Tree datastructures
You are encouraged to solve this task according to the task description, using any language you may know.
The following shows a tree of data with nesting denoted by visual levels of indentation:
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
A common datastructure for trees is to define node structures having a name and a, (possibly empty), list of child nodes. The nesting of nodes captures the indentation of the tree. Lets call this the nest form.
# E.g. if child nodes are surrounded by brackets # and separated by commas then: RosettaCode(rocks(code, ...), ...) # But only an _example_
Another datastructure for trees is to construct from the root an ordered list of the nodes level of indentation and the name of that node. The indentation for the root node is zero; node 'rocks is indented by one level from the left, and so on. Lets call this the indent form.
0 RosettaCode 1 rocks 2 code ...
- Task
- Create/use a nest datastructure format and textual representation for arbitrary trees.
- Create/use an indent datastructure format and textual representation for arbitrary trees.
- Create methods/classes/proceedures/routines etc to:
- Change from a nest tree datastructure to an indent one.
- Change from an indent tree datastructure to a nest one
- Use the above to encode the example at the start into the nest format, and show it.
- transform the initial nest format to indent format and show it.
- transform the indent format to final nest format and show it.
- Compare initial and final nest formats which should be the same.
- Note
- It's all about showing aspects of the contrasting datastructures as they hold the tree.
- Comparing nested datastructures is secondary - saving formatted output as a string then a string compare would suffice for this task, if its easier.
Show all output on this page.
C++
<lang cpp>#include <iomanip>
- include <iostream>
- include <list>
- include <string>
- include <vector>
- include <utility>
- include <vector>
class nest_tree;
bool operator==(const nest_tree&, const nest_tree&);
class nest_tree { public:
explicit nest_tree(const std::string& name) : name_(name) {}
nest_tree& add_child(const std::string& name) {
children_.emplace_back(name);
return children_.back();
}
void print(std::ostream& out) const {
print(out, 0);
}
const std::string& name() const {
return name_;
}
const std::list<nest_tree>& children() const {
return children_;
}
bool equals(const nest_tree& n) const {
return name_ == n.name_ && children_ == n.children_;
}
private:
void print(std::ostream& out, int level) const {
std::string indent(level * 4, ' ');
out << indent << name_ << '\n';
for (const nest_tree& child : children_)
child.print(out, level + 1);
}
std::string name_;
std::list<nest_tree> children_;
};
bool operator==(const nest_tree& a, const nest_tree& b) {
return a.equals(b);
}
class indent_tree { public:
explicit indent_tree(const nest_tree& n) {
items_.emplace_back(0, n.name());
from_nest(n, 0);
}
void print(std::ostream& out) const {
for (const auto& item : items_)
std::cout << item.first << ' ' << item.second << '\n';
}
nest_tree to_nest() const {
nest_tree n(items_[0].second);
to_nest_(n, 1, 0);
return n;
}
private:
void from_nest(const nest_tree& n, int level) {
for (const nest_tree& child : n.children()) {
items_.emplace_back(level + 1, child.name());
from_nest(child, level + 1);
}
}
size_t to_nest_(nest_tree& n, size_t pos, int level) const {
while (pos < items_.size() && items_[pos].first == level + 1) {
nest_tree& child = n.add_child(items_[pos].second);
pos = to_nest_(child, pos + 1, level + 1);
}
return pos;
}
std::vector<std::pair<int, std::string>> items_;
};
int main() {
nest_tree n("RosettaCode");
auto& child1 = n.add_child("rocks");
auto& child2 = n.add_child("mocks");
child1.add_child("code");
child1.add_child("comparison");
child1.add_child("wiki");
child2.add_child("trolling");
std::cout << "Initial nest format:\n";
n.print(std::cout);
indent_tree i(n);
