[Python] Python fixed size array

python/flatbuffers/table.py

@@ -113,6 +113,15 @@ def GetVectorAsNumpy(self, flags, off):
         numpy_dtype = N.to_numpy_type(flags)
         return encode.GetVectorAsNumpy(numpy_dtype, self.Bytes, length, offset)
 
+    def GetArrayAsNumpy(self, flags, off, length):
+        """
+        GetArrayAsNumpy returns the array with fixed width that starts at `Vector(offset)`
+        with length `length` as a numpy array with the type specified by `flags`. The
+        array is a `view` into Bytes so modifying the returned will modify Bytes in place.
+        """
+        numpy_dtype = N.to_numpy_type(flags)
+        return encode.GetVectorAsNumpy(numpy_dtype, self.Bytes, length, off)
+
     def GetVOffsetTSlot(self, slot, d):
         """
         GetVOffsetTSlot retrieves the VOffsetT that the given vtable location
@@ -125,5 +134,5 @@ def GetVOffsetTSlot(self, slot, d):
 
         off = self.Offset(slot)
         if off == 0:
-                return d
+            return d
         return off

src/idl_gen_python.cpp

@@ -83,11 +83,11 @@ class PythonGenerator : public BaseGenerator {
 
   // Most field accessors need to retrieve and test the field offset first,
   // this is the prefix code for that.
-  std::string OffsetPrefix(const FieldDef &field) const {
+  std::string OffsetPrefix(const FieldDef &field, bool new_line = true) const {
     return "\n" + Indent + Indent +
            "o = flatbuffers.number_types.UOffsetTFlags.py_type" +
            "(self._tab.Offset(" + NumToString(field.value.offset) + "))\n" +
-           Indent + Indent + "if o != 0:\n";
+           Indent + Indent + "if o != 0:" + (new_line ? "\n" : "");
   }
 
   // Begin a class declaration.
@@ -164,9 +164,14 @@ class PythonGenerator : public BaseGenerator {
 
     GenReceiver(struct_def, code_ptr);
     code += namer_.Method(field) + "Length(self";
-    code += "):" + OffsetPrefix(field);
-    code += Indent + Indent + Indent + "return self._tab.VectorLen(o)\n";
-    code += Indent + Indent + "return 0\n\n";
+    code += "):";
+    if(!IsArray(field.value.type)){
+      code += OffsetPrefix(field,false);
+      code += GenIndents(3) + "return self._tab.VectorLen(o)";
+      code += GenIndents(2) + "return 0\n\n";
+    }else{
+      code += GenIndents(2) + "return "+NumToString(field.value.type.fixed_length)+"\n\n";
+    }
   }
 
   // Determines whether a vector is none or not.
@@ -177,10 +182,15 @@ class PythonGenerator : public BaseGenerator {
     GenReceiver(struct_def, code_ptr);
     code += namer_.Method(field) + "IsNone(self";
     code += "):";
-    code += GenIndents(2) +
-            "o = flatbuffers.number_types.UOffsetTFlags.py_type" +
-            "(self._tab.Offset(" + NumToString(field.value.offset) + "))";
-    code += GenIndents(2) + "return o == 0";
+    if(!IsArray(field.value.type)){
+      code += GenIndents(2) +
+              "o = flatbuffers.number_types.UOffsetTFlags.py_type" +
+              "(self._tab.Offset(" + NumToString(field.value.offset) + "))";
+      code += GenIndents(2) + "return o == 0";
+    } else {
+      //assume that we always have an array as memory is preassigned
+      code += GenIndents(2) + "return False";
+    }
     code += "\n\n";
   }
 
