361 lines
8.2 KiB
Go
361 lines
8.2 KiB
Go
package lexer
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import "io"
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import "git.tebibyte.media/sashakoshka/arf/file"
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import "git.tebibyte.media/sashakoshka/arf/types"
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// LexingOperation holds information about an ongoing lexing operataion.
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type LexingOperation struct {
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file *file.File
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char rune
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tokens []Token
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}
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// Tokenize converts a file into a slice of tokens (lexemes).
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func Tokenize (file *file.File) (tokens []Token, err error) {
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lexer := LexingOperation { file: file }
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err = lexer.tokenize()
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tokens = lexer.tokens
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// if the lexing operation returned io.EOF, nothing went wrong so we
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// return nil for err.
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if err == io.EOF {
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err = nil
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}
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return
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}
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// tokenize converts a file into a slice of tokens (lexemes). It will always
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// return a non-nil error, but if nothing went wrong it will return io.EOF.
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func (lexer *LexingOperation) tokenize () (err error) {
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// check to see if the beginning of the file says :arf
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var shebangCheck = []rune(":arf\n")
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for index := 0; index < 5; index ++ {
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err = lexer.nextRune()
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if err != nil || shebangCheck[index] != lexer.char {
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err = file.NewError (
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lexer.file.Location(1),
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"not an arf file",
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file.ErrorKindError)
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return
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}
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}
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err = lexer.nextRune()
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if err != nil { return }
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for {
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lowercase := lexer.char >= 'a' && lexer.char <= 'z'
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uppercase := lexer.char >= 'A' && lexer.char <= 'Z'
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number := lexer.char >= '0' && lexer.char <= '9'
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if number {
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err = lexer.tokenizeNumberBeginning(false)
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if err != nil { return }
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} else if lowercase || uppercase {
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err = lexer.tokenizeAlphaBeginning()
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if err != nil { return }
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} else {
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err = lexer.tokenizeSymbolBeginning()
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if err != nil { return }
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}
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err = lexer.skipSpaces()
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if err != nil { return }
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}
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if lexer.tokens[len(lexer.tokens) - 1].kind != TokenKindNewline {
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token := lexer.newToken()
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token.kind = TokenKindNewline
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lexer.addToken(token)
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}
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return
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}
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func (lexer *LexingOperation) tokenizeAlphaBeginning () (err error) {
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token := lexer.newToken()
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token.kind = TokenKindName
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got := ""
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for {
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lowercase := lexer.char >= 'a' && lexer.char <= 'z'
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uppercase := lexer.char >= 'A' && lexer.char <= 'Z'
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number := lexer.char >= '0' && lexer.char <= '9'
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if !lowercase && !uppercase && !number { break }
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got += string(lexer.char)
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lexer.nextRune()
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}
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token.value = got
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if len(got) == 2 {
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firstValid := got[0] == 'n' || got[0] == 'r' || got[0] == 'w'
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secondValid := got[1] == 'n' || got[1] == 'r' || got[1] == 'w'
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if firstValid && secondValid {
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token.kind = TokenKindPermission
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token.value = types.PermissionFrom(got)
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}
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}
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lexer.addToken(token)
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return
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}
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func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
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switch lexer.char {
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case '#':
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// comment
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for lexer.char != '\n' {
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err = lexer.nextRune()
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if err != nil { return }
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}
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case '\t':
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// indent level
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previousToken := lexer.tokens[len(lexer.tokens) - 1]
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if !previousToken.Is(TokenKindNewline) {
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err = lexer.nextRune()
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file.NewError (
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lexer.file.Location(1),
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"tab not used as indent",
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file.ErrorKindWarn).Print()
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return
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}
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token := lexer.newToken()
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token.kind = TokenKindIndent
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// eat up tabs while increasing the indent level
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indentLevel := 0
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for lexer.char == '\t' {
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indentLevel ++
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err = lexer.nextRune()
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if err != nil { return }
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}
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token.value = indentLevel
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lexer.addToken(token)
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case '\n':
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// line break
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// if the last line is empty, discard it
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lastLineEmpty := true
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tokenIndex := len(lexer.tokens) - 1
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for lexer.tokens[tokenIndex].kind != TokenKindNewline {
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if lexer.tokens[tokenIndex].kind != TokenKindIndent {
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lastLineEmpty = false
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break
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}
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tokenIndex --
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}
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if lastLineEmpty {
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lexer.tokens = lexer.tokens[:tokenIndex]
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}
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token := lexer.newToken()
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token.kind = TokenKindNewline
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lexer.addToken(token)
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err = lexer.nextRune()
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case '"':
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err = lexer.tokenizeString(false)
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case '\'':
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err = lexer.tokenizeString(true)
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case ':':
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token := lexer.newToken()
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token.kind = TokenKindColon
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lexer.addToken(token)
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err = lexer.nextRune()
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case '.':
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token := lexer.newToken()
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token.kind = TokenKindDot
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lexer.addToken(token)
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err = lexer.nextRune()
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case '[':
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token := lexer.newToken()
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token.kind = TokenKindLBracket
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lexer.addToken(token)
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err = lexer.nextRune()
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case ']':