std::cout << "\nIndent format:\n";
i.print(std::cout);
nest_tree n2(i.to_nest());
std::cout << "\nFinal nest format:\n";
n2.print(std::cout);
std::cout << "\nAre initial and final nest formats equal? "
<< std::boolalpha << n.equals(n2) << '\n';
return 0;
}</lang>
- Output:
Initial nest format:
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
Indent format:
0 RosettaCode
1 rocks
2 code
2 comparison
2 wiki
1 mocks
2 trolling
Final nest format:
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
Are initial and final nest formats equal? true
Go
<lang go>package main
import (
"fmt" "io" "os" "strings"
)
type nNode struct {
name string children []nNode
}
type iNode struct {
level int name string
}
func printNest(n nNode, level int, w io.Writer) {
if level == 0 {
fmt.Fprintln(w, "\n==Nest form==\n")
}
fmt.Fprintf(w, "%s%s\n", strings.Repeat(" ", level), n.name)
for _, c := range n.children {
fmt.Fprintf(w, "%s", strings.Repeat(" ", level+1))
printNest(c, level+1, w)
}
}
func toNest(iNodes []iNode, start, level int, n *nNode) {
if level == 0 {
n.name = iNodes[0].name
}
for i := start + 1; i < len(iNodes); i++ {
if iNodes[i].level == level+1 {
c := nNode{iNodes[i].name, nil}
toNest(iNodes, i, level+1, &c)
n.children = append(n.children, c)
} else if iNodes[i].level <= level {
return
}
}
}
func printIndent(iNodes []iNode, w io.Writer) {
fmt.Fprintln(w, "\n==Indent form==\n")
for _, n := range iNodes {
fmt.Fprintf(w, "%d %s\n", n.level, n.name)
}
}
func toIndent(n nNode, level int, iNodes *[]iNode) {
*iNodes = append(*iNodes, iNode{level, n.name})
for _, c := range n.children {
toIndent(c, level+1, iNodes)
}
}
func main() {
n1 := nNode{"RosettaCode", nil}
n2 := nNode{"rocks", []nNode{{"code", nil}, {"comparison", nil}, {"wiki", nil}}}
n3 := nNode{"mocks", []nNodeTemplate:"trolling", nil}
n1.children = append(n1.children, n2, n3)
var sb strings.Builder printNest(n1, 0, &sb) s1 := sb.String() fmt.Print(s1)
var iNodes []iNode toIndent(n1, 0, &iNodes) printIndent(iNodes, os.Stdout)
var n nNode toNest(iNodes, 0, 0, &n) sb.Reset() printNest(n, 0, &sb) s2 := sb.String() fmt.Print(s2)
fmt.Println("\nRound trip test satisfied? ", s1 == s2)
}</lang>
- Output:
==Nest form==
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
==Indent form==
0 RosettaCode
1 rocks
2 code
2 comparison
2 wiki
1 mocks
2 trolling
==Nest form==
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
Round trip test satisfied? true
Julia
<lang julia>const nesttext = """ RosettaCode
rocks
code
comparison
wiki
mocks
trolling
"""
function nesttoindent(txt)
ret = ""
windent = gcd(length.([x.match for x in eachmatch(r"\s+", txt)]) .- 1)
for lin in split(txt, "\n")
ret *= isempty(lin) ? "\n" : isspace(lin[1]) ?
replace(lin, r"\s+" => (s) -> "$(length(s)÷windent) ") * "\n" :
"0 " * lin * "\n"
end
return ret, " "^windent
end
function indenttonest(txt, indenttext)
ret = ""
for lin in filter(x -> length(x) > 1, split(txt, "\n"))
(num, name) = split(lin, r"\s+", limit=2)
indentnum = parse(Int, num)
ret *= indentnum == 0 ? name * "\n" : indenttext^indentnum * name * "\n"
end
return ret
end
indenttext, itext = nesttoindent(nesttext) restorednesttext = indenttonest(indenttext, itext)
println("Original:\n", nesttext, "\n") println("Indent form:\n", indenttext, "\n") println("Back to nest form:\n", restorednesttext, "\n") println("original == restored: ", strip(nesttext) == strip(restorednesttext))
</lang>
- Output:
Original:
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
Indent form:
0 RosettaCode
1 rocks
2 code
2 comparison
2 wiki
1 mocks
2 trolling
Back to nest form:
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
original == restored: true
Perl
<lang perl>use strict; use warnings; use feature 'say'; use JSON; use Data::Printer;
my $trees = <<~END;
RosettaCode
encourages
code
diversity
comparison
discourages
golfing
trolling
emphasising execution speed
code-golf.io
encourages
golfing
discourages
comparison
END
