Merge branch 'arrayapi' into defcleanup

8 files changed, 1470 insertions, 101 deletions

diff --git a/tests/pb/test_decoder.cc b/tests/pb/test_decoder.cc
index 8012405..7450445 100644
--- a/tests/pb/test_decoder.cc
+++ b/tests/pb/test_decoder.cc
@@ -980,7 +980,7 @@ void test_valid() {
       LINE("%u:{")
       LINE("  <")
       LINE("  %u:(5)\"abcde")
-      LINE("  %u:\"")
+      LINE("    %u:\"")
       LINE("  >")
       LINE("}")
       LINE(">"), msg_fn, UPB_DESCRIPTOR_TYPE_STRING,
diff --git a/tools/dump_cinit.lua b/tools/dump_cinit.lua
new file mode 100644
index 0000000..34d6ac6
--- /dev/null
+++ b/tools/dump_cinit.lua
@@ -0,0 +1,751 @@
+--[[
+
+  Routines for dumping internal data structures into C initializers
+  that can be compiled into a .o file.
+
+--]]
+
+local upbtable = require "upb.table"
+local upb = require "upb"
+local export = {}
+
+-- A tiny little abstraction that decouples the dump_* functions from
+-- what they're writing to (appending to a string, writing to file I/O, etc).
+-- This could possibly matter since naive string building is O(n^2) in the
+-- number of appends.
+function export.str_appender()
+  local str = ""
+  local function append(fmt, ...)
+    str = str .. string.format(fmt, ...)
+  end
+  local function get()
+    return str
+  end
+  return append, get
+end
+
+function export.file_appender(file)
+  local f = file
+  local function append(fmt, ...)
+    f:write(string.format(fmt, ...))
+  end
+  return append
+end
+
+function handler_types(base)
+  local ret = {}
+  for k, _ in pairs(base) do
+    if string.find(k, "^" .. "HANDLER_") then
+      ret[#ret + 1] = k
+    end
+  end
+  return ret
+end
+
+function octchar(num)
+  assert(num < 8)
+  local idx = num + 1  -- 1-based index
+  return string.sub("01234567", idx, idx)
+end
+
+function c_escape(num)
+  assert(num < 256)
+  return string.format("\\%s%s%s",
+                       octchar(math.floor(num / 64)),
+                       octchar(math.floor(num / 8) % 8),
+                       octchar(num % 8));
+end
+
+-- const(f, label) -> UPB_LABEL_REPEATED, where f:label() == upb.LABEL_REPEATED
+function const(obj, name, base)
+  local val = obj[name]
+  base = base or upb
+
+  -- Support both f:label() and f.label.
+  if type(val) == "function" then
+    val = val(obj)
+  end
+
+  for k, v in pairs(base) do
+    if v == val and string.find(k, "^" .. string.upper(name)) then
+      return "UPB_" .. k
+    end
+  end
+  assert(false, "Couldn't find UPB_" .. string.upper(name) ..
+                " constant for value: " .. val)
+end
+
+function sortedkeys(tab)
+  arr = {}
+  for key in pairs(tab) do
+    arr[#arr + 1] = key
+  end
+  table.sort(arr)
+  return arr
+end
+
+function sorted_defs(defs)
+  local sorted = {}
+
+  for def in defs do
+    if def.type == deftype then
+      sorted[#sorted + 1] = def
+    end
+  end
+
+  table.sort(sorted,
+             function(a, b) return a:full_name() < b:full_name() end)
+
+  return sorted
+end
+
+function constlist(pattern)
+  local ret = {}
+  for k, v in pairs(upb) do
+    if string.find(k, "^" .. pattern) then
+      ret[k] = v
+    end
+  end
+  return ret
+end
+
+function boolstr(val)
+  if val == true then
+    return "true"
+  elseif val == false then
+    return "false"
+  else
+    assert(false, "Bad bool value: " .. tostring(val))
+  end
+end
+
+--[[
+
+  LinkTable: an object that tracks all linkable objects and their offsets to
+  facilitate linking.
+
+--]]
+
+local LinkTable = {}
+function LinkTable:new(types)
+  local linktab = {
+    types = types,
+    table = {},  -- ptr -> {type, 0-based offset}
+    obj_arrays = {}  -- Establishes the ordering for each object type
+  }
+  for type, _ in pairs(types) do
+    linktab.obj_arrays[type] = {}
+  end
+  setmetatable(linktab, {__index = LinkTable})  -- Inheritance
+  return linktab
+end
+
+-- Adds a new object to the sequence of objects of this type.
+function LinkTable:add(objtype, ptr, obj)
+  obj = obj or ptr
+  assert(self.table[obj] == nil)
+  assert(self.types[objtype])
+  local arr = self.obj_arrays[objtype]
+  self.table[ptr] = {objtype, #arr}
+  arr[#arr + 1] = obj
+end
+
+-- Returns a C symbol name for the given objtype and offset.
+function LinkTable:csym(objtype, offset)
+  local typestr = assert(self.types[objtype])
+  return string.format("%s[%d]", typestr, offset)
+end
+
+-- Returns the address of the given C object.
+function LinkTable:addr(obj)
+  if obj == upbtable.NULL then
+    return "NULL"
+  else
+    local tabent = assert(self.table[obj], "unknown object: " .. tostring(obj))
+    return "&" .. self:csym(tabent[1], tabent[2])
+  end
+end
+
+-- Returns an array declarator indicating how many objects have been added.
+function LinkTable:cdecl(objtype)
+  return self:csym(objtype, #self.obj_arrays[objtype])
+end
+
+function LinkTable:objs(objtype)
+  -- Return iterator function, allowing use as:
+  --   for obj in linktable:objs(type) do
+  --     -- ...
+  --   done
+  local array = self.obj_arrays[objtype]
+  local i = 0
+  return function()
+    i = i + 1
+    if array[i] then return array[i] end
+  end
+end
+
+function LinkTable:empty(objtype)
+  return #self.obj_arrays[objtype] == 0
+end
+
+--[[
+
+  Dumper: an object that can dump C initializers for several constructs.
+  Uses a LinkTable to resolve references when necessary.
+
+--]]
+
+local Dumper = {}
+function Dumper:new(linktab)
+  local obj = {linktab = linktab}
+  setmetatable(obj, {__index = Dumper})  -- Inheritance
+  return obj
+end
+
+-- Dumps a upb_tabval, eg:
+--   UPB_TABVALUE_INIT(5)
+function Dumper:_value(val, upbtype)
+  if type(val) == "nil" then
+    return "UPB_TABVALUE_EMPTY_INIT"
+  elseif type(val) == "number" then
+    -- Use upbtype to disambiguate what kind of number it is.
+    if upbtype == upbtable.CTYPE_INT32 then
+      return string.format("UPB_TABVALUE_INT_INIT(%d)", val)
+    else
+      -- TODO(haberman): add support for these so we can properly support
+      -- default values.
+      error("Unsupported number type " .. upbtype)
+    end
+  elseif type(val) == "string" then
+    return string.format('UPB_TABVALUE_PTR_INIT("%s")', val)
+  else
+    -- We take this as an object reference that has an entry in the link table.
+    return string.format("UPB_TABVALUE_PTR_INIT(%s)", self.linktab:addr(val))
+  end
+end
+
+-- Dumps a table key.
+function Dumper:tabkey(key)
+  if type(key) == "nil" then
+    return "UPB_TABKEY_NONE"
+  elseif type(key) == "string" then
+    local len = #key
+    local len1 = c_escape(len % 256)
+    local len2 = c_escape(math.floor(len / 256) % 256)
+    local len3 = c_escape(math.floor(len / (256 * 256)) % 256)
+    local len4 = c_escape(math.floor(len / (256 * 256 * 256)) % 256)
+    return string.format('UPB_TABKEY_STR("%s", "%s", "%s", "%s", "%s")',
+                         len1, len2, len3, len4, key)
+  else
+    return string.format("UPB_TABKEY_NUM(%d)", key)
+  end
+end
+
+-- Dumps a table entry.
+function Dumper:tabent(ent)
+  local key = self:tabkey(ent.key)
+  local val = self:_value(ent.value, ent.valtype)
+  local next = self.linktab:addr(ent.next)
+  return string.format('  {%s, %s, %s},\n', key, val, next)
+end
+
+-- Dumps an inttable array entry.  This is almost the same as value() above,
+-- except that nil values have a special value to indicate "empty".
+function Dumper:arrayval(val)
+  if val.val then
+    return string.format("  %s,\n", self:_value(val.val, val.valtype))
+  else
+    return "  UPB_TABVALUE_EMPTY_INIT,\n"
+  end
+end
+
+-- Dumps an initializer for the given strtable/inttable (respectively).  Its
+-- entries must have previously been added to the linktable.
+function Dumper:strtable(t)
+  -- UPB_STRTABLE_INIT(count, mask, type, size_lg2, entries)
+  return string.format(
+      "UPB_STRTABLE_INIT(%d, %d, %s, %d, %s)",
+      t.count, t.mask, const(t, "ctype", upbtable) , t.size_lg2,
+      self.linktab:addr(t.entries[1].ptr))
+end
+
+function Dumper:inttable(t)
+  local lt = assert(self.linktab)
+  -- UPB_INTTABLE_INIT(count, mask, type, size_lg2, ent, a, asize, acount)
+  local entries = "NULL"
+  if #t.entries > 0 then
+    entries = lt:addr(t.entries[1].ptr)
+  end
+  return string.format(
+      "UPB_INTTABLE_INIT(%d, %d, %s, %d, %s, %s, %d, %d)",
+      t.count, t.mask, const(t, "ctype", upbtable), t.size_lg2, entries,
+      lt:addr(t.array[1].ptr), t.array_size, t.array_count)
+end
+
+-- A visitor for visiting all tables of a def.  Used first to count entries
