Description
2 Notation
In the convention that has been followed, syntactic categories (non-terminals)
are indicated by italic type, and literal words and character set members (terminals) by bold type. A colon (:) following a non-terminal introduces its
definition. Alternative definitions are listed on separate lines, except when prefixed by the phrase “one of”. An optional symbol is indicated by the subscript
“opt”, so that the following indicates an optional expression enclosed in braces.
{ expressionopt }
3 Lexical Grammar of tinyC
1. Lexical Elements
token:
keyword
identifier
constant
string-literal
punctuator
2. Keywords
keyword: one of
break float static
case for struct
char goto switch
continue if typedef
default int union
do long void
double return wlile
else short
extern sizeof
3. Identifiers
identifier:
identifier-nondigit
identifier identifier-nondigit
identifier digit
identifier-nondigit: one of
1
a b c d e f g h i j k l m
n o p q r s t u v w x y z
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z
digit: one of
0 1 2 3 4 5 6 7 8 9
4. Constants
constant:
integer-constant
floating-constant
character-constant
integer-constant:
nonzero-digit
integer-constant digit
nonzero-digit: one of
1 2 3 4 5 6 7 8 9
floating-constant:
fractional-constant exponent-partopt
digit-sequence exponent-part
fractional-constant:
digit-sequenceopt . digit-sequence
digit-sequence .
exponent-part:
e signopt digit-sequence
E signopt digit-sequence
sign: one of
+ –
digit-sequence:
digit
digit-sequence digit
character-constant:
‘ c-char-sequence ‘
c-char-sequence:
c-char
c-char-sequence c-char
c-char:
any member of the source character set except
the single-quote ‘, backslash \, or new-line character
escape-sequence
escape-sequence: one of
\’ \” \? \\
\a \b \f \n \r \t \v
5. String literals
string-literal:
” s-char-sequenceopt ”
s-char-sequence:
s-char
s-char-sequence s-char
s-char:
any member of the source character set except
the double-quote ”, backslash \, or new-line character
escape-sequence
2 CS 39003
6. Punctuators
punctuator: one of
[ ] ( ) { } . ->
++ — & * + – ~ !
/ % << >> < > <= >= == != ^ | && ||
? : ; …
= *= /= %= += -= <<= >>= &= ^= |=
, #
7. Comments
(a) Multi-line Comment
Except within a character constant, a string literal, or a comment, the
characters /* introduce a comment. The contents of such a comment
are examined only to identify multibyte characters and to find the
characters */ that terminate it. Thus, /* … */ comments do not
nest.
(b) Single-line Comment
Except within a character constant, a string literal, or a comment,
the characters // introduce a comment that includes all multibyte
characters up to, but not including, the next new-line character. The
contents of such a comment are examined only to identify multibyte
characters and to find the terminating new-line character.
4 The Assignment
a) Write a flex specification for the language of tinyC using the above lexical grammar. Name of your file should be ass3 roll.l, which should not
contain the function main().
b) Write your main() function in a separate file ass3 roll.c to test your lexer.
c) Prepare a Makefile to compile the specifications and generate the lexer.
d) Prepare a test input file ass3 roll test.c that will test all the lexical rules
that you have coded.
e) Prepare a zip-archive with the name ass3 roll.zip containing all the above
files and upload to Moodle.
5 Credit Distribution
• Flex Specifications: 60
• Main function and Makefile: 15 + 5 = 20
• Test file: 20
3 CS 39003