my $level = ' '; sub nested_to_indent { shift =~ s#^($level*)# ($1 ? length($1)/length $level : 0) . ' ' #egmr } sub indent_to_nested { shift =~ s#^(\d+)\s*# $level x $1 #egmr }
say my $indent = nested_to_indent $trees;
my $nest = indent_to_nested $indent;
use Test::More; is($trees, $nest, 'Round-trip'); done_testing();
- Import outline paragraph into native data structure
sub import {
my($trees) = @_; my $level = ' '; my $forest; my $last = -999;
for my $branch (split /\n/, $trees) {
$branch =~ m/(($level*))*/;
my $this = $1 ? length($1)/length($level) : 0;
$forest .= do {
if ($this gt $last) { '[' . trim_and_quote($branch) }
elsif ($this lt $last) { ']'x($last-$this).',' . trim_and_quote($branch) }
else { trim_and_quote($branch) }
};
$last = $this;
}
sub trim_and_quote { shift =~ s/^\s*(.*\S)\s*$/"$1",/r }
eval $forest . ']' x (1+$last);
}
my $forest = import $trees; say "Native data structure:\n" . np $forest; say "\nJSON:\n" . encode_json($forest);</lang>
- Output:
RosettaCode
1 encourages
2 code
3 diversity
3 comparison
1 discourages
2 golfing
2 trolling
2 emphasising execution speed
code-golf.io
1 encourages
2 golfing
1 discourages
2 comparison
ok 1 - Round-trip
1..1
Native data structure:
\ [
[0] "RosettaCode",
[1] [
[0] "encourages",
[1] [
[0] "code",
[1] [
[0] "diversity",
[1] "comparison"
]
],
[2] "discourages",
[3] [
[0] "golfing",
[1] "trolling",
[2] "emphasising execution speed"
]
],
[2] "code-golf.io",
[3] [
[0] "encourages",
[1] [
[0] "golfing"
],
[2] "discourages",
[3] [
[0] "comparison"
]
]
]
JSON:
["RosettaCode",["encourages",["code",["diversity","comparison"]],"discourages",["golfing","trolling","emphasising execution speed"]],"code-golf.io",["encourages",["golfing"],"discourages",["comparison"]]]
Phix
The standard Phix sequence is perfect for handling all of these kinds of structures.
function text_to_indent(string plain_text) sequence lines = split(plain_text,"\n",no_empty:=true), parents = {} for i=1 to length(lines) do string line = trim_tail(lines[i]), text = trim_head(line) integer indent = length(line)-length(text) -- remove any completed parents while length(parents) and indent<=parents[$] do parents = parents[1..$-1] end while -- append potential new parent parents &= indent integer depth = length(parents) lines[i] = {depth,text} end for return lines end function function indent_to_nested(sequence indent, integer idx=1, level=1) sequence res = {} while idx<=length(indent) do {integer lvl, string text} = indent[idx] if lvl<level then exit end if {sequence children,idx} = indent_to_nested(indent,idx+1,level+1) res = append(res,{text,children}) end while return {res,idx} end function function nested_to_indent(sequence nested, integer level=1) sequence res = {} for i=1 to length(nested) do {string text, sequence children} = nested[i] res = append(res,{level,text}) res &= nested_to_indent(children,level+1) end for return res end function constant text = """ RosettaCode encourages code diversity comparison discourages emphasising execution speed code-golf.io encourages golfing discourages comparison""" sequence indent = text_to_indent(text), nested = indent_to_nested(indent)[1], n2ichk = nested_to_indent(nested) puts(1,"Indent form:\n") pp(indent,{pp_Nest,1}) puts(1,"\nNested form:\n") pp(nested,{pp_Nest,8}) printf(1,"\nNested to indent:%s\n",{iff(n2ichk==indent?"same":"***ERROR***")})
- Output:
Indent form:
{{1, `RosettaCode`},
{2, `encourages`},
{3, `code`},
{4, `diversity`},
{4, `comparison`},
{2, `discourages`},
{3, `emphasising execution speed`},
{1, `code-golf.io`},
{2, `encourages`},
{3, `golfing`},
{2, `discourages`},
{3, `comparison`}}
Nested form:
{{`RosettaCode`,
{{`encourages`,
{{`code`,
{{`diversity`,
{}},
{`comparison`,
{}}}}}},
{`discourages`,
{{`emphasising execution speed`,
{}}}}}},
{`code-golf.io`,
{{`encourages`,
{{`golfing`,
{}}}},
{`discourages`,
{{`comparison`,
{}}}}}}}
Nested to indent:same
You can also strictly enforce these structures, which is obviously useful for debugging.
