Lobster: added builder API for tables

docs/source/Tutorial.md

@@ -815,10 +815,11 @@ our `orc` Monster, lets create some `Weapon`s: a `Sword` and an `Axe`.
 
   let weapon_offsets = map(weapon_names) name, i:
       let ns = builder.CreateString(name)
-      builder.MyGame_Sample_WeaponStart()
-      builder.MyGame_Sample_WeaponAddName(ns)
-      builder.MyGame_Sample_WeaponAddDamage(weapon_damages[i])
-      builder.MyGame_Sample_WeaponEnd()
+      MyGame_Sample_WeaponBuilder { b }
+          .start()
+          .add_name(ns)
+          .add_damage(weapon_damages[i])
+          .end()
 ~~~
 </div>
 <div class="language-rust">
@@ -1503,17 +1504,18 @@ can serialize the monster itself:
 </div>
 <div class="language-lobster">
 ~~~{.lobster}
-  builder.MyGame_Sample_MonsterStart()
-  builder.MyGame_Sample_MonsterAddPos(builder.MyGame_Sample_CreateVec3(1.0, 2.0, 3.0))
-  builder.MyGame_Sample_MonsterAddHp(300)
-  builder.MyGame_Sample_MonsterAddName(name)
-  builder.MyGame_Sample_MonsterAddInventory(inv)
-  builder.MyGame_Sample_MonsterAddColor(MyGame_Sample_Color_Red)
-  builder.MyGame_Sample_MonsterAddWeapons(weapons)
-  builder.MyGame_Sample_MonsterAddEquippedType(MyGame_Sample_Equipment_Weapon)
-  builder.MyGame_Sample_MonsterAddEquipped(weapon_offsets[1])
-  builder.MyGame_Sample_MonsterAddPath(path)
-  let orc = builder.MyGame_Sample_MonsterEnd()
+  let orc = MyGame_Sample_MonsterBuilder { b }
+      .start()
+      .add_pos(b.MyGame_Sample_CreateVec3(1.0, 2.0, 3.0))
+      .add_hp(300)
+      .add_name(name)
+      .add_inventory(inv)
+      .add_color(MyGame_Sample_Color_Red)
+      .add_weapons(weapons)
+      .add_equipped_type(MyGame_Sample_Equipment_Weapon)
+      .add_equipped(weapon_offsets[1])
+      .add_path(path)
+      .end()
 ~~~
 </div>
 <div class="language-rust">
@@ -1687,8 +1689,8 @@ Here is a repetition these lines, to help highlight them more clearly:
 </div>
 <div class="language-lobster">
 ~~~{.lobster}
-  builder.MyGame_Sample_MonsterAddEquippedType(MyGame_Sample_Equipment_Weapon)
-  builder.MyGame_Sample_MonsterAddEquipped(axe)
+    .add_equipped_type(MyGame_Sample_Equipment_Weapon)
+    .add_equipped(axe)
 ~~~
 </div>
 <div class="language-rust">

lobster/flatbuffers.lobster

@@ -282,4 +282,3 @@ class builder:
             // elsewhere.
