lexer impl and tests

go.mod

@@ -1,3 +1,3 @@
-module robaertschi.xyz/robaertschi/thorgot
+module git.robaertschi.xyz/robaertschi/thorgot
 
 go 1.23.2

lexer/lexer.go

@@ -1,6 +1,8 @@
 package lexer
 
-import "robaertschi.xyz/robaertschi/thorgot/token"
+import (
+	"git.robaertschi.xyz/robaertschi/thorgot/token"
+)
 
 type Lexer struct {
 	input   string
@@ -15,6 +17,7 @@ type Lexer struct {
 
 func New(input string) Lexer {
 	lexer := Lexer{input: input}
+	lexer.line = 1
 
 	lexer.readChar()
 
@@ -42,13 +45,86 @@ func (l *Lexer) makeToken(t token.TokenType, literal string) token.Token {
 	return token.Token{Token: t, Literal: literal, Loc: token.Loc{Line: l.line, Col: l.col}}
 }
 
-func (l *Lexer) NextToken() token.Token {
-	var token token.Token
+func isDigit(ch byte) bool {
+	return '0' <= ch && ch <= '9'
+}
 
-	switch l.ch {
-	case 0:
+func isLetter(ch byte) bool {
+	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z'
+}
 
+func isValidIdentChar(ch byte) bool {
+	return ch == '_' || isLetter(ch)
+}
+
+func (l *Lexer) skipWhitespace() {
+	for l.ch == '\r' || l.ch == '\b' || l.ch == '\t' || l.ch == ' ' {
+		l.readChar()
+	}
+}
+
+func (l *Lexer) readIdentifier() token.Token {
+	loc := token.Loc{Line: l.line, Col: l.col}
+	pos := l.pos
+
+	l.readChar()
+
+	for isDigit(l.ch) || isLetter(l.ch) {
+		l.readChar()
 	}
 
-	return token
+	t := token.LookupKeyword(l.input[pos:l.pos])
+
+	return token.Token{Token: t, Loc: loc, Literal: l.input[pos:l.pos]}
+}
+
+func (l *Lexer) readNumber() token.Token {
+	pos := l.pos
+	loc := token.Loc{Line: l.line, Col: l.col}
+
+	for isDigit(l.ch) {
+		l.readChar()
+	}
+
+	return token.Token{Token: token.Integer, Loc: loc, Literal: l.input[pos:l.pos]}
+}
+
+func (l *Lexer) NextToken() token.Token {
+	l.skipWhitespace()
+	var tok token.Token
+	tok.Literal = string(l.ch)
+
+	switch l.ch {
+	case '\n':
+		tok.Token = token.EndLine
+	case ';':
+		tok.Token = token.Semicolon
+	case ':':
+		tok.Token = token.Colon
+	case '=':
+		tok.Token = token.Equal
+	case '{':
+		tok.Token = token.LBrace
+	case '}':
+		tok.Token = token.RBrace
+	case '(':
+		tok.Token = token.LParen
+	case ')':
+		tok.Token = token.RParen
+
+	case 0:
+		return l.makeToken(token.Eof, "")
+
+	default:
+		if isValidIdentChar(l.ch) {
+			return l.readIdentifier()
+		} else if isDigit(l.ch) {
+			return l.readNumber()
+		}
+
+		tok.Token = token.Illegal
+	}
+
+	l.readChar()
+	return tok
 }

lexer/lexer_test.go

@@ -0,0 +1,49 @@
+package lexer_test
+
+import (
+	"testing"
+
+	"git.robaertschi.xyz/robaertschi/thorgot/lexer"
+	"git.robaertschi.xyz/robaertschi/thorgot/token"
+)
+
+func TestCorrectTokens(t *testing.T) {
+	tests := []struct {
+		expectedTokens []token.Token
+		input          string
+	}{{
+		expectedTokens: []token.Token{{Token: token.Eof, Literal: "", Loc: token.Loc{Line: 1, Col: 1}}},
+		input:          "",
+	}, {input: "hello 1234 ; () {}",
+		expectedTokens: []token.Token{
+			{Token: token.Identifier, Literal: "hello", Loc: token.Loc{Line: 1, Col: 1}},
+			{Token: token.Integer, Literal: "1234", Loc: token.Loc{Line: 1, Col: 7}},
+			{Token: token.Semicolon, Literal: ";", Loc: token.Loc{Line: 1, Col: 12}},
+			{Token: token.LParen, Literal: "(", Loc: token.Loc{Line: 1, Col: 14}},
+			{Token: token.RParen, Literal: ")", Loc: token.Loc{Line: 1, Col: 15}},
+		}}}
+
+	for _, test := range tests {
+		lexer := lexer.New(test.input)
+		for _, expected := range test.expectedTokens {
+			actual := lexer.NextToken()
+
+			if expected.Literal != actual.Literal {
+				t.Errorf("Literal is not equal: actual = (%v) is not expected = (%v)", actual.Literal, expected.Literal)
+			}
+
+			if expected.Token != actual.Token {
+				t.Errorf("Token is not equal: actual = (%v) is not expected = (%v)", actual.Token, expected.Token)
+			}
+
+			if expected.Loc.Line != actual.Loc.Line {
+				t.Errorf("Loc Line is not equal: actual = (%v) is not expected = (%v)", actual.Loc.Line, expected.Loc.Line)
+			}
+
+			if expected.Loc.Col != actual.Loc.Col {
+				t.Errorf("Loc Col is not equal: actual = (%v) is not expected = (%v)", actual.Loc.Col, expected.Loc.Col)
+			}
+
+		}
+	}
+}

token/token.go

@@ -29,6 +29,8 @@ const (
 
 	Identifier = "Identifier"
 
+	Integer = "Integer" // 19232
+
 	// Keywords
 	Fn = "Fn" // fn
 )