feat(single): Implement links and images

1 files changed, 67 insertions, 7 deletions

diff --git a/single.awk b/single.awk
index 65883f7..3568844 100644
--- a/single.awk
+++ b/single.awk
@@ -9,15 +9,15 @@
 #     [ ] Lists
 #     [x] Code blocks
 #     [x] Horizontal rules
-# [.] Span elements
-#     [ ] Links
-#         [ ] Inline
-#         [ ] Reference
+# [x] Span elements
+#     [x] Links
+#         [x] Inline
+#         [x] Reference
 #     [x] Emphasis
 #     [x] Code
-#     [ ] Images
-#         [ ] Inline
-#         [ ] Reference
+#     [x] Images
+#         [x] Inline
+#         [x] Reference
 # [ ] Other
 #     [ ] Autolinks
 #     [ ] Escapes
@@ -56,6 +56,22 @@ function _next() {
 	next
 }
 
+function char(string, ind) {
+	if (1 > ind || ind > length(string)) {
+		return "";
+	}
+	return substr(string, ind, 1)
+}
+
+function backup_match() {
+	backup_rstart = RSTART
+	backup_rlength = RLENGTH
+}
+function restore_match() {
+	RSTART = backup_rstart
+	RLENGTH = backup_rlength
+}
+
 {
 	not_paragraph_p1 = not_paragraph
 	not_paragraph = 0
@@ -74,6 +90,11 @@ function _next() {
 	_next()
 }
 
+# Link definition
+!inside_codeblock && /^\[[^\]]+\]:[ \t]+.*/ {
+	next
+}
+
 # Blockquotes
 blockquote_level > 0 && empty0 {
 	for (P1 = P1 ORS; blockquote_level > 0; --blockquote_level) {
@@ -190,6 +211,45 @@ function gsurround(brace, left, right, blen) {
 	gsurround("`"     , "<code>"  , "</code>")
 }
 
+# Links
+/!?\[[^\]]*\] ?[(\[][^)\]]*[\])]/ {
+	while (match($0, /!?\[[^\]]*\] ?[(\[][^)\]]*[\])]/)) {
+		link = substr($0, RSTART, RLENGTH)
+		backup_match()
+
+		## ](xxxxx)
+		match(link, /\] ?[(\[][^)\]]*[\])]$/)
+		has_space = char(link, RSTART + 1) == " "
+		is_img    = char(link, 1) == "!"
+
+		## ...[xxxxx](...)...
+		text = substr(link, 2 + is_img, RSTART - 2 - is_img)
+		## ...[...](xxxxx)...
+		href = substr(link, RSTART + has_space + 2, RLENGTH - has_space - 3)
+
+		title = "\"\""
+		if (char(link, RSTART + RLENGTH - 1) == "]") { ## is reference link
+			if (href == "") href = text # [...][]
+			## [...]: ... "xxxxx"
+			title = reference[href, "title"]
+			## [...]: xxxxx "..."
+			href = reference[href, "href"]
+		}
+		else if (match(href, /[ \t]"[^"]*"[ \t]*$/)) { ## has title
+			## ...[...](... "xxxxx")...
+			title = substr(href, RSTART + 1, RLENGTH - 1)
+			## ...[...](xxxxx "...")...
+			href  = substr(href, 1, RSTART - 1)
+		}
+
+		if (is_img) elem = "<img src=\"" href "\" alt=\"" text "\" title=" title ">"
+		else        elem = "<a href=\"" href "\" title=" title ">" text "</a>"
+
+		restore_match()
+		sub_match(elem)
+	}
+}
+
 # Paragraph
 emptyP1 && !empty0 && !not_paragraph { $0 = "<p>" $0 }
 !emptyP1 && empty0 && !not_paragraph_p1 { P1 = P1 "</p>" }