             assert x.o == head
             Slot(v)
-

samples/monster_generated.lobster

@@ -64,44 +64,60 @@ class Monster : flatbuffers_handle
 
 def GetRootAsMonster(buf:string): return Monster { buf, buf.flatbuffers_indirect(0) }
 
-def MonsterStart(b_:flatbuffers_builder):
-    b_.StartObject(11)
-def MonsterAddPos(b_:flatbuffers_builder, pos:flatbuffers_offset):
-    b_.PrependStructSlot(0, pos)
-def MonsterAddMana(b_:flatbuffers_builder, mana:int):
-    b_.PrependInt16Slot(1, mana, 150)
-def MonsterAddHp(b_:flatbuffers_builder, hp:int):
-    b_.PrependInt16Slot(2, hp, 100)
-def MonsterAddName(b_:flatbuffers_builder, name:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(3, name)
-def MonsterAddInventory(b_:flatbuffers_builder, inventory:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(5, inventory)
+struct MonsterBuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(11)
+        return this
+    def add_pos(pos:flatbuffers_offset):
+        b_.PrependStructSlot(0, pos)
+        return this
+    def add_mana(mana:int):
+        b_.PrependInt16Slot(1, mana, 150)
+        return this
+    def add_hp(hp:int):
+        b_.PrependInt16Slot(2, hp, 100)
+        return this
+    def add_name(name:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(3, name)
+        return this
+    def add_inventory(inventory:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(5, inventory)
+        return this
+    def add_color(color:Color):
+        b_.PrependInt8Slot(6, color, 2)
+        return this
+    def add_weapons(weapons:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(7, weapons)
+        return this
+    def add_equipped_type(equipped_type:Equipment):
+        b_.PrependUint8Slot(8, equipped_type, 0)
+        return this
+    def add_equipped(equipped:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(9, equipped)
+        return this
+    def add_path(path:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(10, path)
+        return this
+    def end():
+        return b_.EndObject()
+
 def MonsterStartInventoryVector(b_:flatbuffers_builder, n_:int):
     b_.StartVector(1, n_, 1)
 def MonsterCreateInventoryVector(b_:flatbuffers_builder, v_:[int]):
     b_.StartVector(1, v_.length, 1)
     reverse(v_) e_: b_.PrependUint8(e_)
     return b_.EndVector(v_.length)
-def MonsterAddColor(b_:flatbuffers_builder, color:Color):
-    b_.PrependInt8Slot(6, color, 2)
-def MonsterAddWeapons(b_:flatbuffers_builder, weapons:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(7, weapons)
+
 def MonsterStartWeaponsVector(b_:flatbuffers_builder, n_:int):
     b_.StartVector(4, n_, 4)
 def MonsterCreateWeaponsVector(b_:flatbuffers_builder, v_:[flatbuffers_offset]):
     b_.StartVector(4, v_.length, 4)
     reverse(v_) e_: b_.PrependUOffsetTRelative(e_)
     return b_.EndVector(v_.length)
-def MonsterAddEquippedType(b_:flatbuffers_builder, equipped_type:Equipment):
-    b_.PrependUint8Slot(8, equipped_type, 0)
-def MonsterAddEquipped(b_:flatbuffers_builder, equipped:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(9, equipped)
-def MonsterAddPath(b_:flatbuffers_builder, path:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(10, path)
+
 def MonsterStartPathVector(b_:flatbuffers_builder, n_:int):
     b_.StartVector(12, n_, 4)
-def MonsterEnd(b_:flatbuffers_builder):
-    return b_.EndObject()
 
 class Weapon : flatbuffers_handle
     def name():
@@ -111,12 +127,17 @@ class Weapon : flatbuffers_handle
 
 def GetRootAsWeapon(buf:string): return Weapon { buf, buf.flatbuffers_indirect(0) }
 
-def WeaponStart(b_:flatbuffers_builder):
-    b_.StartObject(2)
-def WeaponAddName(b_:flatbuffers_builder, name:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(0, name)
-def WeaponAddDamage(b_:flatbuffers_builder, damage:int):
-    b_.PrependInt16Slot(1, damage, 0)
-def WeaponEnd(b_:flatbuffers_builder):
-    return b_.EndObject()
+struct WeaponBuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(2)
+        return this
+    def add_name(name:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(0, name)
+        return this
+    def add_damage(damage:int):
+        b_.PrependInt16Slot(1, damage, 0)
+        return this
+    def end():
+        return b_.EndObject()
 

samples/sample_binary.lobster

@@ -26,10 +26,11 @@ let weapon_damages = [ 3, 5 ]
 
 let weapon_offsets = map(weapon_names) name, i:
     let ns = b.CreateString(name)
-    b.MyGame_Sample_WeaponStart()
-    b.MyGame_Sample_WeaponAddName(ns)
-    b.MyGame_Sample_WeaponAddDamage(weapon_damages[i])
-    b.MyGame_Sample_WeaponEnd()
+    MyGame_Sample_WeaponBuilder { b }
+        .start()
+        .add_name(ns)
+        .add_damage(weapon_damages[i])
+        .end()
 
 let weapons = b.MyGame_Sample_MonsterCreateWeaponsVector(weapon_offsets)
 
@@ -40,16 +41,17 @@ let name = b.CreateString("Orc")
 let inv = b.MyGame_Sample_MonsterCreateInventoryVector(map(10): _)
 
 // Now pack it all together in our root monster object.
