Some expression parsing

lexer.go

@@ -19,6 +19,7 @@ const (
 	Type_Keyword
 	Type_Separator
 	Type_Literal
+	Type_Operator
 )
 
 type Keyword uint32
@@ -26,6 +27,7 @@ type Keyword uint32
 const (
 	Keyword_Import Keyword = iota
 	Keyword_Void
+	Keyword_Return
 )
 
 type Separator uint32
@@ -39,6 +41,20 @@ const (
 	Separator_Comma
 )
 
+type Operator uint32
+
+const (
+	Operator_Equals Operator = iota
+	Operator_Greater
+	Operator_Less
+	Operator_Not
+	Operator_Plus
+	Operator_Minus
+	Operator_Multiply
+	Operator_Divide
+	Operator_Modulo
+)
+
 type LiteralType uint32
 
 const (
@@ -64,7 +80,7 @@ type Lexer struct {
 }
 
 func (l *Lexer) error(message string) error {
-	return errors.New(message + " (at " + strconv.FormatUint(l.Position, 10) + ")")
+	return CompilerError{Position: l.Position, Message: message}
 }
 
 func (l *Lexer) peekRune() *rune {
@@ -230,6 +246,8 @@ func (l *Lexer) parseToken(token string) (*LexToken, error) {
 		return &LexToken{Type: Type_Keyword, Position: l.Position, Value: Keyword_Void}, nil
 	case "import":
 		return &LexToken{Type: Type_Keyword, Position: l.Position, Value: Keyword_Import}, nil
+	case "return":
+		return &LexToken{Type: Type_Keyword, Position: l.Position, Value: Keyword_Return}, nil
 	case "(":
 		return &LexToken{Type: Type_Separator, Position: l.Position, Value: Separator_OpenParen}, nil
 	case ")":

main.go

@@ -26,6 +26,10 @@ func main() {
 	parser := Parser{Tokens: tokens}
 	parsed, err := parser.parseFile()
 	if err != nil {
+		if c, ok := err.(CompilerError); ok {
+			log.Fatalln(err, "\nv- here\n"+string([]rune(string(content))[c.Position:]))
+		}
+
 		log.Fatalln(err)
 	}
 

parser.go

@@ -1,9 +1,7 @@
 package main
 
 import (
-	"errors"
 	"slices"
-	"strconv"
 	"strings"
 )
 
@@ -58,7 +56,7 @@ type ReturnStatement struct {
 
 type DeclareLocalVariableStatement struct {
 	Variable    string
-	Initializer Expression
+	Initializer *Expression
 }
 
 type ExpressionType uint32
@@ -68,6 +66,7 @@ const (
 	Expression_Literal
 	Expression_VariableReference
 	Expression_Arithmetic
+	Expression_Tuple
 )
 
 type Expression struct {
@@ -105,6 +104,10 @@ type ArithmeticExpression struct {
 	Right     Expression
 }
 
+type TupleExpression struct {
+	Members []Expression
+}
+
 type Block struct {
 	Statements []Statement
 }
@@ -135,8 +138,12 @@ type Parser struct {
 	Position uint64
 }
 
-func (p *Parser) error(message string) error {
-	return errors.New(message + " (at " + strconv.FormatUint(p.Position, 10) + ")")
+func (p Parser) copy() Parser {
+	return p
+}
+
+func (p *Parser) error(message string) CompilerError {
+	return CompilerError{Position: p.Position, Message: message}
 }
 
 func (p *Parser) peekToken() *LexToken {
@@ -158,23 +165,40 @@ func (p *Parser) nextToken() *LexToken {
 	return &token
 }
 
+func (p *Parser) trySeparator(separators ...Separator) (*Separator, error) {
+	pCopy := p.copy()
+
+	separator := pCopy.nextToken()
+	if separator == nil || separator.Type != Type_Separator || !slices.Contains(separators, separator.Value.(Separator)) {
+		return nil, nil
+	}
+
+	*p = pCopy
+	sep := separator.Value.(Separator)
+	return &sep, nil
+}
+
 func (p *Parser) expectSeparator(separators ...Separator) (Separator, error) {
+	sep, err := p.trySeparator(separators...)
+	if err != nil {
+		return InvalidValue, err
+	}
+
+	if sep == nil {
 		var separatorNames []string
 		for _, sep := range separators {
 			separatorNames = append(separatorNames, string(Separators[sep]))
 		}
 
-	separator := p.nextToken()
-	if separator == nil || separator.Type != Type_Separator || !slices.Contains(separators, separator.Value.(Separator)) {
 		return InvalidValue, p.error("expected one of " + strings.Join(separatorNames, " "))
 	}
 
-	return separator.Value.(Separator), nil
+	return *sep, nil
 }
 
 func (p *Parser) expectIdentifier() (string, error) {
 	identifier := p.nextToken()
-	if identifier == nil || identifier.Type != Type_Separator && identifier.Type != Type_Identifier {
+	if identifier == nil || identifier.Type != Type_Identifier {
 		return "", p.error("expected identifier")
 	}
 
