terraform/command/jsonconfig/expression.go

120 lines
4.1 KiB
Go

package jsonconfig
import (
"encoding/json"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/hcl2/hcldec"
"github.com/hashicorp/terraform/configs/configschema"
"github.com/hashicorp/terraform/lang"
"github.com/zclconf/go-cty/cty"
ctyjson "github.com/zclconf/go-cty/cty/json"
)
// expression represents any unparsed expression
type expression struct {
// "constant_value" is set only if the expression contains no references to
// other objects, in which case it gives the resulting constant value. This
// is mapped as for the individual values in the common value
// representation.
ConstantValue json.RawMessage `json:"constant_value,omitempty"`
// Alternatively, "references" will be set to a list of references in the
// expression. Multi-step references will be unwrapped and duplicated for
// each significant traversal step, allowing callers to more easily
// recognize the objects they care about without attempting to parse the
// expressions. Callers should only use string equality checks here, since
// the syntax may be extended in future releases.
References []string `json:"references,omitempty"`
}
func marshalExpression(ex hcl.Expression) expression {
var ret expression
if ex != nil {
val, _ := ex.Value(nil)
if val != cty.NilVal {
valJSON, _ := ctyjson.Marshal(val, val.Type())
ret.ConstantValue = valJSON
}
vars, _ := lang.ReferencesInExpr(ex)
var varString []string
if len(vars) > 0 {
for _, v := range vars {
varString = append(varString, v.Subject.String())
}
ret.References = varString
}
return ret
}
return ret
}
func (e *expression) Empty() bool {
return e.ConstantValue == nil && e.References == nil
}
// expressions is used to represent the entire content of a block. Attribute
// arguments are mapped directly with the attribute name as key and an
// expression as value.
type expressions map[string]interface{}
func marshalExpressions(body hcl.Body, schema *configschema.Block) expressions {
// Since we want the raw, un-evaluated expressions we need to use the
// low-level HCL API here, rather than the hcldec decoder API. That means we
// need the low-level schema.
lowSchema := hcldec.ImpliedSchema(schema.DecoderSpec())
// (lowSchema is an hcl.BodySchema:
// https://godoc.org/github.com/hashicorp/hcl2/hcl#BodySchema )
// Use the low-level schema with the body to decode one level We'll just
// ignore any additional content that's not covered by the schema, which
// will effectively ignore "dynamic" blocks, and may also ignore other
// unknown stuff but anything else would get flagged by Terraform as an
// error anyway, and so we wouldn't end up in here.
content, _, _ := body.PartialContent(lowSchema)
if content == nil {
// Should never happen for a valid body, but we'll just generate empty
// if there were any problems.
return nil
}
ret := make(expressions)
// Any attributes we encode directly as expression objects.
for name, attr := range content.Attributes {
ret[name] = marshalExpression(attr.Expr) // note: singular expression for this one
}
// Any nested blocks require a recursive call to produce nested expressions
// objects.
for _, block := range content.Blocks {
typeName := block.Type
blockS, exists := schema.BlockTypes[typeName]
if !exists {
// Should never happen since only block types in the schema would be
// put in blocks list
continue
}
switch blockS.Nesting {
case configschema.NestingSingle:
ret[typeName] = marshalExpressions(block.Body, &blockS.Block)
case configschema.NestingList, configschema.NestingSet:
if _, exists := ret[typeName]; !exists {
ret[typeName] = make([]map[string]interface{}, 0, 1)
}
ret[typeName] = append(ret[typeName].([]map[string]interface{}), marshalExpressions(block.Body, &blockS.Block))
case configschema.NestingMap:
if _, exists := ret[typeName]; !exists {
ret[typeName] = make(map[string]map[string]interface{})
}
// NestingMap blocks always have the key in the first (and only) label
key := block.Labels[0]
retMap := ret[typeName].(map[string]map[string]interface{})
retMap[key] = marshalExpressions(block.Body, &blockS.Block)
}
}
return ret
}