diff options
Diffstat (limited to 'cmd/vartan/describe.go')
| -rw-r--r-- | cmd/vartan/describe.go | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/cmd/vartan/describe.go b/cmd/vartan/describe.go new file mode 100644 index 0000000..d9c3b01 --- /dev/null +++ b/cmd/vartan/describe.go @@ -0,0 +1,241 @@ +package main + +import ( + "encoding/json" + "fmt" + "io" + "io/ioutil" + "os" + "runtime/debug" + "strings" + "text/template" + + "github.com/nihei9/vartan/spec" + "github.com/spf13/cobra" +) + +var describeFlags = struct { +}{} + +func init() { + cmd := &cobra.Command{ + Use: "describe", + Short: "Print a description file in readable format", + Example: ` vartan describe grammar-description.json`, + Args: cobra.ExactArgs(1), + RunE: runDescribe, + } + rootCmd.AddCommand(cmd) +} + +func runDescribe(cmd *cobra.Command, args []string) (retErr error) { + defer func() { + panicked := false + v := recover() + if v != nil { + err, ok := v.(error) + if !ok { + retErr = fmt.Errorf("an unexpected error occurred: %v", v) + fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack())) + return + } + + retErr = err + panicked = true + } + + if retErr != nil { + if panicked { + fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack())) + } else { + fmt.Fprintf(os.Stderr, "%v\n", retErr) + } + } + }() + + desc, err := readDescription(args[0]) + if err != nil { + return err + } + + err = writeDescription(os.Stdout, desc) + if err != nil { + return err + } + + return nil +} + +func readDescription(path string) (*spec.Description, error) { + f, err := os.Open(path) + if err != nil { + return nil, fmt.Errorf("Cannot open the description file %s: %w", path, err) + } + defer f.Close() + + d, err := ioutil.ReadAll(f) + if err != nil { + return nil, err + } + + desc := &spec.Description{} + err = json.Unmarshal(d, desc) + if err != nil { + return nil, err + } + + return desc, nil +} + +const descTemplate = `# Conflicts + +{{ printConflictSummary . }} + +# Terminals + +{{ range slice .Terminals 1 -}} +{{ printTerminal . }} +{{ end }} +# Productions + +{{ range slice .Productions 1 -}} +{{ printProduction . }} +{{ end }} +# States +{{ range .States }} +## State {{ .Number }} + +{{ range .Kernel -}} +{{ printItem . }} +{{ end }} +{{ range .Shift -}} +{{ printShift . }} +{{ end -}} +{{ range .Reduce -}} +{{ printReduce . }} +{{ end -}} +{{ range .GoTo -}} +{{ printGoTo . }} +{{ end }} +{{ range .SRConflict -}} +{{ printSRConflict . }} +{{ end -}} +{{ range .RRConflict -}} +{{ printRRConflict . }} +{{ end -}} +{{ end }}` + +func writeDescription(w io.Writer, desc *spec.Description) error { + termName := func(sym int) string { + if desc.Terminals[sym].Alias != "" { + return desc.Terminals[sym].Alias + } + return desc.Terminals[sym].Name + } + + nonTermName := func(sym int) string { + return desc.NonTerminals[sym].Name + } + + fns := template.FuncMap{ + "printConflictSummary": func(desc *spec.Description) string { + count := 0 + for _, s := range desc.States { + count += len(s.SRConflict) + count += len(s.RRConflict) + } + + if count == 1 { + return fmt.Sprintf("1 conflict was detected.") + } else if count > 1 { + return fmt.Sprintf("%v conflicts were detected.", count) + } + return "No conflict was detected." + }, + "printTerminal": func(term spec.Terminal) string { + if term.Alias != "" { + return fmt.Sprintf("%4v %v (%v)", term.Number, term.Name, term.Alias) + } + return fmt.Sprintf("%4v %v", term.Number, term.Name) + }, + "printProduction": func(prod spec.Production) string { + var b strings.Builder + fmt.Fprintf(&b, "%v →", nonTermName(prod.LHS)) + if len(prod.RHS) > 0 { + for _, e := range prod.RHS { + if e > 0 { + fmt.Fprintf(&b, " %v", termName(e)) + } else { + fmt.Fprintf(&b, " %v", nonTermName(e*-1)) + } + } + } else { + fmt.Fprintf(&b, " ε") + } + + return fmt.Sprintf("%4v %v", prod.Number, b.String()) + }, + "printItem": func(item spec.Item) string { + prod := desc.Productions[item.Production] + + var b strings.Builder + fmt.Fprintf(&b, "%v →", nonTermName(prod.LHS)) + for i, e := range prod.RHS { + if i == item.Dot { + fmt.Fprintf(&b, " ・") + } + if e > 0 { + fmt.Fprintf(&b, " %v", termName(e)) + } else { + fmt.Fprintf(&b, " %v", nonTermName(e*-1)) + } + } + if item.Dot >= len(prod.RHS) { + fmt.Fprintf(&b, " ・") + } + + return fmt.Sprintf("%4v %v", prod.Number, b.String()) + }, + "printShift": func(tran spec.Transition) string { + return fmt.Sprintf("shift %4v on %v", tran.State, termName(tran.Symbol)) + }, + "printReduce": func(reduce spec.Reduce) string { + var b strings.Builder + { + fmt.Fprintf(&b, "%v", termName(reduce.LookAhead[0])) + for _, a := range reduce.LookAhead[1:] { + fmt.Fprintf(&b, ", %v", termName(a)) + } + } + return fmt.Sprintf("reduce %4v on %v", reduce.Production, b.String()) + }, + "printGoTo": func(tran spec.Transition) string { + return fmt.Sprintf("goto %4v on %v", tran.State, nonTermName(tran.Symbol)) + }, + "printSRConflict": func(sr spec.SRConflict) string { + var adopted string + switch { + case sr.AdoptedState != nil: + adopted = fmt.Sprintf("shift %v", *sr.AdoptedState) + case sr.AdoptedProduction != nil: + adopted = fmt.Sprintf("reduce %v", *sr.AdoptedProduction) + } + return fmt.Sprintf("shift/reduce conflict (shift %v, reduce %v) on %v: %v adopted", sr.State, sr.Production, termName(sr.Symbol), adopted) + }, + "printRRConflict": func(rr spec.RRConflict) string { + return fmt.Sprintf("reduce/reduce conflict (%v, %v) on %v: reduce %v adopted", rr.Production1, rr.Production2, termName(rr.Symbol), rr.AdoptedProduction) + }, + } + + tmpl, err := template.New("").Funcs(fns).Parse(descTemplate) + if err != nil { + return err + } + + err = tmpl.Execute(w, desc) + if err != nil { + return err + } + + return nil +} |