Chapter 4, Problem 8E

Explanation of Solution

Justification:

• The Figure 4.3 represents an attribute grammar for constant expressions based on an LL (1) CFG.
• In this grammar several production gave two semantic rules.

  $\begin{array}{l}\text{E}\to \text{T}\text{TT}\\ \Rightarrow \text{TT}\text{.st:=T}\text{.seq}\Rightarrow \text{E}\text{.seq:=TT}\text{.seq}\\ {\text{TT}}_{\text{1}}\to \text{+T}\text{}\text{}{\text{TT}}_{\text{2}}\\ \Rightarrow {\text{TT}}_{\text{2}}{\text{.st:=cat(TT}}_{\text{1}}\text{.st,}\text{T}\text{.seq,}\text{"+")}\Rightarrow {\text{TT}}_{\text{1}}{\text{.seq:=TT}}_{\text{2}}\text{.seq}\end{array}$ $\begin{array}{l}{\text{TT}}_{\text{1}}\to -\text{T}\text{}\text{}{\text{TT}}_{\text{2}}\\ \Rightarrow {\text{TT}}_{\text{2}}{\text{.st:=cat(TT}}_{\text{1}}\text{.st,}\text{T}\text{.seq,}\text{"-")}\Rightarrow {\text{TT}}_{\text{1}}{\text{.seq:=TT}}_{\text{2}}\text{.seq}\\ \text{TT}\to \in \\ \Rightarrow \text{TT}\end{array}$