-b.MyGame_Sample_MonsterStart()
-b.MyGame_Sample_MonsterAddPos(b.MyGame_Sample_CreateVec3(1.0, 2.0, 3.0))
-b.MyGame_Sample_MonsterAddHp(300)
-b.MyGame_Sample_MonsterAddName(name)
-b.MyGame_Sample_MonsterAddInventory(inv)
-b.MyGame_Sample_MonsterAddColor(MyGame_Sample_Color_Red)
-b.MyGame_Sample_MonsterAddWeapons(weapons)
-b.MyGame_Sample_MonsterAddEquippedType(MyGame_Sample_Equipment_Weapon)
-b.MyGame_Sample_MonsterAddEquipped(weapon_offsets[1])
-let orc = b.MyGame_Sample_MonsterEnd()
+let orc = MyGame_Sample_MonsterBuilder { b }
+    .start()
+    .add_pos(b.MyGame_Sample_CreateVec3(1.0, 2.0, 3.0))
+    .add_hp(300)
+    .add_name(name)
+    .add_inventory(inv)
+    .add_color(MyGame_Sample_Color_Red)
+    .add_weapons(weapons)
+    .add_equipped_type(MyGame_Sample_Equipment_Weapon)
+    .add_equipped(weapon_offsets[1])
+    .end()
 
 // Finish the buffer!
 b.Finish(orc)

src/idl_gen_lobster.cpp

@@ -180,22 +180,28 @@ class LobsterGenerator : public BaseGenerator {
   void GenTableBuilders(const StructDef &struct_def,
                         std::string *code_ptr) {
     std::string &code = *code_ptr;
-    code += "def " + NormalizedName(struct_def) +
-            "Start(b_:flatbuffers_builder):\n    b_.StartObject(" +
-            NumToString(struct_def.fields.vec.size()) + ")\n";
+    code += "struct " + NormalizedName(struct_def) +
+            "Builder:\n    b_:flatbuffers_builder\n";
+    code += "    def start():\n        b_.StartObject(" +
+            NumToString(struct_def.fields.vec.size()) + ")\n        return this\n";
     for (auto it = struct_def.fields.vec.begin();
-        it != struct_def.fields.vec.end(); ++it) {
+         it != struct_def.fields.vec.end(); ++it) {
       auto &field = **it;
       if (field.deprecated) continue;
       auto offset = it - struct_def.fields.vec.begin();
-      code += "def " + NormalizedName(struct_def) + "Add" +
-              MakeCamel(NormalizedName(field)) + "(b_:flatbuffers_builder, " +
+      code += "    def add_" + NormalizedName(field) + "(" +
               NormalizedName(field) + ":" + LobsterType(field.value.type) +
-              "):\n    b_.Prepend" + GenMethod(field.value.type) + "Slot(" +
+              "):\n        b_.Prepend" + GenMethod(field.value.type) + "Slot(" +
               NumToString(offset) + ", " + NormalizedName(field);
       if (IsScalar(field.value.type.base_type))
         code += ", " + field.value.constant;
-      code += ")\n";
+      code += ")\n        return this\n";
+    }
+    code += "    def end():\n        return b_.EndObject()\n\n";
+    for (auto it = struct_def.fields.vec.begin();
+         it != struct_def.fields.vec.end(); ++it) {
+      auto &field = **it;
+      if (field.deprecated) continue;
       if (field.value.type.base_type == BASE_TYPE_VECTOR) {
         code += "def " + NormalizedName(struct_def) + "Start" +
                 MakeCamel(NormalizedName(field)) +
@@ -217,10 +223,9 @@ class LobsterGenerator : public BaseGenerator {
                   GenMethod(vector_type) +
