highlight single line comments

kilo.c

@@ -40,6 +40,7 @@ enum editorKey {
 
 enum editorHighlight {
 	HL_NORMAL = 0,
+	HL_COMMENT,
 	HL_STRING,
 	HL_NUMBER,
 	HL_MATCH
@@ -53,6 +54,7 @@ enum editorHighlight {
 struct editorSyntax {
 	char *filetype;
 	char **filematch;
+	char *singleline_comment_start;
 	int flags;
 };
 
@@ -84,12 +86,14 @@ struct editorConfig {
 struct editorConfig E;
 
 /*** filetypes ***/
+
 char *C_HL_extensions[] = { ".c", ".h", ".cpp", NULL };
 
 struct editorSyntax HLDB[] = {
 	{
 		"c",
 		C_HL_extensions,
+		"//",
 		HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRINGS
 	},
 };
@@ -154,6 +158,7 @@ int editorReadKey()
 		}
 	}
 
+	// The character code starts with the escape sequence (\x1b)
 	if (c == '\x1b')
 	{
 		char seq[3];
@@ -298,6 +303,9 @@ void editorUpdateSyntax(erow *row)
 		return;
 	}
 
+	char *scs = E.syntax->singleline_comment_start;
+	int scs_len = scs ? strlen(scs) : 0;
+
 	int prev_sep = 1;
 	int in_string = 0;
 
@@ -307,6 +315,15 @@ void editorUpdateSyntax(erow *row)
 		char c = row->render[i];
 		unsigned char prev_hl = (i > 0) ? row->hl[i - 1] : HL_NORMAL;
 
+		if (scs_len && ! in_string)
+		{
+			if ( ! strncmp(&row->render[i], scs, scs_len))
+			{
+				memset(&row->hl[i], HL_COMMENT, row->rsize - i);
+				break;
+			}
+		}
+
 		if (E.syntax->flags & HL_HIGHLIGHT_STRINGS)
 		{
 			if (in_string)
@@ -360,14 +377,17 @@ int editorSyntaxToColor(int hl)
 {
 	switch (hl)
 	{
+		case HL_COMMENT:
+			return 36; // cyan
+
 		case HL_STRING:
-			return 35;
+			return 35; // magenta
 
 		case HL_NUMBER:
-			return 31;
+			return 31; // red
 
 		case HL_MATCH:
-			return 34;
+			return 34; // blue
 
 		default:
 			return 37;
@@ -463,7 +483,7 @@ void editorUpdateRow(erow *row)
 	}
 
 	free(row->render);
-	row->render = malloc(row->size + tabs*(KILO_TAB_STOP - 1) + 1);
+	row->render = malloc(row->size + tabs *(KILO_TAB_STOP - 1) + 1);
 
 	int idx = 0;
 	for (j = 0; j < row->size; j++)