From 21faa99f847a4f88c6b3647158515564a7d1528f Mon Sep 17 00:00:00 2001
From: Linnnus <linnnus@users.noreply.github.com>
Date: Sun, 4 Feb 2024 14:29:34 +0100
Subject: feat(creole): Add basic paragraphs

In the future, we may need to keep track of state, if encountering
block-level elements ends paragraphs.
---
 src/creole-test.c | 77 +++++++++++++++++++++++++++++--------------------------
 src/creole.c      | 26 ++++++++++++++++++-
 2 files changed, 65 insertions(+), 38 deletions(-)

diff --git a/src/creole-test.c b/src/creole-test.c
index 23702a1..1e25a0f 100644
--- a/src/creole-test.c
+++ b/src/creole-test.c
@@ -10,6 +10,46 @@
 struct {
 	const char *name, *input, *output;
 } tests[] = {
+	{
+		.name    =  "Two paragraphs next to each other.",
+		.input   =  "Hello,\n\nworld!",
+		.output  =  "<p>Hello,</p><p>world!</p>"
+	},
+	{
+		.name    =  "h1",
+		.input   =  "= Header =",
+		.output  =  "<h1>Header</h1>"
+	},
+	{
+		.name    =  "h2",
+		.input   =  "== Header =",
+		.output  =  "<h2>Header</h2>"
+	},
+	{
+		.name    =  "h3",
+		.input   =  "=== Header =",
+		.output  =  "<h3>Header</h3>"
+	},
+	{
+		.name    =  "h4",
+		.input   =  "==== Header =",
+		.output  =  "<h4>Header</h4>"
+	},
+	{
+		.name    =  "h5",
+		.input   =  "===== Header",
+		.output  =  "<h5>Header</h5>"
+	},
+	{
+		.name    =  "h6",
+		.input   =  "====== Header =",
+		.output  =  "<h6>Header</h6>"
+	},
+	{
+		.name    =  ">h6",
+		.input   =  "======= Header =",
+		.output  =  "<p>======= Header =</p>"
+	},
 #if 0
 	{
 		.name    =  "Basic paragraph markup",
@@ -66,43 +106,6 @@ struct {
 		.input   =  "{{{\nPreformatted block\n}}}\n{{{Block 2}}}",
 		.output  =  "<pre>Preformatted block\n</pre><pre>Block 2</pre>"
 	},
-#endif
-	{
-		.name    =  "h1",
-		.input   =  "= Header =",
-		.output  =  "<h1>Header</h1>"
-	},
-	{
-		.name    =  "h2",
-		.input   =  "== Header =",
-		.output  =  "<h2>Header</h2>"
-	},
-	{
-		.name    =  "h3",
-		.input   =  "=== Header =",
-		.output  =  "<h3>Header</h3>"
-	},
-	{
-		.name    =  "h4",
-		.input   =  "==== Header =",
-		.output  =  "<h4>Header</h4>"
-	},
-	{
-		.name    =  "h5",
-		.input   =  "===== Header",
-		.output  =  "<h5>Header</h5>"
-	},
-	{
-		.name    =  "h6",
-		.input   =  "====== Header =",
-		.output  =  "<h6>Header</h6>"
-	},
-	{
-		.name    =  ">h6",
-		.input   =  "======= Header =",
-		.output  =  "<p>======= Header =</p>"
-	},
-#if 0
 	{
 		.name    =  "Tables",
 		.input   =  "| A | B |\n| //C// | **D** \\\\ E |",
diff --git a/src/creole.c b/src/creole.c
index 7eb6ad5..b3d1a87 100644
--- a/src/creole.c
+++ b/src/creole.c
@@ -13,6 +13,7 @@
 
 void process(const char *begin, const char *end, bool new_block, FILE *out);
 int do_headers(const char *begin, const char *end, bool new_block, FILE *out);
+int do_paragraph(const char *begin, const char *end, bool new_block, FILE *out);
 
 // A parser takes a (sub)string and returns the number of characters consumed, if any.
 //
@@ -20,7 +21,7 @@ int do_headers(const char *begin, const char *end, bool new_block, FILE *out);
 // The sign of the return value determines whether a new block should begin, after the consumed text.
 typedef int (* parser_t)(const char *begin, const char *end, bool new_block, FILE *out);
 
-static parser_t parsers[] = { do_headers };
+static parser_t parsers[] = { do_headers, do_paragraph };
 
 int do_headers(const char *begin, const char *end, bool new_block, FILE *out) {
 	if (!new_block) { // Headers are block-level elements.
@@ -63,6 +64,29 @@ int do_headers(const char *begin, const char *end, bool new_block, FILE *out) {
 	return -(eol - begin);
 }
 
+int do_paragraph(const char *begin, const char *end, bool new_block, FILE *out) {
+	if (!new_block) { // Paragraphs are block-level elements.
+		return 0;
+	}
+
+	const char *stop = begin + 1;
+	while (stop + 1 < end) {
+		if (stop[0] == '\n' && stop[1] == '\n') {
+			goto found_double_newline;
+		} else {
+			stop += 1;
+		}
+	}
+	stop = end;
+found_double_newline:
+
+	fputs("<p>", out);
+	process(begin, stop, false, out);
+	fputs("</p>", out);
+
+	return -(stop - begin);
+}
+
 void process(const char *begin, const char *end, bool new_block, FILE *out) {
 	const char *p = begin;
 	while (p < end) {
-- 
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