+-- and later to dump them.
+local function gettables(def)
+  if def:def_type() == upb.DEF_MSG then
+    return {int = upbtable.msgdef_itof(def), str = upbtable.msgdef_ntof(def)}
+  elseif def:def_type() == upb.DEF_ENUM then
+    return {int = upbtable.enumdef_iton(def), str = upbtable.enumdef_ntoi(def)}
+  end
+end
+
+local function emit_file_warning(filedef, append)
+  append('/* This file was generated by upbc (the upb compiler) from the input\n')
+  append(' * file:\n')
+  append(' *\n')
+  append(' *     %s\n', filedef:name())
+  append(' *\n')
+  append(' * Do not edit -- your changes will be discarded when the file is\n')
+  append(' * regenerated. */\n\n')
+end
+
+local function join(...)
+  return table.concat({...}, ".")
+end
+
+local function split(str)
+  local ret = {}
+  for word in string.gmatch(str, "%w+") do
+    table.insert(ret, word)
+  end
+  return ret
+end
+
+local function to_cident(...)
+  return string.gsub(join(...), "[%./]", "_")
+end
+
+local function to_preproc(...)
+  return string.upper(to_cident(...))
+end
+
+-- Strips away last path element, ie:
+--   foo.Bar.Baz -> foo.Bar
+local function remove_name(name)
+  local package_end = 0
+  for i=1,string.len(name) do
+    if string.byte(name, i) == string.byte(".", 1) then
+      package_end = i - 1
+    end
+  end
+  return string.sub(name, 1, package_end)
+end
+
+local function start_namespace(package, append)
+  local package_components = split(package)
+  for _, component in ipairs(package_components) do
+    append("namespace %s {\n", component)
+  end
+end
+
+local function end_namespace(package, append)
+  local package_components = split(package)
+  for i=#package_components,1,-1 do
+    append("}  /* namespace %s */\n", package_components[i])
+  end
+end
+
+local function well_known_type(m)
+  local type_map = {}
+  type_map["google.protobuf.Any"]         = "UPB_WELLKNOWN_ANY"
+  type_map["google.protobuf.FieldMask"]   = "UPB_WELLKNOWN_FIELDMASK"
+  type_map["google.protobuf.Duration"]    = "UPB_WELLKNOWN_DURATION"
+  type_map["google.protobuf.Timestamp"]   = "UPB_WELLKNOWN_TIMESTAMP"
+  type_map["google.protobuf.Value"]       = "UPB_WELLKNOWN_VALUE"
+  type_map["google.protobuf.ListValue"]   = "UPB_WELLKNOWN_LISTVALUE"
+  type_map["google.protobuf.Struct"]      = "UPB_WELLKNOWN_STRUCT"
+  type_map["google.protobuf.DoubleValue"] = "UPB_WELLKNOWN_DOUBLEVALUE"
+  type_map["google.protobuf.FloatValue"]  = "UPB_WELLKNOWN_FLOATVALUE"
+  type_map["google.protobuf.Int64Value"]  = "UPB_WELLKNOWN_INT64VALUE"
+  type_map["google.protobuf.UInt64Value"] = "UPB_WELLKNOWN_UINT64VALUE"
+  type_map["google.protobuf.Int32Value"]  = "UPB_WELLKNOWN_INT32VALUE"
+  type_map["google.protobuf.UInt32Value"] = "UPB_WELLKNOWN_UINT32VALUE"
+  type_map["google.protobuf.BoolValue"]   = "UPB_WELLKNOWN_BOOLVALUE"
+  type_map["google.protobuf.StringValue"] = "UPB_WELLKNOWN_STRINGVALUE"
+  type_map["google.protobuf.BytesValue"]  = "UPB_WELLKNOWN_BYTESVALUE"
+  local t = type_map[m:full_name()]
+  if (t == nil) then
+    t = "UPB_WELLKNOWN_UNSPECIFIED"
+  end
+  return t
+end
+
+--[[
+
+  Top-level, exported dumper functions
+
+--]]
+
+local function dump_defs_c(filedef, append)
+  local defs = {}
+  for def in filedef:defs(upb.DEF_ANY) do
+    defs[#defs + 1] = def
+    if (def:def_type() == upb.DEF_MSG) then
+      for field in def:fields() do
+        defs[#defs + 1] = field
+      end
+    end
+  end
+
+  -- Sort all defs by (type, name).
+  -- This gives us a linear ordering that we can use to create offsets into
+  -- shared arrays like REFTABLES, hash table entries, and arrays.
+  table.sort(defs, function(a, b)
+    if a:def_type() ~= b:def_type() then
+      return a:def_type() < b:def_type()
+    else
+      return a:full_name() < b:full_name() end
+    end
+  )
+
+  -- Perform pre-pass to build the link table.
+  local linktab = LinkTable:new{
+    [upb.DEF_MSG] = "msgs",
+    [upb.DEF_FIELD] = "fields",
+    [upb.DEF_ENUM] = "enums",
+    intentries = "intentries",
+    strentries = "strentries",
+    arrays = "arrays",
+  }
+  local reftable_count = 0
+
+  for _, def in ipairs(defs) do
+    assert(def:is_frozen(), "can only dump frozen defs.")
+    linktab:add(def:def_type(), def)
+    reftable_count = reftable_count + 2
+    local tables = gettables(def)
+    if tables then
+      for _, e in ipairs(tables.str.entries) do
+        linktab:add("strentries", e.ptr, e)
+      end
+      for _, e in ipairs(tables.int.entries) do
+        linktab:add("intentries", e.ptr, e)
+      end
+      for _, e in ipairs(tables.int.array) do
+        linktab:add("arrays", e.ptr, e)
+      end
+    end
+  end
+
+  -- Emit forward declarations.
+  emit_file_warning(filedef, append)
+  append('#include "upb/def.h"\n')
+  append('#include "upb/structdefs.int.h"\n\n')
+  append("static const upb_msgdef %s;\n", linktab:cdecl(upb.DEF_MSG))
+  append("static const upb_fielddef %s;\n", linktab:cdecl(upb.DEF_FIELD))
+  if not linktab:empty(upb.DEF_ENUM) then
+    append("static const upb_enumdef %s;\n", linktab:cdecl(upb.DEF_ENUM))
+  end
+  append("static const upb_tabent %s;\n", linktab:cdecl("strentries"))
+  if not linktab:empty("intentries") then
+    append("static const upb_tabent %s;\n", linktab:cdecl("intentries"))
+  end
+  append("static const upb_tabval %s;\n", linktab:cdecl("arrays"))
+  append("\n")
+  append("#ifdef UPB_DEBUG_REFS\n")
+  append("static upb_inttable reftables[%d];\n", reftable_count)
+  append("#endif\n")
+  append("\n")
+
+  -- Emit defs.
+  local dumper = Dumper:new(linktab)
+
+  local reftable = 0
+
+  append("static const upb_msgdef %s = {\n", linktab:cdecl(upb.DEF_MSG))
+  for m in linktab:objs(upb.DEF_MSG) do
+    local tables = gettables(m)
+    -- UPB_MSGDEF_INIT(name, selector_count, submsg_field_count, itof, ntof,
+    --                 refs, ref2s)
+    append('  UPB_MSGDEF_INIT("%s", %d, %d, %s, %s, %s, %s, %s,' ..
+           ' &reftables[%d], &reftables[%d]),\n',
+           m:full_name(),
+           upbtable.msgdef_selector_count(m),
+           upbtable.msgdef_submsg_field_count(m),
+           dumper:inttable(tables.int),
+           dumper:strtable(tables.str),
+           boolstr(m:_map_entry()),
+           const(m, "syntax"),
+           well_known_type(m),
+           reftable, reftable + 1)
+    reftable = reftable + 2
+  end
+  append("};\n\n")
+
+  append("static const upb_fielddef %s = {\n", linktab:cdecl(upb.DEF_FIELD))
+  for f in linktab:objs(upb.DEF_FIELD) do
+    local subdef = "NULL"
+    if f:has_subdef() then
+      subdef = string.format("(const upb_def*)(%s)", linktab:addr(f:subdef()))
+    end
+    local intfmt
+    if f:type() == upb.TYPE_UINT32 or
+       f:type() == upb.TYPE_INT32 or
+       f:type() == upb.TYPE_UINT64 or
+       f:type() == upb.TYPE_INT64 then
+      intfmt = const(f, "intfmt")
+    else
+      intfmt = "0"
+    end
+    -- UPB_FIELDDEF_INIT(label, type, intfmt, tagdelim, is_extension, lazy,
+    --                   packed, name, num, msgdef, subdef, selector_base,
+    --                   index, --                   default_value)
+    append('  UPB_FIELDDEF_INIT(%s, %s, %s, %s, %s, %s, %s, "%s", %d, %s, ' ..
+           '%s, %d, %d, {0},' .. -- TODO: support default value
+           '&reftables[%d], &reftables[%d]),\n',
+           const(f, "label"), const(f, "type"), intfmt,
+           boolstr(f:istagdelim()), boolstr(f:is_extension()),
+           boolstr(f:lazy()), boolstr(f:packed()), f:name(), f:number(),
+           linktab:addr(f:containing_type()), subdef,
+           upbtable.fielddef_selector_base(f), f:index(),
+           reftable, reftable + 1
+           )
+    reftable = reftable + 2
+  end
+  append("};\n\n")
+
+  if not linktab:empty(upb.DEF_ENUM) then
+    append("static const upb_enumdef %s = {\n", linktab:cdecl(upb.DEF_ENUM))
+    for e in linktab:objs(upb.DEF_ENUM) do
+      local tables = gettables(e)
+      -- UPB_ENUMDEF_INIT(name, ntoi, iton, defaultval)
+      append('  UPB_ENUMDEF_INIT("%s", %s, %s, %d, ' ..
+             '&reftables[%d], &reftables[%d]),\n',
+             e:full_name(),
+             dumper:strtable(tables.str),
+             dumper:inttable(tables.int),
+             --e:default())
+             0,
+             reftable, reftable + 1)
+      reftable = reftable + 2
+    end
+    append("};\n\n")
+  end
+
+  append("static const upb_tabent %s = {\n", linktab:cdecl("strentries"))
+  for ent in linktab:objs("strentries") do
+    append(dumper:tabent(ent))
