Implement _experimental_output/2

src/builtin.c

@@ -1346,7 +1346,31 @@ 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"));
+
+  const char *name_str = jv_string_value(filename);
+  int sandbox = 0; // TODO: --sandbox
+  if (sandbox) {
+    fprintf(stderr, "jq: dry run: %s\n", name_str);
+  } else {
+    FILE *fp = fopen(name_str, "w");
+    if (!fp) {
+      fprintf(stderr, "jq: error: could not open %s\n", name_str);
+    } else {
+      if (jv_get_kind(data) == JV_KIND_STRING)
+        priv_fwrite(jv_string_value(jv_copy(data)), jv_string_length_bytes(jv_copy(data)), fp, 0);
+      else
+        jv_dumpf(jv_copy(data), fp, JV_PRINT_ASCII);
+      fclose(fp);
+    }
+  }
 
+  jv_free(filename);
+  jv_free(data);
+  return input;
+}
 static jv f_debug(jq_state *jq, jv input) {
   jq_msg_cb cb;
   void *data;
@@ -1856,6 +1880,7 @@ BINOPS
   {f_match, "_match_impl", 4},
   {f_modulemeta, "modulemeta", 1},
   {f_input, "input", 1},
+  {f_output, "_experimental_output", 3},
   {f_debug, "debug", 1},
   {f_stderr, "stderr", 1},
   {f_strptime, "strptime", 2},

tests/shtest

@@ -275,6 +275,22 @@ 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 $JQ -r 'to_entries[] | _experimental_output(.key;.value) | .key' >$d/keys
+{
+  "$d/a.json": "aaa",
+  "$d/b/b.json": "invalid",
+  "$d/c/c.json": ["not","valid"],
+  "$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