// Package token provides generic token types and scanning/parsing primitives
// for building language-specific lexers and parsers.
package token

// A Type is a constraint for language-specific token type enums.
// It must be comparable (for equality checks) and must have a Name method
// that returns a human-readable string for error messages.
type Type interface {
	comparable
	// Name returns a human-readable name for this token type.
	Name() string
}

// A Token is a lexical unit in a source language.
type Token[T Type] struct {
	Column int    // Where the token begins in the source text.
	Type   T      // What type the token is.
	Value  string // The value of the token.
}

// New creates a Token of the given type at the given column.
// The token's value is derived from its type's Name method.
func New[T Type](typ T, column int) *Token[T] {
	return &Token[T]{Type: typ, Column: column, Value: typ.Name()}
}

// NewAtom creates a Token of the given type with a custom value at the given
// column.
func NewAtom[T Type](typ T, name string, column int) *Token[T] {
	return &Token[T]{Type: typ, Column: column, Value: name}
}

// Name returns the type of the Token, as a string.
func (t Token[T]) Name() string {
	return t.Type.Name()
}