+  end
+  append("};\n\n");
+
+  if not linktab:empty("intentries") then
+    append("static const upb_tabent %s = {\n", linktab:cdecl("intentries"))
+    for ent in linktab:objs("intentries") do
+      append(dumper:tabent(ent))
+    end
+    append("};\n\n");
+  end
+
+  append("static const upb_tabval %s = {\n", linktab:cdecl("arrays"))
+  for ent in linktab:objs("arrays") do
+    append(dumper:arrayval(ent))
+  end
+  append("};\n\n");
+
+  append("#ifdef UPB_DEBUG_REFS\n")
+  append("static upb_inttable reftables[%d] = {\n", reftable_count)
+  for i = 1,reftable_count do
+    append("  UPB_EMPTY_INTTABLE_INIT(UPB_CTYPE_PTR),\n")
+  end
+  append("};\n")
+  append("#endif\n\n")
+
+  append("static const upb_msgdef *refm(const upb_msgdef *m, const void *owner) {\n")
+  append("  upb_msgdef_ref(m, owner);\n")
+  append("  return m;\n")
+  append("}\n\n")
+  append("static const upb_enumdef *refe(const upb_enumdef *e, const void *owner) {\n")
+  append("  upb_enumdef_ref(e, owner);\n")
+  append("  return e;\n")
+  append("}\n\n")
+
+  append("/* Public API. */\n")
+
+  for m in linktab:objs(upb.DEF_MSG) do
+    append("const upb_msgdef *upbdefs_%s_get(const void *owner)" ..
+           " { return refm(%s, owner); }\n",
+           to_cident(m:full_name()), linktab:addr(m))
+  end
+
+  append("\n")
+
+  for e in linktab:objs(upb.DEF_ENUM) do
+    append("const upb_enumdef *upbdefs_%s_get(const void *owner)" ..
+           " { return refe(%s, owner); }\n",
+           to_cident(e:full_name()), linktab:addr(e))
+  end
+
+  return linktab
+end
+
+local function dump_defs_for_type(format, defs, append)
+  local sorted = sorted_defs(defs)
+  for _, def in ipairs(sorted) do
+    append(format, to_cident(def:full_name()), def:full_name())
+  end
+
+  append("\n")
+end
+
+local function make_children_map(file)
+  -- Maps file:package() or msg:full_name() -> children.
+  local map = {}
+  for def in file:defs(upb.DEF_ANY) do
+    local container = remove_name(def:full_name())
+    if not map[container] then
+      map[container] = {}
+    end
+    table.insert(map[container], def)
+  end
+
+  -- Sort all the lists for a consistent ordering.
+  for name, children in pairs(map) do
+    table.sort(children, function(a, b) return a:name() < b:name() end)
+  end
+
+  return map
+end
+
+local print_classes
+
+local function print_message(def, map, indent, append)
+  append("\n")
+  append("%sclass %s : public ::upb::reffed_ptr<const ::upb::MessageDef> {\n",
+         indent, def:name())
+  append("%s public:\n", indent)
+  append("%s  %s(const ::upb::MessageDef* m, const void *ref_donor = NULL)\n",
+         indent, def:name())
+  append("%s      : reffed_ptr(m, ref_donor) {\n", indent)
+  append("%s    UPB_ASSERT(upbdefs_%s_is(m));\n", indent, to_cident(def:full_name()))
+  append("%s  }\n", indent)
+  append("\n")
+  append("%s  static %s get() {\n", indent, def:name())
+  append("%s    const ::upb::MessageDef* m = upbdefs_%s_get(&m);\n", indent, to_cident(def:full_name()))
+  append("%s    return %s(m, &m);\n", indent, def:name())
+  append("%s  }\n", indent)
+  -- TODO(haberman): add fields
+  print_classes(def:full_name(), map, indent .. "  ", append)
+  append("%s};\n", indent)
+end
+
+local function print_enum(def, indent, append)
+  append("\n")
+  append("%sclass %s : public ::upb::reffed_ptr<const ::upb::EnumDef> {\n",
+         indent, def:name())
+  append("%s public:\n", indent)
+  append("%s  %s(const ::upb::EnumDef* e, const void *ref_donor = NULL)\n",
+         indent, def:name())
+  append("%s      : reffed_ptr(e, ref_donor) {\n", indent)
+  append("%s    UPB_ASSERT(upbdefs_%s_is(e));\n", indent, to_cident(def:full_name()))
+  append("%s  }\n", indent)
+  append("%s  static %s get() {\n", indent, def:name())
+  append("%s    const ::upb::EnumDef* e = upbdefs_%s_get(&e);\n", indent, to_cident(def:full_name()))
+  append("%s    return %s(e, &e);\n", indent, def:name())
+  append("%s  }\n", indent)
+  append("%s};\n", indent)
+end
+
+function print_classes(name, map, indent, append)
+  if not map[name] then
+    return
+  end
+
+  for _, def in ipairs(map[name]) do
+    if def:def_type() == upb.DEF_MSG then
+      print_message(def, map, indent, append)
+    elseif def:def_type() == upb.DEF_ENUM then
+      print_enum(def, indent, append)
+    else
+      error("Unknown def type for " .. def:full_name())
+    end
+  end
+end
+
+local function dump_defs_h(file, append, linktab)
+  local basename_preproc = to_preproc(file:name())
+  append("/* This file contains accessors for a set of compiled-in defs.\n")
+  append(" * Note that unlike Google's protobuf, it does *not* define\n")
+  append(" * generated classes or any other kind of data structure for\n")
+  append(" * actually storing protobufs.  It only contains *defs* which\n")
+  append(" * let you reflect over a protobuf *schema*.\n")
+  append(" */\n")
+  emit_file_warning(file, append)
+  append('#ifndef %s_UPB_H_\n', basename_preproc)
+  append('#define %s_UPB_H_\n\n', basename_preproc)
+  append('#include "upb/def.h"\n\n')
+  append('UPB_BEGIN_EXTERN_C\n\n')
+
+  -- Dump C enums for proto enums.
+
+  append("/* MessageDefs: call these functions to get a ref to a msgdef. */\n")
+  dump_defs_for_type(
+      "const upb_msgdef *upbdefs_%s_get(const void *owner);\n",
+      file:defs(upb.DEF_MSG), append)
+
+  append("/* EnumDefs: call these functions to get a ref to an enumdef. */\n")
+  dump_defs_for_type(
+      "const upb_enumdef *upbdefs_%s_get(const void *owner);\n",
+      file:defs(upb.DEF_ENUM), append)
+
+  append("/* Functions to test whether this message is of a certain type. */\n")
+  dump_defs_for_type(
+      "UPB_INLINE bool upbdefs_%s_is(const upb_msgdef *m) {\n" ..
+      "  return strcmp(upb_msgdef_fullname(m), \"%s\") == 0;\n}\n",
+      file:defs(upb.DEF_MSG), append)
+
+  append("/* Functions to test whether this enum is of a certain type. */\n")
+  dump_defs_for_type(
+      "UPB_INLINE bool upbdefs_%s_is(const upb_enumdef *e) {\n" ..
+      "  return strcmp(upb_enumdef_fullname(e), \"%s\") == 0;\n}\n",
+      file:defs(upb.DEF_ENUM), append)
+
+  append("\n")
+
+  -- fields
+  local fields = {}
+
+  for f in linktab:objs(upb.DEF_FIELD) do
+    local symname = f:containing_type():full_name() .. "." .. f:name()
+    fields[#fields + 1] = {to_cident(symname), f}
+  end
+
+  table.sort(fields, function(a, b) return a[1] < b[1] end)
+
+  append("/* Functions to get a fielddef from a msgdef reference. */\n")
+  for _, field in ipairs(fields) do
+    local f = field[2]
+    local msg_cident = to_cident(f:containing_type():full_name())
+    local field_cident = to_cident(f:name())
+    append("UPB_INLINE const upb_fielddef *upbdefs_%s_f_%s(const upb_msgdef *m) {" ..
+           " UPB_ASSERT(upbdefs_%s_is(m));" ..
+           " return upb_msgdef_itof(m, %d); }\n",
+           msg_cident, field_cident, msg_cident, f:number())
+  end
+
+  append('\nUPB_END_EXTERN_C\n\n')
+
+  -- C++ wrappers.
+  local children_map = make_children_map(file)
+
+  append("#ifdef __cplusplus\n\n")
+  append("namespace upbdefs {\n")
+  start_namespace(file:package(), append)
+  print_classes(file:package(), children_map, "", append)
+  append("\n")
+  end_namespace(file:package(), append)
+  append("}  /* namespace upbdefs */\n\n")
+  append("#endif  /* __cplusplus */\n")
+
+  append("\n")
+  append('#endif  /* %s_UPB_H_ */\n', basename_preproc)
+end
+
+function export.dump_defs(filedef, append_h, append_c)
+  local linktab = dump_defs_c(filedef, append_c)
+  dump_defs_h(filedef, append_h, linktab)
+end
+
+return export
diff --git a/upb/def.c b/upb/def.c
index 4a893d1..5b239dd 100644
--- a/upb/def.c
+++ b/upb/def.c
@@ -311,6 +311,8 @@ static void assign_msg_wellknowntype(upb_msgdef *m) {
   }
   if (!strcmp(name, "google.protobuf.Any")) {
     m->well_known_type = UPB_WELLKNOWN_ANY;
+  } else if (!strcmp(name, "google.protobuf.FieldMask")) {
+    m->well_known_type = UPB_WELLKNOWN_FIELDMASK;
   } else if (!strcmp(name, "google.protobuf.Duration")) {
     m->well_known_type = UPB_WELLKNOWN_DURATION;
   } else if (!strcmp(name, "google.protobuf.Timestamp")) {
diff --git a/upb/json/parser.c b/upb/json/parser.c
index 70ebfcf..38a0535 100644
--- a/upb/json/parser.c
+++ b/upb/json/parser.c
@@ -63,6 +63,12 @@ static bool is_string_wrapper_object(upb_json_parser *p);
 static bool does_string_wrapper_start(upb_json_parser *p);
 static bool does_string_wrapper_end(upb_json_parser *p);
 
