Deck 6: Syntax

Question 1

In a regular expression,curly braces are used to indicate a range of characters.

Answer 1

False

Question 2

Most modern languages are in a completely fixed format.

Answer 2

False

Question 3

Derivation is the process that replaces left-hand sides by choices of right-hand sides appearing in prior rules.

Answer 3

True

Question 4

Abstract syntax trees abstract the essential structure of the parse tree.

Question 5

Productions are in Backus-Naur form if they are given using only the metasymbols "<" and ">".

Question 6

Reserved words,or keywords,are not considered to be a typical token category.

Question 7

In extended Backus-Naur form,square brackets [ ] indicate optional parts of the syntax.

Question 8

Backus-Naur forms are used to describe the syntax of programming languages such as Algol60.

Question 9

Regular expressions can be used to describe tokens.

Question 10

The description of simple integer arithmetic expressions with addition and multiplication cannot be represented by a context-free grammar.

Question 11

The curly bracket { } notation used in extended Backus-Naur form stands for "at least one or more repetitions of."

Question 12

The lexical structure of a programming language is the structure of its tokens,or words.

Question 13

The start symbol is used to identify the start of the grammar.

Question 14

A recognizer is a program that accepts or rejects strings based on whether they have occurred before.

Question 15

White space is an example of a token delimiter.

Question 16

A grammar for which two distinct parse trees are possible for the same string is considered to be ambiguous.

Question 17

Words or tokens are called terminals,since they cannot be broken down further.

Question 18

The process of associating the semantics of a construct to its syntactic structure is called syntax-directed semantics.

Question 19

Ordinary syntax is sometimes called concrete syntax to distinguish it from abstract syntax.

Question 20

A left-recursive rule for an operation causes it to left-associate.

Question 21

Recursive-descent parsers turn the nonterminals into a group of mutually recursive procedures whose actions are based on the right-hand side of the BNFs.

Question 22

Shift-reduce parsers shift tokens onto a stack before reducing strings to nonterminals.

Question 23

____ are symbols used to distinguish between parts of a rule.

A) Distinguishers
B) Identifiers
C) Metasymbols
D) Abstract characters

Question 24

In a regular expression,repetition is indicated by ____.

A) an exclamation mark
B) a vertical bar
C) a hyphen
D) an asterisk

Question 25

A language is considered to be ____ when format has no effect on the program structure (other than to satisfy the principle of longest substring).

A) open-format
B) free-format
C) loose-format
D) fixed format

Question 26

Grammar rules are also called ____.

A) productions
B) compilations
C) instructions
D) documentation

Question 27

____ are phrase structures that are broken down into further phrase structures.

A) Nonterminals
B) Complex grammars
C) Compressed structures
D) Terminals

Question 28

Which of the following is not considered to be a token category?

A) reserved word
B) identifier
C) literal
D) white space

Question 29

____ languages require all tokens to occur in prespecified locations on the page.

A) Free-format
B) Precise-format
C) Fixed-format
D) Specified-format

Question 30

Predictive parsing allows tokens that begin optional parts of the syntax to also appear after the optional part.

Question 31

During its ____ phase,a translator collects sequences of characters from the input program and forms them into tokens.

A) parsing
B) analyzing
C) generating
D) scanning

Question 32

The lexical structure of a programming language is the structure of its ____.

A) variables
B) tokens
C) comments
D) references

Question 33

A context-free grammar consists of a series of ____.

A) grammar rules
B) positional rules
C) semantic rules
D) algebraic expressions

Question 34

A conflict between syntax and semantics arises when languages require certain strings to be predefined identifiers rather than reserved words.

Question 35

____ have been given an initial meaning for all programs in the language but are capable of being redefined.

A) Predefined identifiers
B) Keywords
C) Global literals
D) Constants

Question 36

____ are descriptions of patterns of characters.

A) Syntax diagrams
B) Regular expressions
C) Canonical diagrams
D) Variable expressions

Question 37

The principle of ____ takes the longest possible string of nonblank characters into a single token.

A) greatest aggregate
B) maximized grouping
C) longest substring
D) multipass parsing

Question 38

During the ____ phase,the translator processes the tokens,determining the program's syntactic structure.

A) generation
B) parsing
C) implementation
D) scanning

Question 39

A context-free grammar has a special nonterminal called the ____ symbol which stands for the entire top-level phrase being defined.

A) initial
B) start
C) forward
D) abstract

Question 40

A bottom-up parser constructs derivations and parse trees from the leaves to the root.

Question 41

The use of a single token to direct a parse is called single-symbol ____.

A) interpretation
B) prediction
C) directives
D) lookahead

Question 42

The purpose of a(n)____ is to apply grammar rules to a source program and report syntax or lexical errors,without performing any additional analysis.

A) parsing shell
B) interpreter
C) verifying shells
D) reducing shells

Question 43

____ automatically translate a BNF description into a parser.

A) Shift-reduce parsers
B) Scanners
C) Parser generators
D) Syntax generators

Question 44

A grammar is considered to be context-free if ____.

A) each terminal can be replaced by any right-hand side choice, no matter where it appears
B) each nonterminal can be replaced by any right-hand side choice, no matter where it appears
C) context strings appear on the left-hand sides of grammar rules
D) the grammar also expresses the semantics of the language

Question 45

A ____ is the standard graphical depiction of syntax-directed semantics.

A) flow chart
B) UML diagram
C) chained list
D) parse tree

Question 46

A parser that commits itself to a particular action based only on a lookahead is called a(n)____ parser.

A) foresight
B) insightful
C) predictive
D) exhaustive

Question 47

The simplest form of a parser is a(n)____.

A) recognizer
B) translator
C) compiler
D) interpreter

Question 48

A requirement that a sentence must start with a capitalized letter is an example of a ____.

A) terminal
B) nonterminal
C) grammar rule
D) positional property

Question 49

A ____ rule must be stated to overcome ambiguous grammars.

A) clarifying
B) disambiguating
C) specifying
D) overriding

Question 50

The processing of white space is generally handled by a ____.

A) parser
B) scanner
C) predictive parser
D) parser generator