Add hyperlink support to MarkdownParser

MarkdownParser now supports hyperlinks.

src/MarkdownParser.cxx

@@ -22,18 +22,53 @@
 #include "MarkdownParser.hxx"
 
 #include <assert.h>
+#include <iostream>
 
 #define ASCII_DIGIT_START	48
 
+enum HyperlinkStage {
+	NONE,			// not reading a hyperlink
+	READING_CONTENTS,	// reading the contents (like text) of a hyperlink
+	EXPECTING_URL,		// done reading contents of hyperlink; expecting its URL to be specified
+	READING_URL		// reading the hyperlink url
+};
+
+std::string html,
+	tag_a_text_buf,		// used for storing the text contents of a hyperlink
+	tag_a_buf;		// used for storing the hyperlink address
+enum HyperlinkStage tag_a = NONE;
+
+void append(std::string const &s) {
+	// TODO: add proper error handling.
+	assert(tag_a != EXPECTING_URL);
+	switch(tag_a) {
+		case NONE:
+			html += s;
+			break;
+		case READING_CONTENTS:
+			tag_a_text_buf += s;
+			break;
+		case READING_URL:
+			tag_a_buf += s;
+			break;
+	}
+}
+void append(const char *c) {
+	append(std::string(c));
+}
+
+void cleanup() {
+	html = "";
+}
+
 namespace MarkdownParser {
 
 std::string make_html(std::filesystem::path const &path) {
+	cleanup();
 	FILE *mdFile = fopen(path.string().c_str(), "r");
 	// TODO: Add proper error handling.
 	assert(mdFile != NULL);
 
-	std::string html;
-
 	int buflen = 64;
 	char buf[buflen];
 
@@ -105,25 +140,24 @@ std::string make_html(std::filesystem::path const &path) {
 					// Bold check
 					// Check whether this character has been escaped.
 					if (buf[x-1] == '\\') {
-						html += "*";
+						append(&c);
 						break;
 					}
 
-					html += tag_b ? "</b>" : "<b>";
+					append(tag_b ? "</b>" : "<b>");
 					tag_b = !tag_b;
 					break;
 				case '_':
 					// Italics check
-					
 					// Check whether this character has
 					// been escaped.
 					
 					if (buf[x-1] == '\\') {
-						html += "_";
+						append(&c);
 						break;
 					}
 
-					html += tag_i ? "</i>" : "<i>";
+					append(tag_i ? "</i>" : "<i>");
 					tag_i = !tag_i;
 					break;
 				case '#':
@@ -133,7 +167,7 @@ std::string make_html(std::filesystem::path const &path) {
 					// beginning of a new line. Ignore it
 					// if this is not a new line.
 					if (!newline) {
-						html += "#";
+						append(&c);
 						break;
 					}
 
@@ -143,7 +177,7 @@ std::string make_html(std::filesystem::path const &path) {
 					// Check if this header was specified
 					// right at the beginning of the line.
 					    (tag_h == 0 && x != 0)) {
-						html += "#";
+						append(&c);
 						break;
 					}
 
@@ -192,14 +226,55 @@ std::string make_html(std::filesystem::path const &path) {
 					ignoreSpace = true;
 					tag_li = true;
 					break;
+				case '[':
+					// Hyperlink text declaration has begun
+					if (tag_a != NONE) {
+						// Cannot add hyperlinks inside of hyperlinks;
+						append(&c);
+						break;
+					}
+					tag_a_buf = "";
+					tag_a_text_buf = "";
+					tag_a = READING_CONTENTS;
+					break;
+				case ']':
+					// Hyperlink text declaration ended
+					if (tag_a != READING_CONTENTS) {
+						// Ignore if not reading hyperlink.
+						append(&c);
+						break;
+					}
+					tag_a = EXPECTING_URL;
+					break;
+				case '(':
+					// Hyperlink address declaration has begun
+					if (tag_a != EXPECTING_URL) {
+						append(&c);
+						break;
+					}
+					tag_a = READING_URL;
+					break;
+				case ')':
+					// Hyperlink address declaration ended
+					if (tag_a != READING_URL) {
+						append(&c);
+						break;
+					}
+					tag_a = NONE;
+					append("<a href=\"");
+					append(tag_a_buf);
+					append("\">");
+					append(tag_a_text_buf);
+					append("</a>");
+					break;
 				case ' ':
 					if (ignoreSpace) {
 						ignoreSpace = false;
 						break;
-					} else html += ' ';
+					} else append(" ");
 					break;
 				default:
-					html += c;
+					append(&c);
 					break;
 			}
 		}