+static bool is_fieldmask_object(upb_json_parser *p);
+static bool does_fieldmask_start(upb_json_parser *p);
+static bool does_fieldmask_end(upb_json_parser *p);
+static void start_fieldmask_object(upb_json_parser *p);
+static void end_fieldmask_object(upb_json_parser *p);
+
 static void start_wrapper_object(upb_json_parser *p);
 static void end_wrapper_object(upb_json_parser *p);
 
@@ -1164,6 +1170,9 @@ static bool start_stringval(upb_json_parser *p) {
   if (is_top_level(p)) {
     if (is_string_wrapper_object(p)) {
       start_wrapper_object(p);
+    } else if (is_wellknown_msg(p, UPB_WELLKNOWN_FIELDMASK)) {
+      start_fieldmask_object(p);
+      return true;
     } else if (is_wellknown_msg(p, UPB_WELLKNOWN_TIMESTAMP) ||
                is_wellknown_msg(p, UPB_WELLKNOWN_DURATION)) {
       start_object(p);
@@ -1177,6 +1186,12 @@ static bool start_stringval(upb_json_parser *p) {
       return false;
     }
     start_wrapper_object(p);
+  } else if (does_fieldmask_start(p)) {
+    if (!start_subobject(p)) {
+      return false;
+    }
+    start_fieldmask_object(p);
+    return true;
   } else if (is_wellknown_field(p, UPB_WELLKNOWN_TIMESTAMP) ||
              is_wellknown_field(p, UPB_WELLKNOWN_DURATION)) {
     if (!start_subobject(p)) {
@@ -1317,8 +1332,13 @@ static bool end_stringval_nontop(upb_json_parser *p) {
 
     case UPB_TYPE_STRING: {
       upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
+<<<<<<< HEAD
       p->top--;
       upb_sink_endstr(p->top->sink, sel);
+=======
+      upb_sink_endstr(&p->top->sink, sel);
+      p->top--;
+>>>>>>> arrayapi
       break;
     }
 
@@ -1364,6 +1384,16 @@ static bool end_stringval_nontop(upb_json_parser *p) {
 }
 
 static bool end_stringval(upb_json_parser *p) {
+  /* FieldMask's stringvals have been ended when handling them. Only need to
+   * close FieldMask here.*/
+  if (does_fieldmask_end(p)) {
+    end_fieldmask_object(p);
+    if (!is_top_level(p)) {
+      end_subobject(p);
+    }
+    return true;
+  }
+
   if (!end_stringval_nontop(p)) {
     return false;
   }
@@ -1385,7 +1415,8 @@ static bool end_stringval(upb_json_parser *p) {
   }
 
   if (is_wellknown_msg(p, UPB_WELLKNOWN_TIMESTAMP) ||
-      is_wellknown_msg(p, UPB_WELLKNOWN_DURATION)) {
+      is_wellknown_msg(p, UPB_WELLKNOWN_DURATION) ||
+      is_wellknown_msg(p, UPB_WELLKNOWN_FIELDMASK)) {
     end_object(p);
     if (!is_top_level(p)) {
       end_subobject(p);
@@ -1639,6 +1670,75 @@ static bool end_timestamp_zone(upb_json_parser *p, const char *ptr) {
   return true;
 }
 
+static void start_fieldmask_path_text(upb_json_parser *p, const char *ptr) {
+  capture_begin(p, ptr);
+}
+
+static bool end_fieldmask_path_text(upb_json_parser *p, const char *ptr) {
+  if (!capture_end(p, ptr)) {
+    return false;
+  }
+}
+
+static bool start_fieldmask_path(upb_json_parser *p) {
+  upb_jsonparser_frame *inner;
+  upb_selector_t sel;
+
+  if (!check_stack(p)) return false;
+
+  /* Start a new parser frame: parser frames correspond one-to-one with
+   * handler frames, and string events occur in a sub-frame. */
+  inner = p->top + 1;
+  sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSTR);
+  upb_sink_startstr(&p->top->sink, sel, 0, &inner->sink);
+  inner->m = p->top->m;
+  inner->f = p->top->f;
+  inner->name_table = NULL;
+  inner->is_map = false;
+  inner->is_mapentry = false;
+  inner->is_any = false;
+  inner->any_frame = NULL;
+  inner->is_unknown_field = false;
+  p->top = inner;
+
+  multipart_startaccum(p);
+  return true;
+}
+
+static bool lower_camel_push(
+    upb_json_parser *p, upb_selector_t sel, const char *ptr, size_t len) {
+  const char *limit = ptr + len;
+  bool first = true;
+  for (;ptr < limit; ptr++) {
+    if (*ptr >= 'A' && *ptr <= 'Z' && !first) {
+      char lower = tolower(*ptr);
+      upb_sink_putstring(&p->top->sink, sel, "_", 1, NULL);
+      upb_sink_putstring(&p->top->sink, sel, &lower, 1, NULL);
+    } else {
+      upb_sink_putstring(&p->top->sink, sel, ptr, 1, NULL);
+    }
+    first = false;
+  }
+  return true;
+}
+
+static bool end_fieldmask_path(upb_json_parser *p) {
+  upb_selector_t sel;
+
+  if (!lower_camel_push(
+           p, getsel_for_handlertype(p, UPB_HANDLER_STRING),
+           p->accumulated, p->accumulated_len)) {
+    return false;
+  }
+
+  sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
+  upb_sink_endstr(&p->top->sink, sel);
+  p->top--;
+
+  multipart_end(p);
+  return true;
+}
+
 static void start_member(upb_json_parser *p) {
   UPB_ASSERT(!p->top->f);
   multipart_startaccum(p);
@@ -1696,7 +1796,11 @@ static bool parse_mapentry_key(upb_json_parser *p) {
       sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
       upb_sink_putstring(subsink, sel, buf, len, NULL);
       sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
+<<<<<<< HEAD
       upb_sink_endstr(p->top->sink, sel);
+=======
+      upb_sink_endstr(&subsink, sel);
+>>>>>>> arrayapi
       multipart_end(p);
       break;
     }
@@ -2221,6 +2325,31 @@ static bool is_string_wrapper(const upb_msgdef *m) {
          type == UPB_WELLKNOWN_BYTESVALUE;
 }
 
+static bool is_fieldmask(const upb_msgdef *m) {
+  upb_wellknowntype_t type = upb_msgdef_wellknowntype(m);
+  return type == UPB_WELLKNOWN_FIELDMASK;
+}
+
+static void start_fieldmask_object(upb_json_parser *p) {
+  const char *membername = "paths";
+
+  start_object(p);
+
+  /* Set up context for parsing value */
+  start_member(p);
+  capture_begin(p, membername);
+  capture_end(p, membername + 5);
+  end_membername(p);
+
+  start_array(p);
+}
+
+static void end_fieldmask_object(upb_json_parser *p) {
+  end_array(p);
+  end_member(p);
+  end_object(p);
+}
+
 static void start_wrapper_object(upb_json_parser *p) {
   const char *membername = "value";
 
@@ -2359,6 +2488,20 @@ static bool is_string_wrapper_object(upb_json_parser *p) {
   return p->top->m != NULL && is_string_wrapper(p->top->m);
 }
 
+static bool does_fieldmask_start(upb_json_parser *p) {
+  return p->top->f != NULL &&
+         upb_fielddef_issubmsg(p->top->f) &&
+         is_fieldmask(upb_fielddef_msgsubdef(p->top->f));
+}
+
+static bool does_fieldmask_end(upb_json_parser *p) {
+  return p->top->m != NULL && is_fieldmask(p->top->m);
+}
+
+static bool is_fieldmask_object(upb_json_parser *p) {
+  return p->top->m != NULL && is_fieldmask(p->top->m);
+}
+
 #define CHECK_RETURN_TOP(x) if (!(x)) goto error
 
 
@@ -2380,26 +2523,35 @@ static bool is_string_wrapper_object(upb_json_parser *p) {
  * final state once, when the closing '"' is seen. */
 
 
+<<<<<<< HEAD
 #line 2542 "upb/json/parser.rl"
 
 
 
 #line 2388 "upb/json/parser.c"
+=======
+#line 2730 "upb/json/parser.rl"
+
+
+
+#line 2556 "upb/json/parser.c"
+>>>>>>> arrayapi
 static const char _json_actions[] = {
 	0, 1, 0, 1, 1, 1, 3, 1, 
 	4, 1, 6, 1, 7, 1, 8, 1, 
 	9, 1, 10, 1, 11, 1, 12, 1, 
-	13, 1, 21, 1, 23, 1, 24, 1, 
-	26, 1, 27, 1, 28, 1, 30, 1, 
-	32, 1, 33, 1, 34, 1, 35, 1, 
-	37, 1, 38, 2, 4, 9, 2, 5, 
-	6, 2, 7, 3, 2, 7, 9, 2, 
-	14, 15, 2, 16, 17, 2, 18, 19, 
-	2, 22, 20, 2, 24, 26, 2, 29, 
-	2, 2, 30, 38, 2, 31, 20, 2, 
-	33, 38, 2, 34, 38, 2, 35, 38, 
-	2, 36, 25, 2, 37, 38, 4, 14, 
-	15, 16, 17
+	13, 1, 24, 1, 26, 1, 28, 1, 
+	29, 1, 31, 1, 32, 1, 33, 1, 
+	35, 1, 37, 1, 38, 1, 39, 1, 
+	40, 1, 42, 1, 43, 2, 4, 9, 
+	2, 5, 6, 2, 7, 3, 2, 7, 
+	9, 2, 14, 15, 2, 16, 17, 2, 
+	18, 19, 2, 21, 23, 2, 22, 20, 
+	2, 27, 25, 2, 29, 31, 2, 34, 
+	2, 2, 35, 43, 2, 36, 25, 2, 
+	38, 43, 2, 39, 43, 2, 40, 43, 
+	2, 41, 30, 2, 42, 43, 3, 21, 
+	23, 24, 4, 14, 15, 16, 17
 };
 
