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|
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"runtime/debug"
"strings"
verr "github.com/nihei9/vartan/error"
"github.com/nihei9/vartan/grammar"
"github.com/nihei9/vartan/spec"
"github.com/spf13/cobra"
)
var compileFlags = struct {
grammar *string
output *string
class *string
}{}
func init() {
cmd := &cobra.Command{
Use: "compile",
Short: "Compile a grammar into a parsing table",
Example: ` cat grammar | vartan compile -o grammar.json`,
RunE: runCompile,
}
compileFlags.grammar = cmd.Flags().StringP("grammar", "g", "", "grammar file path (default stdin)")
compileFlags.output = cmd.Flags().StringP("output", "o", "", "output file path (default stdout)")
compileFlags.class = cmd.Flags().StringP("class", "", "lalr", "LALR or SLR")
rootCmd.AddCommand(cmd)
}
func runCompile(cmd *cobra.Command, args []string) (retErr error) {
var tmpDirPath string
defer func() {
if tmpDirPath == "" {
return
}
os.RemoveAll(tmpDirPath)
}()
grmPath := *compileFlags.grammar
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 {
specErrs, ok := retErr.(verr.SpecErrors)
if ok {
for _, err := range specErrs {
if *compileFlags.grammar != "" {
err.FilePath = grmPath
err.SourceName = grmPath
} else {
err.FilePath = grmPath
err.SourceName = "stdin"
}
}
}
if panicked {
fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
} else {
fmt.Fprintf(os.Stderr, "%v\n", retErr)
}
}
}()
if grmPath == "" {
var err error
tmpDirPath, err = os.MkdirTemp("", "vartan-compile-*")
if err != nil {
return err
}
src, err := ioutil.ReadAll(os.Stdin)
if err != nil {
return err
}
grmPath = filepath.Join(tmpDirPath, "stdin.vr")
err = ioutil.WriteFile(grmPath, src, 0600)
if err != nil {
return err
}
}
gram, err := readGrammar(grmPath)
if err != nil {
return err
}
var descFileName string
{
_, grmFileName := filepath.Split(grmPath)
descFileName = fmt.Sprintf("%v-description.json", strings.TrimSuffix(grmFileName, ".vr"))
}
opts := []grammar.CompileOption{
grammar.EnableDescription(descFileName),
}
switch strings.ToLower(*compileFlags.class) {
case "slr":
opts = append(opts, grammar.SpecifyClass(grammar.ClassSLR))
case "lalr":
opts = append(opts, grammar.SpecifyClass(grammar.ClassLALR))
default:
return fmt.Errorf("invalid class: %v", *compileFlags.class)
}
cgram, err := grammar.Compile(gram, opts...)
if err != nil {
return err
}
err = writeCompiledGrammar(cgram, *compileFlags.output)
if err != nil {
return fmt.Errorf("Cannot write a compiled grammar: %w", err)
}
return nil
}
func readGrammar(path string) (grm *grammar.Grammar, retErr error) {
f, err := os.Open(path)
if err != nil {
return nil, fmt.Errorf("Cannot open the grammar file %s: %w", path, err)
}
defer f.Close()
ast, err := spec.Parse(f)
if err != nil {
return nil, err
}
b := grammar.GrammarBuilder{
AST: ast,
}
return b.Build()
}
func writeCompiledGrammar(cgram *spec.CompiledGrammar, path string) error {
out, err := json.Marshal(cgram)
if err != nil {
return err
}
w := os.Stdout
if path != "" {
f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
if err != nil {
return fmt.Errorf("Cannot open the output file %s: %w", path, err)
}
defer f.Close()
w = f
}
fmt.Fprintf(w, "%v\n", string(out))
return nil
}
|
