Print warning when a tab is discovered where it shouldn't be

file/error.go

@@ -63,6 +63,7 @@ func (err Error) Error () (formattedMessage string) {
 			columnCountdown --
 		}
 		for err.width > 1 {
+			// TODO: for tabs, print out 8 of these instead.
 			formattedMessage += "-"
 		}
 		formattedMessage += "-\n"

lexer/lexer.go

@@ -36,9 +36,9 @@ func (lexer *LexingOperation) tokenize () (err error) {
 		number    := lexer.char >= '0' && lexer.char <= '9'
 
 		if number {
-			// TODO: tokenize number
+			// TODO: tokenize number begin
 		} else if lowercase || uppercase {
-			// TODO: tokenize multi
+			// TODO: tokenize alpha begin
 		} else {
 			err = lexer.tokenizeSymbolBeginning()
 			if err != nil { return err }
@@ -52,13 +52,37 @@ func (lexer *LexingOperation) tokenize () (err error) {
 
 func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
 	switch lexer.char {
+	case '#':
+		// comment
+		for lexer.char != '\n' {
+			lexer.nextRune()
+		}
 	case '\t':
+		// indent level
+		previousToken := lexer.tokens[len(lexer.tokens) - 1]
+
+		if !previousToken.Is(TokenKindNewline) ||
+			!previousToken.Is(TokenKindNewline) {
+
+			file.NewError (
+				lexer.file.Location(), 1,
+				"tab not used as indent",
+				file.ErrorKindWarn)
+			break
+		}
+		
 		for lexer.char == '\t' {
 			lexer.addToken (Token {
 				kind: TokenKindIndent,
 			})
 			lexer.nextRune()
 		}
+	case '\n':
+		// line break
+		lexer.addToken (Token {
+			kind: TokenKindNewline,
+		})
+		lexer.nextRune()
 	case '"':
 		// TODO: tokenize string literal
 		lexer.nextRune()
@@ -95,8 +119,56 @@ func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
 			kind: TokenKindRBrace,
 		})
 		lexer.nextRune()
-	// TODO: add more for things like math symbols, return
-	// direction operators, indentation, etc
+	case '+':
+		lexer.addToken (Token {
+			kind: TokenKindPlus,
+		})
+		lexer.nextRune()
+	case '-':
+		// TODO: tokenize dash begin
+		lexer.nextRune()
+	case '*':
+		lexer.addToken (Token {
+			kind: TokenKindAsterisk,
+		})
+		lexer.nextRune()
+	case '/':
+		lexer.addToken (Token {
+			kind: TokenKindSlash,
+		})
+		lexer.nextRune()
+	case '@':
+		lexer.addToken (Token {
+			kind: TokenKindAt,
+		})
+		lexer.nextRune()
+	case '!':
+		lexer.addToken (Token {
+			kind: TokenKindExclamation,
+		})
+		lexer.nextRune()
+	case '%':
+		lexer.addToken (Token {
+			kind: TokenKindPercent,
+		})
+		lexer.nextRune()
+	case '~':
+		lexer.addToken (Token {
+			kind: TokenKindTilde,
+		})
+		lexer.nextRune()
+	case '<':
+		// TODO: tokenize less than begin
+		lexer.nextRune()
+	case '>':
+		// TODO: tokenize greater than begin
+		lexer.nextRune()
+	case '|':
+		// TODO: tokenize bar begin
+		lexer.nextRune()
+	case '&':
+		// TODO: tokenize and begin
+		lexer.nextRune()
 	default:
 		err = file.NewError (
 			lexer.file.Location(), 1,

lexer/token.go

@@ -11,6 +11,7 @@ const (
 
         TokenKindSeparator
         TokenKindPermission
+        TokenKindReturnDirection
 
         TokenKindInt
         TokenKindFloat
@@ -27,6 +28,25 @@ const (
         TokenKindRBracket
         TokenKindLBrace
         TokenKindRBrace
+
+        TokenKindPlus
+        TokenKindMinus
+        TokenKindAsterisk
+        TokenKindSlash
+
+        TokenKindAt
+        TokenKindExclamation
+        TokenKindPercent
+        TokenKindTilde
+
+        TokenKindLessThan
+        TokenKindLShift
+        TokenKindGreaterThan
+        TokenKindRShift
+        TokenKindBinaryOr
+        TokenKindLogicalOr
+        TokenKindBinaryAnd
+        TokenKindLogicalAnd
 )
 
 // Token represents a single token. It holds its location in the file, as well
@@ -42,6 +62,11 @@ 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) {