 static const short _json_key_offsets[] = {
@@ -2412,12 +2564,12 @@ static const short _json_key_offsets[] = {
 	156, 158, 160, 162, 163, 165, 167, 168, 
 	170, 172, 173, 175, 177, 178, 180, 182, 
 	183, 185, 187, 191, 193, 195, 196, 197, 
-	198, 199, 201, 206, 215, 216, 216, 216, 
-	221, 226, 231, 232, 233, 234, 235, 235, 
-	236, 237, 238, 238, 239, 240, 241, 241, 
-	246, 247, 251, 256, 261, 266, 270, 270, 
-	273, 276, 279, 282, 285, 288, 288, 288, 
-	288, 288
+	198, 199, 201, 206, 208, 210, 212, 221, 
+	222, 222, 222, 227, 232, 237, 238, 239, 
+	240, 241, 241, 242, 243, 244, 244, 245, 
+	246, 247, 247, 252, 253, 257, 262, 267, 
+	272, 276, 276, 279, 282, 285, 288, 291, 
+	294, 294, 294, 294, 294, 294
 };
 
 static const char _json_trans_keys[] = {
@@ -2446,18 +2598,18 @@ static const char _json_trans_keys[] = {
 	57, 58, 48, 57, 48, 57, 58, 48, 
 	57, 48, 57, 43, 45, 46, 90, 48, 
 	57, 48, 57, 58, 48, 48, 34, 48, 
-	57, 43, 45, 90, 48, 57, 34, 45, 
-	91, 102, 110, 116, 123, 48, 57, 34, 
-	32, 93, 125, 9, 13, 32, 44, 93, 
-	9, 13, 32, 93, 125, 9, 13, 97, 
-	108, 115, 101, 117, 108, 108, 114, 117, 
-	101, 32, 34, 125, 9, 13, 34, 32, 
-	58, 9, 13, 32, 93, 125, 9, 13, 
-	32, 44, 125, 9, 13, 32, 44, 125, 
-	9, 13, 32, 34, 9, 13, 32, 9, 
-	13, 32, 9, 13, 32, 9, 13, 32, 
+	57, 43, 45, 90, 48, 57, 34, 44, 
+	34, 44, 34, 44, 34, 45, 91, 102, 
+	110, 116, 123, 48, 57, 34, 32, 93, 
+	125, 9, 13, 32, 44, 93, 9, 13, 
+	32, 93, 125, 9, 13, 97, 108, 115, 
+	101, 117, 108, 108, 114, 117, 101, 32, 
+	34, 125, 9, 13, 34, 32, 58, 9, 
+	13, 32, 93, 125, 9, 13, 32, 44, 
+	125, 9, 13, 32, 44, 125, 9, 13, 
+	32, 34, 9, 13, 32, 9, 13, 32, 
 	9, 13, 32, 9, 13, 32, 9, 13, 
-	0
+	32, 9, 13, 32, 9, 13, 0
 };
 
 static const char _json_single_lengths[] = {
@@ -2470,12 +2622,12 @@ static const char _json_single_lengths[] = {
 	0, 0, 0, 1, 0, 0, 1, 0, 
 	0, 1, 0, 0, 1, 0, 0, 1, 
 	0, 0, 4, 0, 0, 1, 1, 1, 
-	1, 0, 3, 7, 1, 0, 0, 3, 
-	3, 3, 1, 1, 1, 1, 0, 1, 
-	1, 1, 0, 1, 1, 1, 0, 3, 
-	1, 2, 3, 3, 3, 2, 0, 1, 
-	1, 1, 1, 1, 1, 0, 0, 0, 
-	0, 0
+	1, 0, 3, 2, 2, 2, 7, 1, 
+	0, 0, 3, 3, 3, 1, 1, 1, 
+	1, 0, 1, 1, 1, 0, 1, 1, 
+	1, 0, 3, 1, 2, 3, 3, 3, 
+	2, 0, 1, 1, 1, 1, 1, 1, 
+	0, 0, 0, 0, 0, 0
 };
 
 static const char _json_range_lengths[] = {
@@ -2488,12 +2640,12 @@ static const char _json_range_lengths[] = {
 	1, 1, 1, 0, 1, 1, 0, 1, 
 	1, 0, 1, 1, 0, 1, 1, 0, 
 	1, 1, 0, 1, 1, 0, 0, 0, 
-	0, 1, 1, 1, 0, 0, 0, 1, 
-	1, 1, 0, 0, 0, 0, 0, 0, 
-	0, 0, 0, 0, 0, 0, 0, 1, 
-	0, 1, 1, 1, 1, 1, 0, 1, 
-	1, 1, 1, 1, 1, 0, 0, 0, 
-	0, 0
+	0, 1, 1, 0, 0, 0, 1, 0, 
+	0, 0, 1, 1, 1, 0, 0, 0, 
+	0, 0, 0, 0, 0, 0, 0, 0, 
+	0, 0, 1, 0, 1, 1, 1, 1, 
+	1, 0, 1, 1, 1, 1, 1, 1, 
+	0, 0, 0, 0, 0, 0
 };
 
 static const short _json_index_offsets[] = {
@@ -2506,12 +2658,12 @@ static const short _json_index_offsets[] = {
 	166, 168, 170, 172, 174, 176, 178, 180, 
 	182, 184, 186, 188, 190, 192, 194, 196, 
 	198, 200, 202, 207, 209, 211, 213, 215, 
-	217, 219, 221, 226, 235, 237, 238, 239, 
-	244, 249, 254, 256, 258, 260, 262, 263, 
-	265, 267, 269, 270, 272, 274, 276, 277, 
-	282, 284, 288, 293, 298, 303, 307, 308, 
-	311, 314, 317, 320, 323, 326, 327, 328, 
-	329, 330
+	217, 219, 221, 226, 229, 232, 235, 244, 
+	246, 247, 248, 253, 258, 263, 265, 267, 
+	269, 271, 272, 274, 276, 278, 279, 281, 
+	283, 285, 286, 291, 293, 297, 302, 307, 
+	312, 316, 317, 320, 323, 326, 329, 332, 
+	335, 336, 337, 338, 339, 340
 };
 
 static const unsigned char _json_indicies[] = {
@@ -2543,64 +2695,67 @@ static const unsigned char _json_indicies[] = {
 	88, 1, 89, 89, 90, 91, 1, 92, 
 	1, 93, 1, 94, 1, 95, 1, 96, 
 	1, 97, 1, 98, 1, 99, 99, 100, 
-	98, 1, 101, 102, 103, 104, 105, 106, 
-	107, 102, 1, 108, 1, 109, 110, 112, 
-	113, 1, 112, 111, 114, 115, 113, 114, 
-	1, 115, 1, 1, 115, 111, 116, 1, 
-	117, 1, 118, 1, 119, 1, 120, 121, 
-	1, 122, 1, 123, 1, 124, 125, 1, 
-	126, 1, 127, 1, 128, 129, 130, 131, 
-	129, 1, 132, 1, 133, 134, 133, 1, 
-	134, 1, 1, 134, 135, 136, 137, 138, 
-	136, 1, 139, 140, 131, 139, 1, 140, 
-	130, 140, 1, 141, 142, 142, 1, 143, 
-	143, 1, 144, 144, 1, 145, 145, 1, 
-	146, 146, 1, 147, 147, 1, 1, 1, 
-	1, 1, 1, 0
+	98, 1, 102, 1, 101, 104, 105, 103, 
+	1, 1, 101, 106, 107, 108, 109, 110, 
+	111, 112, 107, 1, 113, 1, 114, 115, 
+	117, 118, 1, 117, 116, 119, 120, 118, 
+	119, 1, 120, 1, 1, 120, 116, 121, 
+	1, 122, 1, 123, 1, 124, 1, 125, 
+	126, 1, 127, 1, 128, 1, 129, 130, 
+	1, 131, 1, 132, 1, 133, 134, 135, 
+	136, 134, 1, 137, 1, 138, 139, 138, 
+	1, 139, 1, 1, 139, 140, 141, 142, 
+	143, 141, 1, 144, 145, 136, 144, 1, 
+	145, 135, 145, 1, 146, 147, 147, 1, 
+	148, 148, 1, 149, 149, 1, 150, 150, 
+	1, 151, 151, 1, 152, 152, 1, 1, 
+	1, 1, 1, 1, 1, 0
 };
 
 static const char _json_trans_targs[] = {
-	1, 0, 2, 104, 3, 6, 10, 13, 
-	16, 103, 4, 3, 103, 4, 5, 7, 
-	8, 9, 105, 11, 12, 106, 14, 15, 
-	107, 16, 17, 108, 18, 18, 19, 20, 
-	21, 22, 108, 21, 22, 24, 25, 31, 
-	109, 26, 28, 27, 29, 30, 33, 110, 
-	34, 33, 110, 34, 32, 35, 36, 37, 
-	38, 39, 33, 110, 34, 41, 42, 46, 
-	42, 46, 43, 45, 44, 111, 48, 49, 
+	1, 0, 2, 107, 3, 6, 10, 13, 
+	16, 106, 4, 3, 106, 4, 5, 7, 
+	8, 9, 108, 11, 12, 109, 14, 15, 
+	110, 16, 17, 111, 18, 18, 19, 20, 
+	21, 22, 111, 21, 22, 24, 25, 31, 
+	112, 26, 28, 27, 29, 30, 33, 113, 
+	34, 33, 113, 34, 32, 35, 36, 37, 
+	38, 39, 33, 113, 34, 41, 42, 46, 
+	42, 46, 43, 45, 44, 114, 48, 49, 
 	50, 51, 52, 53, 54, 55, 56, 57, 
 	58, 59, 60, 61, 62, 63, 64, 65, 
 	66, 67, 73, 72, 68, 69, 70, 71, 
-	72, 112, 74, 67, 72, 76, 78, 79, 
-	82, 87, 91, 95, 77, 113, 113, 80, 
-	79, 77, 80, 81, 83, 84, 85, 86, 
-	113, 88, 89, 90, 113, 92, 93, 94, 
-	113, 95, 96, 102, 97, 97, 98, 99, 
-	100, 101, 102, 100, 101, 113, 103, 103, 
-	103, 103, 103, 103
+	72, 115, 74, 67, 72, 76, 116, 76, 
+	116, 77, 79, 81, 82, 85, 90, 94, 
+	98, 80, 117, 117, 83, 82, 80, 83, 
+	84, 86, 87, 88, 89, 117, 91, 92, 
+	93, 117, 95, 96, 97, 117, 98, 99, 
+	105, 100, 100, 101, 102, 103, 104, 105, 
+	103, 104, 117, 106, 106, 106, 106, 106, 
+	106
 };
 
