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parser.go
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/
parser.go
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package parse
import (
"errors"
"io"
"github.com/fission/fission-workflows/pkg/parse/protobuf"
"github.com/fission/fission-workflows/pkg/parse/yaml"
"github.com/fission/fission-workflows/pkg/types"
"github.com/sirupsen/logrus"
)
var (
DefaultParser = NewMetaParser(map[string]Parser{
"yaml": yaml.DefaultParser,
"pb": protobuf.DefaultParser,
})
)
type Parser interface {
Parse(r io.Reader) (*types.WorkflowSpec, error)
}
func Parse(r io.Reader) (*types.WorkflowSpec, error) {
return DefaultParser.Parse(r)
}
func ParseWith(r io.Reader, parsers ...string) (*types.WorkflowSpec, error) {
return DefaultParser.ParseWith(r, parsers...)
}
func Supports(parser string) bool {
return DefaultParser.Supports(parser)
}
func Parsers() []string {
return DefaultParser.Parsers()
}
type MetaParser struct {
parsers map[string]Parser
}
func NewMetaParser(parsers map[string]Parser) *MetaParser {
return &MetaParser{
parsers: parsers,
}
}
func (mp *MetaParser) Parse(r io.Reader) (*types.WorkflowSpec, error) {
return mp.ParseWith(r, mp.Parsers()...)
}
func (mp *MetaParser) ParseWith(r io.Reader, parsers ...string) (*types.WorkflowSpec, error) {
if parsers == nil {
return nil, errors.New("no parsers provided")
}
var result *types.WorkflowSpec
for _, name := range parsers {
p, ok := mp.parsers[name]
if !ok {
continue
}
wf, err := p.Parse(r)
if err != nil {
logrus.WithField("parser", name).Warnf("parser failed: %v", err)
wf = nil
continue
}
result = wf
break
}
var err error
if result == nil {
err = errors.New("failed to parse workflow")
}
return result, err
}
func (mp *MetaParser) Supports(s string) bool {
_, ok := mp.parsers[s]
return ok
}
func (mp *MetaParser) Parsers() []string {
ps := make([]string, len(mp.parsers))
var i int
for name := range mp.parsers {
ps[i] = name
i++
}
return ps
}