cli: implement limit flag

The new "-l" flag allows limiting the number of results getting printed.
This is useful for expressions which match many items when only the first
is desired.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

diff --git a/main.c b/main.c
index 2da2acf2944d469a39b4ea29a99b3b18469e58c8..0f1a39b30c507e5a775e6dfa538e74716645e165 100644 (file)
--- a/main.c
+++ b/main.c
@@ -126,7 +126,8 @@ print_separator(const char *sep, int *sc, int sl)
 }
 
 static void
-export_value(struct list_head *matches, const char *prefix, const char *sep)
+export_value(struct list_head *matches, const char *prefix, const char *sep,
+             int limit)
 {
        int n, len;
        int sc = 0, sl = strlen(sep);
@@ -141,6 +142,9 @@ export_value(struct list_head *matches, const char *prefix, const char *sep)
 
                list_for_each_entry(item, matches, list)
                {
+                       if (limit-- <= 0)
+                               break;
+
                        switch (json_object_get_type(item->jsobj))
                        {
                        case json_type_object:
@@ -195,6 +199,9 @@ export_value(struct list_head *matches, const char *prefix, const char *sep)
        {
                list_for_each_entry(item, matches, list)
                {
+                       if (limit-- <= 0)
+                               break;
+
                        switch (json_object_get_type(item->jsobj))
                        {
                        case json_type_object:
@@ -217,7 +224,7 @@ export_value(struct list_head *matches, const char *prefix, const char *sep)
 }
 
 static void
-export_type(struct list_head *matches, const char *prefix)
+export_type(struct list_head *matches, const char *prefix, int limit)
 {
        bool first = true;
        struct match_item *item;
@@ -242,6 +249,9 @@ export_type(struct list_head *matches, const char *prefix)
                if (!first)
                        printf("\\ ");
 
+               if (limit-- <= 0)
+                       break;
+
                printf("%s", types[json_object_get_type(item->jsobj)]);
                first = false;
        }
@@ -317,7 +327,8 @@ print_error(struct jp_state *state, char *expr)
 }
 
 static bool
-filter_json(int opt, struct json_object *jsobj, char *expr, const char *sep)
+filter_json(int opt, struct json_object *jsobj, char *expr, const char *sep,
+            int limit)
 {
        struct jp_state *state;
        const char *prefix = NULL;
@@ -346,11 +357,11 @@ filter_json(int opt, struct json_object *jsobj, char *expr, const char *sep)
        switch (opt)
        {
        case 't':
-               export_type(&matches, prefix);
+               export_type(&matches, prefix, limit);
                break;
 
        default:
-               export_value(&matches, prefix, sep);
+               export_value(&matches, prefix, sep, limit);
                break;
        }
 
@@ -366,12 +377,12 @@ out:
 
 int main(int argc, char **argv)
 {
-       int opt, rv = 0;
+       int opt, rv = 0, limit = 0x7FFFFFFF;
        FILE *input = stdin;
        struct json_object *jsobj = NULL;
        const char *jserr = NULL, *source = NULL, *separator = " ";
 
-       while ((opt = getopt(argc, argv, "i:s:e:t:F:q")) != -1)
+       while ((opt = getopt(argc, argv, "i:s:e:t:F:l:q")) != -1)
        {
                switch (opt)
                {
@@ -398,6 +409,10 @@ int main(int argc, char **argv)
                                separator = optarg;
                        break;
 
+               case 'l':
+                       limit = atoi(optarg);
+                       break;
+
                case 't':
                case 'e':
                        if (!jsobj)
@@ -414,7 +429,7 @@ int main(int argc, char **argv)
                                }
                        }
 
-                       if (!filter_json(opt, jsobj, optarg, separator))
+                       if (!filter_json(opt, jsobj, optarg, separator, limit))
                                rv = 1;
 
                        break;