 static const char _json_trans_actions[] = {
-	0, 0, 84, 78, 33, 0, 0, 0, 
-	96, 39, 25, 0, 35, 0, 0, 0, 
+	0, 0, 92, 86, 35, 0, 0, 0, 
+	104, 41, 27, 0, 37, 0, 0, 0, 
 	0, 0, 0, 0, 0, 0, 0, 0, 
-	0, 0, 72, 31, 27, 0, 0, 25, 
-	29, 29, 75, 0, 0, 0, 0, 0, 
+	0, 0, 80, 33, 29, 0, 0, 27, 
+	31, 31, 83, 0, 0, 0, 0, 0, 
 	3, 0, 0, 0, 0, 0, 5, 15, 
-	0, 0, 51, 7, 13, 0, 54, 9, 
-	9, 9, 57, 60, 11, 17, 17, 17, 
+	0, 0, 53, 7, 13, 0, 56, 9, 
+	9, 9, 59, 62, 11, 17, 17, 17, 
 	0, 0, 0, 19, 0, 21, 23, 0, 
 	0, 0, 0, 0, 0, 0, 0, 0, 
 	0, 0, 0, 0, 0, 0, 0, 0, 
-	0, 102, 63, 102, 0, 0, 0, 0, 
-	0, 69, 0, 66, 66, 84, 78, 33, 
-	0, 0, 0, 96, 39, 49, 81, 25, 
-	0, 35, 0, 0, 0, 0, 0, 0, 
-	90, 0, 0, 0, 93, 0, 0, 0, 
-	87, 0, 72, 31, 27, 0, 0, 25, 
-	29, 29, 75, 0, 0, 99, 0, 37, 
-	43, 45, 41, 47
+	0, 114, 65, 114, 0, 0, 0, 0, 
+	0, 71, 0, 68, 68, 77, 25, 0, 
+	110, 74, 92, 86, 35, 0, 0, 0, 
+	104, 41, 51, 89, 27, 0, 37, 0, 
+	0, 0, 0, 0, 0, 98, 0, 0, 
+	0, 101, 0, 0, 0, 95, 0, 80, 
+	33, 29, 0, 0, 27, 31, 31, 83, 
+	0, 0, 107, 0, 39, 45, 47, 43, 
+	49
 };
 
 static const char _json_eof_actions[] = {
@@ -2617,8 +2772,8 @@ static const char _json_eof_actions[] = {
 	0, 0, 0, 0, 0, 0, 0, 0, 
 	0, 0, 0, 0, 0, 0, 0, 0, 
 	0, 0, 0, 0, 0, 0, 0, 0, 
-	37, 43, 45, 41, 47, 0, 0, 0, 
-	0, 0
+	0, 0, 0, 39, 45, 47, 43, 49, 
+	0, 0, 0, 0, 0, 0
 };
 
 static const int json_start = 1;
@@ -2627,11 +2782,16 @@ static const int json_en_number_machine = 23;
 static const int json_en_string_machine = 32;
 static const int json_en_duration_machine = 40;
 static const int json_en_timestamp_machine = 47;
-static const int json_en_value_machine = 75;
+static const int json_en_fieldmask_machine = 75;
+static const int json_en_value_machine = 78;
 static const int json_en_main = 1;
 
 
+<<<<<<< HEAD
 #line 2545 "upb/json/parser.rl"
+=======
+#line 2733 "upb/json/parser.rl"
+>>>>>>> arrayapi
 
 size_t parse(void *closure, const void *hd, const char *buf, size_t size,
              const upb_bufhandle *handle) {
@@ -2654,7 +2814,11 @@ size_t parse(void *closure, const void *hd, const char *buf, size_t size,
   capture_resume(parser, buf);
 
   
+<<<<<<< HEAD
 #line 2658 "upb/json/parser.c"
+=======
+#line 2831 "upb/json/parser.c"
+>>>>>>> arrayapi
 	{
 	int _klen;
 	unsigned int _trans;
@@ -2729,6 +2893,7 @@ _match:
 		switch ( *_acts++ )
 		{
 	case 1:
+<<<<<<< HEAD
 #line 2393 "upb/json/parser.rl"
 	{ p--; {cs = stack[--top]; goto _again;} }
 	break;
@@ -2806,22 +2971,132 @@ _match:
 	break;
 	case 20:
 #line 2454 "upb/json/parser.rl"
+=======
+#line 2561 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
+	break;
+	case 2:
+#line 2563 "upb/json/parser.rl"
+	{ p--; {stack[top++] = cs; cs = 23;goto _again;} }
+	break;
+	case 3:
+#line 2567 "upb/json/parser.rl"
+	{ start_text(parser, p); }
+	break;
+	case 4:
+#line 2568 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_text(parser, p)); }
+	break;
+	case 5:
+#line 2574 "upb/json/parser.rl"
+	{ start_hex(parser); }
+	break;
+	case 6:
+#line 2575 "upb/json/parser.rl"
+	{ hexdigit(parser, p); }
+	break;
+	case 7:
+#line 2576 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_hex(parser)); }
+	break;
+	case 8:
+#line 2582 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(escape(parser, p)); }
+	break;
+	case 9:
+#line 2588 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
+	break;
+	case 10:
+#line 2600 "upb/json/parser.rl"
+	{ start_duration_base(parser, p); }
+	break;
+	case 11:
+#line 2601 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_duration_base(parser, p)); }
+	break;
+	case 12:
+#line 2603 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
+	break;
+	case 13:
+#line 2608 "upb/json/parser.rl"
+	{ start_timestamp_base(parser, p); }
+	break;
+	case 14:
+#line 2609 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_timestamp_base(parser, p)); }
+	break;
+	case 15:
+#line 2611 "upb/json/parser.rl"
+	{ start_timestamp_fraction(parser, p); }
+	break;
+	case 16:
+#line 2612 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_timestamp_fraction(parser, p)); }
+	break;
+	case 17:
+#line 2614 "upb/json/parser.rl"
+	{ start_timestamp_zone(parser, p); }
+	break;
+	case 18:
+#line 2615 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_timestamp_zone(parser, p)); }
+	break;
+	case 19:
+#line 2617 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
+	break;
+	case 20:
+#line 2622 "upb/json/parser.rl"
+	{ start_fieldmask_path_text(parser, p); }
+	break;
+	case 21:
+#line 2623 "upb/json/parser.rl"
+	{ end_fieldmask_path_text(parser, p); }
+	break;
+	case 22:
+#line 2628 "upb/json/parser.rl"
+	{ start_fieldmask_path(parser); }
+	break;
+	case 23:
+#line 2629 "upb/json/parser.rl"
+	{ end_fieldmask_path(parser); }
+	break;
+	case 24:
+#line 2635 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
+	break;
+	case 25:
+#line 2640 "upb/json/parser.rl"
+>>>>>>> arrayapi
 	{
         if (is_wellknown_msg(parser, UPB_WELLKNOWN_TIMESTAMP)) {
           {stack[top++] = cs; cs = 47;goto _again;}
         } else if (is_wellknown_msg(parser, UPB_WELLKNOWN_DURATION)) {
           {stack[top++] = cs; cs = 40;goto _again;}
+        } else if (is_wellknown_msg(parser, UPB_WELLKNOWN_FIELDMASK)) {
+          {stack[top++] = cs; cs = 75;goto _again;}
         } else {
           {stack[top++] = cs; cs = 32;goto _again;}
         }
       }
 	break;
+<<<<<<< HEAD
 	case 21:
 #line 2465 "upb/json/parser.rl"
 	{ p--; {stack[top++] = cs; cs = 75;goto _again;} }
 	break;
 	case 22:
 #line 2470 "upb/json/parser.rl"
+=======
+	case 26:
+#line 2653 "upb/json/parser.rl"
+	{ p--; {stack[top++] = cs; cs = 78;goto _again;} }
+	break;
+	case 27:
+#line 2658 "upb/json/parser.rl"
+>>>>>>> arrayapi
 	{
         if (is_wellknown_msg(parser, UPB_WELLKNOWN_ANY)) {
           start_any_member(parser, p);
@@ -2830,12 +3105,21 @@ _match:
         }
       }
 	break;
+<<<<<<< HEAD
 	case 23:
 #line 2477 "upb/json/parser.rl"
 	{ CHECK_RETURN_TOP(end_membername(parser)); }
 	break;
 	case 24:
 #line 2480 "upb/json/parser.rl"
+=======
+	case 28:
+#line 2665 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_membername(parser)); }
+	break;
+	case 29:
+#line 2668 "upb/json/parser.rl"
+>>>>>>> arrayapi
 	{
         if (is_wellknown_msg(parser, UPB_WELLKNOWN_ANY)) {
           end_any_member(parser, p);
@@ -2844,8 +3128,13 @@ _match:
         }
       }
 	break;
+<<<<<<< HEAD
 	case 25:
 #line 2491 "upb/json/parser.rl"
+=======
+	case 30:
+#line 2679 "upb/json/parser.rl"
+>>>>>>> arrayapi
 	{
         if (is_wellknown_msg(parser, UPB_WELLKNOWN_ANY)) {
           start_any_object(parser, p);
@@ -2854,8 +3143,13 @@ _match:
         }
       }
 	break;
+<<<<<<< HEAD
 	case 26:
 #line 2500 "upb/json/parser.rl"
+=======
+	case 31:
+#line 2688 "upb/json/parser.rl"
+>>>>>>> arrayapi
 	{
         if (is_wellknown_msg(parser, UPB_WELLKNOWN_ANY)) {
           CHECK_RETURN_TOP(end_any_object(parser, p));
@@ -2864,6 +3158,7 @@ _match:
         }
       }
 	break;
+<<<<<<< HEAD
 	case 27:
 #line 2512 "upb/json/parser.rl"
 	{ CHECK_RETURN_TOP(start_array(parser)); }
@@ -2913,6 +3208,57 @@ _match:
 	{ p--; {cs = stack[--top]; goto _again;} }
 	break;
 #line 2916 "upb/json/parser.c"
+=======
+	case 32:
+#line 2700 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_array(parser)); }
+	break;
+	case 33:
+#line 2704 "upb/json/parser.rl"
+	{ end_array(parser); }
+	break;
+	case 34:
+#line 2709 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_number(parser, p)); }
+	break;
+	case 35:
+#line 2710 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_number(parser, p)); }
+	break;
+	case 36:
+#line 2712 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_stringval(parser)); }
+	break;
+	case 37:
+#line 2713 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_stringval(parser)); }
+	break;
+	case 38:
+#line 2715 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_bool(parser, true)); }
+	break;
+	case 39:
+#line 2717 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_bool(parser, false)); }
+	break;
+	case 40:
+#line 2719 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_null(parser)); }
+	break;
+	case 41:
+#line 2721 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(start_subobject_full(parser)); }
+	break;
+	case 42:
+#line 2722 "upb/json/parser.rl"
+	{ end_subobject_full(parser); }
+	break;
+	case 43:
+#line 2727 "upb/json/parser.rl"
+	{ p--; {cs = stack[--top]; goto _again;} }
+	break;
+#line 3111 "upb/json/parser.c"
+>>>>>>> arrayapi
 		}
 	}
 
