TDD

src/builtin.c

@@ -1304,7 +1304,21 @@ static jv f_input(jq_state *jq, jv input) {
     return v;
   return jv_invalid_with_msg(jv_string("break"));
 }
-
+static jv f_output(jq_state *jq, jv input, jv filename, jv data) {
+  if (jv_get_kind(filename) != JV_KIND_STRING)
+    return ret_error(filename, jv_string("filename must be a string"));
+  FILE *fp = fopen(jv_string_value(filename), "w");
+  jv_free(filename);
+
+  if (fp) {
+    if (jv_get_kind(data) == JV_KIND_STRING)
+      priv_fwrite(jv_string_value(data), jv_string_length_bytes(jv_copy(data)), fp, 0);
+    else
+      jv_dumpf(data, fp, JV_PRINT_ASCII);
+    fclose(fp);
+  }
+  return input;
+}
 static jv f_debug(jq_state *jq, jv input) {
   jq_msg_cb cb;
   void *data;
@@ -1816,6 +1830,7 @@ BINOPS
   {f_match, "_match_impl", 4},
   {f_modulemeta, "modulemeta", 1},
   {f_input, "input", 1},
+  {f_output, "_experiment_output", 3},
   {f_debug, "debug", 1},
   {f_stderr, "stderr", 1},
   {f_strptime, "strptime", 2},

tests/shtest

@@ -275,6 +275,21 @@ grep "Expected string key after '{', not '\\['" $d/err > /dev/null
 echo '{"x":"y",["a","b"]}' | $JQ --stream > /dev/null 2> $d/err || true
 grep "Expected string key after ',' in object, not '\\['" $d/err > /dev/null
 
+## Test IO
+
+# output
+cat <<EOF | $VALGRIND $Q $JQ -r 'to_entries[] | _experiment_output(.key;.value) | .key' >$d/keys
+{
+  "$d/a.json": "aaa",
+  "$d/b/c.json": "invalid",
+  "$d/d.json": {"e":10},
+  "$d/f.json": 8
+}
+EOF
+cat $(cat $d/keys) > $d/out || true
+printf 'aaa{"e":10}8' > $d/expected
+cmp $d/out $d/expected
+
 # debug, stderr
 $VALGRIND $Q $JQ -n '"test", {} | debug, stderr' >/dev/null
 $JQ -n -c -j '"hello\nworld", null, [false, 0], {"foo":["bar"]}, "\n" | stderr' >$d/out 2>$d/err