@@ -202,24 +226,55 @@ func (p *Parser) expectImport() (*Import, error) {
 	return &Import{Import: identifier.Value.(string)}, nil
 }
 
-func (p *Parser) expectType() (*Type, error) {
-	var err error
+func (p *Parser) tryType() (*Type, error) {
+	pCopy := p.copy()
 
-	tok := p.nextToken()
+	tok := pCopy.nextToken()
 	if tok == nil {
-		return nil, p.error("expected type")
+		return nil, nil
 	}
 
 	if tok.Type == Type_Keyword && tok.Value.(Keyword) == Keyword_Void {
+		*p = pCopy
 		return &Type{Type: Type_Void, Value: nil}, nil
 	}
 
+	if tok.Type == Type_Identifier {
+		// TODO: array type
+		*p = pCopy
+		return &Type{Type: Type_Named, Value: tok.Value}, nil
+	}
+
+	return nil, nil
+}
+
+func (p *Parser) expectType() (*Type, error) {
+	t, err := p.tryType()
+	if err != nil {
+		return nil, err
+	}
+
+	if t != nil {
+		return t, nil
+	}
+
+	return nil, p.error("expected type")
+}
+
+func (p *Parser) expectTypeOrTupleType() (*Type, error) {
+	var err error
+
+	tok := p.peekToken()
+	if tok == nil {
+		return nil, p.error("expected type or tuple type")
+	}
+
 	if tok.Type == Type_Separator && tok.Value.(Separator) == Separator_OpenParen {
 		// Tuple type
+		p.nextToken()
 		var types []Type
 		for {
-			var parsedType *Type
-			parsedType, err = p.expectType()
+			parsedType, err := p.expectType()
 			if err != nil {
 				return nil, err
 			}
@@ -244,11 +299,236 @@ func (p *Parser) expectType() (*Type, error) {
 		return &Type{Type: Type_Tuple, Value: TupleType{Types: types}}, nil
 	}
 
-	if tok.Type == Type_Identifier {
-		return &Type{Type: Type_Named, Value: tok.Value}, nil
+	t, err := p.tryType()
+	if err != nil {
+		return nil, err
 	}
 
