77 lines
3.5 KiB
Go
77 lines
3.5 KiB
Go
// Copyright 2016-2017, Pulumi Corporation
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package encoding can unmarshal LumiPack and LumiIL metadata formats. Because of their complex structure, we cannot
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// rely on the standard JSON marshaling and unmarshaling routines. Instead, we will need to do it mostly "by hand".
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package encoding
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import (
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"reflect"
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"github.com/pulumi/lumi/pkg/compiler/ast"
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"github.com/pulumi/lumi/pkg/pack"
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"github.com/pulumi/lumi/pkg/util/mapper"
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)
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// Decode unmarshals the entire contents of the given byte array into a Package object.
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func Decode(m Marshaler, b []byte) (*pack.Package, error) {
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// First convert the whole contents of the metadata into a map. Although it would be more efficient to walk the
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// token stream, token by token, this allows us to reuse existing YAML packages in addition to JSON ones.
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var obj map[string]interface{}
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if err := m.Unmarshal(b, &obj); err != nil {
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return nil, err
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}
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// Now decode the top-level Package metadata; this will automatically recurse throughout the whole structure.
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md := mapper.New(&mapper.Opts{CustomDecoders: customDecoders()})
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var pack pack.Package
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if err := md.Decode(obj, &pack); err != nil {
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return nil, err
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}
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return &pack, nil
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}
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// customDecoders makes a complete map of all known custom AST decoders. In general, any polymorphic node kind that
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// appears as a field in another concrete marshalable structure must have an associated custom decoder. If not, the
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// Mapper will error out. This is typically an interface type and that method typically switches on the kind property.
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// Note that interfaces that are used as "markers" and don't show up in fields are okay and don't require a decoder.
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func customDecoders() mapper.Decoders {
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return mapper.Decoders{
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reflect.TypeOf((*ast.ModuleMember)(nil)).Elem(): moduleMemberDecoder,
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reflect.TypeOf((*ast.ClassMember)(nil)).Elem(): classMemberDecoder,
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reflect.TypeOf((*ast.Statement)(nil)).Elem(): statementDecoder,
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reflect.TypeOf((*ast.Expression)(nil)).Elem(): expressionDecoder,
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reflect.TypeOf((*ast.ObjectLiteralProperty)(nil)).Elem(): objectLiteralPropertyDecoder,
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}
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}
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// Each of the custom decoders is a variable that points to a decoder function; this is done so that the decode*
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// functions can remain strongly typed, as the mapper's decoder signature requires a weakly-typed interface{} return.
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var moduleMemberDecoder = func(m mapper.Mapper, obj map[string]interface{}) (interface{}, error) {
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return decodeModuleMember(m, obj)
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}
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var classMemberDecoder = func(m mapper.Mapper, obj map[string]interface{}) (interface{}, error) {
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return decodeClassMember(m, obj)
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}
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var statementDecoder = func(m mapper.Mapper, obj map[string]interface{}) (interface{}, error) {
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return decodeStatement(m, obj)
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}
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var expressionDecoder = func(m mapper.Mapper, obj map[string]interface{}) (interface{}, error) {
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return decodeExpression(m, obj)
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}
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var objectLiteralPropertyDecoder = func(m mapper.Mapper, obj map[string]interface{}) (interface{}, error) {
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return decodeObjectLiteralProperty(m, obj)
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}
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