GATE | GATE CS 2012 | Question 34
Consider the program given below, in a block-structured pseudo-language with lexical scoping and nesting of procedures permitted.
Program main; Var ... Procedure A1; Var ... Call A2; End A1 Procedure A2; Var ... Procedure A21; Var ... Call A1; End A21 Call A21; End A21 Call A1; End main.
Consider the calling chain : Main->A1->A2->A21->A1
The correct set of activation records along with their access links is given by :
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Explanation: Access link is defined as link to activation record of closest lexically enclosing block in program text, so the closest enclosing blocks respectively for A1 ,A2 and A21 are main , main and A2 Since, Activation records are created at procedure entry time and destroyed at procedure exit time.
Link to activation record of closest lexically enclosing block in program text. It depends on the static program text.
Here Calling sequence is given as,
Now A1,A2 are defined under Main…So A1,A2 Access link are pointed to main A21 is defined under A2 hence its Access link will point to A2 .
This solution is contributed by Nitika Bansal