                   "(e_)\n    return b_.EndVector(v_.length)\n";
         }
+        code += "\n";
       }
     }
-    code += "def " + NormalizedName(struct_def) +
-            "End(b_:flatbuffers_builder):\n    return b_.EndObject()\n\n";
   }
 
   void GenStructPreDecl(const StructDef &struct_def, std::string *code_ptr) {

tests/lobstertest.lobster

@@ -70,9 +70,10 @@ def make_monster_from_generated_code():
 
     let inv = b.MyGame_Example_MonsterCreateInventoryVector([ 0, 1, 2, 3, 4 ])
 
-    b.MyGame_Example_MonsterStart()
-    b.MyGame_Example_MonsterAddName(fred)
-    let mon2 = b.MyGame_Example_MonsterEnd()
+    let mon2 = MyGame_Example_MonsterBuilder { b }
+        .start()
+        .add_name(fred)
+        .end()
 
     b.MyGame_Example_MonsterStartTest4Vector(2)
     b.MyGame_Example_CreateTest(10, 20)
@@ -88,19 +89,20 @@ def make_monster_from_generated_code():
     let vector_of_doubles = b.MyGame_Example_MonsterCreateVectorOfDoublesVector(
                                 [ -1.7976931348623157e+308, 0, 1.7976931348623157e+308 ])
 
-    b.MyGame_Example_MonsterStart()
-    b.MyGame_Example_MonsterAddPos(b.MyGame_Example_CreateVec3(1.0, 2.0, 3.0, 3.0,
-                                   MyGame_Example_Color_Green, 5, 6))
-    b.MyGame_Example_MonsterAddHp(80)
-    b.MyGame_Example_MonsterAddName(name)
-    b.MyGame_Example_MonsterAddInventory(inv)
-    b.MyGame_Example_MonsterAddTestType(MyGame_Example_Any_Monster)
-    b.MyGame_Example_MonsterAddTest(mon2)
-    b.MyGame_Example_MonsterAddTest4(test4)
-    b.MyGame_Example_MonsterAddTestarrayofstring(test_array_of_string)
-    b.MyGame_Example_MonsterAddVectorOfLongs(vector_of_longs)
-    b.MyGame_Example_MonsterAddVectorOfDoubles(vector_of_doubles)
-    let mon = b.MyGame_Example_MonsterEnd()
+    let mon = MyGame_Example_MonsterBuilder { b }
+        .start()
+        .add_pos(b.MyGame_Example_CreateVec3(1.0, 2.0, 3.0, 3.0,
+                 MyGame_Example_Color_Green, 5, 6))
+        .add_hp(80)
+        .add_name(name)
+        .add_inventory(inv)
+        .add_test_type(MyGame_Example_Any_Monster)
+        .add_test(mon2)
+        .add_test4(test4)
+        .add_testarrayofstring(test_array_of_string)
+        .add_vector_of_longs(vector_of_longs)
+        .add_vector_of_doubles(vector_of_doubles)
+        .end()
 
     b.Finish(mon)
 

tests/namespace_test/namespace_test1_generated.lobster

@@ -18,12 +18,16 @@ class TableInNestedNS : flatbuffers_handle
 
 def GetRootAsTableInNestedNS(buf:string): return TableInNestedNS { buf, buf.flatbuffers_indirect(0) }
 
-def TableInNestedNSStart(b_:flatbuffers_builder):
-    b_.StartObject(1)
-def TableInNestedNSAddFoo(b_:flatbuffers_builder, foo:int):
-    b_.PrependInt32Slot(0, foo, 0)
-def TableInNestedNSEnd(b_:flatbuffers_builder):
-    return b_.EndObject()
+struct TableInNestedNSBuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(1)
+        return this
+    def add_foo(foo:int):
+        b_.PrependInt32Slot(0, foo, 0)
+        return this
+    def end():
+        return b_.EndObject()
 