@@ -244,21 +254,40 @@ class PythonGenerator : public BaseGenerator {
     const auto vec_type = field.value.type.VectorType();
     GenReceiver(struct_def, code_ptr);
     code += namer_.Method(field);
-    if (IsStruct(vec_type)) {
-      code += "(self, obj, i):\n";
-      code += Indent + Indent + "obj.Init(self._tab.Bytes, self._tab.Pos + ";
-      code += NumToString(field.value.offset) + " + i * ";
-      code += NumToString(InlineSize(vec_type));
-      code += ")\n" + Indent + Indent + "return obj\n\n";
-    } else {
-      auto getter = GenGetter(vec_type);
-      code += "(self): return [" + getter;
-      code += "self._tab.Pos + flatbuffers.number_types.UOffsetTFlags.py_type(";
-      code += NumToString(field.value.offset) + " + i * ";
-      code += NumToString(InlineSize(vec_type));
-      code += ")) for i in range(";
-      code += NumToString(field.value.type.fixed_length) + ")]\n";
+    code += "(self, i: int):";
+    if (parser_.opts.include_dependence_headers) {
+      code += GenIndents(2);
+      code += "from " + GenPackageReference(field.value.type) + " import " +
+              TypeName(field);
     }
+    code += GenIndents(2) + "obj = " + TypeName(field) + "()";
+    code += GenIndents(2) + "obj.Init(self._tab.Bytes, self._tab.Pos + ";
+    code += NumToString(field.value.offset) + " + i * ";
+    code += NumToString(InlineSize(vec_type));
+    code += ")" + GenIndents(2) + "return obj\n\n";
+  }
+
+  // Get the value of a vector's non-struct member. Uses a named return
+  // argument to conveniently set the zero value for the result.
+  void GetArrayOfNonStruct(const StructDef &struct_def, const FieldDef &field,
+                           std::string *code_ptr) const {
+    auto &code = *code_ptr;
+    GenReceiver(struct_def, code_ptr);
+    code += namer_.Method(field);
+    code += "(self, j = None):";
+    code += GenIndents(2) + "if j==None:";
+    code += GenIndents(3) + "return [" + GenGetter(field.value.type);
+    code += "self._tab.Pos + flatbuffers.number_types.UOffsetTFlags.py_type(";
+    code += NumToString(field.value.offset) + " + i * ";
+    code += NumToString(InlineSize(field.value.type.VectorType()));
+    code += ")) for i in range(";
+    code += NumToString(field.value.type.fixed_length) + ")]";
+    code += GenIndents(2) +"else:";
+    code += GenIndents(3) + "return " + GenGetter(field.value.type);
+    code += "self._tab.Pos + flatbuffers.number_types.UOffsetTFlags.py_type(";
+    code += NumToString(field.value.offset) + " + j * ";
+    code += NumToString(InlineSize(field.value.type.VectorType()));
+    code += "))\n";
   }
 
   // Get a struct by initializing an existing struct.
@@ -403,18 +432,25 @@ class PythonGenerator : public BaseGenerator {
 
     GenReceiver(struct_def, code_ptr);
     code += namer_.Method(field) + "AsNumpy(self):";
-    code += OffsetPrefix(field);
+    if(!IsArray(field.value.type)){
+      code += OffsetPrefix(field, false);
 
-    code += Indent + Indent + Indent;
-    code += "return ";
-    code += "self._tab.GetVectorAsNumpy(flatbuffers.number_types.";
-    code += namer_.Method(GenTypeGet(field.value.type));
-    code += "Flags, o)\n";
+      code += GenIndents(3);
+      code += "return ";
+      code += "self._tab.GetVectorAsNumpy(flatbuffers.number_types.";
+      code += namer_.Method(GenTypeGet(field.value.type));
+      code += "Flags, o)";
 
-    if (IsString(vectortype)) {
-      code += Indent + Indent + "return \"\"\n";
-    } else {
-      code += Indent + Indent + "return 0\n";
+      if (IsString(vectortype)) {
+        code += GenIndents(2) + "return \"\"\n";
+      } else {
+        code += GenIndents(2) + "return 0\n";
+      }
+    }else{
+      code += GenIndents(2) + "return ";
+      code += "self._tab.GetArrayAsNumpy(flatbuffers.number_types.";
+      code += namer_.Method(GenTypeGet(field.value.type.VectorType()));
+      code += "Flags, self._tab.Pos + "+NumToString(field.value.offset)+", "+NumToString(field.value.type.VectorType().fixed_length)+")\n";
     }
     code += "\n";
   }
@@ -714,8 +750,6 @@ class PythonGenerator : public BaseGenerator {
       } else {
         GetScalarFieldOfTable(struct_def, field, code_ptr);
       }
-    } else if (IsArray(field.value.type)) {
-      GetArrayOfStruct(struct_def, field, code_ptr);
     } else {
       switch (field.value.type.base_type) {
         case BASE_TYPE_STRUCT:
@@ -739,6 +773,17 @@ class PythonGenerator : public BaseGenerator {
           }
           break;
         }
+        case BASE_TYPE_ARRAY: {
+          auto vectortype = field.value.type.VectorType();
+          if (vectortype.base_type == BASE_TYPE_STRUCT) {
+            GetArrayOfStruct(struct_def, field, code_ptr);
+          } else {
+            GetArrayOfNonStruct(struct_def, field, code_ptr);
+            GetVectorOfNonStructAsNumpy(struct_def, field, code_ptr);
+            GetVectorAsNestedFlatbuffer(struct_def, field, code_ptr);
+          }
+          break;
+        }
         case BASE_TYPE_UNION: GetUnionField(struct_def, field, code_ptr); break;
         default: FLATBUFFERS_ASSERT(0);
       }
@@ -1061,8 +1106,9 @@ class PythonGenerator : public BaseGenerator {
 
