Add %D Flag

Added %D flag which expands to the directory part of the current file path. Example: "path/to/file.txt" -> "path/to/". Updated tup.1 to include new flag documentation.

Author: WSWhitehouse

src/tup/parser.c

@@ -4039,6 +4039,25 @@ static char *tup_printf(struct tupfile *tf, const char *cmd, int cmd_len,
 				 */
 				estring_append(&e, tent->name.s, tent->name.len);
 			}
+		} else if(*next == 'D') {
+			/* D: Expands to the directory portion of the current file path.
+			 *    Example: "path/to/file.txt" -> "path/to/"
+			 */
+			int first = 1;
+			if(nl->num_entries == 0) {
+				fprintf(tf->f, "tup error: %%D used in rule pattern and no input files were specified.\n");
+				return NULL;
+			}
+			TAILQ_FOREACH(nle, &nl->entries, list) {
+				if(!first) {
+					estring_append(&e, " ", 1);
+				}
+				int dirlen = nle->len - nle->baselen - (*p == '/' ? 1 : 0);
+				if (dirlen > 0) {
+					estring_append(&e, nle->path, dirlen);
+				}
+				first = 0;
+			}
 		} else if(*next == 'g') {
 			/* g: Expands to the "glob" portion of an *, ?, [] expansion.
 			 *    Given the filnames: a_text.txt, b_text.txt and c_text.txt,

tup.1

@@ -548,6 +548,9 @@ The name of the lowest level of the directory. For example, in foo/bar/Tupfile,
 .fi
 Using this macro in foo/bar/Tupfile would then create foo/bar/libbar.a
 .TP
+.B %D
+Like %f, but is just the directory part of the file path. The basename is stripped off. For example, "src/foo.c" would become "src/".
+.TP
 .B %g
 The string that a glob operator matched. For example with the files a_text.txt and b_text.txt, the rule:
 .nf