class Ameba::Rule::Performance::FirstLastAfterFilter

Overview

This rule is used to identify usage of first/last/first?/last? calls that follow filters.

For example, this is considered inefficient:

[-1, 0, 1, 2].select { |e| e > 0 }.first?
[-1, 0, 1, 2].select { |e| e > 0 }.last?

And can be written as this:

[-1, 0, 1, 2].find { |e| e > 0 }
[-1, 0, 1, 2].reverse_each.find { |e| e > 0 }

YAML configuration example:

Performance/FirstLastAfterFilter
  Enabled: true
  FilterNames:
    - select

Included Modules

Defined in:

ameba/rule/performance/first_last_after_filter.cr

Constant Summary

CALL_NAMES = ["first", "last", "first?", "last?"] of ::String
MSG = "Use `find {...}` instead of `%s {...}.%s`"
MSG_REVERSE = "Use `reverse_each.find {...}` instead of `%s {...}.%s`"

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from module Ameba::AST::Util

abort?(node) abort?, control_exp_code(node : Crystal::ControlExpression, code_lines) control_exp_code, dynamic_literal?(node) : Bool dynamic_literal?, exit?(node) exit?, flow_command?(node, in_loop) flow_command?, flow_expression?(node, in_loop = false) flow_expression?, literal?(node) : Bool literal?, loop?(node) loop?, name_end_location(node) name_end_location, name_location(node) name_location, name_size(node) name_size, node_source(node, code_lines) node_source, path_named?(node, name) : Bool path_named?, raise?(node) raise?, source_between(loc, end_loc, code_lines) : String | Nil source_between, static_literal?(node) : Bool static_literal?

Instance methods inherited from class Ameba::Rule::Performance::Base

catch(source : Source) catch

Constructor methods inherited from class Ameba::Rule::Performance::Base

new(ctx : YAML::ParseContext, node : YAML::Nodes::Node)
new(config = nil) new

Class methods inherited from class Ameba::Rule::Performance::Base

parsed_doc : String | Nil parsed_doc

Instance methods inherited from class Ameba::Rule::Base

==(other) ==, catch(source : Source) catch, excluded?(source) excluded?, group group, hash hash, name name, special? special?, test(source : Source, node : Crystal::ASTNode, *opts)
test(source : Source) test

Class methods inherited from class Ameba::Rule::Base

default_severity : Ameba::Severity default_severity

Macros inherited from class Ameba::Rule::Base

issue_for(*args, **kwargs, &block) issue_for

Macros inherited from module Ameba::Config::RuleConfig

properties(&block) properties

Constructor Detail

def self.new(ctx : YAML::ParseContext, node : YAML::Nodes::Node) #

This rule is used to identify usage of first/last/first?/last? calls that follow filters.

For example, this is considered inefficient:

[-1, 0, 1, 2].select { |e| e > 0 }.first?
[-1, 0, 1, 2].select { |e| e > 0 }.last?

And can be written as this:

[-1, 0, 1, 2].find { |e| e > 0 }
[-1, 0, 1, 2].reverse_each.find { |e| e > 0 }

YAML configuration example:

Performance/FirstLastAfterFilter
  Enabled: true
  FilterNames:
    - select

def self.new(config = nil) #

This rule is used to identify usage of first/last/first?/last? calls that follow filters.

For example, this is considered inefficient:

[-1, 0, 1, 2].select { |e| e > 0 }.first?
[-1, 0, 1, 2].select { |e| e > 0 }.last?

And can be written as this:

[-1, 0, 1, 2].find { |e| e > 0 }
[-1, 0, 1, 2].reverse_each.find { |e| e > 0 }

YAML configuration example:

Performance/FirstLastAfterFilter
  Enabled: true
  FilterNames:
    - select

[View source]

Class Method Detail

def self.parsed_doc : String | Nil #

Returns documentation for this rule, if there is any.

module Ameba
  # This is a test rule.
  # Does nothing.
  class MyRule < Ameba::Rule::Base
    def test(source)
    end
  end
end

MyRule.parsed_doc # => "This is a test rule.\nDoes nothing."

Instance Method Detail

def description : String #

def description=(description : String) #

def enabled=(enabled : Bool) #

def enabled? : Bool #

def excluded : Array(String) | Nil #

def excluded=(excluded : Array(String) | Nil) #

def filter_names : Array(String) #

def filter_names=(filter_names : Array(String)) #

def severity : Ameba::Severity #

def severity=(severity : Ameba::Severity) #

def since_version : SemanticVersion | Nil #

[View source]
def since_version=(since_version : String) #

def test(source, node : Crystal::Call) #

[View source]
def test(source) #

[View source]