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Implement Rust object API defaults (#6444)

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* Implment Rust object API defaults

* satisfy return analysis

* git clang format

Co-authored-by: Casper Neo <cneo@google.com>
This commit is contained in:
Casper
2021-02-07 16:51:33 -05:00
committed by GitHub
parent 815d3e820d
commit 6f3e45eca1
8 changed files with 403 additions and 32 deletions
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75
src/idl_gen_rust.cpp
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@@ -883,31 +883,60 @@ class RustGenerator : public BaseGenerator {
return "VT_" + MakeUpper(Name(field));
}
std::string GetDefaultScalarValue(const FieldDef &field) {
std::string GetDefaultValue(const FieldDef &field, bool for_builder) {
if (for_builder) {
// Builders and Args structs model nonscalars "optional" even if they're
// required or have defaults according to the schema. I guess its because
// WIPOffset is not nullable.
if (!IsScalar(field.value.type.base_type) || field.IsOptional()) {
return "None";
}
} else {
// This for defaults in objects.
// Unions have a NONE variant instead of using Rust's None.
if (field.IsOptional() && !IsUnion(field.value.type)) { return "None"; }
}
switch (GetFullType(field.value.type)) {
case ftInteger:
case ftFloat: {
return field.IsOptional() ? "None" : field.value.constant;
return field.value.constant;
}
case ftBool: {
return field.IsOptional() ? "None"
: field.value.constant == "0" ? "false" : "true";
return field.value.constant == "0" ? "false" : "true";
}
case ftUnionKey:
case ftEnumKey: {
if (field.IsOptional()) { return "None"; }
auto ev = field.value.type.enum_def->FindByValue(field.value.constant);
if (!ev) return "Default::default()"; // Bitflags enum.
return WrapInNameSpace(field.value.type.enum_def->defined_namespace,
GetEnumValue(*field.value.type.enum_def, *ev));
}
// All pointer-ish types have a default value of None, because they are
// wrapped in Option.
default: {
return "None";
case ftUnionValue: {
return ObjectFieldType(field, true) + "::NONE";
}
case ftString: {
// Required strings.
return "String::new()"; // No default strings yet.
}
case ftVectorOfBool:
case ftVectorOfFloat:
case ftVectorOfInteger:
case ftVectorOfString:
case ftVectorOfStruct:
case ftVectorOfTable:
case ftVectorOfEnumKey:
case ftVectorOfUnionValue: {
// Required vectors.
return "Vec::new()"; // No default strings yet.
}
case ftStruct:
case ftTable: {
// Required struct/tables.
return "Default::default()"; // punt.
}
}
FLATBUFFERS_ASSERT("Unreachable.");
return "INVALID_CODE_GENERATION";
}
// Create the return type for fields in the *BuilderArgs structs that are
@@ -1138,14 +1167,14 @@ class RustGenerator : public BaseGenerator {
case ftFloat: {
const auto typname = GetTypeBasic(field.value.type);
return (field.IsOptional() ? "self.fbb_.push_slot_always::<"
: "self.fbb_.push_slot::<") +
: "self.fbb_.push_slot::<") +
typname + ">";
}
case ftEnumKey:
case ftUnionKey: {
const auto underlying_typname = GetTypeBasic(type);
return (field.IsOptional() ? "self.fbb_.push_slot_always::<"
: "self.fbb_.push_slot::<") +
: "self.fbb_.push_slot::<") +
underlying_typname + ">";
}
@@ -1325,7 +1354,7 @@ class RustGenerator : public BaseGenerator {
// Default-y fields (scalars so far) are neither optional nor required.
const std::string default_value =
!(field.IsOptional() || field.IsRequired())
? "Some(" + GetDefaultScalarValue(field) + ")"
? "Some(" + GetDefaultValue(field, /*builder=*/true) + ")"
: "None";
const std::string unwrap = field.IsOptional() ? "" : ".unwrap()";
@@ -1396,7 +1425,7 @@ class RustGenerator : public BaseGenerator {
code_.SetValue("OFFSET_NAME", GetFieldOffsetName(field));
code_.SetValue("OFFSET_VALUE", NumToString(field.value.offset));
code_.SetValue("FIELD_NAME", Name(field));
code_.SetValue("DEFAULT_VALUE", GetDefaultScalarValue(field));
code_.SetValue("BLDR_DEF_VAL", GetDefaultValue(field, /*builder=*/true));
cb(field);
};
const auto &fields = struct_def.fields.vec;
@@ -1769,7 +1798,7 @@ class RustGenerator : public BaseGenerator {
code_ += " fn default() -> Self {";
code_ += " {{STRUCT_NAME}}Args {";
ForAllTableFields(struct_def, [&](const FieldDef &field) {
code_ += " {{FIELD_NAME}}: {{DEFAULT_VALUE}},\\";
code_ += " {{FIELD_NAME}}: {{BLDR_DEF_VAL}},\\";
code_ += field.IsRequired() ? " // required field" : "";
});
code_ += " }";
@@ -1810,7 +1839,7 @@ class RustGenerator : public BaseGenerator {
if (is_scalar && !field.IsOptional()) {
code_ +=
" {{FUNC_BODY}}({{FIELD_OFFSET}}, {{FIELD_NAME}}, "
"{{DEFAULT_VALUE}});";
"{{BLDR_DEF_VAL}});";
} else {
code_ += " {{FUNC_BODY}}({{FIELD_OFFSET}}, {{FIELD_NAME}});";
}
@@ -1899,7 +1928,7 @@ class RustGenerator : public BaseGenerator {
// Generate the native object.
code_ += "#[non_exhaustive]";
code_ += "#[derive(Debug, Clone, PartialEq, Default)]";
code_ += "#[derive(Debug, Clone, PartialEq)]";
code_ += "pub struct {{OBJECT_NAME}} {";
ForAllObjectTableFields(table, [&](const FieldDef &field) {
// Union objects combine both the union discriminant and value, so we
@@ -1909,6 +1938,18 @@ class RustGenerator : public BaseGenerator {
});
code_ += "}";
code_ += "impl Default for {{OBJECT_NAME}} {";
code_ += " fn default() -> Self {";
code_ += " Self {";
ForAllObjectTableFields(table, [&](const FieldDef &field) {
if (field.value.type.base_type == BASE_TYPE_UTYPE) return;
std::string default_value = GetDefaultValue(field, /*builder=*/false);
code_ += " {{FIELD_NAME}}: " + default_value + ",";
});
code_ += " }";
code_ += " }";
code_ += "}";
// TODO(cneo): Generate defaults for Native tables. However, since structs
// may be required, they, and therefore enums need defaults.