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package token
// TokenType represents the type of the token
type TokenType string
// Token represents a token, with the type and the literal value of the token
type Token struct {
Type TokenType
Literal string
}
const (
ILLEGAL = "ILLEGAL"
EOF = "EOF"
IDENT = "IDENT"
INT = "INT"
COMMA = ","
SEMICOLON = ";"
LPAREN = "("
RPAREN = ")"
LBRACE = "{"
RBRACE = "}"
// The following tokens are keywords
FUNCTION = "FUNCTION"
LET = "LET"
TRUE = "TRUE"
FALSE = "FALSE"
IF = "IF"
ELSE = "ELSE"
RETURN = "RETURN"
// The following tokens are for operators
ASSIGN = "="
PLUS = "+"
MINUS = "-"
BANG = "!"
ASTERISK = "*"
SLASH = "/"
LT = "<"
GT = ">"
)
// List of our keywords for the language
var keywords = map[string]TokenType{
"fn": FUNCTION,
"let": LET,
"true": TRUE,
"false": FALSE,
"if": IF,
"else": ELSE,
"return": RETURN,
}
// LookupIdent returns the token type for a given identifier.
// First we check if the identifier is a keyword. If it is, we return they
// keyword TokenType constant. If it isn't, we return the token.IDENT which is
// the TokenType for all user-defined identifiers.
func LookupIdent(ident string) TokenType {
if tok, ok := keywords[ident]; ok {
return tok
}
return IDENT
}
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