ECMAScript::AST traversal example

solarradiation_ecma_ast.out

# 1:  Program
# 2:    Statement
# 3:      VariableStatement
# 3:      VAR: 'var' @0:3
# 3:      IDENTIFIER: 'i' @4:5
# 3:      ASSIGN: '=' @6:7
# 3:      DECIMALLITERAL: '0' @8:9
# 2:    Statement
# 3:      ExpressionStatement
# 3:      IDENTIFIER: 'i' @11:12
# 3:      ASSIGN: '=' @13:14
# 3:      IDENTIFIER: 'i' @15:16
# 3:      PLUS: '+' @17:18
# 3:      DECIMALLITERAL: '1' @19:20

solarradiation_ecma_ast.pl

#!/usr/bin/env perl
use 5.010;

use strict;
use warnings FATAL => 'all';

use MarpaX::Languages::ECMAScript::AST;

use Data::Dumper;
$Data::Dumper::Deepcopy = 1;
$Data::Dumper::Indent = 0;
$Data::Dumper::Terse = 1;
$Data::Dumper::Sortkeys = 1;

my $ecmaSourceCode = 'var i = 0; i = i + 1;';
my $ecmaAstObject = MarpaX::Languages::ECMAScript::AST->new();
my $ast = $ecmaAstObject->parse($ecmaSourceCode);

my %semantic = map{ $_ => 1 } qw{
	Program Statement VariableStatement ExpressionStatement
	VAR IDENTIFIER ASSIGN DECIMALLITERAL PLUS
};

sub traverse{
	my ($node) = @_;

	state $level = 0;

	# unpack node
	my ($lhs, $rhs, $values) = map { $node->{$_} } qw { lhs rhs values };

	# print debug info: uncomment to see what you may need to distill
	# say "$level:", ' ' x $level, Dumper $node;

	$level++ if $semantic{$lhs};

	# process node based on its LHS -- node id -- unless it's just syntax
	say qq{# $level:}, '  ' x $level, $lhs
		if $semantic{$lhs}; # skip syntactic nodes

	# process node RHS -- node children
	for my $i (0..@$values-1){

		# name & value -- node child
		my $name  = $rhs->[$i];
		my $value = $values->[$i];

		# process child as literal
		if (ref $value eq "ARRAY"){
			my ($start, $length, $literal) = @$value;
			if (exists $semantic{$name}){
				say qq{# $level:}, '  ' x $level, qq{$name: '$literal'}, ' @', $start, ':', $start + $length;
			}
		}
		# process child recursively
		elsif (ref $value eq "HASH"){
			traverse($value);
			$level--
				if $semantic{$lhs}; # skip syntactic nodes
		}
	}
}

traverse($ast);

origin: http://irclog.perlgeek.de/marpa/2016-05-18#i_12498971