 class StructInNestedNS : flatbuffers_handle
     def a():

tests/namespace_test/namespace_test2_generated.lobster

@@ -25,16 +25,22 @@ class TableInFirstNS : flatbuffers_handle
 
 def GetRootAsTableInFirstNS(buf:string): return TableInFirstNS { buf, buf.flatbuffers_indirect(0) }
 
-def TableInFirstNSStart(b_:flatbuffers_builder):
-    b_.StartObject(3)
-def TableInFirstNSAddFooTable(b_:flatbuffers_builder, foo_table:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(0, foo_table)
-def TableInFirstNSAddFooEnum(b_:flatbuffers_builder, foo_enum:EnumInNestedNS):
-    b_.PrependInt8Slot(1, foo_enum, 0)
-def TableInFirstNSAddFooStruct(b_:flatbuffers_builder, foo_struct:flatbuffers_offset):
-    b_.PrependStructSlot(2, foo_struct)
-def TableInFirstNSEnd(b_:flatbuffers_builder):
-    return b_.EndObject()
+struct TableInFirstNSBuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(3)
+        return this
+    def add_foo_table(foo_table:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(0, foo_table)
+        return this
+    def add_foo_enum(foo_enum:EnumInNestedNS):
+        b_.PrependInt8Slot(1, foo_enum, 0)
+        return this
+    def add_foo_struct(foo_struct:flatbuffers_offset):
+        b_.PrependStructSlot(2, foo_struct)
+        return this
+    def end():
+        return b_.EndObject()
 
 namespace NamespaceC
 
@@ -48,14 +54,19 @@ class TableInC : flatbuffers_handle
 
 def GetRootAsTableInC(buf:string): return TableInC { buf, buf.flatbuffers_indirect(0) }
 
-def TableInCStart(b_:flatbuffers_builder):
-    b_.StartObject(2)
-def TableInCAddReferToA1(b_:flatbuffers_builder, refer_to_a1:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(0, refer_to_a1)
-def TableInCAddReferToA2(b_:flatbuffers_builder, refer_to_a2:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(1, refer_to_a2)
-def TableInCEnd(b_:flatbuffers_builder):
-    return b_.EndObject()
+struct TableInCBuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(2)
+        return this
+    def add_refer_to_a1(refer_to_a1:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(0, refer_to_a1)
+        return this
+    def add_refer_to_a2(refer_to_a2:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(1, refer_to_a2)
+        return this
+    def end():
+        return b_.EndObject()
 
 namespace NamespaceA
 
@@ -66,10 +77,14 @@ class SecondTableInA : flatbuffers_handle
 
 def GetRootAsSecondTableInA(buf:string): return SecondTableInA { buf, buf.flatbuffers_indirect(0) }
 
-def SecondTableInAStart(b_:flatbuffers_builder):
-    b_.StartObject(1)
-def SecondTableInAAddReferToC(b_:flatbuffers_builder, refer_to_c:flatbuffers_offset):
-    b_.PrependUOffsetTRelativeSlot(0, refer_to_c)
-def SecondTableInAEnd(b_:flatbuffers_builder):
-    return b_.EndObject()
+struct SecondTableInABuilder:
+    b_:flatbuffers_builder
+    def start():
+        b_.StartObject(1)
+        return this
+    def add_refer_to_c(refer_to_c:flatbuffers_offset):
+        b_.PrependUOffsetTRelativeSlot(0, refer_to_c)
+        return this
+    def end():
+        return b_.EndObject()