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package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"runtime/debug"
"github.com/nihei9/vartan/driver"
"github.com/nihei9/vartan/spec"
"github.com/spf13/cobra"
)
var parseFlags = struct {
source *string
onlyParse *bool
cst *bool
}{}
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,
}
parseFlags.source = cmd.Flags().StringP("source", "s", "", "source file path (default stdin)")
parseFlags.onlyParse = cmd.Flags().Bool("only-parse", false, "when this option is enabled, the parser performs only parse and doesn't semantic actions")
parseFlags.cst = cmd.Flags().Bool("cst", false, "when this option is enabled, the parser generates a CST")
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", v)
fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
return
}
retErr = err
}
if retErr != nil {
fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
}
}()
if *parseFlags.onlyParse && *parseFlags.cst {
return fmt.Errorf("You cannot enable --only-parse and --cst at the same time")
}
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 *parseFlags.source != "" {
f, err := os.Open(*parseFlags.source)
if err != nil {
return fmt.Errorf("Cannot open the source file %s: %w", *parseFlags.source, err)
}
defer f.Close()
src = f
}
var opts []driver.ParserOption
switch {
case *parseFlags.cst:
opts = append(opts, driver.MakeCST())
case !*parseFlags.onlyParse:
opts = append(opts, driver.MakeAST())
}
p, err = driver.NewParser(cgram, src, opts...)
if err != nil {
return err
}
}
err = p.Parse()
if err != nil {
return err
}
if !*parseFlags.onlyParse {
var tree *driver.Node
if *parseFlags.cst {
tree = p.CST()
} else {
tree = p.AST()
}
driver.PrintTree(os.Stdout, tree)
}
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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