-	return nil, p.error("expected type")
+	if t != nil {
+		return t, nil
+	}
+
+	return nil, p.error("expected type or tuple type")
+}
+
+func (p *Parser) tryParanthesizedExpression() (*Expression, error) {
+	pCopy := p.copy()
+
+	token := pCopy.nextToken()
+	if token == nil || token.Type != Type_Separator || token.Value.(Separator) != Separator_OpenParen {
+		return nil, nil
+	}
+
+	expr, err := pCopy.tryExpression()
+	if err != nil {
+		*p = pCopy
+		return nil, err
+	}
+
+	if expr == nil {
+		return nil, nil
+	}
+
+	// Assuming we're in a paranthesized statement
+	_, err = pCopy.expectSeparator(Separator_CloseParen)
+	if err != nil {
+		*p = pCopy
+		return nil, err
+	}
+
+	*p = pCopy
+	return expr, nil
+}
+
+func (p *Parser) tryUnaryExpression() (*Expression, error) {
+	pCopy := p.copy()
+
+	token := pCopy.peekToken()
+	if token == nil {
+		return nil, nil
+	}
+
+	if token.Type == Type_Separator && token.Value.(Separator) == Separator_OpenParen {
+		paren, err := pCopy.tryParanthesizedExpression()
+		if err != nil {
+			*p = pCopy
+			return nil, err
+		}
+
+		if paren != nil {
+			*p = pCopy
+			return paren, nil
+		}
+
+		// TODO: cast
+	}
+
+	if token.Type == Type_Identifier {
+		pCopy.nextToken()
+		*p = pCopy
+		return &Expression{Type: Expression_VariableReference, Value: VariableReferenceExpression{Variable: token.Value.(string)}}, nil
+	}
+
+	return nil, nil
+}
+
+func (p *Parser) tryMultiplicativeExpression() (*Expression, error) {
+	return p.tryUnaryExpression()
+}
+
+func (p *Parser) tryAdditiveExpression() (*Expression, error) {
+	return p.tryMultiplicativeExpression()
+}
+
+func (p *Parser) tryArithmeticExpression() (*Expression, error) {
+	return p.tryAdditiveExpression()
+}
+
+func (p *Parser) tryExpression() (*Expression, error) {
+	return p.tryArithmeticExpression()
+}
+
+func (p *Parser) tryTupleExpression() (*Expression, error) {
+	pCopy := p.copy()
+
+	var members []Expression
+	for {
+		expr, err := pCopy.tryExpression()
+		if err != nil {
+			return nil, err
+		}
+
+		if expr == nil {
+			return nil, nil
+		}
+
+		members = append(members, *expr)
+
+		token := pCopy.peekToken()
+		if token == nil || token.Type != Type_Separator || token.Value.(Separator) != Separator_Comma {
+			if len(members) <= 1 {
+				return nil, nil // None/One experession -> not a tuple expression
+			}
+
+			break
+		}
+
+		pCopy.nextToken()
+	}
+
+	*p = pCopy
+	return &Expression{Type: Expression_Tuple, Value: TupleExpression{Members: members}}, nil
+}
+
+func (p *Parser) expectTupleExpression() (*Expression, error) {
+	return p.expect(p.tryTupleExpression, "expected tuple expression")
+}
+
+func (p *Parser) expect(try func() (*Expression, error), message string) (*Expression, error) {
+	expr, err := try()
+	if err != nil {
+		return nil, err
+	}
+
+	if expr == nil {
+		return nil, p.error(message)
+	}
+
+	return expr, nil
+}
+
+func (p *Parser) tryDeclareLocalVariableStatement() (*Statement, error) {
+	pCopy := p.copy()
+
+	token := pCopy.nextToken()
+	if token == nil {
+		return nil, nil
+	}
+
+	variableType, err := pCopy.tryType()
+	if err != nil {
+		*p = pCopy
+		return nil, err
+	}
+
+	if variableType == nil {
+		return nil, nil
+	}
+
+	name := pCopy.nextToken()
+	if name == nil || name.Type != Type_Identifier {
+		return nil, nil
+	}
+
+	variableName := name.Value.(string)
+
+	token = pCopy.nextToken()
+	if token.Type == Type_Separator && token.Value.(Separator) == Separator_Semicolon {
+		return &Statement{Type: Statement_DeclareLocalVariable, Value: DeclareLocalVariableStatement{Variable: variableName, Initializer: nil}}, nil
+	}
+
+	if token.Type != Type_Operator || token.Value.(Operator) != Operator_Equals {
+		return nil, nil
+	}
+
+	initializer, err := p.expect(p.tryExpression, "expected initializer expression")
+	if err != nil {
+		*p = pCopy
+		return nil, err
+	}
+
+	_, err = p.expectSeparator(Separator_Semicolon)
+	if err != nil {
+		*p = pCopy
+		return nil, err
+	}
+
+	*p = pCopy
+	return &Statement{Type: Statement_DeclareLocalVariable, Value: DeclareLocalVariableStatement{Variable: variableName, Initializer: initializer}}, nil
+}
+
+func (p *Parser) expectStatement() (*Statement, error) {
+	token := p.peekToken()
+	if token == nil {
+		return nil, p.error("expected statement")
+	}
+
+	if token.Type == Type_Keyword && token.Value.(Keyword) == Keyword_Return {
+		p.nextToken()
+
+		token = p.peekToken()
+		if token == nil {
+			return nil, p.error("expected expression or ;")
+		}
+
+		if token.Type == Type_Separator && token.Value.(Separator) == Separator_Semicolon {
+			p.nextToken()
+			return &Statement{Type: Statement_Return, Value: ReturnStatement{Value: nil}}, nil
+		}
+
+		expr, err := p.expectTupleExpression()
+		if err != nil {
+			return nil, err
+		}
+
+		_, err = p.expectSeparator(Separator_Semicolon)
+		if err != nil {
+			return nil, err
+		}
+
+		return &Statement{Type: Statement_Return, Value: ReturnStatement{Value: expr}}, nil
+	}
+
+	if token.Type == Type_Separator && token.Value.(Separator) == Separator_OpenCurly {
+		block, err := p.expectBlock()
+		if err != nil {
+			return nil, err
+		}
+
+		return &Statement{Type: Statement_Block, Value: BlockStatement{Block: *block}}, nil
+	}
+
+	return nil, p.error("expected statement")
 }
 
 func (p *Parser) expectBlock() (*Block, error) {
@@ -269,8 +549,12 @@ func (p *Parser) expectBlock() (*Block, error) {
 			break
 		}
 
-		// TODO: parse statement
-		p.nextToken()
+		stmt, err := p.expectStatement()
+		if err != nil {
+			return nil, err
+		}
+
+		statements = append(statements, *stmt)
 	}
 
 	return &Block{Statements: statements}, nil
@@ -284,7 +568,7 @@ func (p *Parser) expectFunction() (*ParsedFunction, error) {
 	var returnType *Type
 	var body *Block
 
-	returnType, err = p.expectType()
+	returnType, err = p.expectTypeOrTupleType()
 	if err != nil {
 		return nil, err
 	}

types.go

@@ -33,6 +33,15 @@ const (
 
 const InvalidValue = 0xEEEEEE // Magic value
 
+type CompilerError struct {
+	Position uint64
+	Message  string
+}
+
+func (e CompilerError) Error() string {
+	return e.Message + " (at " + strconv.FormatUint(e.Position, 10) + ")"
+}
+
 func isSignedInt(primitiveType PrimitiveType) bool {
 	switch primitiveType {
 	case Primitive_I8, Primitive_I16, Primitive_I32, Primitive_I64: