iv-org-mirror/shard-ameba
1
0
Fork 0
mirror of https://gitea.invidious.io/iv-org/shard-ameba.git synced 2024-08-15 00:53:29 +00:00
Code Issues Projects Releases Packages Wiki Activity

Variable scope & useless assignments (#41)

Browse source 
* AST::Visitor -> AST::NodeVisitor

* Scope & ScopeVisitor

* Useless assignment rule

* Instance vars and useless assignments

* Multiple assigns one by one

* Support outer scope

* Variable used in the useless assignment

* Support OpAssign & MultiAssign

* Captured by block

* Variable, Assignment, Reference & Refactoring

* Variable has references, Assignment can be referenced

* Branch entity

* Handle useless assignments in branches

* Handle assignments in a loop

* Handle branch equality

* Handle special var `$?` assignment

* Improve captured by block stuff

* Avoid assignments in property definitions

(UselessAssign rule reports an warning)

* Support MacroIf and MacroFor branches

* Handle assignments with shadowed vars in inner scopes

* Add method arguments as scope variables

* Handle case if branch is blank

* Top level scope

* Handle case when branch is nop?
This commit is contained in:
V. Elenhaupt 2018-05-03 18:57:47 +03:00 committed by GitHub
parent 60c1b86890
commit 6475c2bb25
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
50 changed files with 2521 additions and 124 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

364
spec/ameba/ast/branch_spec.cr Normal file
View file

@ -0,0 +1,364 @@
require "../../spec_helper"
private def branch_of_assign_in_def(source)
nodes = as_nodes source
Ameba::AST::Branch.of(nodes.assign_nodes.first, nodes.def_nodes.first)
end
module Ameba::AST
describe Branch do
describe ".of" do
context "Crystal::If" do
it "constructs a branch in If.cond" do
branch = branch_of_assign_in_def %(
def method
if a = get_something # --> Crystal::Assign
puts a
end
end
)
branch.to_s.should eq "a = get_something"
end
it "constructs a branch in If.then" do
branch = branch_of_assign_in_def %(
def method
if true
a = 2 # --> Crystal::Assign
end
end
)
branch.to_s.should eq "a = 2"
end
it "constructs a branch in If.else" do
branch = branch_of_assign_in_def %(
def method
if true
nil
else
a = 2 # --> Crystal::Assign
end
end
)
branch.to_s.should eq "a = 2"
end
it "constructs a branch in inline If" do
branch = branch_of_assign_in_def %(
def method(a)
a = 0 if a == 2 # --> Crystal::Assign
end
)
branch.to_s.should eq "a = 0"
end
end
context "Crystal::Unless" do
it "constructs a branch in Unless.cond" do
branch = branch_of_assign_in_def %(
def method
unless a = get_something # --> Crystal::Assign
puts a
end
end
)
branch.to_s.should eq "a = get_something"
end
it "constructs a branch in Unless.then" do
branch = branch_of_assign_in_def %(
def method
unless true
a = 2 # --> Crystal::Assign
end
end
)
branch.to_s.should eq "a = 2"
end
it "constructs a new branch in Unless.else" do
branch = branch_of_assign_in_def %(
def method
unless true
nil
else
a = 2 # --> Crystal::Assign
end
end
)
branch.to_s.should eq "a = 2"
end
it "constructs a branch in inline Unless" do
branch = branch_of_assign_in_def %(
def method(a)
(a = 0; b = 3) unless a == 2 # --> Crystal::Expressions
end
)
branch.to_s.should eq "(a = 0\nb = 3)"
end
end
context "Crystal::BinaryOp" do
it "constructs a branch in left node" do
branch = branch_of_assign_in_def %(
def method(a)
(a = 2) && do_something
end
)
branch.to_s.should eq "(a = 2)"
end
it "constructs a branch in right node" do
branch = branch_of_assign_in_def %(
def method(a)
do_something || (a = 0)
end
)
branch.to_s.should eq "(a = 0)"
end
end
context "Crystal::Case" do
# FIXME:
# https://github.com/crystal-lang/crystal/pull/6032
# it "constructs a branch in cond" do
# branch = branch_of_assign_in_def %(
# def method(a)
# case (a = 2)
# when true then nil
# end
# end
# )
# branch.to_s.should eq "(a = 2)"
# end
it "constructs a branch in when" do
branch = branch_of_assign_in_def %(
def method(a)
case a
when a = 3 then nil
end
end
)
branch.to_s.should eq "when a = 3\n nil\n"
end
it "constructs a branch in else" do
branch = branch_of_assign_in_def %(
def method(a)
case a
when true then nil
else a = 4
end
end
)
branch.to_s.should eq "a = 4"
end
end
context "Crystal::While" do
it "constructs a branch in cond" do
branch = branch_of_assign_in_def %(
def method(a)
while a = 1
nil
end
end
)
branch.to_s.should eq "a = 1"
end
it "constructs a branch in body" do
branch = branch_of_assign_in_def %(
def method(a)
while true
b = (a = 1)
end
end
)
branch.to_s.should eq "b = (a = 1)"
end
end
context "Crystal::Until" do
it "constructs a branch in cond" do
branch = branch_of_assign_in_def %(
def method(a)
until a = 1
nil
end
end
)
branch.to_s.should eq "a = 1"
end
it "constructs a branch in body" do
branch = branch_of_assign_in_def %(
def method(a)
until false
b = (a = 1)
end
end
)
branch.to_s.should eq "b = (a = 1)"
end
end
context "Crystal::ExceptionHandler" do
it "constructs a branch in body" do
branch = branch_of_assign_in_def %(
def method(a)
a = 1
rescue
nil
end
)
branch.to_s.should eq "a = 1"
end
it "constructs a branch in a rescue" do
branch = branch_of_assign_in_def %(
def method(a)
rescue
a = 1
end
)
branch.to_s.should eq "a = 1"
end
it "constructs a branch in else" do
branch = branch_of_assign_in_def %(
def method(a)
rescue
else
a = 1
end
)
branch.to_s.should eq "a = 1"
end
it "constructs a branch in ensure" do
branch = branch_of_assign_in_def %(
def method(a)
rescue
ensure
a = 1
end
)
branch.to_s.should eq "a = 1"
end
end
context "Crystal::MacroIf" do
it "constructs a branch in cond" do
branch = branch_of_assign_in_def %(
def method(a)
{% if a = 2 %}
{% end %}
end
)
branch.to_s.should eq "a = 2"
end
it "constructs a branch in then" do
nodes = as_nodes %(
def method(a)
{% if true %}
a = 2
{% end %}
end
)
branch = Branch.of(nodes.macro_literal_nodes.first, nodes.def_nodes.first)
branch.to_s.strip.should eq "a = 2"
end
end
context "Crystal::MacroFor" do
it "constructs a branch in body" do
nodes = as_nodes %(
def method(a)
{% for x in [1, 2, 3] %}
a = 2
{% end %}
end
)
branch = Branch.of(nodes.macro_literal_nodes.first, nodes.def_nodes.first)
branch.to_s.strip.should eq "a = 2"
end
end
it "returns nil if branch does not exist" do
nodes = as_nodes %(
def method
a = 2
end
)
branch = Branch.of(nodes.assign_nodes.first, nodes.def_nodes.first)
branch.should be_nil
end
end
describe "#initialize" do
it "creates new branch" do
nodes = as_nodes %(
if true
a = 2
end
)
branchable = Branchable.new nodes.if_nodes.first
branch = Branch.new nodes.assign_nodes.first, branchable
branch.node.should_not be_nil
end
end
describe "delegation" do
it "delegates to_s to node" do
nodes = as_nodes %(
if true
a = 2
end
)
branchable = Branchable.new nodes.if_nodes.first
branch = Branch.new nodes.assign_nodes.first, branchable
branch.to_s.should eq branch.node.to_s
end
it "delegates location to node" do
nodes = as_nodes %(
if true
a = 2
end
)
branchable = Branchable.new nodes.if_nodes.first
branch = Branch.new nodes.assign_nodes.first, branchable
branch.location.should eq branch.node.location
end
end
describe "#in_loop?" do
it "returns true if branch is in a loop" do
nodes = as_nodes %(
while true
a = 1
end
)
branchable = Branchable.new nodes.while_nodes.first
branch = Branch.new nodes.assign_nodes.first, branchable
branch.in_loop?.should be_true
end
it "returns false if branch is not in a loop" do
nodes = as_nodes %(
if a > 2
a = 1
end
)
branchable = Branchable.new nodes.if_nodes.first
branch = Branch.new nodes.assign_nodes.first, branchable
branch.in_loop?.should be_false
end
end
end
end

