Initial commit of lexer

This commit is contained in:
Fabian Becker 2022-01-12 10:44:45 +01:00
parent 8c79f0f9a5
commit 80efeb1c7d
7 changed files with 373 additions and 0 deletions

10
go.mod Normal file
View File

@ -0,0 +1,10 @@
module git.geekproject.eu/halfdan/glox
go 1.17
require (
golang.org/x/mod v0.5.1 // indirect
golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 // indirect
golang.org/x/tools v0.1.8 // indirect
golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
)

8
go.sum Normal file
View File

@ -0,0 +1,8 @@
golang.org/x/mod v0.5.1 h1:OJxoQ/rynoF0dcCdI7cLPktw/hR2cueqYfjm43oqK38=
golang.org/x/mod v0.5.1/go.mod h1:5OXOZSfqPIIbmVBIIKWRFfZjPR0E5r58TLhUjH0a2Ro=
golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 h1:id054HUawV2/6IGm2IV8KZQjqtwAOo2CYlOToYqa0d0=
golang.org/x/sys v0.0.0-20211019181941-9d821ace8654/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/tools v0.1.8 h1:P1HhGGuLW4aAclzjtmJdf0mJOjVUZUzOTqkAkWL+l6w=
golang.org/x/tools v0.1.8/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

33
lox/lox.go Normal file
View File

@ -0,0 +1,33 @@
package lox
import (
"bufio"
"fmt"
"io/ioutil"
"os"
)
func RunFile(filename string) {
bytes, err := ioutil.ReadFile(filename)
if err != nil {
panic(err)
}
lexer := newLexer(string(bytes))
lexer.lex()
}
func RunFormat(filename string) {
}
func RunPrompt() {
scanner := bufio.NewScanner(os.Stdin)
scanner.Split(bufio.ScanLines)
fmt.Print("> ")
for scanner.Scan() {
text := scanner.Text()
fmt.Printf("Input was: %s\n", text)
fmt.Print("> ")
}
}

140
lox/scanner.go Normal file
View File

@ -0,0 +1,140 @@
package lox
type Lexer struct {
start int
current int
line int
column int
source []rune
tokens []Token
}
func (lexer Lexer) lex() {
for !lexer.eof() {
lexer.start = lexer.current
c := lexer.advance()
switch c {
case '(':
lexer.addToken(LeftParen)
case ')':
lexer.addToken(RightParen)
case '{':
lexer.addToken(LeftBrace)
case '}':
lexer.addToken(RightBrace)
case ',':
lexer.addToken(Comma)
case '.':
lexer.addToken(Dot)
case '-':
lexer.addToken(Minus)
case '+':
lexer.addToken(Plus)
case ';':
lexer.addToken(Semicolon)
case '*':
lexer.addToken(Star)
case '!':
if lexer.match('=') {
lexer.addToken(BangEqual)
} else {
lexer.addToken(Bang)
}
case '=':
if lexer.match('=') {
lexer.addToken(EqualEqual)
} else {
lexer.addToken(Equal)
}
case '<':
if lexer.match('=') {
lexer.addToken(LessEqual)
} else {
lexer.addToken(Less)
}
case '>':
if lexer.match('=') {
lexer.addToken(GreaterEqual)
} else {
lexer.addToken(Greater)
}
case '/':
if lexer.match('/') {
for lexer.peek() != '\n' && !lexer.eof() {
lexer.advance()
}
} else {
lexer.addToken(Slash)
}
case ' ', '\r', '\t': // Ignore whitespace
continue
case '\n':
lexer.line++
lexer.column = 0
case '"':
for lexer.peek() != '"' && !lexer.eof() {
if lexer.peek() == '\n' {
lexer.line++
lexer.column--
}
lexer.advance()
}
// if lexer.eof() {
// // Add error (unterminated string)
// }
// Consume the terminating "
lexer.advance()
//value := lexer.source[lexer.start+1 : lexer.current-1]
//lexer.addToken(String, value)
}
}
lexer.addToken(Eof)
}
func (s *Lexer) addToken(tt TokenType) {
s.tokens = append(s.tokens, *makeToken(tt, "", nil, s.line, s.column))
}
// eof returns true if the read pointer has reached the end of the source file
func (s Lexer) eof() bool {
return s.current >= len(s.source)
}
// peek looks one rune ahead without advancing the cursor
func (s Lexer) peek() rune {
if s.eof() {
return '\u0004' // emit end of file character
}
return s.source[s.current]
}
// advance increments the read pointer and returns the rune at that position
func (s *Lexer) advance() rune {
r := s.source[s.current]
s.current++
s.column++
return r
}
// match tried to match a single rune and advances the read pointer if it does.
func (s *Lexer) match(expected rune) bool {
if s.eof() {
return false
}
if s.source[s.current] != expected {
return false
}
s.current++
s.column++
return true
}
func newLexer(source string) *Lexer {
return &Lexer{line: 1, column: 0, source: []rune(source)}
}

