qatom: add a --format flag for controlling output

Rather than forcing people to deal with the ad-hoc output and run it
through another program to reassemble things, add a --format flag so
they can explicitly get the output hey care about.

This drops support for the letter field, but no one was really using
that in the first place.  If anyone does care, we can re-add it as a
new field.

This does change the output slightly from existing behavior: there
will be extra spaces between the latter fields, but this shouldn't
break existing programs as they generally split on whitespace.

1 files changed, 88 insertions, 16 deletions

diff --git a/qatom.c b/qatom.c
index f2c7ae4d..16445dd1 100644
--- a/qatom.c
+++ b/qatom.c
@@ -8,20 +8,104 @@
 
 #ifdef APPLET_qatom
 
-#define QATOM_FLAGS "c" COMMON_FLAGS
+#define QATOM_FORMAT "%{CATEGORY} %{PN} %{PV} %[PR] %[SLOT] %[pfx] %[sfx]"
+
+#define QATOM_FLAGS "F:c" COMMON_FLAGS
 static struct option const qatom_long_opts[] = {
+	{"format",     a_argument, NULL, 'F'},
 	{"compare",   no_argument, NULL, 'c'},
 	COMMON_LONG_OPTS
 };
 static const char * const qatom_opts_help[] = {
+	"Custom output format (default: " QATOM_FORMAT ")",
 	"Compare two atoms",
 	COMMON_OPTS_HELP
 };
 #define qatom_usage(ret) usage(ret, QATOM_FLAGS, qatom_long_opts, qatom_opts_help, lookup_applet_idx("qatom"))
 
+/* Run printf on an atom!  The format field takes the form:
+ *  %{keyword}: Always display the field that matches "keyword"
+ *  %[keyword]: Only display the field when it's valid (or pverbose)
+ * The possible "keywords" are:
+ *  CATEGORY  P  PN  PV  PVR  PF  PR  SLOT
+ *    - these are all the standard portage variables (so see ebuild(5))
+ *  pfx - the version qualifier if set (e.g. > < = !)
+ *  sfx - the version qualifier if set (e.g. *)
+ */
+_q_static
+void qatom_printf(const char *format, const depend_atom *atom, int pverbose)
+{
+	char bracket;
+	const char *fmt, *p;
+
+	if (!atom) {
+		printf("(NULL:atom)");
+		return;
+	}
+
+	p = format;
+	while (*p != '\0') {
+		fmt = strchr(p, '%');
+		if (fmt == NULL) {
+			printf("%s", p);
+			return;
+		} else if (fmt != p)
+			printf("%.*s", (int)(fmt - p), p);
+
+		bracket = fmt[1];
+		if (bracket == '{' || bracket == '[') {
+			fmt += 2;
+			p = strchr(fmt, bracket == '{' ? '}' : ']');
+			if (p) {
+				size_t len = p - fmt;
+				bool showit = (bracket == '{') || pverbose;
+				if (!strncmp("CATEGORY", fmt, len)) {
+					if (showit || atom->CATEGORY)
+						printf("%s", atom->CATEGORY);
+				} else if (!strncmp("P", fmt, len)) {
+					if (showit || atom->P)
+						printf("%s", atom->P);
+				} else if (!strncmp("PN", fmt, len)) {
+					if (showit || atom->PN)
+						printf("%s", atom->PN);
+				} else if (!strncmp("PV", fmt, len)) {
+					if (showit || atom->PV)
+						printf("%s", atom->PV);
+				} else if (!strncmp("PVR", fmt, len)) {
+					if (showit || atom->PVR)
+						printf("%s", atom->PVR);
+				} else if (!strncmp("PF", fmt, len)) {
+					printf("%s", atom->PN);
+					if (atom->PV)
+						printf("-%s", atom->PV);
+					if (atom->PR_int)
+						printf("-r%i", atom->PR_int);
+				} else if (!strncmp("PR", fmt, len)) {
+					if (showit || atom->PR_int)
+						printf("r%i", atom->PR_int);
+				} else if (!strncmp("SLOT", fmt, len)) {
+					if (showit || atom->SLOT)
+						printf(":%s", atom->SLOT ? : "-");
+				} else if (!strncmp("pfx", fmt, len)) {
+					if (showit || atom->pfx_op != ATOM_OP_NONE)
+						fputs(atom->pfx_op == ATOM_OP_NONE ? "-" : atom_op_str[atom->pfx_op], stdout);
+				} else if (!strncmp("sfx", fmt, len)) {
+					if (showit || atom->sfx_op != ATOM_OP_NONE)
+						fputs(atom->sfx_op == ATOM_OP_NONE ? "-" : atom_op_str[atom->sfx_op], stdout);
+				} else
+					printf("<BAD:%.*s>", (int)len, fmt);
+				++p;
+			} else
+				p = fmt + 1;
+		} else
+			++p;
+	}
+}
+
 int qatom_main(int argc, char **argv)
 {
 	enum qatom_atom { _EXPLODE=0, _COMPARE } action = _EXPLODE;
+	const char *format = QATOM_FORMAT;
 	depend_atom *atom;
 	int i;
 
@@ -30,6 +114,7 @@ int qatom_main(int argc, char **argv)
 
 	while ((i = GETOPT_LONG(QATOM, qatom, "")) != -1) {
 		switch (i) {
+		case 'F': format = optarg; break;
 		case 'c': action = _COMPARE; break;
 		COMMON_GETOPTS_CASES(qatom)
 		}
@@ -49,23 +134,10 @@ int qatom_main(int argc, char **argv)
 			break;
 		case _EXPLODE:
 			atom = atom_explode(argv[i]);
-			if (!atom) {
-				warnf("failed exploding atom %s", argv[i]);
-				continue;
-			}
-			printf("%s %s %s", atom->CATEGORY, atom->PN, atom->PV);
-			if (verbose || atom->PR_int)
-				printf(" r%i", atom->PR_int);
-			if (verbose || atom->SLOT)
-				printf(" :%s", atom->SLOT ? atom->SLOT : "-");
-			if (verbose || atom->pfx_op != ATOM_OP_NONE)
-				printf(" %s", atom->pfx_op == ATOM_OP_NONE ? "-" : atom_op_str[atom->pfx_op]);
-			if (verbose || atom->sfx_op != ATOM_OP_NONE)
-				printf(" %s", atom->sfx_op == ATOM_OP_NONE ? "-" : atom_op_str[atom->sfx_op]);
-			if (verbose > 1)
-				printf(" %c", (atom->letter ? : '-'));
+			qatom_printf(format, atom, verbose);
 			putchar('\n');
 			atom_implode(atom);
+			break;
 		}
 	}