arf/lexer/token.go

package lexer

import "fmt"
import "git.tebibyte.media/sashakoshka/arf/file"
import "git.tebibyte.media/sashakoshka/arf/infoerr"

// TokenKind is an enum represzenting what role a token has.
type TokenKind int

const (
	TokenKindNewline TokenKind = iota
	TokenKindIndent

        TokenKindSeparator
        TokenKindPermission
        TokenKindReturnDirection

        TokenKindInt
        TokenKindUInt
        TokenKindFloat
        TokenKindString
        TokenKindRune

        TokenKindName

        TokenKindColon
        TokenKindDot
        TokenKindElipsis
        TokenKindComma
        
        TokenKindLBracket
        TokenKindRBracket
        TokenKindLBrace
        TokenKindRBrace

        TokenKindPlus
        TokenKindMinus
        TokenKindIncrement
        TokenKindDecrement
        TokenKindAsterisk
        TokenKindSlash

        TokenKindAt
        TokenKindExclamation
        TokenKindPercent
        TokenKindTilde

	// TODO: add equal to, less than or equal to, greater than or equal to,
	// not equal to
        TokenKindEqualTo
        TokenKindNotEqualTo
        TokenKindLessThanEqualTo
        TokenKindLessThan
        TokenKindLShift
        TokenKindGreaterThan
        TokenKindGreaterThanEqualTo
        TokenKindRShift
        TokenKindBinaryOr
        TokenKindLogicalOr
        TokenKindBinaryAnd
        TokenKindLogicalAnd
)

// Token represents a single token. It holds its location in the file, as well
// as a value and some semantic information defining the token's role.
type Token struct {
	kind     TokenKind
	location file.Location
	value    any
}

// Kind returns the semantic role of the token.
func (token Token) Kind () (kind TokenKind) {
	return token.kind
}

// Is returns whether or not the token is of kind kind.
func (token Token) Is (kind TokenKind) (match bool) {
	return token.kind == kind
}

// Value returns the value of the token. Depending on what kind of token it is,
// this value may be nil.
func (token Token) Value () (value any) {
	return token.value
}

// Equals returns whether this token is equal to another token
func (token Token) Equals (testToken Token) (match bool) {
	return token.value == testToken.value && token.Is(testToken.kind)
} 

// Location returns the location of the token in its file.
func (token Token) Location () (location file.Location) {
	return token.location
}

// NewError creates a new error at this token's location.
func (token Token) NewError (
	message string,
	kind    infoerr.ErrorKind,
) (
	err infoerr.Error,
) {
	return infoerr.NewError(token.location, message, kind)
}

// Describe generates a textual description of the token to be used in debug
// logs.
func (token Token) Describe () (description string) {
	description = token.kind.Describe()

	if token.value != nil {
		description += fmt.Sprint(": ", token.value)
	}

	return
}

// Describe generates a textual description of the token kind to be used in
// debug logs.
func (tokenKind TokenKind) Describe () (description string) {
	switch tokenKind {
	case TokenKindNewline:
		description = "Newline"
	case TokenKindIndent:
		description = "Indent"
	case TokenKindSeparator:
		description = "Separator"
	case TokenKindPermission:
		description = "Permission"
	case TokenKindReturnDirection:
		description = "ReturnDirection"
	case TokenKindInt:
		description = "Int"
	case TokenKindUInt:
		description = "UInt"
	case TokenKindFloat:
		description = "Float"
	case TokenKindString:
		description = "String"
	case TokenKindRune:
		description = "Rune"
	case TokenKindName:
		description = "Name"
	case TokenKindColon:
		description = "Colon"
	case TokenKindDot:
		description = "Dot"
	case TokenKindElipsis:
		description = "Elipsis"
	case TokenKindComma:
		description = "Comma"
	case TokenKindLBracket:
		description = "LBracket"
	case TokenKindRBracket:
		description = "RBracket"
	case TokenKindLBrace:
		description = "LBrace"
	case TokenKindRBrace:
		description = "RBrace"
	case TokenKindPlus:
		description = "Plus"
	case TokenKindMinus:
		description = "Minus"
	case TokenKindIncrement:
		description = "Increment"
	case TokenKindDecrement:
		description = "Decrement"
	case TokenKindAsterisk:
		description = "Asterisk"
	case TokenKindSlash:
		description = "Slash"
	case TokenKindAt:
		description = "At"
	case TokenKindExclamation:
		description = "Exclamation"
	case TokenKindPercent:
		description = "Percent"
	case TokenKindTilde:
		description = "Tilde"
	case TokenKindLessThan:
		description = "LessThan"
	case TokenKindLShift:
		description = "LShift"
	case TokenKindGreaterThan:
		description = "GreaterThan"
	case TokenKindRShift:
		description = "RShift"
	case TokenKindBinaryOr:
		description = "BinaryOr"
	case TokenKindLogicalOr:
		description = "LogicalOr"
	case TokenKindBinaryAnd:
		description = "BinaryAnd"
	case TokenKindLogicalAnd:
		description = "LogicalAnd"
	}

	return
}