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package hcl
import (
// File is the top-level node that results from parsing a HCL file.
type File struct {
Body Body
Bytes []byte
// Nav is used to integrate with the "hcled" editor integration package,
// and with diagnostic information formatters. It is not for direct use
// by a calling application.
Nav interface{}
// Block represents a nested block within a Body.
type Block struct {
Type string
Labels []string
Body Body
DefRange Range // Range that can be considered the "definition" for seeking in an editor
TypeRange Range // Range for the block type declaration specifically.
LabelRanges []Range // Ranges for the label values specifically.
// Blocks is a sequence of Block.
type Blocks []*Block
// Attributes is a set of attributes keyed by their names.
type Attributes map[string]*Attribute
// Body is a container for attributes and blocks. It serves as the primary
// unit of heirarchical structure within configuration.
// The content of a body cannot be meaningfully intepreted without a schema,
// so Body represents the raw body content and has methods that allow the
// content to be extracted in terms of a given schema.
type Body interface {
// Content verifies that the entire body content conforms to the given
// schema and then returns it, and/or returns diagnostics. The returned
// body content is valid if non-nil, regardless of whether Diagnostics
// are provided, but diagnostics should still be eventually shown to
// the user.
Content(schema *BodySchema) (*BodyContent, Diagnostics)
// PartialContent is like Content except that it permits the configuration
// to contain additional blocks or attributes not specified in the
// schema. If any are present, the returned Body is non-nil and contains
// the remaining items from the body that were not selected by the schema.
PartialContent(schema *BodySchema) (*BodyContent, Body, Diagnostics)
// JustAttributes attempts to interpret all of the contents of the body
// as attributes, allowing for the contents to be accessed without a priori
// knowledge of the structure.
// The behavior of this method depends on the body's source language.
// Some languages, like JSON, can't distinguish between attributes and
// blocks without schema hints, but for languages that _can_ error
// diagnostics will be generated if any blocks are present in the body.
// Diagnostics may be produced for other reasons too, such as duplicate
// declarations of the same attribute.
JustAttributes() (Attributes, Diagnostics)
// MissingItemRange returns a range that represents where a missing item
// might hypothetically be inserted. This is used when producing
// diagnostics about missing required attributes or blocks. Not all bodies
// will have an obvious single insertion point, so the result here may
// be rather arbitrary.
MissingItemRange() Range
// BodyContent is the result of applying a BodySchema to a Body.
type BodyContent struct {
Attributes Attributes
Blocks Blocks
MissingItemRange Range
// Attribute represents an attribute from within a body.
type Attribute struct {
Name string
Expr Expression
Range Range
NameRange Range
// Expression is a literal value or an expression provided in the
// configuration, which can be evaluated within a scope to produce a value.
type Expression interface {
// Value returns the value resulting from evaluating the expression
// in the given evaluation context.
// The context may be nil, in which case the expression may contain
// only constants and diagnostics will be produced for any non-constant
// sub-expressions. (The exact definition of this depends on the source
// language.)
// The context may instead be set but have either its Variables or
// Functions maps set to nil, in which case only use of these features
// will return diagnostics.
// Different diagnostics are provided depending on whether the given
// context maps are nil or empty. In the former case, the message
// tells the user that variables/functions are not permitted at all,
// while in the latter case usage will produce a "not found" error for
// the specific symbol in question.
Value(ctx *EvalContext) (cty.Value, Diagnostics)
// Variables returns a list of variables referenced in the receiving
// expression. These are expressed as absolute Traversals, so may include
// additional information about how the variable is used, such as
// attribute lookups, which the calling application can potentially use
// to only selectively populate the scope.
Variables() []Traversal
Range() Range
StartRange() Range
// OfType filters the receiving block sequence by block type name,
// returning a new block sequence including only the blocks of the
// requested type.
func (els Blocks) OfType(typeName string) Blocks {
ret := make(Blocks, 0)
for _, el := range els {
if el.Type == typeName {
ret = append(ret, el)
return ret
// ByType transforms the receiving block sequence into a map from type
// name to block sequences of only that type.
func (els Blocks) ByType() map[string]Blocks {
ret := make(map[string]Blocks)
for _, el := range els {
ty := el.Type
if ret[ty] == nil {
ret[ty] = make(Blocks, 0, 1)
ret[ty] = append(ret[ty], el)
return ret
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