Admittedly this is somewhat more tedious, but at the same time infinitely more flexible and powerful than a "plain old struct".
type indent_struct(object o) if sequence(o) then for i=1 to length(o) do object oi = o[i] if not sequence(oi) or length(oi)!=2 or not integer(oi[1]) or not string(oi[2]) then return false end if end for return true end if return false end type type nested_struct(object o) if sequence(o) then for i=1 to length(o) do object oi = o[i] if not sequence(oi) or length(oi)!=2 or not string(oi[1]) or not nested_struct(oi[2]) then return false end if end for return true end if return false end type -- and as above except: function indent_to_nested(indent_struct indent, integer idx=1, level=1) function nested_to_indent(nested_struct nested, integer level=1) -- also make the output sequences better typed: indent_struct indent = text_to_indent(text) nested_struct nested = indent_to_nested(indent)[1] indent_struct r2ichk = nested_to_indent(nested)
Python
Just arranges the standard lists and tuples for the datastructures allowing pprint to show the different arrangement of storage.
<lang python>from pprint import pprint as pp
def to_indent(node, depth=0, flat=None):
if flat is None:
flat = []
if node:
flat.append((depth, node[0]))
for child in node[1]:
to_indent(child, depth + 1, flat)
return flat
def to_nest(lst, depth=0, level=None):
if level is None:
level = []
while lst:
d, name = lst[0]
if d == depth:
children = []
level.append((name, children))
lst.pop(0)
elif d > depth: # down
to_nest(lst, d, children)
elif d < depth: # up
return
return level[0] if level else None
if __name__ == '__main__':
print('Start Nest format:')
nest = ('RosettaCode', [('rocks', [('code', []), ('comparison', []), ('wiki', [])]),
('mocks', [('trolling', [])])])
pp(nest, width=25)
print('\n... To Indent format:')
as_ind = to_indent(nest)
pp(as_ind, width=25)
print('\n... To Nest format:')
as_nest = to_nest(as_ind)
pp(as_nest, width=25)
if nest != as_nest:
print("Whoops round-trip issues")</lang>
- Output:
Start Nest format:
('RosettaCode',
[('rocks',
[('code', []),
('comparison', []),
('wiki', [])]),
('mocks',
[('trolling', [])])])
... To Indent format:
[(0, 'RosettaCode'),
(1, 'rocks'),
(2, 'code'),
(2, 'comparison'),
(2, 'wiki'),
(1, 'mocks'),
(2, 'trolling')]
... To Nest format:
('RosettaCode',
[('rocks',
[('code', []),
('comparison', []),
('wiki', [])]),
('mocks',
[('trolling', [])])])
Raku
(formerly Perl 6)
Code golf is a entertaining passtime, even if it isn't appropriate for this site. To a large extent, I agree with Hout, I am not really on board with mocking anybody, especially espousing it as an official RosettaCode position. So, feel free to mark this incorrect.
