terraform/configs/parser.go

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package configs
import (
"fmt"
"strings"
"github.com/hashicorp/hcl2/hcl"
"github.com/hashicorp/hcl2/hclparse"
"github.com/spf13/afero"
)
// Parser is the main interface to read configuration files and other related
// files from disk.
//
// It retains a cache of all files that are loaded so that they can be used
// to create source code snippets in diagnostics, etc.
type Parser struct {
fs afero.Afero
p *hclparse.Parser
}
// NewParser creates and returns a new Parser that reads files from the given
// filesystem. If a nil filesystem is passed then the system's "real" filesystem
// will be used, via afero.OsFs.
func NewParser(fs afero.Fs) *Parser {
if fs == nil {
fs = afero.OsFs{}
}
return &Parser{
fs: afero.Afero{Fs: fs},
p: hclparse.NewParser(),
}
}
// LoadHCLFile is a low-level method that reads the file at the given path,
// parses it, and returns the hcl.Body representing its root. In many cases
// it is better to use one of the other Load*File methods on this type,
// which additionally decode the root body in some way and return a higher-level
// construct.
//
// If the file cannot be read at all -- e.g. because it does not exist -- then
// this method will return a nil body and error diagnostics. In this case
// callers may wish to ignore the provided error diagnostics and produce
// a more context-sensitive error instead.
//
// The file will be parsed using the HCL native syntax unless the filename
// ends with ".json", in which case the HCL JSON syntax will be used.
func (p *Parser) LoadHCLFile(path string) (hcl.Body, hcl.Diagnostics) {
src, err := p.fs.ReadFile(path)
if err != nil {
return nil, hcl.Diagnostics{
{
Severity: hcl.DiagError,
Summary: "Failed to read file",
Detail: fmt.Sprintf("The file %q could not be read.", path),
},
}
}
var file *hcl.File
var diags hcl.Diagnostics
switch {
case strings.HasSuffix(path, ".json"):
file, diags = p.p.ParseJSON(src, path)
default:
file, diags = p.p.ParseHCL(src, path)
}
// If the returned file or body is nil, then we'll return a non-nil empty
// body so we'll meet our contract that nil means an error reading the file.
if file == nil || file.Body == nil {
return hcl.EmptyBody(), diags
}
return file.Body, diags
}
// Sources returns a map of the cached source buffers for all files that
// have been loaded through this parser, with source filenames (as requested
// when each file was opened) as the keys.
func (p *Parser) Sources() map[string][]byte {
return p.p.Sources()
}
// ForceFileSource artificially adds source code to the cache of file sources,
// as if it had been loaded from the given filename.
//
// This should be used only in special situations where configuration is loaded
// some other way. Most callers should load configuration via methods of
// Parser, which will update the sources cache automatically.
func (p *Parser) ForceFileSource(filename string, src []byte) {
// We'll make a synthetic hcl.File here just so we can reuse the
// existing cache.
p.p.AddFile(filename, &hcl.File{
Body: hcl.EmptyBody(),
Bytes: src,
})
}