48
spec/ameba/ast/branchable_spec.cr Normal file
View file

@ -0,0 +1,48 @@
require "../../spec_helper"
module Ameba::AST
describe Branchable do
describe "#initialize" do
it "creates a new branchable" do
branchable = Branchable.new as_node %(a = 2 if true)
branchable.node.should_not be_nil
end
end
describe "delegation" do
it "delegates to_s to @node" do
node = as_node %(a = 2 if true)
branchable = Branchable.new node
branchable.to_s.should eq node.to_s
end
it "delegates location to @node" do
node = as_node %(a = 2 if true)
branchable = Branchable.new node
branchable.location.should eq node.location
end
end
describe "#loop?" do
it "returns true if it is a while loop" do
branchable = Branchable.new as_node %(while true; a = 2; end)
branchable.loop?.should be_true
end
it "returns true if it is the until loop" do
branchable = Branchable.new as_node %(until false; a = 2; end)
branchable.loop?.should be_true
end
it "returns true if it is loop" do
branchable = Branchable.new as_node %(loop {})
branchable.loop?.should be_true
end
it "returns false otherwise" do
branchable = Branchable.new as_node %(a = 2 if true)
branchable.loop?.should be_false
end
end
end
end

72
spec/ameba/ast/scope_spec.cr Normal file
View file

@ -0,0 +1,72 @@
require "../../spec_helper"
module Ameba::AST
describe Scope do
describe "#initialize" do
source = "a = 2"
it "assigns outer scope" do
root = Scope.new as_node(source)
child = Scope.new as_node(source), root
child.outer_scope.should_not be_nil
end
it "assigns node" do
scope = Scope.new as_node(source)
scope.node.should_not be_nil
end
end
end
describe "#add_variable" do
it "adds a new variable to the scope" do
scope = Scope.new as_node("")
scope.add_variable(Crystal::Var.new "foo")
scope.variables.any?.should be_true
end
end
describe "#find_variable" do
it "returns the variable in the scope by name" do
scope = Scope.new as_node("foo = 1")
scope.add_variable Crystal::Var.new "foo"
scope.find_variable("foo").should_not be_nil
end
it "returns nil if variable not exist in this scope" do
scope = Scope.new as_node("foo = 1")
scope.find_variable("bar").should be_nil
end
end
describe "#assign_variable" do
it "creates a new assignment" do
scope = Scope.new as_node("foo = 1")
scope.add_variable Crystal::Var.new "foo"
scope.assign_variable(Crystal::Var.new "foo")
scope.find_variable("foo").not_nil!.assignments.size.should eq 1
end
it "does not create the assignment if variable is wrong" do
scope = Scope.new as_node("foo = 1")
scope.add_variable Crystal::Var.new "foo"
scope.assign_variable(Crystal::Var.new "bar")
scope.find_variable("foo").not_nil!.assignments.size.should eq 0
end
end
describe "#block?" do
it "returns true if Crystal::Block" do
nodes = as_nodes %(
3.times {}
)
scope = Scope.new nodes.block_nodes.first
scope.block?.should be_true
end
it "returns false otherwise" do
scope = Scope.new as_node "a = 1"
scope.block?.should be_false
end
end
end

90
spec/ameba/ast/variabling/assignment_spec.cr Normal file
View file

@ -0,0 +1,90 @@
require "../../../spec_helper"
module Ameba::AST
describe Assignment do
node = Crystal::NilLiteral.new
scope = Scope.new as_node "foo = 1"
variable = Variable.new(Crystal::Var.new("foo"), scope)
describe "#initialize" do
it "creates a new assignment with node and var" do
assignment = Assignment.new(node, variable)
assignment.node.should_not be_nil
end
end
describe "#reference=" do
it "creates a new reference" do
assignment = Assignment.new(node, variable)
assignment.referenced = true
assignment.referenced?.should be_true
end
end
describe "delegation" do
it "delegates location" do
assignment = Assignment.new(node, variable)
assignment.location.should eq node.location
end
it "delegates to_s" do
assignment = Assignment.new(node, variable)
assignment.to_s.should eq node.to_s
end
it "delegates scope" do
assignment = Assignment.new(node, variable)
assignment.scope.should eq variable.scope
end
end
describe "#branch" do
it "returns the branch of the assignment" do
nodes = as_nodes %(
def method(a)
if a
a = 3 # --> Crystal::Expressions
puts a
end
end
)
scope = Scope.new nodes.def_nodes.first
variable = Variable.new(nodes.var_nodes.first, scope)
assignment = Assignment.new(nodes.assign_nodes.first, variable)
assignment.branch.should_not be_nil
assignment.branch.not_nil!.node.class.should eq Crystal::Expressions
end
it "returns inner branch" do
nodes = as_nodes %(
def method(a, b)
if a
if b
a = 3 # --> Crystal::Assign
end
end
end
)
scope = Scope.new nodes.def_nodes.first
variable = Variable.new(nodes.var_nodes.first, scope)
assignment = Assignment.new(nodes.assign_nodes.first, variable)
assignment.branch.should_not be_nil
assignment.branch.not_nil!.node.class.should eq Crystal::Assign
end
it "returns nil if assignment does not have a branch" do
nodes = as_nodes %(
def method(a)
a = 2
end
)
scope = Scope.new nodes.def_nodes.first
variable = Variable.new(nodes.var_nodes.first, scope)
assignment = Assignment.new(nodes.assign_nodes.first, variable)
assignment.branch.should be_nil
end
end
end
end

10
spec/ameba/ast/variabling/reference_spec.cr Normal file
View file

@ -0,0 +1,10 @@
require "../../../spec_helper"
module Ameba::AST
describe Reference do
it "is derived from a Variable" do
node = Crystal::Var.new "foo"
Reference.new(node, Scope.new as_node "foo = 1").is_a?(Variable).should be_true
end
end
end

