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package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"github.com/nihei9/vartan/driver"
"github.com/nihei9/vartan/spec"
"github.com/spf13/cobra"
)
var lexFlags = struct {
source *string
}{}
func init() {
cmd := &cobra.Command{
Use: "parse <grammar file path>",
Short: "Parse a text stream",
Example: ` cat src | vartan parse grammar.json`,
Args: cobra.ExactArgs(1),
RunE: runParse,
}
lexFlags.source = cmd.Flags().StringP("source", "s", "", "source file path (default stdin)")
rootCmd.AddCommand(cmd)
}
func runParse(cmd *cobra.Command, args []string) (retErr error) {
defer func() {
v := recover()
if v != nil {
err, ok := v.(error)
if !ok {
retErr = fmt.Errorf("an unexpected error occurred: %v\n", v)
fmt.Fprintln(os.Stderr, retErr)
return
}
retErr = err
}
if retErr != nil {
fmt.Fprintln(os.Stderr, retErr)
}
}()
cgram, err := readCompiledGrammar(args[0])
if err != nil {
return fmt.Errorf("Cannot read a compiled grammar: %w", err)
}
var p *driver.Parser
{
src := os.Stdin
if *lexFlags.source != "" {
f, err := os.Open(*lexFlags.source)
if err != nil {
return fmt.Errorf("Cannot open the source file %s: %w", *lexFlags.source, err)
}
defer f.Close()
src = f
}
p, err = driver.NewParser(cgram, src)
if err != nil {
return err
}
}
err = p.Parse()
if err != nil {
return err
}
fmt.Printf("Accepted\n")
driver.PrintTree(os.Stdout, p.AST())
return nil
}
func readCompiledGrammar(path string) (*spec.CompiledGrammar, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
data, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
cgram := &spec.CompiledGrammar{}
err = json.Unmarshal(data, cgram)
if err != nil {
return nil, err
}
return cgram, nil
}
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