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class Lexical {
fun analyze(source: String): MutableList<Pair<String, TokenType>> {
var buffer = ""
val tokens = mutableListOf<Pair<String, TokenType>>()
for (i in source.indices) {
if (source.length > i + 1 && getType(source[i]) == getType(source[i + 1])) {
buffer += source[i]
} else {
buffer += source[i]
if (getType(source[i]) != Type.Empty)
tokens += buffer to getTokenType(buffer to getType(source[i]))
buffer = ""
}
}
return tokens
}
/**
* Matches the characters to groups ([Type])
*/
private fun getType(char: Char): Type {
return when (char) {
in 'a'..'z', in 'A'..'Z' -> Type.Alphabetic
in '1'..'9' -> Type.Numeric
' ' -> Type.Empty
else -> Type.Unknown
}
}
/**
* Matches the tokens to a [TokenType]
*/
private fun getTokenType(token: Pair<String, Type>): TokenType {
var type = when (token.first) {
"print" -> TokenType.Keyword // TODO: DataType matching
"=", "+", "-", "*", "/", "==", ">", "<" -> TokenType.Operator
";", ":" -> TokenType.Symbol
else -> TokenType.Unknown
}
if (type == TokenType.Unknown)
type = when (token.second) {
Type.Numeric -> TokenType.Constant
Type.Alphabetic -> TokenType.Identifier
else -> TokenType.Unknown
}
return type
}
}
private enum class Type {
Alphabetic,
Numeric,
Empty,
Unknown
}
enum class TokenType {
Keyword,
Identifier,
Operator,
Constant,
Symbol,
Unknown
}
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