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arf/lexer/lexer.go

377 lines
8.3 KiB
Go

package lexer
import "io"
import "fmt"
import "github.com/sashakoshka/arf/file"
import "github.com/sashakoshka/arf/types"
// LexingOperation holds information about an ongoing lexing operataion.
type LexingOperation struct {
file *file.File
char rune
tokens []Token
}
// Tokenize converts a file into a slice of tokens (lexemes).
func Tokenize (file *file.File) (tokens []Token, err error) {
lexer := LexingOperation { file: file }
err = lexer.tokenize()
tokens = lexer.tokens
// if the lexing operation returned io.EOF, nothing went wrong so we
// return nil for err.
if err == io.EOF {
err = nil
}
return
}
// tokenize converts a file into a slice of tokens (lexemes). It will always
// return a non-nil error, but if nothing went wrong it will return io.EOF.
func (lexer *LexingOperation) tokenize () (err error) {
err = lexer.nextRune()
if err != nil { return }
for {
fmt.Println(string(lexer.char))
lowercase := lexer.char >= 'a' && lexer.char <= 'z'
uppercase := lexer.char >= 'A' && lexer.char <= 'Z'
number := lexer.char >= '0' && lexer.char <= '9'
if number {
// TODO: tokenize number begin\
err = lexer.tokenizeNumberBeginning(false)
if err != nil { return }
} else if lowercase || uppercase {
err = lexer.tokenizeAlphaBeginning()
if err != nil { return }
} else if lexer.char >= '0' && lexer.char <= '9' {
err = lexer.tokenizeSymbolBeginning()
if err != nil { return }
}
err = lexer.skipSpaces()
if err != nil { return }
}
return
}
// tokenizeSymbolBeginning lexes a token that starts with a number.
func (lexer *LexingOperation) tokenizeNumberBeginning (negative bool) (err error) {
var number uint64
if lexer.char == '0' {
lexer.nextRune()
if lexer.char == 'x' {
lexer.nextRune()
number, err = lexer.tokenizeHexidecimalNumber()
} else if lexer.char == 'b' {
lexer.nextRune()
number, err = lexer.tokenizeBinaryNumber()
} else if lexer.char == '.' {
number, err = lexer.tokenizeDecimalNumber()
} else if lexer.char >= '0' && lexer.char <= '9' {
number, err = lexer.tokenizeOctalNumber()
} else {
return file.NewError (
lexer.file.Location(), 1,
"unexpected character in number literal",
file.ErrorKindError)
}
} else {
number, err = lexer.tokenizeDecimalNumber()
}
if err != nil { return }
token := Token { }
if negative {
token.kind = TokenKindInt
token.value = int64(number) * -1
} else {
token.kind = TokenKindUInt
token.value = uint64(number)
}
lexer.addToken(token)
return
}
// tokenizeHexidecimalNumber Reads and tokenizes a hexidecimal number.
func (lexer *LexingOperation) tokenizeHexidecimalNumber () (number uint64, err error) {
for {
if lexer.char >= '0' && lexer.char <= '9' {
number *= 16
number += uint64(lexer.char - '0')
} else if lexer.char >= 'A' && lexer.char <= 'F' {
number *= 16
number += uint64(lexer.char - 'A' + 9)
} else if lexer.char >= 'a' && lexer.char <= 'f' {
number *= 16
number += uint64(lexer.char - 'a' + 9)
} else {
break
}
err = lexer.nextRune()
if err != nil { return }
}
return
}
// tokenizeBinaryNumber Reads and tokenizes a binary number.
func (lexer *LexingOperation) tokenizeBinaryNumber () (number uint64, err error) {
for {
if lexer.char == '0' {
number *= 2
} else if lexer.char == '1' {
number *= 2
number += 1
} else {
break
}
err = lexer.nextRune()
if err != nil { return }
}
return
}
// tokenizeDecimalNumber Reads and tokenizes a decimal number.
func (lexer *LexingOperation) tokenizeDecimalNumber () (number uint64, err error) {
for lexer.char >= '0' && lexer.char <= '9' {
number *= 10
number += uint64(lexer.char - '0')
err = lexer.nextRune()
if err != nil { return }
}
return
}
// tokenizeOctalNumber Reads and tokenizes an octal number.