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token := lexer.newToken()
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token.kind = TokenKindRBracket
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lexer.addToken(token)
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err = lexer.nextRune()
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case '{':
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token := lexer.newToken()
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token.kind = TokenKindLBrace
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lexer.addToken(token)
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err = lexer.nextRune()
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case '}':
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token := lexer.newToken()
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token.kind = TokenKindRBrace
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lexer.addToken(token)
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err = lexer.nextRune()
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case '+':
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err = lexer.nextRune()
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if err != nil { return }
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token := lexer.newToken()
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token.kind = TokenKindPlus
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if lexer.char == '+' {
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token.kind = TokenKindIncrement
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}
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lexer.addToken(token)
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err = lexer.nextRune()
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case '-':
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err = lexer.tokenizeDashBeginning()
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case '*':
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token := lexer.newToken()
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token.kind = TokenKindAsterisk
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lexer.addToken(token)
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err = lexer.nextRune()
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case '/':
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token := lexer.newToken()
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token.kind = TokenKindSlash
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lexer.addToken(token)
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err = lexer.nextRune()
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case '@':
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token := lexer.newToken()
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token.kind = TokenKindAt
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lexer.addToken(token)
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err = lexer.nextRune()
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case '!':
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token := lexer.newToken()
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token.kind = TokenKindExclamation
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lexer.addToken(token)
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err = lexer.nextRune()
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case '%':
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token := lexer.newToken()
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token.kind = TokenKindPercent
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lexer.addToken(token)
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err = lexer.nextRune()
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case '~':
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token := lexer.newToken()
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token.kind = TokenKindTilde
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lexer.addToken(token)
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err = lexer.nextRune()
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case '<':
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err = lexer.nextRune()
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if err != nil { return }
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token := lexer.newToken()
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token.kind = TokenKindLessThan
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if lexer.char == '<' {
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token.kind = TokenKindLShift
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}
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lexer.addToken(token)
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err = lexer.nextRune()
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case '>':
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err = lexer.nextRune()
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if err != nil { return }
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token := lexer.newToken()
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token.kind = TokenKindGreaterThan
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if lexer.char == '>' {
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token.kind = TokenKindRShift
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}
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lexer.addToken(token)
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err = lexer.nextRune()
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case '|':
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err = lexer.nextRune()
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if err != nil { return }
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token := lexer.newToken()
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token.kind = TokenKindBinaryOr
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if lexer.char == '|' {
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token.kind = TokenKindLogicalOr
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}
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lexer.addToken(token)
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err = lexer.nextRune()
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case '&':
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err = lexer.nextRune()
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if err != nil { return }
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token := lexer.newToken()
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token.kind = TokenKindBinaryAnd
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if lexer.char == '&' {
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token.kind = TokenKindLogicalAnd
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}
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lexer.addToken(token)
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err = lexer.nextRune()
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default:
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err = file.NewError (
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lexer.file.Location(1),
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"unexpected symbol character " +
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string(lexer.char),
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file.ErrorKindError)
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return
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}
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return
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}
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func (lexer *LexingOperation) tokenizeDashBeginning () (err error) {
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err = lexer.nextRune()
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if err != nil { return }
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if lexer.char == '-' {
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token := lexer.newToken()
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token.kind = TokenKindDecrement
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err = lexer.nextRune()
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if err != nil { return }
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if lexer.char == '-' {
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token.kind = TokenKindSeparator
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lexer.nextRune()
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}
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lexer.addToken(token)
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} else if lexer.char == '>' {
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token := lexer.newToken()
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token.kind = TokenKindReturnDirection
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err = lexer.nextRune()
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if err != nil { return }
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lexer.addToken(token)
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} else if lexer.char >= '0' && lexer.char <= '9' {
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lexer.tokenizeNumberBeginning(true)
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} else {
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token := lexer.newToken()
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token.kind = TokenKindMinus
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lexer.addToken(token)
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}
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return
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}
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// newToken creates a new token from the lexer's current position in the file.
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func (lexer *LexingOperation) newToken () (token Token) {
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return Token { location: lexer.file.Location(1) }
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}
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// addToken adds a new token to the lexer's token slice.
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func (lexer *LexingOperation) addToken (token Token) {
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lexer.tokens = append(lexer.tokens, token)
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}
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// skipSpaces skips all space characters (not tabs or newlines)
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func (lexer *LexingOperation) skipSpaces () (err error) {
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for lexer.char == ' ' {
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err = lexer.nextRune()
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if err != nil { return }
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}
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return
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}
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// nextRune advances the lexer to the next rune in the file.
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func (lexer *LexingOperation) nextRune () (err error) {
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lexer.char, _, err = lexer.file.ReadRune()
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if err != nil && err != io.EOF {
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return file.NewError (
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lexer.file.Location(1),
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err.Error(), file.ErrorKindError)
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}
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return
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}
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