154
spec/ameba/ast/variabling/variable_spec.cr Normal file
View file

@ -0,0 +1,154 @@
require "../../../spec_helper"
module Ameba::AST
describe Variable do
var_node = Crystal::Var.new("foo")
scope = Scope.new as_node "foo = 1"
describe "#initialize" do
it "creates a new variable" do
variable = Variable.new(var_node, scope)
variable.node.should_not be_nil
end
end
describe "delegation" do
it "delegates location" do
variable = Variable.new(var_node, scope)
variable.location.should eq var_node.location
end
it "delegates name" do
variable = Variable.new(var_node, scope)
variable.name.should eq var_node.name
end
it "delegates to_s" do
variable = Variable.new(var_node, scope)
variable.to_s.should eq var_node.to_s
end
end
describe "#special?" do
it "returns truthy if it is a special `$?` var" do
variable = Variable.new Crystal::Var.new("$?"), scope
variable.special?.should be_truthy
end
it "returns falsey otherwise" do
variable = Variable.new Crystal::Var.new("a"), scope
variable.special?.should be_falsey
end
end
describe "#assign" do
assign_node = as_node("foo=1")
it "assigns the variable (creates a new assignment)" do
variable = Variable.new(var_node, scope)
variable.assign(assign_node)
variable.assignments.any?.should be_true
end
it "can create multiple assignments" do
variable = Variable.new(var_node, scope)
variable.assign(assign_node)
variable.assign(assign_node)
variable.assignments.size.should eq 2
end
end
describe "#reference" do
it "references the existed assignment" do
variable = Variable.new(var_node, scope)
variable.assign(as_node "foo=1")
variable.reference(var_node, scope)
variable.references.any?.should be_true
end
end
describe "#captured_by_block?" do
it "returns truthy if the variable is captured by block" do
nodes = as_nodes %(
def method
a = 2
3.times { |i| a = a + i }
end
)
scope = Scope.new nodes.def_nodes.first
var_node = nodes.var_nodes.first
scope.add_variable var_node
scope.inner_scopes << Scope.new(nodes.block_nodes.first, scope)
variable = Variable.new(var_node, scope)
variable.reference nodes.var_nodes.last, scope.inner_scopes.last
variable.captured_by_block?.should be_truthy
end
it "returns falsey if the variable is not captured by the block" do
scope = Scope.new as_node %(
def method
a = 1
end
)
scope.add_variable Crystal::Var.new "a"
variable = scope.variables.first
variable.captured_by_block?.should be_falsey
end
end
describe "#target_of?" do
it "returns true if the variable is a target of Crystal::Assign node" do
assign_node = as_nodes("foo=1").assign_nodes.last
variable = Variable.new assign_node.target.as(Crystal::Var), scope
variable.target_of?(assign_node).should be_true
end
it "returns true if the variable is a target of Crystal::OpAssign node" do
assign_node = as_nodes("foo=1;foo+=1").op_assign_nodes.last
variable = Variable.new assign_node.target.as(Crystal::Var), scope
variable.target_of?(assign_node).should be_true
end
it "returns true if the variable is a target of Crystal::MultiAssign node" do
assign_node = as_nodes("a,b,c={1,2,3}").multi_assign_nodes.last
assign_node.targets.size.should_not eq 0
assign_node.targets.each do |target|
variable = Variable.new target.as(Crystal::Var), scope
variable.target_of?(assign_node).should be_true
end
end
it "returns false if the node is not assign" do
variable = Variable.new(Crystal::Var.new("v"), scope)
variable.target_of?(as_node "nil").should be_false
end
it "returns false if the variable is not a target of the assign" do
variable = Variable.new(Crystal::Var.new("foo"), scope)
variable.target_of?(as_node("bar = 1")).should be_false
end
end
describe "#eql?" do
var = Crystal::Var.new("foo").at(Crystal::Location.new(nil, 1, 2))
variable = Variable.new var, scope
it "is false if node is not a Crystal::Var" do
variable.eql?(as_node("nil")).should be_false
end
it "is false if node name is different" do
variable.eql?(Crystal::Var.new "bar").should be_false
end
it "is false if node has a different location" do
variable.eql?(Crystal::Var.new "foo").should be_false
end
it "is true otherwise" do
variable.eql?(variable.node).should be_true
end
end
end
end

6
spec/ameba/ast/traverse_spec.cr → spec/ameba/ast/visitors/node_visitor_spec.cr
View file

@ -1,14 +1,14 @@
require "../../spec_helper"
require "../../../spec_helper"
module Ameba::AST
rule = DummyRule.new
source = Source.new ""
describe "Traverse" do
describe NodeVisitor do
{% for name in NODES %}
describe "{{name}}" do
it "allow to visit {{name}} node" do
visitor = Visitor.new rule, source
visitor = NodeVisitor.new rule, source
nodes = Crystal::Parser.new("").parse
nodes.accept visitor
end

58
spec/ameba/ast/visitors/scope_visitor_spec.cr Normal file
View file

@ -0,0 +1,58 @@
require "../../../spec_helper"
module Ameba::AST
describe ScopeVisitor do
it "creates a scope for the def" do
rule = ScopeRule.new
ScopeVisitor.new rule, Source.new %(
def method
end
)
rule.scopes.size.should eq 1
end
it "creates a scope for the proc" do
rule = ScopeRule.new
ScopeVisitor.new rule, Source.new %(
-> {}
)
rule.scopes.size.should eq 1
end
it "creates a scope for the block" do
rule = ScopeRule.new
ScopeVisitor.new rule, Source.new %(
3.times {}
)
rule.scopes.size.should eq 2
end
context "inner scopes" do
it "creates scope for block inside def" do
rule = ScopeRule.new
ScopeVisitor.new rule, Source.new %(
def method
3.times {}
end
)
rule.scopes.size.should eq 2
rule.scopes.last.outer_scope.should_not be_nil
rule.scopes.first.outer_scope.should eq rule.scopes.last
end
it "creates scope for block inside block" do
rule = ScopeRule.new
ScopeVisitor.new rule, Source.new %(
3.times do
2.times {}
end
)
rule.scopes.size.should eq 3
inner_block = rule.scopes.first
outer_block = rule.scopes.last
inner_block.outer_scope.should_not eq outer_block
outer_block.outer_scope.should be_nil
end
end
end
end

2
spec/ameba/rule/unneded_disable_directive_spec.cr
View file

@ -35,7 +35,7 @@ module Ameba::Rule
subject.catch(s).should be_valid
end
it "failes if there is unneeded directive" do
it "fails if there is unneeded directive" do
s = Source.new %Q(
# ameba:disable #{NamedRule.name}
a = 1

