Compiler Design
Q131.
Consider the syntax directed translation given by the following grammar and semantic rules. Here N, I, F \; and \; B are non-terminals. N is the starting non-terminal, and \#,0 \; and \; 1 are lexical tokens corresponding to input letters "\#","0" \; and \; "1", respectively. X.val denotes the synthesized attribute (a numeric value) associated with a non-terminal X. I_1 and F_1 denote occurrences of I and F on the right hand side of a production, respectively. For the tokens 0 and 1, 0.val=0 and 1.val=1.The value computed by the translation scheme for the input string\begin{aligned} N & \rightarrow I \# F & N.val=I.val+F.val \\ I &\rightarrow I_1B & I.val = (2 I1.val) + B.val\\ I &\rightarrow B&I.val = B.val\\ F &\rightarrow BF_1& F.val = \frac{1}{2}(B.val + F1.val)\\ F &\rightarrow B& F.val = \frac{1}{2} B.val\\ B&\rightarrow 0& B.val = 0.val\\ B &\rightarrow 1&B.val = 1.val \end{aligned} 10\# 011is ____ (Rounded off to three decimal places)Q133.
In a bottom-up evaluation of a syntax directed definition, inherited attributes canQ134.
Consider the following grammar (that admits a series of declarations, followed by expressions) and the associated syntax directed translation (SDT) actions, given as pseudo-code\begin{array}{lll} P & \rightarrow & D^* E^* \\ D & \rightarrow & \textsf{int ID} \{ \text{record that } \textsf{ID.} \text{lexeme is of type} \textsf{ int\}} \\ D & \rightarrow & \textsf{bool ID} \{ \text{record that } \textsf{ID.} \text{lexeme is of type} \textsf{ bool\}} \\ E& \rightarrow & E_1 +E_2 \{ \text{check that } E_1. \text{type}=E_2. \text{type} = \textsf{int}; \text{set } E.\text{type }:= \textsf{int} \} \\ E & \rightarrow & !E_1 \{ \text{check that } E_1. \text{type} = \textsf{bool}; \text{ set } E.\text{type} := \textsf{bool} \} \\ E & \rightarrow & \textsf{ID} \{ \text{set } E. \text{type } := \textsf{int} \} \end{array} With respect to the above grammar, which one of the following choices is correct?Q136.
Consider the program given below, in a block-structured pseudo-language with lexical scoping and nesting of procedures permitted. Consider the calling chain: Main \rightarrow A1 \rightarrow A2 \rightarrow A21 \rightarrow A1 The correct set of activation records along with their access links is given byQ137.
A shift reduce parser carries out the actions specified within braces immediately after reducing with the corresponding rule of grammar S \rightarrow xxW \;\text{{print "1"}} S \rightarrow y \;\text{{print "2"}} W \rightarrow Sz\; \text{{print "3"}} What is the translation of xxxxyzz using the syntax directed translation scheme described by the above rules?