     code += GenIndents(1) + "@classmethod";
     code += GenIndents(1) + "def InitFromBuf(cls, buf, pos):";
+    code += GenIndents(2) + "n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, 0)";
     code += GenIndents(2) + struct_var + " = " + struct_type + "()";
-    code += GenIndents(2) + struct_var + ".Init(buf, pos)";
+    code += GenIndents(2) + struct_var + ".Init(buf, pos+n)";
     code += GenIndents(2) + "return cls.InitFromObj(" + struct_var + ")";
     code += "\n";
   }
@@ -1143,12 +1189,41 @@ class PythonGenerator : public BaseGenerator {
     auto field_type = TypeName(field);
     auto one_instance = field_type + "_";
     one_instance[0] = CharToLower(one_instance[0]);
-
     if (parser_.opts.include_dependence_headers) {
       auto package_reference = GenPackageReference(field.value.type);
       field_type = package_reference + "." + TypeName(field);
     }
+    code += GenIndents(4) + "if " + struct_var + "." + field_method +
+            "(i) is None:";
+    code += GenIndents(5) + "self." + field_field + ".append(None)";
+    code += GenIndents(4) + "else:";
+    code += GenIndents(5) + one_instance + " = " + field_type +
+            "T.InitFromObj(" + struct_var + "." + field_method + "(i))";
+    code +=
+        GenIndents(5) + "self." + field_field + ".append(" + one_instance + ")";
+  }
+
+  void GenUnpackForTableVector(const StructDef &struct_def,
+                               const FieldDef &field,
+                               std::string *code_ptr) const {
+    auto &code = *code_ptr;
+    const auto field_field = namer_.Field(field);
+    const auto field_method = namer_.Method(field);
+    const auto struct_var = namer_.Variable(struct_def);
+
+    code += GenIndents(2) + "if not " + struct_var + "." + field_method +
+            "IsNone():";
+    code += GenIndents(3) + "self." + field_field + " = []";
+    code += GenIndents(3) + "for i in range(" + struct_var + "." +
+            field_method + "Length()):";
 
+    auto field_type = TypeName(field);
+    auto one_instance = field_type + "_";
+    one_instance[0] = CharToLower(one_instance[0]);
+    if (parser_.opts.include_dependence_headers) {
+      auto package_reference = GenPackageReference(field.value.type);
+      field_type = package_reference + "." + TypeName(field);
+    }
     code += GenIndents(4) + "if " + struct_var + "." + field_method +
             "(i) is None:";
     code += GenIndents(5) + "self." + field_field + ".append(None)";
@@ -1233,6 +1308,7 @@ class PythonGenerator : public BaseGenerator {
           GenUnPackForUnion(struct_def, field, &code);
           break;
         }
+        case BASE_TYPE_ARRAY:
         case BASE_TYPE_VECTOR: {
           auto vectortype = field.value.type.VectorType();
           if (vectortype.base_type == BASE_TYPE_STRUCT) {
@@ -1242,10 +1318,6 @@ class PythonGenerator : public BaseGenerator {
           }
           break;
         }
-        case BASE_TYPE_ARRAY: {
-          GenUnPackForScalarVector(struct_def, field, &code);
-          break;
-        }
         default: GenUnPackForScalar(struct_def, field, &code);
       }
     }
@@ -1482,6 +1554,7 @@ class PythonGenerator : public BaseGenerator {
           GenPackForUnionField(struct_def, field, &code_prefix, &code);
           break;
         }
+        case BASE_TYPE_ARRAY:
         case BASE_TYPE_VECTOR: {
           auto vectortype = field.value.type.VectorType();
           if (vectortype.base_type == BASE_TYPE_STRUCT) {
@@ -1491,10 +1564,6 @@ class PythonGenerator : public BaseGenerator {
           }
           break;
         }
-        case BASE_TYPE_ARRAY: {
-          GenPackForScalarVectorField(struct_def, field, &code_prefix, &code);
-          break;
-        }
         case BASE_TYPE_STRING: {
           code_prefix +=
               GenIndents(2) + "if self." + field_field + " is not None:";
@@ -1667,6 +1736,7 @@ class PythonGenerator : public BaseGenerator {
     switch (type.base_type) {
       case BASE_TYPE_STRING: return "string";
       case BASE_TYPE_VECTOR: return GenTypeGet(type.VectorType());
+      case BASE_TYPE_ARRAY: return GenTypeGet(type.VectorType());
       case BASE_TYPE_STRUCT: return type.struct_def->name;
       case BASE_TYPE_UNION:
         // fall through

src/util.cpp

@@ -109,7 +109,7 @@ static std::string ToSnakeCase(const std::string &input, bool screaming) {
     } else if (!islower(input[i])) {
       // Prevent duplicate underscores for Upper_Snake_Case strings
       // and UPPERCASE strings.
-      if (islower(input[i - 1])) { s += '_'; }
+      if (islower(input[i - 1]) || (isdigit(input[i-1]) && !isdigit(input[i]))) { s += '_'; }
       s += screaming ? CharToUpper(input[i]) : CharToLower(input[i]);
     } else {
       s += screaming ? CharToUpper(input[i]) : input[i];

tests/MyGame/Example/Ability.py

@@ -38,8 +38,9 @@ def __init__(self):
 
     @classmethod
     def InitFromBuf(cls, buf, pos):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, 0)
         ability = Ability()
-        ability.Init(buf, pos)
+        ability.Init(buf, pos+n)
         return cls.InitFromObj(ability)
 
     @classmethod