813
spec/ameba/rule/useless_assign_spec.cr Normal file
View file

@ -0,0 +1,813 @@
require "../../spec_helper"
module Ameba::Rule
describe UselessAssign do
subject = UselessAssign.new
it "does not report used assigments" do
s = Source.new %(
def method
a = 2
a
end
)
subject.catch(s).should be_valid
end
it "reports a useless assignment in a method" do
s = Source.new %(
def method
a = 2
end
)
subject.catch(s).should_not be_valid
end
it "reports a useless assignment in a proc" do
s = Source.new %(
->() {
a = 2
}
)
subject.catch(s).should_not be_valid
end
it "reports a useless assignment in a block" do
s = Source.new %(
def method
3.times do
a = 1
end
end
)
subject.catch(s).should_not be_valid
end
it "reports a useless assignment in a proc inside def" do
s = Source.new %(
def method
->() {
a = 2
}
end
)
subject.catch(s).should_not be_valid
end
it "reports a useless assignment in a proc inside a block" do
s = Source.new %(
def method
3.times do
->() {
a = 2
}
end
end
)
subject.catch(s).should_not be_valid
end
it "reports rule, position and a message" do
s = Source.new %(
def method
a = 2
end
), "source.cr"
subject.catch(s).should_not be_valid
error = s.errors.first
error.rule.should_not be_nil
error.location.to_s.should eq "source.cr:3:11"
error.message.should eq "Useless assignment to variable `a`"
end
it "does not report useless assignment of instance var" do
s = Source.new %(
class Cls
def initialize(@name)
end
end
)
subject.catch(s).should be_valid
end
it "does not report if assignment used in the inner block scope" do
s = Source.new %(
def method
var = true
3.times { var = false }
end
)
subject.catch(s).should be_valid
end
it "reports if assigned is not referenced in the inner block scope" do
s = Source.new %(
def method
var = true
3.times {}
end
)
subject.catch(s).should_not be_valid
end
it "doesn't report if assignment in referenced in inner block" do
s = Source.new %(
def method
two = true
3.times do
mutex.synchronize do
two = 2
end
end
two.should be_true
end
)
subject.catch(s).should be_valid
end
it "reports if first assignment is useless" do
s = Source.new %(
def method
var = true
var = false
var
end
)
subject.catch(s).should_not be_valid
s.errors.first.location.to_s.should eq ":3:11"
end
it "reports if variable reassigned and not used" do
s = Source.new %(
def method
var = true
var = false
end
)
subject.catch(s).should_not be_valid
end
it "does not report if variable used in a condition" do
s = Source.new %(
def method
a = 1
if a
nil
end
end
)
subject.catch(s).should be_valid
end
it "reports second assignment as useless" do
s = Source.new %(
def method
a = 1
a = a + 1
end
)
subject.catch(s).should_not be_valid
end
it "does not report if variable is referenced in other assignment" do
s = Source.new %(
def method
if f = get_something
@f = f
end
end
)
subject.catch(s).should be_valid
end
it "does not report if variable is referenced in a setter" do
s = Source.new %(
def method
foo = 2
table[foo] ||= "bar"
end
)
subject.catch(s).should be_valid
end
it "does not report if variable is reassigned but not referenced" do
s = Source.new %(
def method
foo = 1
puts foo
foo = 2
end
)
subject.catch(s).should_not be_valid
end
it "does not report if variable is referenced in a call" do
s = Source.new %(
def method
if f = FORMATTER
@formatter = f.new
end
end
)
subject.catch(s).should be_valid
end
it "does not report if a setter is invoked with operator assignment" do
s = Source.new %(
def method
obj = {} of Symbol => Int32
obj[:name] = 3
end
)
subject.catch(s).should be_valid
end
it "does not report if global var" do
s = Source.new %(
def method
$? = 3
end
)
subject.catch(s).should be_valid
end
it "does not report if assignment is referenced in a proc" do
s = Source.new %(
def method
called = false
->() { called = true }
called
end
)
subject.catch(s).should be_valid
end
it "reports if variable is shadowed in inner scope" do
s = Source.new %(
def method
i = 1
3.times do |i|
i + 1
end
end
)
subject.catch(s).should_not be_valid
end
it "does not report if parameter is referenced after the branch" do
s = Source.new %(
def method(param)
3.times do
param = 3
end
param
end
)
subject.catch(s).should be_valid
end
context "op assigns" do
it "does not report if variable is referenced below the op assign" do
s = Source.new %(
def method
a = 1
a += 1
a
end
)
subject.catch(s).should be_valid
end
it "does not report if variable is referenced in op assign few times" do
s = Source.new %(
def method
a = 1
a += 1
a += 1
a = a + 1
a
end
)
subject.catch(s).should be_valid
end
it "reports if variable is not referenced below the op assign" do
s = Source.new %(
def method
a = 1
a += 1
end
)
subject.catch(s).should_not be_valid
end
it "reports rule, location and a message" do
s = Source.new %(
def method
b = 2
a = 3
a += 1
end
), "source.cr"
subject.catch(s).should_not be_valid
error = s.errors.last
error.rule.should_not be_nil
error.location.to_s.should eq "source.cr:5:13"
error.message.should eq "Useless assignment to variable `a`"
end
end
context "multi assigns" do
it "does not report if all assigns are referenced" do
s = Source.new %(
def method
a, b = {1, 2}
a + b
end
)
subject.catch(s).should be_valid
end
it "reports if one assign is not referenced" do
s = Source.new %(
def method
a, b = {1, 2}
a
end
)
subject.catch(s).should_not be_valid
error = s.errors.first
error.location.to_s.should eq ":3:16"
error.message.should eq "Useless assignment to variable `b`"
end
it "reports if both assigns are reassigned and useless" do
s = Source.new %(
def method
a, b = {1, 2}
a, b = {3, 4}
end
)
subject.catch(s).should_not be_valid
end
it "reports if both assigns are not referenced" do
s = Source.new %(
def method
a, b = {1, 2}
end
)
subject.catch(s).should_not be_valid
error = s.errors.first
error.location.to_s.should eq ":3:13"
error.message.should eq "Useless assignment to variable `a`"
error = s.errors.last
error.location.to_s.should eq ":3:16"
error.message.should eq "Useless assignment to variable `b`"
end
end
context "top level" do
it "reports if assignment is not referenced" do
s = Source.new %(
a = 1
a = 2
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 2
s.errors.first.location.to_s.should eq ":2:11"
s.errors.last.location.to_s.should eq ":3:11"
end
it "doesn't report if assignments are referenced" do
s = Source.new %(
a = 1
a += 1
a
b, c = {1, 2}
b
c
)
subject.catch(s).should be_valid
end
it "doesn't report if assignment is captured by block" do
s = Source.new %(
a = 1
3.times do
a = 2
end
)
subject.catch(s).should be_valid
end
end
context "branching" do
context "if-then-else" do
it "doesn't report if assignment is consumed by branches" do
s = Source.new %(
def method
a = 0
if something
a = 1
else
a = 2
end
a
end
)
subject.catch(s).should be_valid
end
it "doesn't report if assignment is in one branch" do
s = Source.new %(
def method
a = 0
if something
a = 1
else
nil
end
a
end
)
subject.catch(s).should be_valid
end
it "doesn't report if assignment is in one line branch" do
s = Source.new %(
def method
a = 0
a = 1 if something
a
end
)
subject.catch(s).should be_valid
end
it "reports if assignment is useless in the branch" do
s = Source.new %(
def method(a)
if a
a = 2
end
end
)
subject.catch(s).should_not be_valid
end
it "reports if only last assignment is referenced in a branch" do
s = Source.new %(
def method(a)
a = 1
if a
a = 2
a = 3
end
a
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 1
s.errors.first.location.to_s.should eq ":5:17"
end
it "does not report of assignments are referenced in all branches" do
s = Source.new %(
def method
if matches
matches = owner.lookup_matches signature
else
matches = owner.lookup_matches signature
end
matches
end
)
subject.catch(s).should be_valid
end
it "does not report referenced assignments in inner branches" do
s = Source.new %(
def method
has_newline = false
if something
do_something unless false
has_newline = false
else
do_something if true
has_newline = true
end
has_newline
end
)
subject.catch(s).should be_valid
end
end
context "unless-then-else" do
it "doesn't report if assignment is consumed by branches" do
s = Source.new %(
def method
a = 0
unless something
a = 1
else
a = 2
end
a
end
)
subject.catch(s).should be_valid
end
it "reports if there is a useless assignment in a branch" do
s = Source.new %(
def method
a = 0
unless something
a = 1
a = 2
else
a = 2
end
a
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 1
s.errors.first.location.to_s.should eq ":5:17"
end
end
context "case" do
it "does not report if assignment is referenced" do
s = Source.new %(
def method(a)
case a
when /foo/
a = 1
when /bar/
a = 2
end
puts a
end
)
subject.catch(s).should be_valid
end
it "reports if assignment is useless" do
s = Source.new %(
def method(a)
case a
when /foo/
a = 1
when /bar/
a = 2
end
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 2
s.errors.first.location.to_s.should eq ":5:17"
s.errors.last.location.to_s.should eq ":7:17"
end
end
context "binary operator" do
it "does not report if assignment is referenced" do
s = Source.new %(
def method(a)
(a = 1) && (b = 1)
a + b
end
)
subject.catch(s).should be_valid
end
it "reports if assignment is useless" do
s = Source.new %(
def method(a)
(a = 1) || (b = 1)
a
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 1
s.errors.first.location.to_s.should eq ":3:27"
end
end
context "while" do
it "does not report if assignment is referenced" do
s = Source.new %(
def method(a)
while a < 10
a = a + 1
end
a
end
)
subject.catch(s).should be_valid
end
it "reports if assignment is useless" do
s = Source.new %(
def method(a)
while a < 10
b = a
end
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 1
s.errors.first.location.to_s.should eq ":4:17"
end
it "does not report if assignment is referenced in a loop" do
s = Source.new %(
def method
a = 3
result = 0
while result < 10
result += a
a = a + 1
end
result
end
)
subject.catch(s).should be_valid
end
it "does not report if assignment is referenced as param in a loop" do
s = Source.new %(
def method(a)
result = 0
while result < 10
result += a
a = a + 1
end
result
end
)
subject.catch(s).should be_valid
end
it "does not report if assignment is referenced in loop and inner branch" do
s = Source.new %(
def method(a)
result = 0
while result < 10
result += a
if result > 0
a = a + 1
else
a = 3
end
end
result
end
)
subject.catch(s).should be_valid
end
it "works properly if there is branch with blank node" do
s = Source.new %(
def visit
count = 0
while true
break if count == 1
case something
when :any
else
:anything_else
end
count += 1
end
end
)
subject.catch(s).should be_valid
end
end
context "until" do
it "does not report if assignment is referenced" do
s = Source.new %(
def method(a)
until a > 10
a = a + 1
end
a
end
)
subject.catch(s).should be_valid
end
it "reports if assignment is useless" do
s = Source.new %(
def method(a)
until a > 10
b = a + 1
end
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 1
s.errors.first.location.to_s.should eq ":4:17"
end
end
context "exception handler" do
it "does not report if assignment is referenced in body" do
s = Source.new %(
def method(a)
a = 2
rescue
a
end
)
subject.catch(s).should be_valid
end
it "doesn't report if assignment is referenced in ensure" do
s = Source.new %(
def method(a)
a = 2
ensure
a
end
)
subject.catch(s).should be_valid
end
it "doesn't report if assignment is referenced in else" do
s = Source.new %(
def method(a)
a = 2
rescue
else
a
end
)
subject.catch(s).should be_valid
end
it "reports if assignment is useless" do
s = Source.new %(
def method(a)
rescue
a = 2
end
)
subject.catch(s).should_not be_valid
s.errors.size.should eq 1
s.errors.first.location.to_s.should eq ":4:15"
end
end
end
context "macro" do
it "doesn't report if assignment is referenced in macro" do
s = Source.new %(
def method
a = 2
{% if flag?(:bits64) %}
a.to_s
{% else %}
a
{% end %}
end
)
subject.catch(s).should be_valid
end
it "doesn't report referenced assignments in macro literal" do
s = Source.new %(
def method
a = 2
{% if flag?(:bits64) %}
a = 3
{% else %}
a = 4
{% end %}
puts a
end
)
subject.catch(s).should be_valid
end
end
end
end

