1 files changed, 79 insertions, 9 deletions

diff --git a/err.c b/err.c
index 0d8c09c..4c81c27 100644
--- a/err.c
+++ b/err.c
@@ -3,15 +3,6 @@
   This file is part of toc. toc is distributed under version 3 of the GNU General Public License, without any warranty whatsoever.
   You should have received a copy of the GNU General Public License along with toc. If not, see <https://www.gnu.org/licenses/>.
 */
-/* #define ERR_EMACS 1 */
-
-#ifndef USE_COLORED_TEXT
-#if ERR_EMACS
-#define USE_COLORED_TEXT 0
-#else
-#define USE_COLORED_TEXT 1
-#endif
-#endif
 
 #define TEXT_ERR_START "\x1b[91m"
 #define TEXT_ERR_END "\x1b[0m"
@@ -23,10 +14,89 @@
 #define TEXT_IMPORTANT_START "\x1b[1m"
 #define TEXT_IMPORTANT_END "\x1b[0m"
 
+#define TEXT_INDICATOR_START "\x1b[96m"
+#define TEXT_INDICATOR_END "\x1b[0m"
+
 #if defined(TOC_DEBUG) && __STDC_VERSION__ >= 199901
 #define ERR_SHOW_SOURCE_LOCATION 1
 #endif
 
+
+static void print_pos_highlight(FILE *out, ErrCtx *ctx, File *file, U32 start_pos, U32 end_pos) {
+	char *str = file->contents;
+	if (!str) {
+		return;
+	}
+	
+	char *start = str + start_pos;
+	char *line_start = start;
+	char *end = str + end_pos;
+
+	/* go back to last newline / 0 byte */
+	while (*line_start != '\0' && *line_start != '\n') --line_start;
+	if (line_start < start) ++line_start;
+
+	/* skip space at start of line */
+	while (isspace(*line_start) && line_start < end)
+		++line_start;
+		
+	char *line_end = strchr(start, '\n');
+	int has_newline = line_end != NULL;
+	if (!has_newline)
+		line_end = strchr(start, '\0');
+	assert(line_end);
+	if (!line_start[0])
+		fprintf(out, "<end of file>");
+	else {
+		/* write up to start of error */
+		fwrite(line_start, 1, (size_t)(start - line_start), out);
+		if (ctx->color_enabled)
+			fprintf(out, TEXT_INDICATOR_START);
+		if (line_end < end) {
+			/* write error part (only go to end of line) */
+			fwrite(start, 1, (size_t)(line_end - start), out);
+			if (ctx->color_enabled)
+				fprintf(out, TEXT_INDICATOR_END);
+		} else {
+			/* write error part */
+			fwrite(start, 1, (size_t)(end - start), out);
+			if (ctx->color_enabled)
+				fprintf(out, TEXT_INDICATOR_END);
+			/* write rest of line */
+			fwrite(end, 1, (size_t)(line_end - end), out);
+		}
+	}
+	fprintf(out, "\n");
+}
+
+static void print_location_highlight(FILE *out, Location where) {
+	if (where.start) {
+		ErrCtx *ctx = where.file->ctx;
+		print_pos_highlight(out, ctx, where.file, where.start->pos.start, where.end[-1].pos.end);
+	}
+	
+}
+
+/* for debugging */
+static void fprint_location(FILE *out, Location location) {
+	if (location.start) {
+		fprintf(out, "Line %ld of %s: ", (long)location.start->pos.line, location.file->filename);
+	} else {
+		U32 line = location.simple_location.line;
+		if (line)
+			fprintf(out, "Line %lu of %s: ", (unsigned long)line, location.file->filename);
+		else
+			fprintf(out, "In file %s: ", location.file->filename);
+		return;
+	}
+	print_location_highlight(out, location);
+}
+
+static void print_location(Location location) {
+	fprint_location(stdout, location);
+}
+
+
 static inline const char *ordinals(size_t x) {
 	switch (x % 10) {
 	case 1: return "st";