1. Assignment 3 Solution Background

2. Constant Expression : Infix to postfix
2 + 3 * 4
( 2 + (3 * 4 ) )
* +
Evaluating postfix expression using stack
| 2 |
| 2 | 3 | 4 |
| 2 | 12 |
|14|

3. Evaluating postfix expression using stack
| 2 |
| 2 | 3 | 4 |
| 2 | 12 |
|14|
Compiling constant expression for a stack machine
Push 2
Push 3
Push 4
Mul
Add

4. Generalizing to expressions with variables i + j * k
Push i
Push j
Push k
Mul
Add
Conversion to abstract syntax tree +
i *
j k

5. Generalizing to expressions with variables i + j * k
Push i
Push j
Push k
Mul
Add
Byte code generation for static f(int i,j,k)
iload_0
iload_1
iload_2
imul
iadd

6. Byte code for i + j + k for static f(int i,j,k)
Right associative “+”
iload_0
iload_1
iload_2
iadd
Left associative “+”
iload_0
iload_1
iadd
iload_2

7. Introducing numeric types with real variables a + b
Push a
Push b
Add
Byte code generation for static f(double a,b)
dload_0
dload_2
dadd

8. Mixing int and double variables (requiring coercion code) for static f(double a,int i, j)
i + j * a
iload_2
i2d
iload_3
dload_0
dmul
dadd

9. Translation algorithm essence trans (e1 * e2) = trans(e1)
[type coercion code?]
trans(e2)
trans(*)
Map grammar rules to control structures
E.g., alternatives, while-loop, etc