52
spec/spec_helper.cr
View file

@ -30,6 +30,17 @@ module Ameba
end
end
struct ScopeRule < Rule::Base
getter scopes = [] of AST::Scope
def test(source)
end
def test(source, node : Crystal::ASTNode, scope : AST::Scope)
@scopes << scope
end
end
class DummyFormatter < Formatter::BaseFormatter
property started_sources : Array(Source)?
property finished_sources : Array(Source)?
@ -71,8 +82,49 @@ module Ameba
"Source expected to be invalid, but it is valid."
end
end
class TestNodeVisitor < Crystal::Visitor
NODES = [
Crystal::Var,
Crystal::Assign,
Crystal::OpAssign,
Crystal::MultiAssign,
Crystal::Block,
Crystal::Def,
Crystal::If,
Crystal::While,
Crystal::MacroLiteral,
]
def initialize(node)
node.accept self
end
def visit(node : Crystal::ASTNode)
true
end
{% for node in NODES %}
{{getter_name = node.stringify.split("::").last.underscore + "_nodes"}}
getter {{getter_name.id}} = [] of {{node}}
def visit(node : {{node}})
{{getter_name.id}} << node
true
end
{% end %}
end
end
def be_valid
Ameba::BeValidExpectation.new
end
def as_node(source)
Crystal::Parser.new(source).parse
end
def as_nodes(source)
Ameba::TestNodeVisitor.new(as_node source)
end

2
src/ameba.cr
View file

@ -1,5 +1,5 @@
require "./ameba/*"
require "./ameba/ast/*"
require "./ameba/ast/**"
require "./ameba/rule/*"
require "./ameba/formatter/*"

193
src/ameba/ast/branch.cr Normal file
View file

@ -0,0 +1,193 @@
module Ameba::AST
# Represents the branch in Crystal code.
# Branch is a part of a branchable statement.
# For example, the branchable if statement contains 3 branches:
#
# ```
# if a = something # --> Branch A
# a = 1 # --> Branch B
# put a if out # --> Branch C
# else
# do_something a # --> Branch D
# end
# ```
#
class Branch
# The actual branch node.
getter node : Crystal::ASTNode
# The parent branchable.
getter parent : Branchable
delegate to_s, to: @node
delegate location, to: @node
def_equals_and_hash node, location
# Creates a new branch.
#
# ```
# Branch.new(if_node)
# ```
def initialize(@node, @parent)
end
# Returns true if current branch is in a loop, false - otherwise.
# For example, this branch is in a loop:
#
# ```
# while true
# handle_input # this branch is in a loop
# if wrong_input
# show_message # this branch is also in a loop.
# end
# end
# ```
#
def in_loop?
@parent.loop?
end
# Constructs a new branch based on the node in scope.
#
# ```
# Branch.of(assign_node, scope)
# ```
def self.of(node : Crystal::ASTNode, scope : Scope)
of(node, scope.node)
end
# Constructs a new branch based on the node some parent scope.
#
# ```
# Branch.of(assign_node, def_node)
# ```
def self.of(node : Crystal::ASTNode, parent_node : Crystal::ASTNode)
BranchVisitor.new(node).tap(&.accept parent_node).branch
end
# :nodoc:
private class BranchVisitor < Crystal::Visitor
@current_branch : Crystal::ASTNode?
property branchable : Branchable?
property branch : Branch?
def initialize(@node : Crystal::ASTNode)
end
private def on_branchable_start(node, *branches)
on_branchable_start(node, branches)
end
private def on_branchable_start(node, branches : Array | Tuple)
@branchable = Branchable.new(node, @branchable)
branches.each do |node|
break if branch # branch found
@current_branch = node if node && !node.nop?
node.try &.accept(self)
end
false
end
private def on_branchable_end(node)
@branchable = @branchable.try &.parent
end
def visit(node : Crystal::ASTNode)
return false if branch
if node.class == @node.class &&
node.location == @node.location &&
(branchable = @branchable) &&
(branch = @current_branch)
@branch = Branch.new(branch, branchable)
end
true
end
def visit(node : Crystal::If)
on_branchable_start node, node.cond, node.then, node.else
end
def end_visit(node : Crystal::If)
on_branchable_end node
end
def visit(node : Crystal::Unless)
on_branchable_start node, node.cond, node.then, node.else
end
def end_visit(node : Crystal::Unless)
on_branchable_end node
end
def visit(node : Crystal::BinaryOp)
on_branchable_start node, node.left, node.right
end
def end_visit(node : Crystal::BinaryOp)
on_branchable_end node
end
def visit(node : Crystal::Case)
on_branchable_start node, [node.cond, node.whens, node.else].flatten
end
def end_visit(node : Crystal::Case)
on_branchable_end node
end
def visit(node : Crystal::While)
on_branchable_start node, node.cond, node.body
end
def end_visit(node : Crystal::While)
on_branchable_end node
end
def visit(node : Crystal::Until)
on_branchable_start node, node.cond, node.body
end
def end_visit(node : Crystal::Until)
on_branchable_end node
end
def visit(node : Crystal::ExceptionHandler)
on_branchable_start node, [node.body, node.rescues, node.else, node.ensure].flatten
end
def end_visit(node : Crystal::ExceptionHandler)
on_branchable_end node
end
def visit(node : Crystal::Rescue)
on_branchable_start node, node.body
end
def end_visit(node : Crystal::Rescue)
on_branchable_end node
end
def visit(node : Crystal::MacroIf)
on_branchable_start node, node.cond, node.then, node.else
end
def end_visit(node : Crystal::MacroIf)
on_branchable_end node
end
def visit(node : Crystal::MacroFor)
on_branchable_start node, node.exp, node.body
end
def end_visit(node : Crystal::MacroFor)
on_branchable_end node
end
end
end
end

42
src/ameba/ast/branchable.cr Normal file
View file

@ -0,0 +1,42 @@
module Ameba::AST
# A generic entity to represent a branchable Crystal node.
# For example, `Crystal::If`, `Crystal::Unless`, `Crystal::While`
# are branchable.
#
# ```
# white a > 100 # Branchable A
# if b > 2 # Branchable B
# a += 1
# end
# end
# ```
class Branchable
getter branches = [] of Crystal::ASTNode
# The actual Crystal node.
getter node : Crystal::ASTNode
# Parent branchable (if any)
getter parent : Branchable?
delegate to_s, to: @node
delegate location, to: @node
# Creates a new branchable
#
# ```
# Branchable.new(node, parent_branchable)
# ```
def initialize(@node, @parent = nil)
end
# Returns true if this node or one of the parent branchables is a loop, false otherwise.
def loop?
return true if node.is_a? Crystal::While ||
node.is_a? Crystal::Until ||
((n = node) && n.is_a?(Crystal::Call) && n.name == "loop")
parent.try(&.loop?) || false
end
end
end

