-static const char sort_usage[] =
-"sort [OPTION]... [FILE]...\n\n"
-;
-
-/* typedefs _______________________________________________________________ */
-
-/* line node */
-typedef struct Line {
- char *data; /* line data */
- struct Line *next; /* pointer to next line node */
-} Line;
-
-/* singly-linked list of lines */
-typedef struct {
- int len; /* number of Lines */
- Line **sorted; /* array fed to qsort */
-
- Line *head; /* head of List */
- Line *current; /* current Line */
-} List;
-
-/* comparison function */
-typedef int (Compare)(const void *, const void *);
-
-
-/* methods ________________________________________________________________ */
-
-static const int max = 1024;
-
-/* mallocate Line */
-static Line *
-line_alloc()
-{
- Line *self;
- self = malloc(1 * sizeof(Line));
- return self;
-}
-
-/* Initialize Line with string */
-static Line *
-line_init(Line *self, const char *string)
-{
- self->data = malloc((strlen(string) + 1) * sizeof(char));
- if (self->data == NULL) { return NULL; }
- strcpy(self->data, string);
- self->next = NULL;
- return self;
-}
-
-/* Construct Line from FILE* */
-static Line *
-line_newFromFile(FILE *src)
-{
- char buffer[max];
- Line *self;
-
- if (fgets(buffer, max, src)) {
- self = line_alloc();
- if (self == NULL) { return NULL; }
- line_init(self, buffer);
- return self;
- }
- return NULL;
-}
-
-/* Line destructor */
-static Line *
-line_release(Line *self)
-{
- if (self->data) {
- free(self->data);
- free(self);
- }
- return self;
-}
-
-
-/* Comparison */
-
-/* ascii order */
-static int
-compare_ascii(const void *a, const void *b)
-{
- Line **doh;
- Line *x, *y;
-
- doh = (Line **) a;
- x = *doh;
- doh = (Line **) b;
- y = *doh;
-
- // fprintf(stdout, "> %p: %s< %p: %s", x, x->data, y, y->data);
- return strcmp(x->data, y->data);
-}
-
-/* numeric order */
-static int
-compare_numeric(const void *a, const void *b)
-{
- Line **doh;
- Line *x, *y;
- int xint, yint;
-
- doh = (Line **) a;
- x = *doh;
- doh = (Line **) b;
- y = *doh;
-
- xint = strtoul(x->data, NULL, 10);
- yint = strtoul(y->data, NULL, 10);
-
- return (xint - yint);
-}
-
-
-/* List */
-
-/* */
-static List *
-list_init(List *self)
-{
- self->len = 0;
- self->sorted = NULL;
- self->head = NULL;
- self->current = NULL;
- return self;
-}
-
-/* for simplicity, the List gains ownership of the line */
-static List *
-list_insert(List *self, Line *line)
-{
- if (line == NULL) { return NULL; }
-
- /* first insertion */
- if (self->head == NULL) {
- self->head = line;
- self->current = line;
-
- /* all subsequent insertions */
- } else {
- self->current->next = line;
- self->current = line;
- }
- self->len++;
- return self;
-}
-
-/* order the list according to compare() */
-static List *
-list_sort(List *self, Compare *compare)
-{
- int i;
- Line *line;
-
- /* mallocate array of Line*s */
- self->sorted = (Line **) malloc(self->len * sizeof(Line*));
- if (self->sorted == NULL) { return NULL; }
-
- /* fill array w/ List's contents */
- i = 0;
- line = self->head;
- while (line) {
- self->sorted[i++] = line;
- line = line->next;
- }
-
- /* apply qsort */
- qsort(self->sorted, self->len, sizeof(Line*), compare);
- return self;
-}
-
-/* precondition: list must be sorted */
-static List *
-list_writeToFile(List *self, FILE* dst)