Moved upb_symtab to def.h/def.c.

This is in anticipation of removing refcounting and
making upb_symtab (soon to be upb_defpool) the unique
owner of all defs inside.

1 files changed, 173 insertions, 0 deletions

diff --git a/upb/def.h b/upb/def.h
index 724a85c..b2c42a6 100644
--- a/upb/def.h
+++ b/upb/def.h
@@ -35,6 +35,7 @@ class FieldDef;
 class FileDef;
 class MessageDef;
 class OneofDef;
+class SymbolTable;
 }
 #endif
 
@@ -43,6 +44,9 @@ UPB_DECLARE_DERIVED_TYPE(upb::OneofDef, upb::RefCounted, upb_oneofdef,
                          upb_refcounted)
 UPB_DECLARE_DERIVED_TYPE(upb::FileDef, upb::RefCounted, upb_filedef,
                          upb_refcounted)
+UPB_DECLARE_DERIVED_TYPE(upb::SymbolTable, upb::RefCounted,
+                         upb_symtab, upb_refcounted)
+
 
 /* The maximum message depth that the type graph can have.  This is a resource
  * limit for the C stack since we sometimes need to recursively traverse the
@@ -1417,6 +1421,175 @@ UPB_INLINE upb_def *upb_filedef_mutabledef(upb_filedef *f, int i) {
 
