Example

the following
sequence of function
calls creates a parse
tree for a- 4 + c
P 1 = mkleaf(id, entry.a)
P 2 = mkleaf(num, 4)
P 3 = mknode(-, P 1 , P 2 )
P 4 = mkleaf(id, entry.c)
P 5 = mknode(+, P 3 , P 4 )

An example showing the formation of an abstract syntax tree by the given function calls for the expression a-4+c.The call sequence can be explained as:

1. P1 = mkleaf(id,entry.a) : A leaf node made for the identifier Qa R and an entry for Qa R is made in the symbol table.

2. P2 = mkleaf(num,4) : A leaf node made for the number Q4 R.

3. P3 = mknode(-,P1,P2) : An internal node for the Q- Q.I takes the previously made nodes as arguments and represents the expression Qa-4 R.

4. P4 = mkleaf(id,entry.c) : A leaf node made for the identifier Qc R and an entry for Qc R is made in the symbol table.

5. P5 = mknode(+,P3,P4) : An internal node for the Q+ Q.I takes the previously made nodes as arguments and represents the expression Qa- 4+c R.