<lang perl6>#`( Sort of vague as to what we are trying to accomplish here. If we are just trying to transform from one format to another, probably easiest to just perform string manipulations. )
my $level = ' ';
my $trees = q:to/END/;
RosettaCode
encourages
code
diversity
comparison
discourages
golfing
trolling
emphasising execution speed
code-golf.io
encourages
golfing
discourages
comparison
END
sub nested-to-indent { $^str.subst: / ^^ ($($level))* /, -> $/ { "{+$0} " }, :g } sub indent-to-nested { $^str.subst: / ^^ (\d+) \s* /, -> $/ { "{$level x +$0}" }, :g }
say $trees; say my $indent = $trees.&nested-to-indent; say my $nest = $indent.&indent-to-nested;
use Test; is($trees, $nest, 'Round-trip equals original');
- `(
If, on the other hand, we want perform more complex transformations; better to load it into a native data structure which will then allow us to manipulate it however we like. )
- Import outline paragraph into native data structure
sub import (Str $trees, $level = ' ') {
my $forest; my $last = -Inf;
for $trees.lines -> $branch {
$branch ~~ / ($($level))* /;
my $this = +$0;
$forest ~= do {
given $this cmp $last {
when More { "\['{esc $branch.trim}', " }
when Same { "'{esc $branch.trim}', " }
when Less { "{']' x $last - $this}, '{esc $branch.trim}', " }
}
}
$last = $this;
}
sub esc { $^s.subst( /(<['\\]>)/, -> $/ { "\\$0" }, :g) }
$forest ~= ']' x 1 + $last; $forest.EVAL;
}
my $forest = import $trees;
say "\nNative data structure:\n", $forest.raku;
{
use JSON::Fast; say "\nJSON:\n", $forest.&to-json;
}
{
use YAML; say "\nYAML:\n", $forest.&dump;
}</lang>
- Output:
RosettaCode
encourages
code
diversity
comparison
discourages
golfing
trolling
emphasising execution speed
code-golf.io
encourages
golfing
discourages
comparison
0 RosettaCode
1 encourages
2 code
3 diversity
3 comparison
1 discourages
2 golfing
2 trolling
2 emphasising execution speed
0 code-golf.io
1 encourages
2 golfing
1 discourages
2 comparison
RosettaCode
encourages
code
diversity
comparison
discourages
golfing
trolling
emphasising execution speed
code-golf.io
encourages
golfing
discourages
comparison
ok 1 - Round-trip equals original
Native data structure:
$["RosettaCode", ["encourages", ["code", ["diversity", "comparison"]], "discourages", ["golfing", "trolling", "emphasising execution speed"]], "code-golf.io", ["encourages", ["golfing"], "discourages", ["comparison"]]]
JSON:
[
"RosettaCode",
[
"encourages",
[
"code",
[
"diversity",
"comparison"
]
],
"discourages",
[
"golfing",
"trolling",
"emphasising execution speed"
]
],
"code-golf.io",
[
"encourages",
[
"golfing"
],
"discourages",
[
"comparison"
]
]
]
YAML:
---
- RosettaCode
- - encourages
- - code
- - diversity
- comparison
- discourages
- - golfing
- trolling
- emphasising execution speed
- code-golf.io
- - encourages
- - golfing
- discourages
- - comparison
...
Wren
<lang ecmascript>import "/dynamic" for Struct import "/fmt" for Fmt
var NNode = Struct.create("NNode", ["name", "children"]) var INode = Struct.create("INode", ["level", "name"])
var sw = ""
var printNest // recursive printNest = Fn.new { |n, level|
if (level == 0) sw = sw + "\n==Nest form==\n\n"
sw = sw + Fmt.swrite("$0s$s\n", " " * level, n.name)
for (c in n.children) {
sw = sw + (" " * (level + 1))
printNest.call(c, level+1)
}
}
var toNest // recursive toNest = Fn.new { |iNodes, start, level, n|
if (level == 0) n.name = iNodes[0].name
var i = start + 1
while (i < iNodes.count) {
if (iNodes[i].level == level + 1) {
var c = NNode.new(iNodes[i].name, [])
toNest.call(iNodes, i, level+1, c)
n.children.add(c)
} else if (iNodes[i].level <= level) return
i = i + 1
}
}
var printIndent = Fn.new { |iNodes|
sw = sw + "\n==Indent form==\n\n"
for (n in iNodes) sw = sw + Fmt.swrite("$d $s\n", n.level, n.name)
}
var toIndent // recursive toIndent = Fn.new { |n, level, iNodes|