@@ -2929,11 +3275,16 @@ _again:
 	while ( __nacts-- > 0 ) {
 		switch ( *__acts++ ) {
 	case 0:
+<<<<<<< HEAD
 #line 2391 "upb/json/parser.rl"
+=======
+#line 2559 "upb/json/parser.rl"
+>>>>>>> arrayapi
 	{ p--; {cs = stack[--top]; 	if ( p == pe )
 		goto _test_eof;
 goto _again;} }
 	break;
+<<<<<<< HEAD
 	case 30:
 #line 2522 "upb/json/parser.rl"
 	{ CHECK_RETURN_TOP(end_number(parser, p)); }
@@ -2955,6 +3306,29 @@ goto _again;} }
 	{ end_subobject_full(parser); }
 	break;
 #line 2958 "upb/json/parser.c"
+=======
+	case 35:
+#line 2710 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_number(parser, p)); }
+	break;
+	case 38:
+#line 2715 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_bool(parser, true)); }
+	break;
+	case 39:
+#line 2717 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_bool(parser, false)); }
+	break;
+	case 40:
+#line 2719 "upb/json/parser.rl"
+	{ CHECK_RETURN_TOP(end_null(parser)); }
+	break;
+	case 42:
+#line 2722 "upb/json/parser.rl"
+	{ end_subobject_full(parser); }
+	break;
+#line 3153 "upb/json/parser.c"
+>>>>>>> arrayapi
 		}
 	}
 	}
@@ -2962,7 +3336,11 @@ goto _again;} }
 	_out: {}
 	}
 
+<<<<<<< HEAD
 #line 2567 "upb/json/parser.rl"
+=======
+#line 2755 "upb/json/parser.rl"
+>>>>>>> arrayapi
 
   if (p != pe) {
     upb_status_seterrf(parser->status, "Parse error at '%.*s'\n", pe - p, p);
@@ -2984,6 +3362,7 @@ static bool end(void *closure, const void *hd) {
   /* Prevent compile warning on unused static constants. */
   UPB_UNUSED(json_start);
   UPB_UNUSED(json_en_duration_machine);
+  UPB_UNUSED(json_en_fieldmask_machine);
   UPB_UNUSED(json_en_number_machine);
   UPB_UNUSED(json_en_string_machine);
   UPB_UNUSED(json_en_timestamp_machine);
@@ -2992,7 +3371,7 @@ static bool end(void *closure, const void *hd) {
 
   parse(parser, hd, &eof_ch, 0, NULL);
 
-  return parser->current_state >= 103;
+  return parser->current_state >= 106;
 }
 
 static void json_parser_reset(upb_json_parser *p) {
@@ -3009,13 +3388,21 @@ static void json_parser_reset(upb_json_parser *p) {
 
   /* Emit Ragel initialization of the parser. */
   
+<<<<<<< HEAD
 #line 3013 "upb/json/parser.c"
+=======
+#line 3210 "upb/json/parser.c"
+>>>>>>> arrayapi
 	{
 	cs = json_start;
 	top = 0;
 	}
 
+<<<<<<< HEAD
 #line 2613 "upb/json/parser.rl"
+=======
+#line 2803 "upb/json/parser.rl"
+>>>>>>> arrayapi
   p->current_state = cs;
   p->parser_top = top;
   accumulate_clear(p);
diff --git a/upb/json/parser.rl b/upb/json/parser.rl
index 11a6955..f722d28 100644
--- a/upb/json/parser.rl
+++ b/upb/json/parser.rl
@@ -61,6 +61,12 @@ static bool is_string_wrapper_object(upb_json_parser *p);
 static bool does_string_wrapper_start(upb_json_parser *p);
 static bool does_string_wrapper_end(upb_json_parser *p);
 
+static bool is_fieldmask_object(upb_json_parser *p);
+static bool does_fieldmask_start(upb_json_parser *p);
+static bool does_fieldmask_end(upb_json_parser *p);
+static void start_fieldmask_object(upb_json_parser *p);
+static void end_fieldmask_object(upb_json_parser *p);
+
 static void start_wrapper_object(upb_json_parser *p);
 static void end_wrapper_object(upb_json_parser *p);
 
@@ -1162,6 +1168,9 @@ static bool start_stringval(upb_json_parser *p) {
   if (is_top_level(p)) {
     if (is_string_wrapper_object(p)) {
       start_wrapper_object(p);
+    } else if (is_wellknown_msg(p, UPB_WELLKNOWN_FIELDMASK)) {
+      start_fieldmask_object(p);
+      return true;
     } else if (is_wellknown_msg(p, UPB_WELLKNOWN_TIMESTAMP) ||
                is_wellknown_msg(p, UPB_WELLKNOWN_DURATION)) {
       start_object(p);
@@ -1175,6 +1184,12 @@ static bool start_stringval(upb_json_parser *p) {
       return false;
     }
     start_wrapper_object(p);
+  } else if (does_fieldmask_start(p)) {
+    if (!start_subobject(p)) {
+      return false;
+    }
+    start_fieldmask_object(p);
+    return true;
   } else if (is_wellknown_field(p, UPB_WELLKNOWN_TIMESTAMP) ||
              is_wellknown_field(p, UPB_WELLKNOWN_DURATION)) {
     if (!start_subobject(p)) {
@@ -1315,8 +1330,8 @@ static bool end_stringval_nontop(upb_json_parser *p) {
 
     case UPB_TYPE_STRING: {
       upb_selector_t sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
-      p->top--;
       upb_sink_endstr(p->top->sink, sel);
+      p->top--;
       break;
     }
 
@@ -1362,6 +1377,16 @@ static bool end_stringval_nontop(upb_json_parser *p) {
 }
 
 static bool end_stringval(upb_json_parser *p) {
+  /* FieldMask's stringvals have been ended when handling them. Only need to
+   * close FieldMask here.*/
+  if (does_fieldmask_end(p)) {
+    end_fieldmask_object(p);
+    if (!is_top_level(p)) {
+      end_subobject(p);
+    }
+    return true;
+  }
+
   if (!end_stringval_nontop(p)) {
     return false;
   }
@@ -1383,7 +1408,8 @@ static bool end_stringval(upb_json_parser *p) {
   }
 
   if (is_wellknown_msg(p, UPB_WELLKNOWN_TIMESTAMP) ||
-      is_wellknown_msg(p, UPB_WELLKNOWN_DURATION)) {
+      is_wellknown_msg(p, UPB_WELLKNOWN_DURATION) ||
+      is_wellknown_msg(p, UPB_WELLKNOWN_FIELDMASK)) {
     end_object(p);
     if (!is_top_level(p)) {
       end_subobject(p);
@@ -1637,6 +1663,75 @@ static bool end_timestamp_zone(upb_json_parser *p, const char *ptr) {
   return true;
 }
 
+static void start_fieldmask_path_text(upb_json_parser *p, const char *ptr) {
+  capture_begin(p, ptr);
+}
+
+static bool end_fieldmask_path_text(upb_json_parser *p, const char *ptr) {
+  if (!capture_end(p, ptr)) {
+    return false;
+  }
+}
+
+static bool start_fieldmask_path(upb_json_parser *p) {
+  upb_jsonparser_frame *inner;
+  upb_selector_t sel;
+
+  if (!check_stack(p)) return false;
+
+  /* Start a new parser frame: parser frames correspond one-to-one with
+   * handler frames, and string events occur in a sub-frame. */
+  inner = p->top + 1;
+  sel = getsel_for_handlertype(p, UPB_HANDLER_STARTSTR);
+  upb_sink_startstr(&p->top->sink, sel, 0, &inner->sink);
+  inner->m = p->top->m;
+  inner->f = p->top->f;
+  inner->name_table = NULL;
+  inner->is_map = false;
+  inner->is_mapentry = false;
+  inner->is_any = false;
+  inner->any_frame = NULL;
+  inner->is_unknown_field = false;
+  p->top = inner;
+
+  multipart_startaccum(p);
+  return true;
+}
+
+static bool lower_camel_push(
+    upb_json_parser *p, upb_selector_t sel, const char *ptr, size_t len) {
+  const char *limit = ptr + len;
+  bool first = true;
+  for (;ptr < limit; ptr++) {
+    if (*ptr >= 'A' && *ptr <= 'Z' && !first) {
+      char lower = tolower(*ptr);
+      upb_sink_putstring(&p->top->sink, sel, "_", 1, NULL);
+      upb_sink_putstring(&p->top->sink, sel, &lower, 1, NULL);
+    } else {
+      upb_sink_putstring(&p->top->sink, sel, ptr, 1, NULL);
+    }
+    first = false;
+  }
+  return true;
+}
+
+static bool end_fieldmask_path(upb_json_parser *p) {
+  upb_selector_t sel;
+
+  if (!lower_camel_push(
+           p, getsel_for_handlertype(p, UPB_HANDLER_STRING),
+           p->accumulated, p->accumulated_len)) {
+    return false;
+  }
+
+  sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
+  upb_sink_endstr(&p->top->sink, sel);
+  p->top--;
+
+  multipart_end(p);
+  return true;
+}
+
 static void start_member(upb_json_parser *p) {
   UPB_ASSERT(!p->top->f);
   multipart_startaccum(p);
@@ -1694,7 +1789,7 @@ static bool parse_mapentry_key(upb_json_parser *p) {
       sel = getsel_for_handlertype(p, UPB_HANDLER_STRING);
       upb_sink_putstring(subsink, sel, buf, len, NULL);
       sel = getsel_for_handlertype(p, UPB_HANDLER_ENDSTR);
-      upb_sink_endstr(p->top->sink, sel);
+      upb_sink_endstr(subsink, sel);
       multipart_end(p);
       break;
     }
@@ -2219,6 +2314,31 @@ static bool is_string_wrapper(const upb_msgdef *m) {
          type == UPB_WELLKNOWN_BYTESVALUE;
 }
 
