Attribute grammars(MCQs)

What is an attribute grammar? a) A type of context-free grammar b) A type of formal grammar used for syntax analysis c) A type of grammar used for parsing and semantic analysis d) A type of regular grammar Answer: c) A type of grammar used for parsing and semantic analysis In attribute grammars, what does an attribute represent? a) A symbol in the grammar b) A type of grammar rule c) A piece of information associated with a grammar symbol d) A type of parser Answer: c) A piece of information associated with a grammar symbol Which of the following is true about synthesized attributes? a) They are computed from attributes of parent nodes b) They are computed from attributes of child nodes c) They are used only in top-down parsing d) They are used only in bottom-up parsing Answer: b) They are computed from attributes of child nodes Inherited attributes are computed from: a) Attributes of child nodes b) Attributes of sibling nodes c) Attributes of parent nodes d) Attributes of all nodes Answer: c) Attributes of parent nodes In an attribute grammar, which of the following is used to define semantic rules? a) Productions b) Attributes c) Functions d) Semantics rules Answer: d) Semantics rules What is the primary purpose of an attribute grammar? a) To define syntax rules b) To define semantic rules c) To implement lexing d) To perform syntax checking only Answer: b) To define semantic rules Which of the following types of attributes is used to represent values computed from the parse tree? a) Synthesized attributes b) Inherited attributes c) Both synthesized and inherited attributes d) None of the above Answer: a) Synthesized attributes In attribute grammars, what is a synthesized attribute’s value computed from? a) Its parent node b) Its sibling nodes c) Its child nodes d) Its own value Answer: c) Its child nodes Which attribute type is used to pass information from parent to child nodes? a) Synthesized b) Inherited c) Global d) Local Answer: b) Inherited Which of the following is an example of an inherited attribute? a) The value of an identifier in a scope b) The type of a variable in a declaration c) The result of an arithmetic expression d) The length of a string Answer: a) The value of an identifier in a scope What is the main challenge in evaluating inherited attributes in attribute grammars? a) They require bottom-up parsing b) They need access to parent node information c) They are computed before synthesized attributes d) They are used only in context-free grammars Answer: b) They need access to parent node information Which method of attribute grammar evaluation is suitable for top-down parsing? a) Post-order traversal b) Pre-order traversal c) Level-order traversal d) Depth-first traversal Answer: b) Pre-order traversal Which of the following is NOT a characteristic of synthesized attributes? a) Computed from child nodes b) Used for bottom-up parsing c) Represent semantic values of a subtree d) Depend on parent node information Answer: d) Depend on parent node information In attribute grammars, what is an attribute evaluation function? a) A function that computes attribute values b) A function that defines grammar rules c) A function that parses input strings d) A function that generates tokens Answer: a) A function that computes attribute values Which attribute type is most commonly used in syntax-directed translation? a) Inherited attributes b) Synthesized attributes c) Global attributes d) Local attributes Answer: b) Synthesized attributes Which of the following statements about attribute grammars is true? a) All attributes must be synthesized b) Inherited attributes are always computed first c) Attribute grammars can be used to specify the semantics of programming languages d) Attribute grammars are only used for syntactic analysis Answer: c) Attribute grammars can be used to specify the semantics of programming languages In an attribute grammar, how are inherited attributes typically computed? a) By traversing the parse tree from leaves to root b) By traversing the parse tree from root to leaves c) By evaluating semantic rules from parent to child d) By evaluating semantic rules from child to parent Answer: c) By evaluating semantic rules from parent to child What is the key advantage of using attribute grammars over context-free grammars alone? a) Attribute grammars can specify semantic constraints and computations b) Attribute grammars are simpler to implement c) Attribute grammars provide faster parsing d) Attribute grammars do not require a syntax tree Answer: a) Attribute grammars can specify semantic constraints and computations What type of attribute is used to carry information from a parent node to a child node? a) Synthesized b) Inherited c) Static d) Dynamic Answer: b) Inherited Which traversal order is typically used for synthesized attributes in a parse tree? a) Pre-order b) Post-order c) Level-order d) Depth-first Answer: b) Post-order In attribute grammars, what is a semantic action? a) A function that modifies the parse tree b) An operation that computes attribute values c) A rule that changes grammar productions d) An action performed during lexical analysis Answer: b) An operation that computes attribute values Which type of attribute is generally associated with attribute grammar rules that depend on parent information? a) Synthesized b) Inherited c) Both synthesized and inherited d) None of the above Answer: b) Inherited What is the role of semantic rules in attribute grammars? a) To define the syntax of a language b) To specify how attributes are computed c) To generate tokens from input strings d) To parse input strings Answer: b) To specify how attributes are computed Which of the following is NOT a typical use of attribute grammars? a) Type checking b) Syntax checking c) Syntax-directed translation d) Code optimization Answer: d) Code optimization What is a “well-formed” attribute grammar? a) A grammar with only synthesized attributes b) A grammar with no inherited attributes c) A grammar where all attributes are properly computed according to their definitions d) A grammar that only