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|
lex start
{
ignore /[\t\n ]+/
literal '^', '|', '-', ',', ':', '!', '?', '.'
literal '(', ')', '{', '}', '*', '&', '+'
literal '--', ':>', ':>>', '<:', '->', '**'
token word /[a-zA-Z_][a-zA-Z0-9_]*/
token uint /[0-9]+/
}
def start [expression]
def expression [term expression_op*]
def expression_op
['|' term]
| ['&' term]
| ['-' term]
| ['--' term]
def term [factor_rep term_rest]
# This list is done manually to get shortest match.
def term_rest
[]
| [term_op term_rest]
def term_op
[factor_rep]
| ['.' factor_rep]
| [':>' factor_rep]
| [':>>' factor_rep]
| ['<:' factor_rep]
def factor_rep
[factor_neg factor_rep_op*]
def factor_rep_op
['*']
| ['**']
| ['?']
| ['+']
| ['{' factor_rep_num '}']
| ['{' ',' factor_rep_num '}']
| ['{' factor_rep_num ',' '}']
| ['{' factor_rep_num ',' factor_rep_num '}']
def factor_rep_num [uint]
def factor_neg
['!' factor_neg]
| ['^' factor_neg]
| [factor]
def factor
[alphabet_num]
| [word]
| ['(' expression ')']
def alphabet_num
[uint]
parse SP: start[stdin]
S: start = SP.tree
#
# Top-Down, Left-Right
#
int do_topdown_leftright( T: ref any )
{
for C:any in child(T) {
yield C
do_topdown_leftright( C )
}
}
iter topdown_leftright( T: ref any )
{
do_topdown_leftright( T )
}
#
# Bottom-Up, Left-Right
#
int do_bottomup_leftright( T: ref any )
{
for C:any in child(T) {
do_bottomup_leftright( C )
yield C
}
}
iter bottomup_leftright( T: ref any )
{
do_bottomup_leftright( T )
}
#
# Top-Down, Right-Left
#
int do_topdown_rightleft( T: ref any )
{
for C:any in rev_child(T) {
yield C
do_topdown_rightleft( C )
}
}
iter topdown_rightleft( T: ref any )
{
do_topdown_rightleft( T )
}
#
# Bottom-Up, Right-Left
#
int do_bottomup_rightleft( T: ref any )
{
for C:any in rev_child(T) {
do_bottomup_rightleft( C )
yield C
}
}
iter bottomup_rightleft( T: ref any )
{
do_bottomup_rightleft( T )
}
#
# Testing
#
print( 'bottomup_leftright\n' )
for T1: any in bottomup_leftright( S )
{
print( ^T1 '\n' )
}
print( 'bottomup_rightleft\n' )
for T2: any in bottomup_rightleft( S )
{
print( ^T2 '\n' )
}
print( 'topdown_leftright\n' )
for T3: any in topdown_leftright( S )
{
print( ^T3 '\n' )
}
print( 'topdown_rightleft\n' )
for T4: any in topdown_rightleft( S )
{
print( ^T4 '\n' )
}
|
