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lib/credo/check/consistency/helper.ex

defmodule Credo.Check.Consistency.Helper do
@moduledoc """
This module contains functions that are used by several
consistency checks.
# On properties and property lists
Imagine a test that checks files for whether they use soft-tabs or hard-tabs
for indentation.
property_values in this case might be :spaces and :tabs
{value, meta}
value can be anything imaginable, meta should contain a filename
(optionally with a line_no, trigger, etc.) or an AST
a `property_list` is simply a list of property_values
[
{value, meta},
{value, meta},
...
]
a property_tuple is a tuple of {property_list, source_file}
So in our example a property_tuple
{[{:spaces, meta}, {:tabs, meta2}], %SourceFile{}}
which would indicate that the check on that SourceFile showed that it mixes
different indentation styles within one file.
"""
alias Credo.Check.PropertyValue
alias Credo.IssueMeta
@doc """
`callback` is expected to return a tuple `{property_values, most_picked_prop_value}`.
"""
def most_picked_prop(source_files, callback) when is_list(source_files) and is_function(callback) do
properties =
source_files
|> Enum.map(callback)
|> Enum.sort
{properties, most_picked_prop_value(properties)}
end
@doc """
Returns a tuple `{most_picked_prop, picked_count, total_count}`
"""
def most_picked_prop_value(list) when is_list(list) do
all_property_values =
list
|> Enum.flat_map(fn({property_list, _source_file}) -> PropertyValue.get(property_list) end)
result =
all_property_values
|> Enum.map(fn(prop_val) ->
current_property_value = PropertyValue.get(prop_val)
prop_size =
all_property_values
|> Enum.filter(fn(property_value) ->
PropertyValue.get(property_value) == current_property_value
end)
|> Enum.count
case prop_size do
0 -> nil
_ -> {prop_size, current_property_value}
end
end)
|> Enum.reject(&is_nil/1)
|> Enum.sort
|> List.last
case result do
{prop_count, prop_name} -> {prop_name, prop_count, Enum.count(all_property_values)}
nil -> nil
end
end
@doc """
Runs a given set of `pattern_mods` (CodePattern modules) against a given
set of `source_files`.
Returns a tuple: {property_tuples, most_picked}
"""
def run_code_patterns(source_files, pattern_mods, params) do
source_files
|> most_picked_prop(&create_property_tuples(&1, pattern_mods, params))
end
@doc """
Takes all the `property_tuples` from run_code_patterns and creates issues in
all source_files that do not sport the most_picked property_value.
Does call `new_issue_fun/4` when necessary to create a new issue.
"""
def append_issues_via_issue_service({property_tuples, most_picked}, new_issue_fun, params) do
property_tuples
|> Enum.map(&append_issues_if_necessary(&1, most_picked, new_issue_fun, params))
end
defp append_issues_if_necessary({_prop_list, _source_file}, nil, _, _) do
nil
end
defp append_issues_if_necessary({prop_list, source_file}, most_picked, new_issue_fun, params) do
{expected_prop, picked_count, total_count} = most_picked
case prop_list |> PropertyValue.get |> Enum.uniq do
[^expected_prop] ->
nil
list ->
new_issues =
prop_list
|> Enum.map(fn(prop) ->
value = PropertyValue.get(prop)
if value != expected_prop && Enum.member?(list, value) do
issue_meta = IssueMeta.for(source_file, params)
new_issue_fun.(issue_meta, prop, expected_prop, picked_count, total_count)
end
end)
|> List.flatten
|> Enum.reject(&is_nil/1)
|> Enum.uniq # TODO: should we really "squash" the issues here?
|> Enum.each(fn(issue) ->
Credo.Service.SourceFileIssues.append(source_file, issue)
end)
end
end
defp create_property_tuples(source_file, pattern_mods, params) do
list = property_list_for(source_file, pattern_mods, params)
{list, source_file}
end
defp property_list_for(source_file, pattern_mods, params) do
pattern_mods
|> collect_property_values(source_file, params)
|> Enum.reject(&is_nil/1)
|> Enum.uniq
end
defp collect_property_values(pattern_mods, source_file, params) do
pattern_mods
|> Enum.reduce([], fn(pattern_mod, acc) ->
result = pattern_mod.property_value_for(source_file, params)
acc ++ List.wrap(result)
end)
end
end