defines syntax rules Answer: c) A grammar where all attributes are properly computed according to their definitions Which algorithm is commonly used to evaluate attributes in attribute grammars? a) LL algorithm b) LR algorithm c) SLR algorithm d) DAG (Directed Acyclic Graph) algorithm Answer: d) DAG (Directed Acyclic Graph) algorithm What does a semantic predicate in an attribute grammar do? a) Specifies a semantic action b) Defines a semantic rule c) Adds a condition to the attribute evaluation d) Changes the grammar production Answer: c) Adds a condition to the attribute evaluation Which of the following is an example of a synthesized attribute in a simple arithmetic expression grammar? a) The type of an operand b) The result of an expression c) The precedence of an operator d) The scope of a variable Answer: b) The result of an expression How does an attribute grammar handle semantic errors? a) By using semantic actions to perform error checking b) By modifying the syntax rules c) By ignoring errors during parsing d) By adding additional attributes to the grammar Answer: a) By using semantic actions to perform error checking Which of the following is a common application of attribute grammars in compiler construction? a) Code generation b) Lexical analysis c) Syntax-directed translation d) Tokenization Answer: c) Syntax-directed translation What is a “semantic function” in the context of attribute grammars? a) A function that modifies the syntax tree b) A function that computes the value of an attribute c) A function used in lexical analysis d) A function that generates tokens Answer: b) A function that computes the value of an attribute In which traversal order are inherited attributes usually computed? a) Post-order b) Pre-order c) Level-order d) Depth-first Answer: b) Pre-order Which attribute type would be used to calculate the type of a variable in a type-checking attribute grammar? a) Synthesized b) Inherited c) Global d) Local Answer: a) Synthesized What is the primary benefit of using a DAG in evaluating attribute grammars? a) It simplifies syntax analysis b) It reduces the complexity of attribute evaluation c) It improves lexical analysis d) It eliminates the need for semantic actions Answer: b) It reduces the complexity of attribute evaluation What is a common characteristic of well-formed attribute grammars? a) They use only inherited attributes b) They use only synthesized attributes c) They ensure that all attributes are computed according to their rules d) They avoid using semantic rules Answer: c) They ensure that all attributes are computed according to their rules In attribute grammars, what does the term “syntax-directed translation” refer to? a) Translating syntax rules into code b) Translating parse trees into semantic actions c) Translating tokens into syntax rules d) Translating semantic actions into code Answer: b) Translating parse trees into semantic actions Which data structure is often used to represent attribute grammars? a) Parse tree b) Abstract syntax tree (AST) c) Directed Acyclic Graph (DAG) d) Linear list Answer: c) Directed Acyclic Graph (DAG) How can attribute grammars be used in type checking? a) By defining semantic rules that enforce type constraints b) By parsing type declarations c) By generating type information from syntax rules d) By creating type conversion functions Answer: a) By defining semantic rules that enforce type constraints Which attribute type is most useful for maintaining context-sensitive information? a) Synthesized b) Inherited c) Both synthesized and inherited d) None of the above Answer: b) Inherited What does a “semantic error” in an attribute grammar usually indicate? a) A problem with syntax rules b) A problem with attribute computation c) A problem with tokenization d) A problem with parsing Answer: b) A problem with attribute computation What role does a “context-free grammar” play in attribute grammars? a) It defines the syntax of the language b) It defines the semantic rules c) It generates tokens for parsing d) It manages semantic actions Answer: a) It defines the syntax of the language Which attribute type is most often used for computing values based on children nodes in a parse tree? a) Inherited b) Synthesized c) Global d) Static Answer: b) Synthesized In attribute grammars, what is a semantic rule typically used for? a) Defining syntax productions b) Computing the values of attributes c) Parsing input strings d) Generating tokens Answer: b) Computing the values of attributes What is the purpose of a “semantic predicate” in an attribute grammar? a) To validate semantic constraints b) To define syntax rules c) To generate tokens d) To perform lexical analysis Answer: a) To validate semantic constraints Which type of attribute is particularly useful for implementing scope rules in a compiler? a) Synthesized b) Inherited c) Both synthesized and inherited d) None of the above Answer: b) Inherited In attribute grammars, which of the following best describes synthesized attributes? a) Computed from parent attributes b) Computed from child attributes c) Computed from sibling attributes d) Computed from global attributes Answer: b) Computed from child attributes Which of the following is a common application of inherited attributes? a) Symbol table management b) Expression evaluation c) Syntax checking d) Token generation Answer: a) Symbol table management In an attribute grammar, what does a “semantic action” typically perform? a) Computes attribute values b) Defines syntax rules c) Parses input strings d) Generates tokens Answer: a) Computes attribute values What is the role of semantic rules in context-sensitive language processing? a) To define syntax rules b) To compute attribute values based on context c) To tokenize input strings d) To parse syntax trees Answer: b) To compute attribute values based on context Which attribute grammar concept is primarily concerned with attributes that depend on the parse tree structure and are computed from it? a) Inherited attributes b) Synthesized attributes c) Global attributes d) Local attributes Answer: b) Synthesized attributes