Description
Description You are required to build a parser (using the Bison parser generator) that accepts the language generated by the MiniGLSL grammar (see
below). Your parser must implement the “trace parser” functionality (-Tp
command-line flag) of the compiler (see the man page for details; make man
in the starter directory). No semantic analysis or AST construction need be
performed. If you do semantic analysis or AST construction, then be sure to
disable it in your submission.
Starter Files You will be provided with a complete implementation of scanner.l, as well as a dummy parser.y files. You are free to use your implementation
of scanner.l from Lab 1. Note: not all lexical rules needed for Lab 1 are needed
for Lab 2, as such, some modification of your scanner from Lab 1 will be necessary.
Language Grammar Below is an (ambiguous) context-free grammar generating the MiniGLSL language:
program → scope
scope → ′
{
′
declarations statements ′
}
′
declarations → declarations declaration
→ ǫ
statements → statements statement
→ ǫ
declaration → type hidentifieri
′
;
′
→ type hidentifieri
′ =
′
expression ′
;
′
→ ′
const′
type hidentifieri
′ =
′
expression ′
;
′
→ ǫ
statement → variable =
′
expression ′
;
′
→ ′
if′ ′(
′
expression ′
)
′
statement else_statement
→ ′while
′ ′(
′
expression ′
)
′
statement
→ scope
1
→ ′
;
′
else_statement → ′
else′
statement
→ ǫ
type → ′
int′
|
′
ivec2
′
|
′
ivec3
′
|
′
ivec4
′
→ ′
bool′
|
′
bvec2
′
|
′
bvec3
′
|
′
bvec4
′
→ ′
float′
|
′
vec2
′
|
′
vec3
′
|
′
vec4
′
expression → constructor
→ function
→ hinteger literali
→ hfloating point literali
→ variable
→ unary_op expression
→ expression binary_op expression
→ ′
true′
|
′
false′
→ ′
(
′
expression ′
)
′
variable → hidentifieri
→ hidentifieri
′
[
′
hinteger literali
′
]
′
unary_op → ′
!
′
|
′ −
′
binary_op → ′&&′
|
′
||′
|
′ ==
′
|
′
! =
′
|
′ <
′
|
′ <= ′ → ′ >
′
|
′ >=
′
|
′ +
′
|
′ −
′
|
′
∗
′
|
′
/
′
|
′
ˆ
′
constructor → type ′
(
′
arguments ′
)
′
function → function_name ′
(
′
arguments_opt ′
)
′
function_name → ′
dp3
′
|
′
lit′
|
′
rsq′
arguments_opt → arguments | ǫ
arguments → arguments ′
,
′
expression | expression
Operator Precedence Below is an operator precedence table for MiniGLSL.
Precedence Operators Associativity
0 (highest) [ ] vector subscript
left-to-right
( ) function call
( ) constructor call
1 – arithmetic negate
! logical negate
2 ^ exponentiation right-to-left
3 * multiply
left-to-right
/ divide
4 + add
2
Precedence Operators Associativity
– subtract
5 == equal to
!= not equal to
< less than
<= less than or equal to > greater than
>= greater than or equal to
6 && Boolean AND
7 (lowest) || Boolean OR
Left-to-right associativity implies that 1 + 2 + 3 is interpreted as (1 + 2) + 3.
Right-to-left associativity implies that 1ˆ2ˆ3 is interpreted as 1ˆ(2ˆ3).
High precedence implies that −1 − 2 is interpreted as (−1) − 2.
Miscellaneous Language Details
Integers Valid integers fall in the open range (−2
21
, 2
21). Integers are base
10, and are generated with the following regular expression: 0|[1 −
10][0 − 10]∗
.
Floats Valid floating point numbers are exactly those represented by the C
float type. Floats are generated with either of the following regular
expressions: (0|[1 − 10][0 − 10]∗
).[0 − 10]∗ or .[0 − 10]+, where ’.’ is
a decimal point.
Identifiers Valid identifiers must be no more than 32 characters in length and
are generated by the following regular expression: [a−zA−Z_][a−
zA − Z0 − 9_]
∗
.
Documentation You must document your code (excessive documentation is
not necessary), and provide a written report detailing the breakdown of work,
challenges faced, overall approach taken, how your group verified the parser,
and (optional) anything interesting that your group would like to highlight.
Testing It is suggested that you test your parser using tests that are expected
to pass and fail. Submitting tests in a subdirectory will be appreciated.
Hint Don’t try to make your parser too smart. The parser is responsible for
syntax only. That is, the parser can accept semantically invalid programs, so
long as they are syntactically correct. The implication here is that the parser
accepts a “bigger” language than MiniGLSL, i.e. every string generated by the
above grammar (not all of which can be compiled).
For example, the expression ’1+true’ is semantically invalid, but syntactically correct.
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