grammar of a new language [closed] - grammar

Question

Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
Improve this question
I have this grammar which I am not able to understand as to how to make a parser for it:
module = properties fields methods module#3 'end'
properties = list#0 (property add#2)*
property = 'class' 'name' class# ';'
fields = list#0 (field add#2)*
field = type list#0 id add#2 [';'/','] ! (',' id add#2)* ';' field#2
methods = list#0 (method add#2)*
method = (type id / nothing#0 id) ! '(' args ')' follow method#4
args = list#0 (arg add#2 (',' arg add#2)*)?
arg = type id ! arg#2 / nothing#0 id ! arg#2
statements = list#0 (statement add#2)*
statement = do / jump / compound / simple
follow = block / jump / compound / simple
jump = break / continue / return
compound = if / while
simple = local / assign
do = 'do' '{' statements '}' do#1
block = '{' statements '}' block#1
break = 'break' ';' break#0
continue = 'continue' ';' continue#0
return = 'return' (exp / nothing#0) ';' return#1
if = 'if' '(' exp ')' follow ('else' follow / nothing#0) if#3
while = 'while' '(' exp ')' follow while#2
local = type id ! init? local#2 ';'
init = 'assign' exp assign#2 / '.' id dot#2 '(' exps ')' call#2
assign = id 'assign' ! exp assign#2 ';'
exp = id ( '(' exps ')' call#2 / '.' id dot#2 '(' exps ')' call#2 )?
exps = list#0 (exp add#2 (',' exp add#2)*)?
type = 'name' type#
id = 'name' id#
'.' = 'DOT'
Could anyone please make me comprehend this grammar.
thanks

Answer 1

This:
module = properties fields methods module#3 'end'
means that:
a module consists of properties, followed by fields, followed by methods, followed by the word "end"
so in order to parse a module the compiler should:
parse properties
parse fields
parse methods
match the word "end"
The item with the "#" is the type of syntax node it should create, the number indicating how many of the previous parse results should be passed to it.
In the Python language the code might look something like this:
def parse_module():
properties = parse_properties()
fields = parse_fields()
methods = parse_methods()
module = make_module(properties, fields, methods)
match("end")
return module
A "/" separates alternatives, "(...)*" indicates any number of repeats, and "?" indicates an optional item.