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|
context tags
{
# Open and close tags by rewriting to generic close tags. Won't work if
# interested in unclosed tags because a token can start as not close_id, but
# then become a close id during the course of parsing.
#
# Regular Definitions
#
rl rl_ws /[ \t\n\r\v]+/
rl rl_id /[a-zA-Z_][a-zA-Z0-9_]*/
#
# Tokens
#
# Any single character can be a literal
lex start
{
literal '!\n', ';\n'
# Ignore whitespace.
ignore /rl_ws/
# Open and close id
token id /rl_id/
}
#
# Global Data
#
def tag_stack
[id tag_stack]
| []
TS: tag_stack
#
# Productions
#
def open_tag
[id]
{
match lhs [Id:id]
match TS [Top:id Rest:tag_stack]
if Id.data == Top.data {
reject
} else {
TS = construct tag_stack [Id TS]
}
}
def close_tag
[id]
{
match lhs [Id: id]
match TS [Top: id Rest: tag_stack]
if Id.data == Top.data
TS = construct tag_stack [Rest]
else
reject
}
def tag
[open_tag tag* close_tag]
def start
[tag* ';\n']
{
print_xml( TS )
print_xml( lhs )
print( 'got structure\n' )
}
| [id* ';\n']
{
print_xml( TS )
print_xml( lhs )
print( 'failed\n' )
}
}
cons Tags: tags[]
Tags.TS = cons tags::tag_stack ["sentinal"]
parse tags::start(Tags)[stdin]
|
