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|
//go:generate maleeni compile lexspec.json -o clexspec.json
//go:generate maleeni-go clexspec.json --package parser
package parser
import (
_ "embed"
"fmt"
"io"
"regexp"
"strings"
verr "github.com/nihei9/vartan/error"
)
type tokenKind string
const (
tokenKindKWFragment = tokenKind("fragment")
tokenKindID = tokenKind("id")
tokenKindTerminalPattern = tokenKind("terminal pattern")
tokenKindStringLiteral = tokenKind("string")
tokenKindColon = tokenKind(":")
tokenKindOr = tokenKind("|")
tokenKindSemicolon = tokenKind(";")
tokenKindLabelMarker = tokenKind("@")
tokenKindDirectiveMarker = tokenKind("#")
tokenKindExpantion = tokenKind("...")
tokenKindOrderedSymbolMarker = tokenKind("$")
tokenKindLParen = tokenKind("(")
tokenKindRParen = tokenKind(")")
tokenKindNewline = tokenKind("newline")
tokenKindEOF = tokenKind("eof")
tokenKindInvalid = tokenKind("invalid")
)
var (
reIDChar = regexp.MustCompile(`^[0-9a-z_]+$`)
reIDInvalidDigitsPos = regexp.MustCompile(`^[0-9]`)
)
type Position struct {
Row int
Col int
}
func newPosition(row, col int) Position {
return Position{
Row: row,
Col: col,
}
}
type token struct {
kind tokenKind
text string
pos Position
}
func newSymbolToken(kind tokenKind, pos Position) *token {
return &token{
kind: kind,
pos: pos,
}
}
func newIDToken(text string, pos Position) *token {
return &token{
kind: tokenKindID,
text: text,
pos: pos,
}
}
func newTerminalPatternToken(text string, pos Position) *token {
return &token{
kind: tokenKindTerminalPattern,
text: text,
pos: pos,
}
}
func newStringLiteralToken(text string, pos Position) *token {
return &token{
kind: tokenKindStringLiteral,
text: text,
pos: pos,
}
}
func newEOFToken() *token {
return &token{
kind: tokenKindEOF,
}
}
func newInvalidToken(text string, pos Position) *token {
return &token{
kind: tokenKindInvalid,
text: text,
pos: pos,
}
}
type lexer struct {
d *Lexer
buf *token
}
func newLexer(src io.Reader) (*lexer, error) {
d, err := NewLexer(NewLexSpec(), src)
if err != nil {
return nil, err
}
return &lexer{
d: d,
}, nil
}
func (l *lexer) next() (*token, error) {
if l.buf != nil {
tok := l.buf
l.buf = nil
return tok, nil
}
var newline *token
for {
tok, err := l.lexAndSkipWSs()
if err != nil {
return nil, err
}
if tok.kind == tokenKindNewline {
newline = tok
continue
}
if newline != nil {
l.buf = tok
return newline, nil
}
return tok, nil
}
}
func (l *lexer) lexAndSkipWSs() (*token, error) {
var tok *Token
for {
var err error
tok, err = l.d.Next()
if err != nil {
return nil, err
}
if tok.Invalid {
return newInvalidToken(string(tok.Lexeme), newPosition(tok.Row+1, tok.Col+1)), nil
}
if tok.EOF {
return newEOFToken(), nil
}
switch tok.KindID {
case KindIDWhiteSpace:
continue
case KindIDLineComment:
continue
}
break
}
switch tok.KindID {
case KindIDNewline:
return newSymbolToken(tokenKindNewline, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDKwFragment:
return newSymbolToken(tokenKindKWFragment, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDIdentifier:
if !reIDChar.Match(tok.Lexeme) {
return nil, &verr.SpecError{
Cause: synErrIDInvalidChar,
Detail: string(tok.Lexeme),
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
if strings.HasPrefix(string(tok.Lexeme), "_") || strings.HasSuffix(string(tok.Lexeme), "_") {
return nil, &verr.SpecError{
Cause: synErrIDInvalidUnderscorePos,
Detail: string(tok.Lexeme),
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
if strings.Contains(string(tok.Lexeme), "__") {
return nil, &verr.SpecError{
Cause: synErrIDConsecutiveUnderscores,
Detail: string(tok.Lexeme),
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
if reIDInvalidDigitsPos.Match(tok.Lexeme) {
return nil, &verr.SpecError{
Cause: synErrIDInvalidDigitsPos,
Detail: string(tok.Lexeme),
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
return newIDToken(string(tok.Lexeme), newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDTerminalOpen:
var b strings.Builder
for {
tok, err := l.d.Next()
if err != nil {
return nil, err
}
if tok.EOF {
return nil, &verr.SpecError{
Cause: synErrUnclosedTerminal,
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
switch tok.KindID {
case KindIDPattern:
// The escape sequences in a pattern string are interpreted by the lexer, except for the \".
// We must interpret the \" before passing them to the lexer because they are delimiters for
// the pattern strings.
fmt.Fprint(&b, strings.ReplaceAll(string(tok.Lexeme), `\"`, `"`))
case KindIDEscapeSymbol:
return nil, &verr.SpecError{
Cause: synErrIncompletedEscSeq,
Row: tok.Row + 1,
Col: tok.Col + 1,
}
case KindIDTerminalClose:
pat := b.String()
if pat == "" {
return nil, &verr.SpecError{
Cause: synErrEmptyPattern,
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
return newTerminalPatternToken(pat, newPosition(tok.Row+1, tok.Col+1)), nil
}
}
case KindIDStringLiteralOpen:
var b strings.Builder
for {
tok, err := l.d.Next()
if err != nil {
return nil, err
}
if tok.EOF {
return nil, &verr.SpecError{
Cause: synErrUnclosedString,
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
switch tok.KindID {
case KindIDCharSeq:
fmt.Fprint(&b, string(tok.Lexeme))
case KindIDStringLiteralClose:
str := b.String()
if str == "" {
return nil, &verr.SpecError{
Cause: synErrEmptyString,
Row: tok.Row + 1,
Col: tok.Col + 1,
}
}
return newStringLiteralToken(str, newPosition(tok.Row+1, tok.Col+1)), nil
}
}
case KindIDColon:
return newSymbolToken(tokenKindColon, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDOr:
return newSymbolToken(tokenKindOr, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDSemicolon:
return newSymbolToken(tokenKindSemicolon, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDLabelMarker:
return newSymbolToken(tokenKindLabelMarker, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDDirectiveMarker:
return newSymbolToken(tokenKindDirectiveMarker, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDExpansion:
return newSymbolToken(tokenKindExpantion, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDOrderedSymbolMarker:
return newSymbolToken(tokenKindOrderedSymbolMarker, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDLParen:
return newSymbolToken(tokenKindLParen, newPosition(tok.Row+1, tok.Col+1)), nil
case KindIDRParen:
return newSymbolToken(tokenKindRParen, newPosition(tok.Row+1, tok.Col+1)), nil
default:
return newInvalidToken(string(tok.Lexeme), newPosition(tok.Row+1, tok.Col+1)), nil
}
}
|
