Support maps in JSON parsing and serialization.

This is a sync of our internal developing of JSON parsing and
serialization. It implements native understanding of MapEntry
submessages, so that map fields with (key, value) pairs are serialized
as JSON maps (objects) natively rather than as arrays of objects with
'key' and 'value' fields. The parser also now understands how to emit
handler calls corresponding to MapEntry objects when processing a map
field.

This sync also picks up a bugfix in `table.c` to handle an alloc-failed
case.

1 files changed, 34 insertions, 0 deletions

diff --git a/tests/test_def.c b/tests/test_def.c
index b85b031..800d685 100644
--- a/tests/test_def.c
+++ b/tests/test_def.c
@@ -344,6 +344,39 @@ static void test_descriptor_flags() {
   upb_msgdef_unref(m2, &m2);
 }
 
+static void test_mapentry_check() {
+  upb_status s = UPB_STATUS_INIT;
+
+  upb_msgdef *m = upb_msgdef_new(&m);
+  upb_msgdef_setfullname(m, "TestMessage", &s);
+  upb_fielddef *f = upb_fielddef_new(&f);
+  upb_fielddef_setname(f, "field1", &s);
+  upb_fielddef_setnumber(f, 1, &s);
+  upb_fielddef_setlabel(f, UPB_LABEL_OPTIONAL);
+  upb_fielddef_settype(f, UPB_TYPE_MESSAGE);
+  upb_fielddef_setsubdefname(f, ".MapEntry", &s);
+  upb_msgdef_addfield(m, f, &f, &s);
+  ASSERT(upb_ok(&s));
+
+  upb_msgdef *subm = upb_msgdef_new(&subm);
+  upb_msgdef_setfullname(subm, "MapEntry", &s);
+  upb_msgdef_setmapentry(subm, true);
+
+  upb_symtab *symtab = upb_symtab_new(&symtab);
+  upb_def *defs[] = {UPB_UPCAST(m), UPB_UPCAST(subm)};
+  upb_symtab_add(symtab, defs, 2, NULL, &s);
+  // Should not have succeeded: non-repeated field pointing to a MapEntry.
+  ASSERT(!upb_ok(&s));
+
+  upb_fielddef_setlabel(f, UPB_LABEL_REPEATED);
+  upb_symtab_add(symtab, defs, 2, NULL, &s);
+  ASSERT(upb_ok(&s));
+
+  upb_symtab_unref(symtab, &symtab);
+  upb_msgdef_unref(subm, &subm);
+  upb_msgdef_unref(m, &m);
+}
+
 static void test_oneofs() {
   upb_status s = UPB_STATUS_INIT;
   bool ok = true;
@@ -412,6 +445,7 @@ int run_tests(int argc, char *argv[]) {
   test_partial_freeze();
   test_noreftracking();
   test_descriptor_flags();
+  test_mapentry_check();
   test_oneofs();
   return 0;
 }