defmodule Graphvix.DotHelpers do
@moduledoc """
This module contains a set of helper methods for converting Elixir graph data
into its DOT representation.
"""
@doc """
Convert top-level node and edge properties for a graph or subgraph into
correct DOT notation.
## Example
iex> graph = Graph.new(edge: [color: "green", style: "dotted"], node: [color: "blue"])
iex> DotHelpers.global_properties_to_dot(graph)
~S( node [color="blue"]
edge [color="green",style="dotted"])
"""
def global_properties_to_dot(graph) do
[:node, :edge]
|> Enum.map(&_global_properties_to_dot(graph, &1))
|> compact()
|> case do
[] -> nil
global_props -> Enum.join(global_props, "\n")
end
end
@doc """
Converts a list of attributes into a properly formatted list of DOT attributes.
## Examples
iex> DotHelpers.attributes_to_dot(color: "blue", shape: "circle")
~S([color="blue",shape="circle"])
"""
def attributes_to_dot([]), do: nil
def attributes_to_dot(attributes) do
[
"[",
attributes
|> Enum.map_join(",", fn {key, value} ->
attribute_to_dot(key, value)
end),
"]"
]
|> Enum.join("")
end
@doc """
Convert a single atribute to DOT format for inclusion in a list of attributes.
## Examples
iex> DotHelpers.attribute_to_dot(:color, "blue")
~S(color="blue")
There is one special case this function handles, which is the label for a record
using HTML to build a table. In this case the generated HTML label must be
surrounded by a set of angle brackets `< ... >` instead of double quotes.
iex> DotHelpers.attribute_to_dot(:label, "<table></table>")
"label=<<table></table>>"
"""
def attribute_to_dot(:label, value = "<table" <> _) do
~s(label=<#{value}>)
end
def attribute_to_dot(key, value) do
~s(#{key}="#{value}")
end
@doc """
Indent a single line or block of text.
An optional second argument can be provided to tell the function how deep
to indent (defaults to one level).
## Examples
iex> DotHelpers.indent("hello")
" hello"
iex> DotHelpers.indent("hello", 3)
" hello"
iex> DotHelpers.indent("line one\\n line two\\nline three")
" line one\\n line two\\n line three"
"""
def indent(string, depth \\ 1)
def indent(string, depth) when is_bitstring(string) do
string
|> String.split("\n")
|> indent(depth)
|> Enum.join("\n")
end
def indent(list, depth) when is_list(list) do
Enum.map(list, fn s -> String.duplicate(" ", depth) <> s end)
end
@doc """
Maps a collection of vertices or nodes to their correct DOT format.
The first argument is a reference to an ETS table or the list of results
from an ETS table. The second argument is the function used to format
each element in the collection.
"""
def elements_to_dot(table, formatting_func) when is_reference(table) or is_integer(table) do
table |> :ets.tab2list() |> elements_to_dot(formatting_func)
end
def elements_to_dot(list, formatting_func) when is_list(list) do
list
|> sort_elements_by_id()
|> Enum.map(&formatting_func.(&1))
|> compact()
|> return_joined_list_or_nil()
end
@doc """
Returns nil if an empty list is passed in. Returns the elements of the list
joined by the optional second parameter (defaults to `\n` otherwise.
## Examples
iex> DotHelpers.return_joined_list_or_nil([])
nil
iex> DotHelpers.return_joined_list_or_nil([], "-")
nil
iex> DotHelpers.return_joined_list_or_nil(["a", "b", "c"])
"a\\nb\\nc"
iex> DotHelpers.return_joined_list_or_nil(["a", "b", "c"], "-")
"a-b-c"
"""
def return_joined_list_or_nil(list, joiner \\ "\n")
def return_joined_list_or_nil([], _joiner), do: nil
def return_joined_list_or_nil(list, joiner) do
Enum.join(list, joiner)
end
@doc """
Takes a list of elements returned from the vertex or edge table and sorts
them by their ID.
This ensures that vertices and edges are written into the `.dot` file in the
same order they were added to the ETS tables. This is important as the order
of vertices and edges in a `.dot` file can ultimately affect the final
layout of the graph.
"""
def sort_elements_by_id(elements) do
Enum.sort_by(elements, fn element ->
[[_ | id] | _] = Tuple.to_list(element)
id
end)
end
@doc """
Removes all `nil` elements from an list.
## Examples
iex> DotHelpers.compact([])
[]
iex> DotHelpers.compact(["a", nil, "b", nil, 1])
["a", "b", 1]
"""
def compact(enum), do: Enum.reject(enum, &is_nil/1)
## Private
defp _global_properties_to_dot(%{global_properties: global_props}, key) do
with props <- Keyword.get(global_props, key) do
case length(props) do
0 -> nil
_ -> indent("#{key} #{attributes_to_dot(props)}")
end
end
end
end