+static bool is_fieldmask(const upb_msgdef *m) {
+  upb_wellknowntype_t type = upb_msgdef_wellknowntype(m);
+  return type == UPB_WELLKNOWN_FIELDMASK;
+}
+
+static void start_fieldmask_object(upb_json_parser *p) {
+  const char *membername = "paths";
+
+  start_object(p);
+
+  /* Set up context for parsing value */
+  start_member(p);
+  capture_begin(p, membername);
+  capture_end(p, membername + 5);
+  end_membername(p);
+
+  start_array(p);
+}
+
+static void end_fieldmask_object(upb_json_parser *p) {
+  end_array(p);
+  end_member(p);
+  end_object(p);
+}
+
 static void start_wrapper_object(upb_json_parser *p) {
   const char *membername = "value";
 
@@ -2357,6 +2477,20 @@ static bool is_string_wrapper_object(upb_json_parser *p) {
   return p->top->m != NULL && is_string_wrapper(p->top->m);
 }
 
+static bool does_fieldmask_start(upb_json_parser *p) {
+  return p->top->f != NULL &&
+         upb_fielddef_issubmsg(p->top->f) &&
+         is_fieldmask(upb_fielddef_msgsubdef(p->top->f));
+}
+
+static bool does_fieldmask_end(upb_json_parser *p) {
+  return p->top->m != NULL && is_fieldmask(p->top->m);
+}
+
+static bool is_fieldmask_object(upb_json_parser *p) {
+  return p->top->m != NULL && is_fieldmask(p->top->m);
+}
+
 #define CHECK_RETURN_TOP(x) if (!(x)) goto error
 
 
@@ -2449,6 +2583,24 @@ static bool is_string_wrapper_object(upb_json_parser *p) {
       @{ fhold; fret; }
     ;
 
+  fieldmask_path_text =
+    /[^",]/+
+      >{ start_fieldmask_path_text(parser, p); }
+      %{ end_fieldmask_path_text(parser, p); }
+    ;
+
+  fieldmask_path =
+    fieldmask_path_text
+      >{ start_fieldmask_path(parser); }
+      %{ end_fieldmask_path(parser); }
+    ;
+
+  fieldmask_machine :=
+    (fieldmask_path ("," fieldmask_path)*)?
+    '"'
+      @{ fhold; fret; }
+    ;
+
   string =
     '"'
       @{
@@ -2456,6 +2608,8 @@ static bool is_string_wrapper_object(upb_json_parser *p) {
           fcall timestamp_machine;
         } else if (is_wellknown_msg(parser, UPB_WELLKNOWN_DURATION)) {
           fcall duration_machine;
+        } else if (is_wellknown_msg(parser, UPB_WELLKNOWN_FIELDMASK)) {
+          fcall fieldmask_machine;
         } else {
           fcall string_machine;
         }
@@ -2585,6 +2739,7 @@ static bool end(void *closure, const void *hd) {
   /* Prevent compile warning on unused static constants. */
   UPB_UNUSED(json_start);
   UPB_UNUSED(json_en_duration_machine);
+  UPB_UNUSED(json_en_fieldmask_machine);
   UPB_UNUSED(json_en_number_machine);
   UPB_UNUSED(json_en_string_machine);
   UPB_UNUSED(json_en_timestamp_machine);
diff --git a/upb/json/printer.c b/upb/json/printer.c
index 2bc978a..5b16861 100644
--- a/upb/json/printer.c
+++ b/upb/json/printer.c
@@ -748,6 +748,57 @@ static void *startseq_nokey(void *closure, const void *handler_data) {
   return closure;
 }
 
+static void *startseq_fieldmask(void *closure, const void *handler_data) {
+  upb_json_printer *p = closure;
+  UPB_UNUSED(handler_data);
+  p->depth_++;
+  p->first_elem_[p->depth_] = true;
+  print_data(p, "\"", 1);
+  return closure;
+}
+
+static bool endseq_fieldmask(void *closure, const void *handler_data) {
+  upb_json_printer *p = closure;
+  UPB_UNUSED(handler_data);
+  p->depth_--;
+  print_data(p, "\"", 1);
+  return true;
+}
+
+static void *repeated_startstr_fieldmask(
+    void *closure, const void *handler_data,
+    size_t size_hint) {
+  upb_json_printer *p = closure;
+  UPB_UNUSED(handler_data);
+  UPB_UNUSED(size_hint);
+  print_comma(p);
+  return p;
+}
+
+static size_t repeated_str_fieldmask(
+    void *closure, const void *handler_data,
+    const char *str, size_t len,
+    const upb_bufhandle *handle) {
+  const char* limit = str + len;
+  bool upper = false;
+  size_t result_len = 0;
+  for (; str < limit; str++) {
+    if (*str == '_') {
+      upper = true;
+      continue;
+    }
+    if (upper && *str >= 'a' && *str <= 'z') {
+      char upper_char = toupper(*str);
+      CHK(putstr(closure, handler_data, &upper_char, 1, handle));
+    } else {
+      CHK(putstr(closure, handler_data, str, 1, handle));
+    }
+    upper = false;
+    result_len++;
+  }
+  return result_len;
+}
+
 static void *startmap_nokey(void *closure, const void *handler_data) {
   upb_json_printer *p = closure;
   UPB_UNUSED(handler_data);
@@ -973,6 +1024,25 @@ void printer_sethandlers_any(const void *closure, upb_handlers *h) {
   UPB_UNUSED(closure);
 }
 
+/* Set up handlers for a fieldmask submessage. */
+void printer_sethandlers_fieldmask(const void *closure, upb_handlers *h) {
+  const upb_msgdef *md = upb_handlers_msgdef(h);
+  const upb_fielddef* f = upb_msgdef_itof(md, 1);
+
+  upb_handlerattr empty_attr = UPB_HANDLERATTR_INITIALIZER;
+
+  upb_handlers_setstartseq(h, f, startseq_fieldmask, &empty_attr);
+  upb_handlers_setendseq(h, f, endseq_fieldmask, &empty_attr);
+
+  upb_handlers_setstartmsg(h, printer_startmsg_noframe, &empty_attr);
+  upb_handlers_setendmsg(h, printer_endmsg_noframe, &empty_attr);
+
+  upb_handlers_setstartstr(h, f, repeated_startstr_fieldmask, &empty_attr);
+  upb_handlers_setstring(h, f, repeated_str_fieldmask, &empty_attr);
+
+  UPB_UNUSED(closure);
+}
+
 /* Set up handlers for a duration submessage. */
 void printer_sethandlers_duration(const void *closure, upb_handlers *h) {
   const upb_msgdef *md = upb_handlers_msgdef(h);
@@ -1129,6 +1199,9 @@ void printer_sethandlers(const void *closure, upb_handlers *h) {
     case UPB_WELLKNOWN_ANY:
       printer_sethandlers_any(closure, h);
       return;
+    case UPB_WELLKNOWN_FIELDMASK:
+      printer_sethandlers_fieldmask(closure, h);
+      return;
     case UPB_WELLKNOWN_DURATION:
       printer_sethandlers_duration(closure, h);
       return;
diff --git a/upb/pb/compile_decoder.c b/upb/pb/compile_decoder.c
index c5d8d9b..75cff48 100644
--- a/upb/pb/compile_decoder.c
+++ b/upb/pb/compile_decoder.c
@@ -615,8 +615,8 @@ static void generate_delimfield(compiler *c, const upb_fielddef *f,
     putop(c, OP_STARTSTR, getsel(f, UPB_HANDLER_STARTSTR));
     /* Need to emit even if no handler to skip past the string. */
     putop(c, OP_STRING, getsel(f, UPB_HANDLER_STRING));
-    putop(c, OP_POP);
     maybeput(c, OP_ENDSTR, h, f, UPB_HANDLER_ENDSTR);
+    putop(c, OP_POP);
     putop(c, OP_SETDELIM);
     putop(c, OP_CHECKDELIM, LABEL_LOOPBREAK);
     putchecktag(c, f, UPB_WIRE_TYPE_DELIMITED, LABEL_LOOPBREAK);
@@ -631,8 +631,8 @@ static void generate_delimfield(compiler *c, const upb_fielddef *f,
     putop(c, OP_PUSHLENDELIM);
     putop(c, OP_STARTSTR, getsel(f, UPB_HANDLER_STARTSTR));
     putop(c, OP_STRING, getsel(f, UPB_HANDLER_STRING));
-    putop(c, OP_POP);
     maybeput(c, OP_ENDSTR, h, f, UPB_HANDLER_ENDSTR);
+    putop(c, OP_POP);
     putop(c, OP_SETDELIM);
   }
 }
diff --git a/upb/upb.h b/upb/upb.h
index fc83902..3848229 100644
--- a/upb/upb.h
+++ b/upb/upb.h
@@ -419,6 +419,7 @@ typedef enum {
 typedef enum {
   UPB_WELLKNOWN_UNSPECIFIED,
   UPB_WELLKNOWN_ANY,
+  UPB_WELLKNOWN_FIELDMASK,
   UPB_WELLKNOWN_DURATION,
   UPB_WELLKNOWN_TIMESTAMP,
   /* number wrappers */