A slide show that shows how expression trees are created with Xtext.

1. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
StackAST
Grammar
Text

2. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text

3. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text

4. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text

5. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text

6. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text

7. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
StackAST
Grammar
Text

8. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
6.PrimaryExpression
StackAST
Grammar
Text

9. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
6.PrimaryExpression
StackAST
Grammar
Text

10. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
6.PrimaryExpression
StackAST
Grammar
Text
1

11. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
6.PrimaryExpression
StackAST
Grammar
Text
1

12. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
StackAST
Grammar
Text
1
Reduce!

13. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text
1
Reduce!

14. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text
1

15. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
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1
+

16. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
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1
+
current = ruleMultiplication();
// {AdditionalExpression.left=current}
AdditionalExpression temp = new AdditionalExpression();
temp.setLeft(current);
current = temp:

17. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text
1
+

18. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text
1
+

19. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text
1
+

20. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
StackAST
Grammar
Text
1
+

21. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
5.Multiplication
6.PrimaryExpression
StackAST
Grammar
Text
1
+

22. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
4.Addition
StackAST
Grammar
Text
1
+
20
Reduce!

23. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text
1
+
20
Reduce!

24. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text
1
+
20

25. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text
1
+
20

26. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
Reduce!

27. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
*

28. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
*

29. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
*

30. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
*

31. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text
1
+
20
*
2

32. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
3.PrimaryExpression
StackAST
Grammar
Text
1
+
20
*
EOF
2

33. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
*
EOF Reduce!
2

34. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
2.Multiplication
StackAST
Grammar
Text
1
+
20
*
EOF
2

35. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
1.Addition
StackAST
Grammar
Text
1
+
20
*
EOF
2
Reduce!

36. Addition returns Expression:
Multiplication ({AdditionalExpression.left=current} '+' right=Multiplication)*;
Multiplication returns Expression:
PrimaryExpression ({MultiplyExpression.left=current} '*' right=PrimaryExpression)*;
PrimaryExpression returns Expression:
{NumberLiteral} value=INT |
'(' Addition ')';
( 1 + 20 ) * 2
StackAST
Grammar
Text
1
+
20
*
EOF
2
Finished!