1 files changed, 56 insertions, 4 deletions
diff --git a/util/err.c b/util/err.c
index 6fd2ac3..5e296da 100644
--- a/util/err.c
+++ b/util/err.c
@@ -1,13 +1,65 @@
+#define USE_COLORED_TEXT 1
+
+#if USE_COLORED_TEXT
+#define TEXT_ERROR(x) "\x1b[91m" x "\x1b[0m"
+#define TEXT_IMPORTANT(x) "\x1b[1m" x "\x1b[0m"
+#else
+#define TEXT_ERROR(x) x
+#define TEXT_IMPORTANT(x) x
+#endif
+
 typedef uint32_t LineNo;
 
-static void err_print(LineNo line, LineNo col, const char *fmt, ...) {
-	/* TODO: Color */
+/* file name of file being processed */
+static const char *err_filename;
+
+/* Write directly to the error file */
+static void err_fwrite(const void *data, size_t size, size_t n) {
+	fwrite(data, size, n, stderr);
+}
+
+static void err_fprint(const char *fmt, ...) {
 	va_list args;
-	fprintf(stderr, TEXT_ERROR("error:") " at line %lu col %lu:\n", (unsigned long)line, (unsigned long)col);
 	va_start(args, fmt);
 	vfprintf(stderr, fmt, args);
 	va_end(args);
-	fprintf(stderr, "\n");
+}
+
+static void err_vfprint(const char *fmt, va_list args) {
+	vfprintf(stderr, fmt, args);
+}
+
+static void err_print_header_(LineNo line) {
+	err_fprint(TEXT_ERROR("error:") " at line %lu of %s:\n", (unsigned long)line, err_filename);
+}
+
+static void err_print_footer_(const char *context) {
+	err_fprint("\n\there --> ");
+	const char *end = strchr(context, '\n');
+	int has_newline = end != NULL;
+	if (!has_newline)
+		end = strchr(context, '\0');
+	assert(end);
+	err_fwrite(context, 1, (size_t)(end - context));
+	if (!has_newline)
+		err_fprint("<end of file>");
+	err_fprint("\n");
+}
+
+/* Write nicely-formatted errors to the error file */
+static void err_print(LineNo line, const char *context, const char *fmt, ...) {
+	err_print_header_(line);
+	va_list args;
+	va_start(args, fmt);
+	err_vfprint(fmt, args);
+	va_end(args);
+	err_print_footer_(context);
+}
+
+static void err_vprint(LineNo line, const char *context, const char *fmt, va_list args) {
+	err_print_header_(line);
+	err_vfprint(fmt, args);
+	err_print_footer_(context);
 }
 
 static void *err_malloc(size_t size) {