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credo
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A static code analysis tool with a focus on code consistency and teaching.
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Files
lib/credo/code.ex
defmodule Credo.Code do
@moduledoc """
`Credo.Code` contains a lot of utility or helper functions that deal with the
analysis of - you guessed it - code.
Whenever a function serves a general purpose in this area, e.g. getting the
value of a module attribute inside a given module, we want to extract that
function and put it in the `Credo.Code` namespace, so others can utilize them
without reinventing the wheel.
"""
alias Credo.Code.Charlists
alias Credo.Code.Heredocs
alias Credo.Code.Sigils
alias Credo.Code.Strings
alias Credo.SourceFile
defmodule ParserError do
@moduledoc """
This is an internal `Issue` raised by Credo when it finds itself unable to
parse the source code in a file.
"""
end
@doc """
Prewalks a given `Credo.SourceFile`'s AST or a given AST.
Technically this is just a wrapper around `Macro.prewalk/3`.
"""
def prewalk(ast_or_source_file, fun, accumulator \\ [])
def prewalk(%SourceFile{} = source_file, fun, accumulator) do
source_file
|> SourceFile.ast()
|> prewalk(fun, accumulator)
end
def prewalk(source_ast, fun, accumulator) do
{_, accumulated} = Macro.prewalk(source_ast, accumulator, fun)
accumulated
end
@doc """
Postwalks a given `Credo.SourceFile`'s AST or a given AST.
Technically this is just a wrapper around `Macro.postwalk/3`.
"""
def postwalk(ast_or_source_file, fun, accumulator \\ [])
def postwalk(%SourceFile{} = source_file, fun, accumulator) do
source_file
|> SourceFile.ast()
|> postwalk(fun, accumulator)
end
def postwalk(source_ast, fun, accumulator) do
{_, accumulated} = Macro.postwalk(source_ast, accumulator, fun)
accumulated
end
@doc """
Returns an AST for a given `String` or `Credo.SourceFile`.
"""
def ast(string_or_source_file)
def ast(%SourceFile{filename: filename} = source_file) do
source_file
|> SourceFile.source()
|> ast(filename)
end
@doc false
def ast(source, filename \\ "nofilename") when is_binary(source) do
case string_to_quoted(source, filename) do
{:ok, value} -> {:ok, value}
{:error, error} -> {:error, [issue_for(error, filename)]}
end
rescue
e in UnicodeConversionError ->
{:error, [issue_for({1, e.message, nil}, filename)]}
end
defp string_to_quoted(source, filename) do
Code.string_to_quoted(source,
line: 1,
columns: true,
file: filename,
emit_warnings: false
)
end
defp issue_for({line_no, error_message, _}, filename) do
%Credo.Issue{
check: ParserError,
category: :error,
filename: filename,
message: error_message,
line_no: line_no
}
end
@doc """
Converts a String or `Credo.SourceFile` into a List of tuples of `{line_no, line}`.
"""
def to_lines(string_or_source_file)
def to_lines(%SourceFile{} = source_file) do
source_file
|> SourceFile.source()
|> to_lines()
end
def to_lines(source) when is_binary(source) do
source
|> String.split("\n")
|> Enum.with_index()
|> Enum.map(fn {line, i} -> {i + 1, line} end)
end
@doc """
Converts a String or `Credo.SourceFile` into a List of tokens using the `:elixir_tokenizer`.
"""
def to_tokens(string_or_source_file)
def to_tokens(%SourceFile{} = source_file) do
source_file
|> SourceFile.source()
|> to_tokens(source_file.filename)
end
def to_tokens(source, filename \\ "nofilename") when is_binary(source) do
source
|> String.to_charlist()
|> :elixir_tokenizer.tokenize(1, file: filename)
|> case do
# Elixir < 1.6
{_, _, _, tokens} ->
tokens
# Elixir >= 1.6
{:ok, tokens} ->
tokens
# Elixir >= 1.13
{:ok, _, _, _, tokens} ->
tokens
# Elixir >= 1.17
{:ok, _, _, _, tokens, _} ->
Enum.reverse(tokens)
{:error, _, _, _, tokens} ->
tokens
end
end
@doc """
Returns true if the given `child` AST node is part of the larger
`parent` AST node.
"""
def contains_child?(parent, child) do
Credo.Code.prewalk(parent, &find_child(&1, &2, child), false)
end
defp find_child({parent, _meta, child}, _acc, child), do: {parent, true}
defp find_child(parent, acc, child), do: {parent, acc || parent == child}
@doc """
Takes a SourceFile and returns its source code stripped of all Strings and
Sigils.
"""
def clean_charlists_strings_and_sigils(source_file_or_source) do
{_source, filename} = Credo.SourceFile.source_and_filename(source_file_or_source)
source_file_or_source
|> Sigils.replace_with_spaces(" ", " ", filename)
|> Strings.replace_with_spaces(" ", " ", filename)
|> Heredocs.replace_with_spaces(" ", " ", "", filename)
|> Charlists.replace_with_spaces(" ", " ", filename)
end
@doc """
Takes a SourceFile and returns its source code stripped of all Strings, Sigils
and code comments.
"""
def clean_charlists_strings_sigils_and_comments(source_file_or_source, sigil_replacement \\ " ") do
{_source, filename} = Credo.SourceFile.source_and_filename(source_file_or_source)
source_file_or_source
|> Heredocs.replace_with_spaces(" ", " ", "", filename)
|> Sigils.replace_with_spaces(sigil_replacement, " ", filename)
|> Strings.replace_with_spaces(" ", " ", filename)
|> Charlists.replace_with_spaces(" ", " ", filename)
|> String.replace(~r/(\A|[^\?])#.+/, "\\1")
end
@doc """
Returns an AST without its metadata.
"""
def remove_metadata(ast) do
Macro.prewalk(ast, &Macro.update_meta(&1, fn _meta -> [] end))
end
end