea852ab14ed7a8243c86d7d21 Mon Sep 17 00:00:00 2001
From: Jonas Smedegaard <dr@jones.dk>
Date: Sun, 18 May 2025 12:41:35 +0200
Subject: define LinkTitle

---
 _def_dia.qmd          |  2 ++
 def.peg               |  7 +++++--
 def_LinkDefinition.py |  4 +---
 def_LinkTitle.py      | 36 ++++++++++++++++++++++++++++++++++++
 def_LinkedWords.py    | 11 ++++++++++-
 5 files changed, 54 insertions(+), 6 deletions(-)
 create mode 100755 def_LinkTitle.py

diff --git a/_def_dia.qmd b/_def_dia.qmd
index d800c02..1afeeec 100644
--- a/_def_dia.qmd
+++ b/_def_dia.qmd
@@ -24,6 +24,8 @@ involving the negative predicate from PEG notation.
 
 ![LinkLabel](def_LinkLabel.svg)
 
+![LinkTitle](def_LinkTitle.svg)
+
 ![PlainWords](def_PlainWords.svg)
 
 ![Url](def_Uri.svg)
diff --git a/def.peg b/def.peg
index 8bec09d..336a446 100644
--- a/def.peg
+++ b/def.peg
@@ -11,17 +11,20 @@ Markdown       <- MetaBlock* Block*
 Block          <- Header / List / LinkDefinition / Paragraph
 Header         <- '#'+ SPACE* !NEWLINE Words? SPACE* NEWLINE
 List           <- ([-*]+ / [[:digit:]]+ [).]) (_ (List / Words))? NEWLINE
-LinkDefinition <- LinkLabel ':' _? Uri (_ '"' !'"' PlainWords '"')? NEWLINE
+LinkDefinition <- LinkLabel ':' _? Uri (_ LinkTitle)? NEWLINE
 Paragraph      <- Words (HardBreak Words)* NEWLINE+
 
 # Inline elements
 Words          <- StyledWords / LinkedWords / AnnotatedWords / PlainWords
 StyledWords    <- '*' Words '*' / '**' Words '**' / '_' Words '_'
-LinkedWords    <- '[' Words ']' '(' Uri ')'
+LinkedWords    <- '[' Words ']' '(' ((Uri _)? LinkTitle / Uri) ')'
                 / '[' Words ']' LinkLabel
                 / LinkLabel
 AnnotatedWords <- '[' Words ']' '{' ![{}] PlainWords '}'
 LinkLabel      <- '[' _? ![\[\]] PlainWords _? ']'
+LinkTitle      <- '"' _? !'"' _? PlainWords _? '"'
+                / "'" _? !"'" PlainWords _? "'"
+                / "(" _? ![()] PlainWords _? ")"
 PlainWords     <- PRINTABLES (_ PRINTABLES)*
 Uri            <- '<' ![<>] PRINTABLES? '>' / ![<>] PRINTABLES
 HardBreak      <- SPACE SPACE+ NEWLINE
diff --git a/def_LinkDefinition.py b/def_LinkDefinition.py
index 67b5797..a5cb2f2 100755
--- a/def_LinkDefinition.py
+++ b/def_LinkDefinition.py
@@ -14,9 +14,7 @@ Diagram(
 	NonTerminal("Uri"),
 	Optional(Sequence(
 		NonTerminal("_"),
-		'"',
-		NonTerminal("!'\"' PlainWords"),
-		'"'
+		NonTerminal("LinkTitle")
 	)),
 	NonTerminal("NEWLINE"),
 	End("complex")
diff --git a/def_LinkTitle.py b/def_LinkTitle.py
new file mode 100755
index 0000000..02f39d6
--- /dev/null
+++ b/def_LinkTitle.py
@@ -0,0 +1,36 @@
+#!/usr/bin/python3
+
+# Copyright 2025, Jonas Smedegaard <dr@jones.dk>
+# SPDX-License-Identifier: GPL-3+
+
+from os.path import basename, splitext
+from railroad import *
+
+Diagram(
+	Start("complex"),
+	Choice(0,
+		Sequence(
+			'"',
+			Optional(NonTerminal("_")),
+			NonTerminal("!'\"' PlainWords"),
+			Optional(NonTerminal("_")),
+			'"',
+		),
+		Sequence(
+			"'",
+			Optional(NonTerminal("_")),
+			NonTerminal("!\"'\" PlainWords"),
+			Optional(NonTerminal("_")),
+			"'",
+		),
+		Sequence(
+			"(",
+			Optional(NonTerminal("_")),
+			NonTerminal("![()] PlainWords"),
+			Optional(NonTerminal("_")),
+			")",
+		)
+	),
+	End("complex")
+).writeStandalone(
+	open(splitext(basename(__file__))[0] + ".svg", "w").write)
diff --git a/def_LinkedWords.py b/def_LinkedWords.py
index f5e2519..83ba83c 100755
--- a/def_LinkedWords.py
+++ b/def_LinkedWords.py
@@ -14,7 +14,16 @@ Diagram(
 			NonTerminal("Words"),
 			"]",
 			"(",
-			NonTerminal("Uri"),
+			Choice(0,
+				Sequence(
+					Optional(Sequence(
+						NonTerminal("Uri"),
+						NonTerminal("_")
+					)),
+					NonTerminal("LinkTitle")
+				),
+				NonTerminal("Uri"),
+			),
 			")"
 		),
 		Sequence(
-- 
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