110
src/ameba/ast/scope.cr Normal file
View file

@ -0,0 +1,110 @@
require "./variabling/*"
module Ameba::AST
# Represents a context of the local variable visibility.
# This is where the local variables belong to.
class Scope
# Link to local variables
getter variables = [] of Variable
# Link to the outer scope
getter outer_scope : Scope?
# List of inner scopes
getter inner_scopes = [] of Scope
# The actual AST node that represents a current scope.
getter node : Crystal::ASTNode
delegate to_s, to: node
delegate location, to: node
def_equals_and_hash node, location
# Creates a new scope. Accepts the AST node and the outer scope.
#
# ```
# scope = Scope.new(class_node, nil)
# ```
def initialize(@node, @outer_scope = nil)
@outer_scope.try &.inner_scopes.<<(self)
end
# Creates a new variable in the current scope.
#
# ```
# scope = Scope.new(class_node, nil)
# scope.add_variable(var_node)
# ```
def add_variable(node)
variables << Variable.new(node, self)
end
# Returns variable by its name or nil if it does not exist.
#
# ```
# scope = Scope.new(class_node, nil)
# scope.find_variable("foo")
# ```
def find_variable(name : String)
variables.find { |v| v.name == name } || outer_scope.try &.find_variable(name)
end
# Creates a new assignment for the variable.
#
# ```
# scope = Scope.new(class_node, nil)
# scope.assign_variable(var_node)
# ```
def assign_variable(node)
node.is_a?(Crystal::Var) && find_variable(node.name).try &.assign(node)
end
# Returns true if current scope represents a block (or proc),
# false if not.
def block?
node.is_a?(Crystal::Block) || node.is_a?(Crystal::ProcLiteral)
end
# Returns true if and only if current scope represents some
# type definition, for example a class.
def type_definition?
node.is_a?(Crystal::ClassDef) ||
node.is_a?(Crystal::ModuleDef) ||
node.is_a?(Crystal::LibDef) ||
node.is_a?(Crystal::FunDef) ||
node.is_a?(Crystal::TypeDef) ||
node.is_a?(Crystal::CStructOrUnionDef)
end
# Returns true if current scope references variable, false if not.
def references?(variable : Variable)
variable.references.any? { |reference| reference.scope == self }
end
# Returns arguments of this scope (if any).
def args
case current_node = node
when Crystal::Block, Crystal::Def then current_node.args
when Crystal::ProcLiteral then current_node.def.args
else
[] of Crystal::Var
end
end
# Returns true if variable is an argument in current scope, false if not.
def arg?(var : Crystal::Var)
args.any? do |arg|
arg.is_a?(Crystal::Var) &&
arg.name == var.name &&
arg.location == var.location
end
end
# Returns true if the `node` represents exactly
# the same Crystal node as `@node`.
def eql?(node)
node == @node && node.location == @node.location
end
end
end

68
src/ameba/ast/traverse.cr
View file

@ -1,68 +0,0 @@
require "compiler/crystal/syntax/*"
# A module that helps to traverse Crystal AST using `Crystal::Visitor`.
module Ameba::AST
# List of nodes to be visited by Ameba's rules.
NODES = [
Alias,
Assign,
Call,
Case,
ClassDef,
ClassVar,
Def,
EnumDef,
ExceptionHandler,
Expressions,
HashLiteral,
If,
InstanceVar,
LibDef,
ModuleDef,
NilLiteral,
StringInterpolation,
Unless,
Var,
When,
While,
]
# An AST Visitor used by rules.
#
# ```
# visitor = Ameba::AST::Visitor.new(rule, source)
# ```
#
class Visitor < Crystal::Visitor
# A corresponding rule that uses this visitor.
@rule : Rule::Base
# A source that needs to be traversed.
@source : Source
# Creates instance of this visitor.
#
# ```
# visitor = Ameba::AST::Visitor.new(rule, source)
# ```
#
def initialize(@rule, @source)
@source.ast.accept self
end
# A main visit method that accepts `Crystal::ASTNode`.
# Returns true meaning all child nodes will be traversed.
def visit(node : Crystal::ASTNode)
true
end
{% for name in NODES %}
# A visit callback for `Crystal::{{name}}` node.
# Returns true meaning that child nodes will be traversed as well.
def visit(node : Crystal::{{name}})
@rule.test @source, node
true
end
{% end %}
end
end

42
src/ameba/ast/variabling/assignment.cr Normal file
View file

@ -0,0 +1,42 @@
require "./reference"
require "./variable"
module Ameba::AST
# Represents the assignment to the variable.
# Holds the assign node and the variable.
class Assignment
property? referenced = false
# The actual assignment node.
getter node : Crystal::ASTNode
# Variable of this assignment.
getter variable : Variable
# Branch of this assignment.
getter branch : Branch?
delegate location, to: @node
delegate to_s, to: @node
delegate scope, to: @variable
# Creates a new assignment.
#
# ```
# Assignment.new(node, variable)
# ```
#
def initialize(@node, @variable)
if scope = @variable.scope
@branch = Branch.of(@node, scope)
@referenced = true if @variable.special? ||
@variable.scope.type_definition? ||
referenced_in_loop?
end
end
def referenced_in_loop?
@variable.referenced? && @branch.try &.in_loop?
end
end
end

9
src/ameba/ast/variabling/reference.cr Normal file
View file

@ -0,0 +1,9 @@
require "./variable"
module Ameba::AST
# Represents a reference to the variable.
# It behaves like a variable is used to distinguish a
# the variable from its reference.
class Reference < Variable
end
end

138
src/ameba/ast/variabling/variable.cr Normal file
View file

@ -0,0 +1,138 @@
module Ameba::AST
# Represents the existence of the local variable.
# Holds the var node and variable assigments.
class Variable
# List of the assigments of this variable.
getter assignments = [] of Assignment
# List of the references of this variable.
getter references = [] of Reference
# The actual var node.
getter node : Crystal::Var
# Scope of this variable.
getter scope : Scope
delegate location, to: @node
delegate name, to: @node
delegate to_s, to: @node
# Creates a new variable(in the scope).
#
# ```
# Variable.new(node, scope)
# ```
#
def initialize(@node, @scope)
end
# Returns true if it is a special variable, i.e `$?`.
def special?
name =~ /^\$/
end
# Assigns the variable (creates a new assignment).
# Variable may have multiple assignments.
#
# ```
# variable = Variable.new(node, scope)
# variable.assign(node1)
# variable.assign(node2)
# variable.assignment.size # => 2
# ```
#
def assign(node)
assignments << Assignment.new(node, self)
end
# Returns true if variable has any reference.
#
# ```
# variable = Variable.new(node, scope)
# variable.reference(var_node)
# variable.referenced? # => true
# ```
def referenced?
references.any?
end
# Creates a reference to this variable in some scope.
#
# ```
# variable = Variable.new(node, scope)
# variable.reference(var_node, some_scope)
# ```
#
def reference(node : Crystal::Var, scope : Scope)
Reference.new(node, scope).tap do |reference|
references << reference
end
end
# Reference variable's assignments.
#
# ```
# variable = Variable.new(node, scope)
# variable.assign(assign_node)
# variable.reference_assignments!
# ```
def reference_assignments!
consumed_branches = Set(Branch).new
assignments.reverse_each do |assignment|
next if consumed_branches.includes?(assignment.branch)
assignment.referenced = true
break unless assignment.branch
consumed_branches << assignment.branch.not_nil!
end
end
# Returns true if the current assignment is referenced in
# in the block. For example this variable is captured
# by block:
#
# ```
# a = 1
# 3.times { |i| a = a + i }
# ```
#
# And this variable is not captured by block.
#
# ```
# i = 1
# 3.times { |i| i + 1 }
# ```
def captured_by_block?(scope = @scope)
return false unless scope
scope.inner_scopes.each do |inner_scope|
return true if inner_scope.block? && inner_scope.references?(self)
return true if captured_by_block?(inner_scope)
end
false
end
# Returns true if the variable is a target (on the left) of the assignment,
# false otherwise.
def target_of?(assign)
case assign
when Crystal::Assign then eql?(assign.target)
when Crystal::OpAssign then eql?(assign.target)
when Crystal::MultiAssign then assign.targets.any? { |t| eql?(t) }
else
false
end
end
# Returns true if the `node` represents exactly
# the same Crystal node as `@node`.
def eql?(node)
node.is_a?(Crystal::Var) &&
node.name == @node.name &&
node.location == @node.location
end
end
end

