Parse HTML.

1 files changed, 195 insertions, 0 deletions

diff --git a/parse.c b/parse.c
new file mode 100644
index 0000000..a9998e3
--- /dev/null
+++ b/parse.c
@@ -0,0 +1,195 @@
+#include <ctype.h>
+#include <stddef.h>
+
+#include "parse.h"
+
+#define ADVANCE(s, n) do { \
+	size_t i_; \
+	for (i_ = 0; i_ < (n); i_++) { \
+		if (!*(++(s))) \
+			goto end; \
+	} \
+} while (0)
+
+typedef enum { 
+	DATA = 1, 
+	TAG_OPEN, 
+	TAG_CLOSE, 
+	ATTR_NAME, 
+	ATTR_VALUE, 
+	DOCTYPE, 
+	COMMENT 
+} parse_mode;
+
+extern void on_open(const char *tag, size_t n);
+extern void on_close(const char *tag, size_t n);
+extern void on_text(const char *text, size_t n);
+extern void on_attr(const char *name, size_t nname, const char *val, size_t nval);
+
+void parse(const char *s)
+{
+	int blank;
+	parse_mode mode;
+	size_t n, attr_name_len;
+	const char *p, *attr_name;
+
+	if (!s)
+		return;
+
+	mode = DATA;
+	
+	while (*s) {
+		switch (mode) {
+		case DATA:
+			p = s;
+			n = 0;
+			blank = 1;
+			while (*s) {
+				if (*s == '<') {
+					if (isalpha((unsigned char)s[1])) {
+						mode = TAG_OPEN;
+						ADVANCE(s, 1);
+						break;
+					} else if (s[1] == '/') {
+						mode = TAG_CLOSE;
+						ADVANCE(s, 2);
+						break;
+					} else if (s[1] == '!') {
+						if (s[2] == '-' && s[3] == '-') {
+							mode = COMMENT;
+							ADVANCE(s, 3);
+						} else {
+							mode = DOCTYPE;
+							ADVANCE(s, 2);
+						}
+						break;
+					}
+				}
+
+				if (!isspace((unsigned char)*s))
+					blank = 0;
+				
+				n++;
+				ADVANCE(s, 1);
+			}
+
+			if (n > 0 && !blank)
+				on_text(p, n);
+
+			break;
+		case TAG_OPEN:
+			p = s;
+			n = 0;
+			while (*s) {
+				if (*s == '>') {
+					mode = DATA;
+					if (n > 0 && s[-1] == '/')
+						n--;
+					ADVANCE(s, 1);
+					break;
+				}
+
+				if (*s == ' ') {
+					while (*s == ' ')
+						ADVANCE(s, 1);
+
+					if (isalpha((unsigned char)*s))
+						mode = ATTR_NAME;
+					else if (*s == '/' && s[1] == '>') {
+						ADVANCE(s, 2);  // ignore self-closing tags
+						mode = DATA;
+					}
+					break;
+				}
+
+				n++;
+				ADVANCE(s, 1);
+			}
+
+			if (n > 0)
+				on_open(p, n);
+
+			break;
+		case TAG_CLOSE:
+			p = s;
+			n = 0;
+			while (*s) {
+				if (*s == '>') {
+					on_close(p, n);
+					mode = DATA;
+					ADVANCE(s, 1);
+					break;
+				}
+				n++;
+				ADVANCE(s, 1);
+			}
+			break;
+		case ATTR_NAME:
+			p = s;
+			n = 0;
+			while (*s) {
+				if (*s == '=') {
+					attr_name = p;
+					attr_name_len = n;
+					mode = ATTR_VALUE;
+					ADVANCE(s, 1);
+					if (*s == '"' || *s == '\'')
+						ADVANCE(s, 1);
+					break;
+				}
+
+				if (*s == '>') {  // <input disabled>
+					on_attr(p, n, NULL, 0);
+					mode = DATA;
+					ADVANCE(s, 1);
+					break;
+				}
+
+				n++;
+				ADVANCE(s, 1);
+			}
+			break;
+		case ATTR_VALUE:
+			p = s;
+			n = 0;
+			while (*s) {
+				if (*s == '"' || *s == '\'' || *s == '>') {
+					on_attr(attr_name, attr_name_len, p, n);
+					mode = *s == '>' ? DATA : TAG_OPEN;
+					ADVANCE(s, 1);
+					break;
+				}
+				n++;
+				ADVANCE(s, 1);
+			}
+			break;
+		case DOCTYPE:
+			while (*s) {
+				if (*s == '>') {
+					mode = DATA;
+					ADVANCE(s, 1);
+					break;
+				}
+				ADVANCE(s, 1);
+			}
+			break;
+		case COMMENT:
+			n = 0;
+			while (*s) {
+				if (*s == '>' && n >= 2 && s[-1] == '-' && s[-2] == '-') {
+					mode = DATA;
+					ADVANCE(s, 1);
+					break;
+				}
+				n++;
+				ADVANCE(s, 1);
+			}
+			break;
+		default:
+			break;
+		}
+	}
+
+end:
+	return;
+}