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|
package main
import (
"encoding/json"
"fmt"
"io"
"os"
"strings"
driver "driver/parser"
spec "spec/grammar"
"tester"
)
var parseFlags = struct {
source *string
onlyParse *bool
cst *bool
disableLAC *bool
format *string
}{}
const (
outputFormatText = "text"
outputFormatTree = "tree"
outputFormatJSON = "json"
)
/*
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")
parseFlags.disableLAC = cmd.Flags().Bool("disable-lac", false, "disable LAC (lookahead correction)")
parseFlags.format = cmd.Flags().StringP("format", "f", "text", "output format: one of text|tree|json")
rootCmd.AddCommand(cmd)
}
*/
func runParse(args []string) error {
if *parseFlags.onlyParse && *parseFlags.cst {
return fmt.Errorf("You cannot enable --only-parse and --cst at the same time")
}
if *parseFlags.format != outputFormatText &&
*parseFlags.format != outputFormatTree &&
*parseFlags.format != outputFormatJSON {
return fmt.Errorf("invalid output format: %v", *parseFlags.format)
}
cg, err := readCompiledGrammar(args[0])
if err != nil {
return fmt.Errorf("Cannot read a compiled grammar: %w", err)
}
var p *driver.Parser
var treeAct *driver.SyntaxTreeActionSet
var tb *driver.DefaultSyntaxTreeBuilder
{
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
}
gram := driver.NewGrammar(cg)
var opts []driver.ParserOption
{
switch {
case *parseFlags.cst:
tb = driver.NewDefaultSyntaxTreeBuilder()
treeAct = driver.NewCSTActionSet(gram, tb)
case !*parseFlags.onlyParse:
tb = driver.NewDefaultSyntaxTreeBuilder()
treeAct = driver.NewASTActionSet(gram, tb)
}
if treeAct != nil {
opts = append(opts, driver.SemanticAction(treeAct))
}
if *parseFlags.disableLAC {
opts = append(opts, driver.DisableLAC())
}
}
toks, err := driver.NewTokenStream(cg, src)
if err != nil {
return err
}
p, err = driver.NewParser(toks, gram, opts...)
if err != nil {
return err
}
}
err = p.Parse()
if err != nil {
return err
}
if !*parseFlags.onlyParse {
// A parser can construct a parse tree even if syntax errors occur.
// When therer is a parse tree, print it.
if tree := tb.Tree(); tree != nil {
switch *parseFlags.format {
case "tree":
b := tester.ConvertSyntaxTreeToTestableTree(tree).Format()
fmt.Fprintln(os.Stdout, string(b))
case "json":
b, err := json.Marshal(tree)
if err != nil {
return err
}
fmt.Fprintln(os.Stdout, string(b))
default:
driver.PrintTree(os.Stdout, tree)
}
}
}
if len(p.SyntaxErrors()) > 0 {
var b strings.Builder
synErrs := p.SyntaxErrors()
writeSyntaxErrorMessage(&b, cg, synErrs[0])
for _, synErr := range synErrs[1:] {
fmt.Fprintf(&b, "\n")
writeSyntaxErrorMessage(&b, cg, synErr)
}
if b.Len() > 0 {
return fmt.Errorf(b.String())
}
}
return nil
}
func readCompiledGrammar(path string) (*spec.CompiledGrammar, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
data, err := io.ReadAll(f)
if err != nil {
return nil, err
}
cg := &spec.CompiledGrammar{}
err = json.Unmarshal(data, cg)
if err != nil {
return nil, err
}
return cg, nil
}
func writeSyntaxErrorMessage(b *strings.Builder, cgram *spec.CompiledGrammar, synErr *driver.SyntaxError) {
fmt.Fprintf(b, "%v:%v: %v: ", synErr.Row+1, synErr.Col+1, synErr.Message)
tok := synErr.Token
switch {
case tok.EOF():
fmt.Fprintf(b, "<eof>")
case tok.Invalid():
fmt.Fprintf(b, "'%v' (<invalid>)", string(tok.Lexeme()))
default:
if kind := cgram.Syntactic.Terminals[tok.TerminalID()]; kind != "" {
fmt.Fprintf(b, "'%v' (%v)", string(tok.Lexeme()), kind)
} else {
fmt.Fprintf(b, "'%v'", string(tok.Lexeme()))
}
}
fmt.Fprintf(b, ": expected: %v", synErr.ExpectedTerminals[0])
for _, t := range synErr.ExpectedTerminals[1:] {
fmt.Fprintf(b, ", %v", t)
}
}
|