29
src/ameba/ast/visitors/base_visitor.cr Normal file
View file

@ -0,0 +1,29 @@
require "compiler/crystal/syntax/*"
# A module that helps to traverse Crystal AST using `Crystal::Visitor`.
module Ameba::AST
# An abstract base visitor that utilizes general logic for all visitors.
abstract class BaseVisitor < Crystal::Visitor
# A corresponding rule that uses this visitor.
@rule : Rule::Base
# A source that needs to be traversed.
@source : Source
# Creates instance of this visitor.
#
# ```
# visitor = Ameba::AST::NodeVisitor.new(rule, source)
# ```
#
def initialize(@rule, @source)
@source.ast.accept self
end
# A main visit method that accepts `Crystal::ASTNode`.
# Returns true meaning all child nodes will be traversed.
def visit(node : Crystal::ASTNode)
true
end
end
end

46
src/ameba/ast/visitors/node_visitor.cr Normal file
View file

@ -0,0 +1,46 @@
require "./base_visitor"
module Ameba::AST
# List of nodes to be visited by Ameba's rules.
NODES = [
Alias,
Assign,
Call,
Case,
ClassDef,
ClassVar,
Def,
EnumDef,
ExceptionHandler,
Expressions,
HashLiteral,
If,
InstanceVar,
LibDef,
ModuleDef,
NilLiteral,
StringInterpolation,
Unless,
Var,
When,
While,
]
# An AST Visitor that traverses the source and allows all nodes
# to be inspected by rules.
#
# ```
# visitor = Ameba::AST::NodeVisitor.new(rule, source)
# ```
#
class NodeVisitor < BaseVisitor
{% for name in NODES %}
# A visit callback for `Crystal::{{name}}` node.
# Returns true meaning that child nodes will be traversed as well.
def visit(node : Crystal::{{name}})
@rule.test @source, node
true
end
{% end %}
end
end

140
src/ameba/ast/visitors/scope_visitor.cr Normal file
View file

@ -0,0 +1,140 @@
require "./base_visitor"
module Ameba::AST
# AST Visitor that traverses the source and constructs scopes.
class ScopeVisitor < BaseVisitor
@current_scope : Scope
def initialize(@rule, @source)
@current_scope = Scope.new(@source.ast) # top level scope
@source.ast.accept self
end
private def on_scope_enter(node)
@current_scope = Scope.new(node, @current_scope)
end
private def on_scope_end(node)
@rule.test @source, node, @current_scope
# go up, if this is not a top level scope
if outer_scope = @current_scope.outer_scope
@current_scope = outer_scope
end
end
# :nodoc:
def end_visit(node : Crystal::ASTNode)
on_scope_end(node) if @current_scope.eql?(node)
end
# :nodoc:
def visit(node : Crystal::ClassDef)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::ModuleDef)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::LibDef)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::FunDef)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::TypeDef)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::CStructOrUnionDef)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::Def)
node.name == "->" || on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::ProcLiteral)
on_scope_enter(node)
end
# :nodoc:
def visit(node : Crystal::Block)
on_scope_enter(node)
end
@current_assign : Crystal::ASTNode?
# :nodoc:
def visit(node : Crystal::Assign | Crystal::OpAssign | Crystal::MultiAssign)
@current_assign = node
end
# :nodoc:
def end_visit(node : Crystal::Assign | Crystal::OpAssign)
@current_scope.assign_variable(node.target)
@current_assign = nil
end
# :nodoc:
def end_visit(node : Crystal::MultiAssign)
node.targets.each { |target| @current_scope.assign_variable(target) }
@current_assign = nil
end
# :nodoc:
def visit(node : Crystal::Arg)
@current_scope.add_variable Crystal::Var.new(node.name).at(node.location)
end
# :nodoc:
def visit(node : Crystal::Var)
if !@current_scope.arg?(node) && (variable = @current_scope.find_variable node.name)
reference = variable.reference node, @current_scope
if @current_assign.is_a?(Crystal::OpAssign) || !reference.target_of?(@current_assign)
variable.reference_assignments!
end
else
@current_scope.add_variable(node)
end
end
# :nodoc:
def visit(node : Crystal::MacroLiteral)
MacroLiteralVarVisitor.new(node).vars.each { |var| visit(var) }
end
end
private class MacroLiteralVarVisitor < Crystal::Visitor
getter vars = [] of Crystal::Var
def initialize(literal)
Crystal::Parser.new(literal.value).parse.accept self
rescue
nil
end
def visit(node : Crystal::ASTNode)
true
end
def visit(node : Crystal::Var)
vars << node
end
def visit(node : Crystal::Call)
vars << Crystal::Var.new(node.name).at(node.location)
end
end
end

4
src/ameba/config.cr
View file

@ -126,12 +126,16 @@ class Ameba::Config
{% definitions = [] of NamedTuple %}
{% if block.body.is_a? Assign %}
{% definitions << {var: block.body.target, value: block.body.value} %}
{% elsif block.body.is_a? Call %}
{% definitions << {var: block.body.name, value: block.body.args.first} %}
{% elsif block.body.is_a? TypeDeclaration %}
{% definitions << {var: block.body.var, value: block.body.value, type: block.body.type} %}
{% elsif block.body.is_a? Expressions %}
{% for prop in block.body.expressions %}
{% if prop.is_a? Assign %}
{% definitions << {var: prop.target, value: prop.value} %}
{% elsif prop.is_a? Call %}
{% definitions << {var: prop.name, value: prop.args.first} %}
{% elsif prop.is_a? TypeDeclaration %}
{% definitions << {var: prop.var, value: prop.value, type: prop.type} %}
{% end %}

2
src/ameba/rule/base.cr
View file

@ -34,7 +34,7 @@ module Ameba::Rule
# that are tested by this rule, it should add an error.
abstract def test(source : Source)
def test(source : Source, node : Crystal::ASTNode)
def test(source : Source, node : Crystal::ASTNode, *opts)
# can't be abstract
end

6
src/ameba/rule/comparison_to_boolean.cr
View file

@ -22,14 +22,14 @@ module Ameba::Rule
#
struct ComparisonToBoolean < Base
properties do
enabled = false
description = "Disallows comparison to booleans"
enabled false
description "Disallows comparison to booleans"
end
MSG = "Comparison to a boolean is pointless"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Call)

4
src/ameba/rule/constant_names.cr
View file

@ -24,13 +24,13 @@ module Ameba::Rule
#
struct ConstantNames < Base
properties do
description = "Enforces constant names to be in screaming case"
description "Enforces constant names to be in screaming case"
end
MSG = "Constant name should be screaming-cased: %s, not %s"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Assign)

4
src/ameba/rule/debugger_statement.cr
View file

@ -13,13 +13,13 @@ module Ameba::Rule
#
struct DebuggerStatement < Base
properties do
description = "Disallows calls to debugger"
description "Disallows calls to debugger"
end
MSG = "Possible forgotten debugger statement detected"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Call)

4
src/ameba/rule/empty_ensure.cr
View file

@ -34,13 +34,13 @@ module Ameba::Rule
#
struct EmptyEnsure < Base
properties do
description = "Disallows empty ensure statement"
description "Disallows empty ensure statement"
end
MSG = "Empty `ensure` block detected"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::ExceptionHandler)

4
src/ameba/rule/empty_expression.cr
View file

@ -32,14 +32,14 @@ module Ameba::Rule
include AST::Util
properties do
description = "Disallows empty expressions"
description "Disallows empty expressions"
end
MSG = "Avoid empty expression %s"
MSG_EXRS = "Avoid empty expressions"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::NilLiteral)