iNodes.add(INode.new(level, n.name)) for (c in n.children) toIndent.call(c, level+1, iNodes)
}
var n1 = NNode.new("RosettaCode", []) var n2 = NNode.new("rocks", [NNode.new("code", []), NNode.new("comparison", []), NNode.new("wiki", [])]) var n3 = NNode.new("mocks", [NNode.new("trolling", [])]) n1.children.add(n2) n1.children.add(n3)
printNest.call(n1, 0) var s1 = sw System.print(s1)
var iNodes = [] toIndent.call(n1, 0, iNodes) sw = "" printIndent.call(iNodes) System.print(sw)
var n = NNode.new("", []) toNest.call(iNodes, 0, 0, n) sw = "" printNest.call(n, 0) var s2 = sw System.print(s2)
System.print("\nRound trip test satisfied? %(s1 == s2)")</lang>
- Output:
==Nest form==
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
==Indent form==
0 RosettaCode
1 rocks
2 code
2 comparison
2 wiki
1 mocks
2 trolling
==Nest form==
RosettaCode
rocks
code
comparison
wiki
mocks
trolling
Round trip test satisfied? true
zkl
<lang zkl>fcn nestToIndent(nestTree){
fcn(out,node,level){
out.append(List(level,node[0])); // (n,name) or ("..",name)
if(node.len()>1){ // (name children), (name, (tree))
level+=1; foreach child in (node[1,*]){ if(String.isType(child)) out.append(List(level,child)); else self.fcn(out,child,level) }
}
out
}(List(),nestTree,0)
} fcn nestToString(nestTree,dot="."){
fcn(out,dot,node,level){
out.writeln(dot*level,node[0]); // (name)
if(node.len()>1){ // (name children), (name, (tree))
level+=1; foreach child in (node[1,*]){ if(String.isType(child)) out.writeln(dot*level,child); else self.fcn(out,dot,child,level) }
}
out
}(Data(),dot,nestTree,0).text
}
fcn indentToNest(iTree,depth=0,nTree=List()){
while(iTree){ // (n,name)
d, name := iTree[0];
if(d==depth){
nTree.append(name);
iTree.pop(0);
}
else if(d>depth){ // assume can't skip levels down
if(nTree.len()>1 and not List.isType((nm:=nTree[-1]))){ nTree[-1]=(children:=List(nm)); indentToNest(iTree,d,children); }else{ nTree.append(children:=List(name)); iTree.pop(0); indentToNest(iTree,d+1,children); }
}
else break; // d<depth
}
return(nTree)
} fcn indentToString(indentTree){ indentTree.apply("concat"," ").concat("\n") }</lang> <lang zkl>tree:=L("RosettaCode",
L("rocks","code","comparison","wiki"),
L("mocks","golfing") );
println("Nest tree internal format:\n",tree.toString(*,*)); println("Formated:\n",nestToString(tree));
indentTree:=nestToIndent(tree); println("To indent format:\n",indentToString(indentTree));
nestTree:=indentToNest(indentTree); println("\nIndent to nested format:\n",nestTree); println("Is this tree the same as what we started with? ",nestTree==tree);</lang>
- Output:
Nest tree internal format:
L("RosettaCode",L("rocks","code","comparison","wiki"),L("mocks","golfing"))
Formated:
RosettaCode
.rocks
..code
..comparison
..wiki
.mocks
..golfing
To indent format:
0 RosettaCode
1 rocks
2 code
2 comparison
2 wiki
1 mocks
2 golfing
Indent to nested format:
L("RosettaCode",L("rocks","code","comparison","wiki"),L("mocks","golfing"))
Is this tree the same as what we started with? True
I'm choosing to only allow one root per tree/forest so the Raku example is coded differently: <lang zkl>rakutrees:=L(
L("RosettaCode",
L("encourages",
L("code",
"diversity","comparison")),
L("discourages",
"golfing","trolling","emphasising execution speed"),
),
L("code-golf.io",
L("encourages","golfing"),
L("discourages","comparison"),
)
); println(rakutrees.apply(nestToString).concat()); iTrees := rakutrees.apply(nestToIndent); println(iTrees.apply(indentToString).concat("\n")); (iTrees.apply(indentToNest)==rakutrees).println();</lang>
- Output:
RosettaCode
encourages
code
diversity
comparison
discourages
golfing
trolling
emphasising execution speed
code-golf.io
encourages
golfing
discourages
comparison
0 RosettaCode
1 encourages
2 code
3 diversity
3 comparison
1 discourages
2 golfing
2 trolling
2 emphasising execution speed
0 code-golf.io
1 encourages
2 golfing
1 discourages
2 comparison
True