noh.h: noh_file_exists and some documentation

src/noh.h

@@ -343,6 +343,9 @@ void noh_string_append_null(Noh_String *string);
 // Resets a Noh_String, setting the count to 0.
 #define noh_string_reset(string) noh_da_reset(string)
 
+// Returns true if a file or directory exists, false otherwise.
+bool noh_file_exists(const char *filename);
+
 // Reads the contents of a file into a Noh_String.
 bool noh_string_read_file(Noh_String *string, const char *filename);
 
@@ -368,12 +371,14 @@ void noh_string_append_sv(Noh_String *string, Noh_String_View sv);
 void noh_sv_increase_position(Noh_String_View *sv, size_t distance);
 
 // Finds the first occurrence of the specified delimiter in a string view and returns the part of the string until
-// that delimiter. The string view itself is shrunk to start after the delimiter.
+// that delimiter. The input string view itself is shrunk to start after the delimiter.
+// If the delimiter is not found, the result is the entire string and the input string view is empty.
 Noh_String_View noh_sv_chop_by_delim(Noh_String_View *sv, char delim);
 
 // Finds the first occurrence of a line separator in a string view and returns the part of the string until
 // that separator. The string view itself is shrunk to start after the separator.
 // Supports '/r', '/n' and '/r/n'.
+// If no line separator is found, the entire string is returned and the input string is empty.
 Noh_String_View noh_sv_chop_line(Noh_String_View *sv);
 
 // Chops a string while a predicate matches.
@@ -842,6 +847,11 @@ void noh_string_append_null(Noh_String *string) {
     noh_da_append(string, '\0');
 }
 
+bool noh_file_exists(const char *filename) {
+    struct stat st;
+    return (stat(filename, &st)) == 0;
+}
+
 bool noh_string_read_file(Noh_String *string, const char *filename) {
     bool result = true;
     size_t buf_size = 32*1024;