4
src/ameba/rule/hash_duplicated_key.cr
View file

@ -22,13 +22,13 @@ module Ameba::Rule
#
struct HashDuplicatedKey < Base
properties do
description = "Disallows duplicated keys in hash literals"
description "Disallows duplicated keys in hash literals"
end
MSG = "Duplicated keys in hash literal: %s"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::HashLiteral)

4
src/ameba/rule/large_numbers.cr
View file

@ -29,8 +29,8 @@ module Ameba::Rule
#
struct LargeNumbers < Base
properties do
description = "Disallows usage of large numbers without underscore"
int_min_digits = 5
description "Disallows usage of large numbers without underscore"
int_min_digits 5
end
MSG = "Large numbers should be written with underscores: %s"

6
src/ameba/rule/line_length.cr
View file

@ -11,9 +11,9 @@ module Ameba::Rule
#
struct LineLength < Base
properties do
enabled = false
description = "Disallows lines longer than `MaxLength` number of symbols"
max_length = 80
enabled false
description "Disallows lines longer than `MaxLength` number of symbols"
max_length 80
end
MSG = "Line too long"

4
src/ameba/rule/literal_in_condition.cr
View file

@ -24,14 +24,14 @@ module Ameba::Rule
include AST::Util
properties do
description = "Disallows useless conditional statements that contain \
description "Disallows useless conditional statements that contain \
a literal in place of a variable or predicate function"
end
MSG = "Literal value found in conditional"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def check_node(source, node)

4
src/ameba/rule/literal_in_interpolation.cr
View file

@ -20,13 +20,13 @@ module Ameba::Rule
include AST::Util
properties do
description = "Disallows useless string interpolations"
description "Disallows useless string interpolations"
end
MSG = "Literal value found in interpolation"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::StringInterpolation)

4
src/ameba/rule/method_names.cr
View file

@ -40,13 +40,13 @@ module Ameba::Rule
#
struct MethodNames < Base
properties do
description = "Enforces method names to be in underscored case"
description "Enforces method names to be in underscored case"
end
MSG = "Method name should be underscore-cased: %s, not %s"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Def)

4
src/ameba/rule/negated_conditions_in_unless.cr
View file

@ -29,13 +29,13 @@ module Ameba::Rule
#
struct NegatedConditionsInUnless < Base
properties do
description = "Disallows negated conditions in unless"
description "Disallows negated conditions in unless"
end
MSG = "Avoid negated conditions in unless blocks"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Unless)

6
src/ameba/rule/percent_arrays.cr
View file

@ -26,9 +26,9 @@ module Ameba::Rule
#
struct PercentArrays < Base
properties do
description = "Disallows some unwanted symbols in percent array literals"
string_array_unwanted_symbols = ",\""
symbol_array_unwanted_symbols = ",:"
description "Disallows some unwanted symbols in percent array literals"
string_array_unwanted_symbols ",\""
symbol_array_unwanted_symbols ",:"
end
MSG = "Symbols `%s` may be unwanted in %s array literals"

4
src/ameba/rule/predicate_name.cr
View file

@ -31,13 +31,13 @@ module Ameba::Rule
#
struct PredicateName < Base
properties do
description = "Disallows tautological predicate names"
description "Disallows tautological predicate names"
end
MSG = "Favour method name '%s?' over '%s'"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Def)

4
src/ameba/rule/rand_zero.cr
View file

@ -25,13 +25,13 @@ module Ameba::Rule
#
struct RandZero < Base
properties do
description = "Disallows rand zero calls"
description "Disallows rand zero calls"
end
MSG = "%s always returns 0"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Call)

4
src/ameba/rule/redundant_begin.cr
View file

@ -59,13 +59,13 @@ module Ameba::Rule
struct RedundantBegin < Base
include AST::Util
properties do
description = "Disallows redundant begin blocks"
description "Disallows redundant begin blocks"
end
MSG = "Redundant `begin` block detected"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Def)

4
src/ameba/rule/shadowed_exception.cr
View file

@ -36,13 +36,13 @@ module Ameba::Rule
#
struct ShadowedException < Base
properties do
description = "Disallows rescued exception that get shadowed"
description "Disallows rescued exception that get shadowed"
end
MSG = "Exception handler has shadowed exceptions: %s"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::ExceptionHandler)

2
src/ameba/rule/trailing_blank_lines.cr
View file

@ -10,7 +10,7 @@ module Ameba::Rule
#
struct TrailingBlankLines < Base
properties do
description = "Disallows trailing blank lines"
description "Disallows trailing blank lines"
end
MSG = "Blank lines detected at the end of the file"

2
src/ameba/rule/trailing_whitespace.cr
View file

@ -10,7 +10,7 @@ module Ameba::Rule
#
struct TrailingWhitespace < Base
properties do
description = "Disallows trailing whitespaces"
description "Disallows trailing whitespaces"
end
MSG = "Trailing whitespace detected"

4
src/ameba/rule/type_names.cr
View file

@ -54,13 +54,13 @@ module Ameba::Rule
#
struct TypeNames < Base
properties do
description = "Enforces type names in camelcase manner"
description "Enforces type names in camelcase manner"
end
MSG = "Type name should be camelcased: %s, but it was %s"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
private def check_node(source, node)

4
src/ameba/rule/unless_else.cr
View file

@ -45,13 +45,13 @@ module Ameba::Rule
#
struct UnlessElse < Base
properties do
description = "Disallows the use of an `else` block with the `unless`"
description "Disallows the use of an `else` block with the `unless`"
end
MSG = "Favour if over unless with else"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::Unless)

2
src/ameba/rule/unneeded_disable_directive.cr
View file

@ -20,7 +20,7 @@ module Ameba::Rule
#
struct UnneededDisableDirective < Base
properties do
description = "Reports unneeded disable directives in comments"
description "Reports unneeded disable directives in comments"
end
MSG = "Unnecessary disabling of %s"

51
src/ameba/rule/useless_assign.cr Normal file
View file

@ -0,0 +1,51 @@
module Ameba::Rule
# A rule that disallows useless assignments.
#
# For example, this is considered invalid:
#
# ```
# def method
# var = 1
# do_something
# end
# ```
#
# And has to be written as the following:
#
# ```
# def method
# var = 1
# do_something(var)
# end
# ```
#
# YAML configuration example:
#
# ```
# UselessAssign:
# Enabled: true
# ```
#
struct UselessAssign < Base
properties do
description "Disallows useless variable assignments"
end
MSG = "Useless assignment to variable `%s`"
def test(source)
AST::ScopeVisitor.new self, source
end
def test(source, node, scope : AST::Scope)
scope.variables.each do |var|
next if var.captured_by_block?
var.assignments.each do |assign|
next if assign.referenced?
source.error self, assign.location, MSG % var.name
end
end
end
end
end

4
src/ameba/rule/useless_condition_in_when.cr
View file

@ -33,7 +33,7 @@ module Ameba::Rule
#
struct UselessConditionInWhen < Base
properties do
description = "Disallows useless conditions in when"
description "Disallows useless conditions in when"
end
MSG = "Useless condition in when detected"
@ -52,7 +52,7 @@ module Ameba::Rule
end
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::When)

4
src/ameba/rule/variable_names.cr
View file

@ -33,13 +33,13 @@ module Ameba::Rule
#
struct VariableNames < Base
properties do
description = "Enforces variable names to be in underscored case"
description "Enforces variable names to be in underscored case"
end
MSG = "Var name should be underscore-cased: %s, not %s"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
private def check_node(source, node)

4
src/ameba/rule/while_true.cr
View file

@ -28,13 +28,13 @@ module Ameba::Rule
#
struct WhileTrue < Base
properties do
description = "Disallows while statements with a true literal as condition"
description "Disallows while statements with a true literal as condition"
end
MSG = "While statement using true literal as condition"
def test(source)
AST::Visitor.new self, source
AST::NodeVisitor.new self, source
end
def test(source, node : Crystal::While)