Basic tokenization

1 files changed, 28 insertions, 0 deletions

diff --git a/util/files.c b/util/files.c
new file mode 100644
index 0000000..0afa843
--- /dev/null
+++ b/util/files.c
@@ -0,0 +1,28 @@
+static int fpeekc(FILE *fp) {
+	int c = getc(fp);
+	if (c == EOF)
+		return c;
+	ungetc(c, fp);
+	return c;
+}
+
+#define fnextc getc /* advance to the next character */
+
+/* NOTE: Advances and returns # of characters advanced iff prefix is found. */
+static int fhasprefix(FILE *fp, const char *prefix) {
+	assert(*prefix);
+	long start = ftell(fp);
+	if (start == -1)
+		return 0;
+	const char *p = prefix;
+	while (*p) {
+		int c = getc(fp);
+		if (c != *p) {
+			/* wrong character / EOF */
+			fseek(fp, start, SEEK_SET);
+			return 0;
+		}
+		p++;
+	}
+	return (int)(p - prefix); /* length of prefix */
+}