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|
//go:generate maleeni compile -l lexspec.json -o clexspec.json
package spec
import (
_ "embed"
"encoding/json"
"fmt"
"io"
"strconv"
"strings"
mldriver "github.com/nihei9/maleeni/driver"
mlspec "github.com/nihei9/maleeni/spec"
)
type tokenKind string
const (
tokenKindKWFragment = tokenKind("fragment")
tokenKindID = tokenKind("id")
tokenKindTerminalPattern = tokenKind("terminal pattern")
tokenKindColon = tokenKind(":")
tokenKindOr = tokenKind("|")
tokenKindSemicolon = tokenKind(";")
tokenKindDirectiveMarker = tokenKind("#")
tokenKindTreeNodeOpen = tokenKind("'(")
tokenKindTreeNodeClose = tokenKind(")")
tokenKindPosition = tokenKind("$")
tokenKindExpantion = tokenKind("...")
tokenKindNewline = tokenKind("newline")
tokenKindEOF = tokenKind("eof")
tokenKindInvalid = tokenKind("invalid")
)
type token struct {
kind tokenKind
text string
num int
}
func newSymbolToken(kind tokenKind) *token {
return &token{
kind: kind,
}
}
func newIDToken(text string) *token {
return &token{
kind: tokenKindID,
text: text,
}
}
func newTerminalPatternToken(text string) *token {
return &token{
kind: tokenKindTerminalPattern,
text: text,
}
}
func newPositionToken(num int) *token {
return &token{
kind: tokenKindPosition,
num: num,
}
}
func newEOFToken() *token {
return &token{
kind: tokenKindEOF,
}
}
func newInvalidToken(text string) *token {
return &token{
kind: tokenKindInvalid,
text: text,
}
}
type lexer struct {
s *mlspec.CompiledLexSpec
d *mldriver.Lexer
buf *token
}
//go:embed clexspec.json
var lexspec []byte
func newLexer(src io.Reader) (*lexer, error) {
s := &mlspec.CompiledLexSpec{}
err := json.Unmarshal(lexspec, s)
if err != nil {
return nil, err
}
d, err := mldriver.NewLexer(s, src)
if err != nil {
return nil, err
}
return &lexer{
s: s,
d: d,
}, nil
}
func (l *lexer) next() (*token, error) {
if l.buf != nil {
tok := l.buf
l.buf = nil
return tok, nil
}
newline := false
for {
tok, err := l.lexAndSkipWSs()
if err != nil {
return nil, err
}
if tok.kind == tokenKindNewline {
newline = true
continue
}
if newline {
l.buf = tok
return newSymbolToken(tokenKindNewline), nil
}
return tok, nil
}
}
func (l *lexer) lexAndSkipWSs() (*token, error) {
var tok *mldriver.Token
for {
var err error
tok, err = l.d.Next()
if err != nil {
return nil, err
}
if tok.Invalid {
newInvalidToken(tok.Text())
}
if tok.EOF {
return newEOFToken(), nil
}
switch tok.KindName {
case "white_space":
continue
case "line_comment":
continue
}
break
}
switch tok.KindName {
case "newline":
return newSymbolToken(tokenKindNewline), nil
case "kw_fragment":
return newSymbolToken(tokenKindKWFragment), nil
case "identifier":
return newIDToken(tok.Text()), nil
case "terminal_open":
var b strings.Builder
for {
tok, err := l.d.Next()
if err != nil {
return nil, err
}
if tok.EOF {
return nil, synErrUnclosedTerminal
}
switch tok.KindName {
case "pattern":
// Remove '\' character.
fmt.Fprintf(&b, strings.ReplaceAll(tok.Text(), `\"`, `"`))
case "escape_symbol":
return nil, synErrIncompletedEscSeq
case "terminal_close":
return newTerminalPatternToken(b.String()), nil
}
}
case "colon":
return newSymbolToken(tokenKindColon), nil
case "or":
return newSymbolToken(tokenKindOr), nil
case "semicolon":
return newSymbolToken(tokenKindSemicolon), nil
case "directive_marker":
return newSymbolToken(tokenKindDirectiveMarker), nil
case "tree_node_open":
return newSymbolToken(tokenKindTreeNodeOpen), nil
case "tree_node_close":
return newSymbolToken(tokenKindTreeNodeClose), nil
case "position":
// Remove '$' character and convert to an integer.
num, err := strconv.Atoi(tok.Text()[1:])
if err != nil {
return nil, err
}
if num == 0 {
return nil, synErrZeroPos
}
return newPositionToken(num), nil
case "expansion":
return newSymbolToken(tokenKindExpantion), nil
default:
return newInvalidToken(tok.Text()), nil
}
}
|