 UPB_END_EXTERN_C
 
+typedef struct {
+ UPB_PRIVATE_FOR_CPP
+  upb_strtable_iter iter;
+  upb_deftype_t type;
+} upb_symtab_iter;
+
+#ifdef __cplusplus
+
+/* Non-const methods in upb::SymbolTable are NOT thread-safe. */
+class upb::SymbolTable {
+ public:
+  /* Returns a new symbol table with a single ref owned by "owner."
+   * Returns NULL if memory allocation failed. */
+  static reffed_ptr<SymbolTable> New();
+
+  /* Include RefCounted base methods. */
+  UPB_REFCOUNTED_CPPMETHODS
+
+  /* For all lookup functions, the returned pointer is not owned by the
+   * caller; it may be invalidated by any non-const call or unref of the
+   * SymbolTable!  To protect against this, take a ref if desired. */
+
+  /* Freezes the symbol table: prevents further modification of it.
+   * After the Freeze() operation is successful, the SymbolTable must only be
+   * accessed via a const pointer.
+   *
+   * Unlike with upb::MessageDef/upb::EnumDef/etc, freezing a SymbolTable is not
+   * a necessary step in using a SymbolTable.  If you have no need for it to be
+   * immutable, there is no need to freeze it ever.  However sometimes it is
+   * useful, and SymbolTables that are statically compiled into the binary are
+   * always frozen by nature. */
+  void Freeze();
+
+  /* Resolves the given symbol using the rules described in descriptor.proto,
+   * namely:
+   *
+   *    If the name starts with a '.', it is fully-qualified.  Otherwise,
+   *    C++-like scoping rules are used to find the type (i.e. first the nested
+   *    types within this message are searched, then within the parent, on up
+   *    to the root namespace).
+   *
+   * If not found, returns NULL. */
+  const Def* Resolve(const char* base, const char* sym) const;
+
+  /* Finds an entry in the symbol table with this exact name.  If not found,
+   * returns NULL. */
+  const Def* Lookup(const char *sym) const;
+  const MessageDef* LookupMessage(const char *sym) const;
+  const EnumDef* LookupEnum(const char *sym) const;
+
+  /* TODO: introduce a C++ iterator, but make it nice and templated so that if
+   * you ask for an iterator of MessageDef the iterated elements are strongly
+   * typed as MessageDef*. */
+
+  /* Adds the given mutable defs to the symtab, resolving all symbols
+   * (including enum default values) and finalizing the defs.  Only one def per
+   * name may be in the list, but defs can replace existing defs in the symtab.
+   * All defs must have a name -- anonymous defs are not allowed.  Anonymous
+   * defs can still be frozen by calling upb_def_freeze() directly.
+   *
+   * Any existing defs that can reach defs that are being replaced will
+   * themselves be replaced also, so that the resulting set of defs is fully
+   * consistent.
+   *
+   * This logic implemented in this method is a convenience; ultimately it
+   * calls some combination of upb_fielddef_setsubdef(), upb_def_dup(), and
+   * upb_freeze(), any of which the client could call themself.  However, since
+   * the logic for doing so is nontrivial, we provide it here.
+   *
+   * The entire operation either succeeds or fails.  If the operation fails,
+   * the symtab is unchanged, false is returned, and status indicates the
+   * error.  The caller passes a ref on all defs to the symtab (even if the
+   * operation fails).
+   *
+   * TODO(haberman): currently failure will leave the symtab unchanged, but may
+   * leave the defs themselves partially resolved.  Does this matter?  If so we
+   * could do a prepass that ensures that all symbols are resolvable and bail
+   * if not, so we don't mutate anything until we know the operation will
+   * succeed.
+   *
+   * TODO(haberman): since the defs must be mutable, refining a frozen def
+   * requires making mutable copies of the entire tree.  This is wasteful if
+   * only a few messages are changing.  We may want to add a way of adding a
+   * tree of frozen defs to the symtab (perhaps an alternate constructor where
+   * you pass the root of the tree?) */
+  bool Add(Def*const* defs, size_t n, void* ref_donor, Status* status);
+
+  bool Add(const std::vector<Def*>& defs, void *owner, Status* status) {
+    return Add((Def*const*)&defs[0], defs.size(), owner, status);
+  }
+
+  /* Resolves all subdefs for messages in this file and attempts to freeze the
+   * file.  If this succeeds, adds all the symbols to this SymbolTable
+   * (replacing any existing ones with the same names). */
+  bool AddFile(FileDef* file, Status* s);
+
+ private:
+  UPB_DISALLOW_POD_OPS(SymbolTable, upb::SymbolTable)
+};
+
+#endif  /* __cplusplus */
+
+UPB_BEGIN_EXTERN_C
+
+/* Native C API. */
+
+/* Include refcounted methods like upb_symtab_ref(). */
+UPB_REFCOUNTED_CMETHODS(upb_symtab, upb_symtab_upcast)
+
+upb_symtab *upb_symtab_new(const void *owner);
+void upb_symtab_freeze(upb_symtab *s);
+const upb_def *upb_symtab_resolve(const upb_symtab *s, const char *base,
+                                  const char *sym);
+const upb_def *upb_symtab_lookup(const upb_symtab *s, const char *sym);
+const upb_msgdef *upb_symtab_lookupmsg(const upb_symtab *s, const char *sym);
+const upb_enumdef *upb_symtab_lookupenum(const upb_symtab *s, const char *sym);
+bool upb_symtab_add(upb_symtab *s, upb_def *const*defs, size_t n,
+                    void *ref_donor, upb_status *status);
+bool upb_symtab_addfile(upb_symtab *s, upb_filedef *file, upb_status* status);
+
+/* upb_symtab_iter i;
+ * for(upb_symtab_begin(&i, s, type); !upb_symtab_done(&i);
+ *     upb_symtab_next(&i)) {
+ *   const upb_def *def = upb_symtab_iter_def(&i);
+ *    // ...
+ * }
+ *
+ * For C we don't have separate iterators for const and non-const.
+ * It is the caller's responsibility to cast the upb_fielddef* to
+ * const if the upb_msgdef* is const. */
+void upb_symtab_begin(upb_symtab_iter *iter, const upb_symtab *s,
+                      upb_deftype_t type);
+void upb_symtab_next(upb_symtab_iter *iter);
+bool upb_symtab_done(const upb_symtab_iter *iter);
+const upb_def *upb_symtab_iter_def(const upb_symtab_iter *iter);
+
+UPB_END_EXTERN_C
+
+#ifdef __cplusplus
+/* C++ inline wrappers. */
+namespace upb {
+inline reffed_ptr<SymbolTable> SymbolTable::New() {
+  upb_symtab *s = upb_symtab_new(&s);
+  return reffed_ptr<SymbolTable>(s, &s);
+}
+
+inline void SymbolTable::Freeze() {
+  return upb_symtab_freeze(this);
+}
+inline const Def *SymbolTable::Resolve(const char *base,
+                                       const char *sym) const {
+  return upb_symtab_resolve(this, base, sym);
+}
+inline const Def* SymbolTable::Lookup(const char *sym) const {
+  return upb_symtab_lookup(this, sym);
+}
+inline const MessageDef *SymbolTable::LookupMessage(const char *sym) const {
+  return upb_symtab_lookupmsg(this, sym);
+}
+inline bool SymbolTable::Add(
+    Def*const* defs, size_t n, void* ref_donor, Status* status) {
+  return upb_symtab_add(this, (upb_def*const*)defs, n, ref_donor, status);
+}
+inline bool SymbolTable::AddFile(FileDef* file, Status* s) {
+  return upb_symtab_addfile(this, file, s);
+}
+}  /* namespace upb */
+#endif
+
 #ifdef __cplusplus
 
 UPB_INLINE const char* upb_safecstr(const std::string& str) {