Function AdditiveLoop

syntax/syntax.go:156–187

AdditiveLoop Additive -> Multiplicative ( (+ | -) Multiplicative)*

(tokenReader *TokenReader)

// AdditiveLoop Additive -> Multiplicative ( (+ | -) Multiplicative)*
func AdditiveLoop(tokenReader *TokenReader) (*ASTNode, error) {
	child1, err := MultiplicativeLoop(tokenReader)
	node := child1
	if err != nil {
		return nil, err
	}
	for {
		// add'
		tokenType := tokenReader.Peek()
		if tokenType != nil && (tokenType.TokenType() == token.Plus || tokenType.TokenType() == token.Minus) {
			tokenType = tokenReader.Read()

			child2, err := MultiplicativeLoop(tokenReader)
			if err != nil {
				return nil, err
			}
			node = NewASTNode(AdditiveType, tokenType.Value())
			node.AddChild(child1)
			node.AddChild(child2)
			child1 = node
		} else {
			break
		}
	}

	if node != nil {
		return node, nil
	} else {
		return nil, errors.New("syntax err, invalid additive")
	}

}

// MultiplicativeLoop Multiplicative -> Primary ((* | /) Primary)*
func MultiplicativeLoop(tokenReader *TokenReader) (*ASTNode, error) {