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|
##### LM #####
#
# Tokens
#
# Any single character can be a literal
lex
# Ignore whitespace.
ignore /[ \t\n\r\v]+/
# Open and close id
token id /[a-zA-Z_][a-zA-Z0-9_]*/
token open_paren /'('/
{
parse_stop NC: nested_comment[ input ]
print( 'discarding: ' NC '\n' )
}
end
#
# Token translation
#
lex
literal `( `)
token nc_data /[^()]+/
end
def nc_item
[nc_data]
| [nested_comment]
def nested_comment
[`( nc_item* `)]
def nested [id*]
#
# Accumulator.
#
context accum_bt
NestedParser: accum<nested>
lex
ignore /[ \t]+/
token word /[a-zA-Z0-9/*+_\-]+/
token stuff /[a-zA-Z0-9()/*+_\- ]+/
literal `! `;
token NL /'\n'/
end
def A1 []
{ print( "A1\n" ) }
def A2 []
{ print( "A2\n" ) }
def item
[word]
{
send NestedParser [' ']
send NestedParser [$r1]
send NestedParser [' ']
}
|
[stuff]
{
send NestedParser [' ']
send NestedParser [$r1]
send NestedParser [' ']
}
def two
[A1 item* `! NL]
| [A2 item* `; NL]
end # accum_bt
cons AccumBt: accum_bt[]
AccumBt.NestedParser = cons parser<nested>[]
parse Two: accum_bt::two(AccumBt)[ stdin ]
send AccumBt.NestedParser [] eos
Nested: nested = AccumBt.NestedParser.tree
print( '\n------------\n' )
print( ^Nested '\n' )
print( ^Two '\n' )
##### IN #####
hello there ( (this is a nested comment /*sdf asd_++_stuff) ) and this is not ;
##### EXP #####
A1
discarding: ( (this is a nested comment /*sdf asd_++_stuff) )
A2
discarding: ( (this is a nested comment /*sdf asd_++_stuff) )
------------
hello there and this is not
hello there ( (this is a nested comment /*sdf asd_++_stuff) ) and this is not ;
|