72
lox/token.go Normal file
View File

@ -0,0 +1,72 @@
package lox
import "fmt"
//go:generate stringer -type=TokenType
type TokenType int
const (
// Single character tokens
LeftParen TokenType = iota
RightParen
LeftBrace
RightBrace
Comma
Dot
Minus
Plus
Semicolon
Slash
Star
// One or two character tokens
Bang
BangEqual
Equal
EqualEqual
Greater
GreaterEqual
Less
LessEqual
// Literals
Identifier
String
Number
// Keywords
And
Class
Else
False
Fun
For
If
Nil
Or
Print
Return
Super
This
True
Var
While
Eof
)
type Token struct {
tokenType TokenType
lexeme string
literal interface{}
line int
column int
}
func (t Token) String() string {
return fmt.Sprintf("%v", t)
}
func makeToken(tt TokenType, lexeme string, lit interface{}, line, column int) *Token {
return &Token{tokenType: tt, lexeme: lexeme, literal: lit, line: line, column: column}
}

61
lox/tokentype_string.go Normal file
View File

@ -0,0 +1,61 @@
// Code generated by "stringer -type=TokenType"; DO NOT EDIT.
package lox
import "strconv"
func _() {
// An "invalid array index" compiler error signifies that the constant values have changed.
// Re-run the stringer command to generate them again.
var x [1]struct{}
_ = x[LeftParen-0]
_ = x[RightParen-1]
_ = x[LeftBrace-2]
_ = x[RightBrace-3]
_ = x[Comma-4]
_ = x[Dot-5]
_ = x[Minus-6]
_ = x[Plus-7]
_ = x[Semicolon-8]
_ = x[Slash-9]
_ = x[Star-10]
_ = x[Bang-11]
_ = x[BangEqual-12]
_ = x[Equal-13]
_ = x[EqualEqual-14]
_ = x[Greater-15]
_ = x[GreaterEqual-16]
_ = x[Less-17]
_ = x[LessEqual-18]
_ = x[Identifier-19]
_ = x[String-20]
_ = x[Number-21]
_ = x[And-22]
_ = x[Class-23]
_ = x[Else-24]
_ = x[False-25]
_ = x[Fun-26]
_ = x[For-27]
_ = x[If-28]
_ = x[Nil-29]
_ = x[Or-30]
_ = x[Print-31]
_ = x[Return-32]
_ = x[Super-33]
_ = x[This-34]
_ = x[True-35]
_ = x[Var-36]
_ = x[While-37]
_ = x[Eof-38]
}
const _TokenType_name = "LeftParenRightParenLeftBraceRightBraceCommaDotMinusPlusSemicolonSlashStarBangBangEqualEqualEqualEqualGreaterGreaterEqualLessLessEqualIdentifierStringNumberAndClassElseFalseFunForIfNilOrPrintReturnSuperThisTrueVarWhileEof"
var _TokenType_index = [...]uint8{0, 9, 19, 28, 38, 43, 46, 51, 55, 64, 69, 73, 77, 86, 91, 101, 108, 120, 124, 133, 143, 149, 155, 158, 163, 167, 172, 175, 178, 180, 183, 185, 190, 196, 201, 205, 209, 212, 217, 220}
func (i TokenType) String() string {
if i < 0 || i >= TokenType(len(_TokenType_index)-1) {
return "TokenType(" + strconv.FormatInt(int64(i), 10) + ")"
}
return _TokenType_name[_TokenType_index[i]:_TokenType_index[i+1]]
}

49
main.go Normal file
View File

@ -0,0 +1,49 @@
package main
import (
"fmt"
"os"
lox "git.geekproject.eu/halfdan/glox/lox"
)
// glox:
// run - run a scripts
// build - build a binary
// fmt - format file
// sh - run interactive shell
func main() {
if len(os.Args) < 2 {
usage()
}
switch os.Args[1] {
case "run":
if len(os.Args) < 3 {
fmt.Print("glox run: no lox file listed\n")
os.Exit(2)
}
lox.RunFile(os.Args[2])
case "fmt":
if len(os.Args) < 3 {
fmt.Print("glox fmt: no lox file listed\n")
os.Exit(2)
}
lox.RunFormat(os.Args[2])
case "sh":
lox.RunPrompt()
default:
usage()
}
}
func usage() {
fmt.Print("glox is a tool for running Lox code.\n\n")
fmt.Print("Usage:\n\n")
fmt.Print("\tglox <command> [arguments]\n\n")
fmt.Print("The commands are:\n\n")
fmt.Print("\trun\trun a lox script\n")
fmt.Print("\tfmt\tformat input file\n")
fmt.Print("\tsh\tstart interactive shell\n\n")
os.Exit(2)
}