func (lexer *LexingOperation) tokenizeOctalNumber () (number uint64, err error) {
for lexer.char >= '0' && lexer.char <= '7' {
number *= 8
number += uint64(lexer.char - '0')
err = lexer.nextRune()
if err != nil { return }
}
return
}
func (lexer *LexingOperation) tokenizeAlphaBeginning () (err error) {
got := ""
for {
lowercase := lexer.char >= 'a' && lexer.char <= 'z'
uppercase := lexer.char >= 'A' && lexer.char <= 'Z'
number := lexer.char >= '0' && lexer.char <= '9'
if !lowercase && !uppercase && !number { break }
got += string(lexer.char)
lexer.nextRune()
}
token := Token { kind: TokenKindName, value: got }
if len(got) == 2 {
firstValid := got[0] == 'n' || got[0] == 'r' || got[0] == 'w'
secondValid := got[1] == 'n' || got[1] == 'r' || got[1] == 'w'
if firstValid && secondValid {
token.kind = TokenKindPermission
token.value = types.PermissionFrom(got)
}
}
lexer.addToken(token)
return
}
func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
switch lexer.char {
case '#':
// comment
for lexer.char != '\n' {
err = lexer.nextRune()
if err != nil { return }
}
case '\t':
// indent level
previousToken := lexer.tokens[len(lexer.tokens) - 1]
if !previousToken.Is(TokenKindNewline) ||
!previousToken.Is(TokenKindNewline) {
file.NewError (
lexer.file.Location(), 1,
"tab not used as indent",
file.ErrorKindWarn)
break
}
for lexer.char == '\t' {
lexer.addToken (Token {
kind: TokenKindIndent,
})
err = lexer.nextRune()
if err != nil { return }
}
case '\n':
// line break
// TODO: if last line was blank, (ony whitespace) discard.
lexer.addToken (Token {
kind: TokenKindNewline,
})
err = lexer.nextRune()
case '"':
// TODO: tokenize string literal
err = lexer.nextRune()
case '\'':
// TODO: tokenize rune literal
err = lexer.nextRune()
case ':':
lexer.addToken (Token {
kind: TokenKindColon,
})
err = lexer.nextRune()
case '.':
lexer.addToken (Token {
kind: TokenKindDot,
})
err = lexer.nextRune()
case '[':
lexer.addToken (Token {
kind: TokenKindLBracket,
})
err = lexer.nextRune()
case ']':
lexer.addToken (Token {
kind: TokenKindRBracket,
})
err = lexer.nextRune()
case '{':
lexer.addToken (Token {
kind: TokenKindLBrace,
})
err = lexer.nextRune()
case '}':
lexer.addToken (Token {
kind: TokenKindRBrace,
})
err = lexer.nextRune()
case '+':
// TODO: tokenize plus begin
err = lexer.nextRune()
case '-':
err = lexer.tokenizeDashBeginning()
case '*':
lexer.addToken (Token {
kind: TokenKindAsterisk,
})
err = lexer.nextRune()
case '/':
lexer.addToken (Token {
kind: TokenKindSlash,
})
err = lexer.nextRune()
case '@':
lexer.addToken (Token {
kind: TokenKindAt,
})
err = lexer.nextRune()
case '!':
lexer.addToken (Token {
kind: TokenKindExclamation,
})
err = lexer.nextRune()
case '%':
lexer.addToken (Token {
kind: TokenKindPercent,
})
err = lexer.nextRune()
case '~':
lexer.addToken (Token {
kind: TokenKindTilde,
})
err = lexer.nextRune()
case '<':
// TODO: tokenize less than begin
err = lexer.nextRune()
case '>':
// TODO: tokenize greater than begin
err = lexer.nextRune()
case '|':
// TODO: tokenize bar begin
err = lexer.nextRune()
case '&':
// TODO: tokenize and begin
err = lexer.nextRune()
default:
err = file.NewError (
lexer.file.Location(), 1,
"unexpected symbol character " +
string(lexer.char),
file.ErrorKindError)
return
}
return
}
func (lexer *LexingOperation) tokenizeDashBeginning () (err error) {
token := Token { kind: TokenKindMinus }
lexer.nextRune()
if lexer.char == '-' {
token.kind = TokenKindDecrement
lexer.nextRune()
} else if lexer.char == '>' {
token.kind = TokenKindReturnDirection
lexer.nextRune()
}
if lexer.char == '-' {
token.kind = TokenKindSeparator
lexer.nextRune()
}
lexer.addToken(token)
return
}
// addToken adds a new token to the lexer's token slice.
func (lexer *LexingOperation) addToken (token Token) {
lexer.tokens = append(lexer.tokens, token)
}
// skipSpaces skips all space characters (not tabs or newlines)
func (lexer *LexingOperation) skipSpaces () (err error) {
for lexer.char == ' ' {
err = lexer.nextRune()
if err != nil { return }
}
return
}
// nextRune advances the lexer to the next rune in the file.
func (lexer *LexingOperation) nextRune () (err error) {
lexer.char, _, err = lexer.file.ReadRune()
if err != nil && err != io.EOF {
return file.NewError (
lexer.file.Location(), 1,
err.Error(), file.ErrorKindError)
}
return
}