Add discrete node classes for assignments.

changelog/new_add_discrete_node_classes_for.md

@@ -0,0 +1 @@
+* [#201](https://github.com/rubocop-hq/rubocop-ast/pull/201): Add discrete node classes for assignments. ([@dvandersluis][])

docs/modules/ROOT/pages/node_types.adoc

@@ -56,7 +56,7 @@ The following fields are given when relevant to nodes in the source code:
 
 |and|And operator|Two children are both expression nodes representing the operands.|a and b && c |https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/AndNode[AndNode]
 
-|and_asgn|And-assignment (AND the receiver with the argument and assign it back to receiver).|First child must be an assignment node, second child is the expression node.|a &&= b |N/A
+|and_asgn|And-assignment (AND the receiver with the argument and assign it back to receiver).|First child must be an assignment node, second child is the expression node.|a &&= b |https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/AndAsgnNode[AndAsgnNode]
 
 |arg|Required positional argument. Must come inside an `args`.|One child - a symbol, representing the argument name.|def foo(bar)|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/ArgNode[ArgNode]
 
@@ -76,7 +76,7 @@ The following fields are given when relevant to nodes in the source code:
 
 |case|Case statement.|First child is an expression node for the condition to check. Last child is an expression node for the "else" condition. All middle nodes are `when` nodes.|case a; when 1; b; when 2; c; else d; end|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/CaseNode[CaseNode]
 
-|casgn|Constant assignment|Three children: the parent object (either an expression, `nil` or `cbase`), the constant name (a symbol), and the expression being assigned.|Foo::Bar = 5|N/A
+|casgn|Constant assignment|Three children: the parent object (either an expression, `nil` or `cbase`), the constant name (a symbol), and the expression being assigned.|Foo::Bar = 5|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/CasgnNode[CasgnNode]
 
 |cbase|Represents the top-module constant (i.e. the '::' before a constant name). Only occurs inside a `const` node.|None|::Foo|N/A
 
@@ -90,7 +90,7 @@ The following fields are given when relevant to nodes in the source code:
 
 |cvar|Class variable access|One child, the variable name `:@@cfoo`|@@cfoo|N/A
 
-|cvasgn|Class variable assignment|Two children: the variable name `:@@foo` and the expression being assigned|@@foo = 5|N/A
+|cvasgn|Class variable assignment|Two children: the variable name `:@@foo` and the expression being assigned|@@foo = 5|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/AsgnNode[AsgnNode]
 
 |def|Instance method definition (full format)|Three children. First child is the name of the method (symbol); second child is `args` or `forward_args` (only if `emit_forward` is false, and it's true by default), and the last child is a body statement.|def foo(some_arg, kwarg: 1); end|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/DefNode[DefNode]
 
@@ -122,7 +122,7 @@ The following fields are given when relevant to nodes in the source code:
 
 |gvar|Global variable access|One child, the variable name as a symbol `:$foo`|$foo|N/A
 
-|gvasgn|Global variable assignment|Two children, the variable name `:$foo` and the expression being assigned|$foo = 5|N/A
+|gvasgn|Global variable assignment|Two children, the variable name `:$foo` and the expression being assigned|$foo = 5|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/AsgnNode[AsgnNode]
 
 |hash|Hash literal.|`pair` s and/or  `kwsplat` s.|{ foo: 'bar' }|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/HashNode[HashNode]
 
@@ -132,7 +132,7 @@ The following fields are given when relevant to nodes in the source code:
 
 |ivar|Instance variable access|One child, the variable name `:@foo`|@foo|N/A
 
-|ivasgn|Instance variable assignment|Two children, the variable name `:@foo` and the expression being assigned|@foo = 5|N/A
+|ivasgn|Instance variable assignment|Two children, the variable name `:@foo` and the expression being assigned|@foo = 5|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/AsgnNode[AsgnNode]
 
 |irange|Inclusive range literal.|Two children, the start and end nodes (including `nil` for beginless/endless)|1..2|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/RangeNode[RangeNode]
 
@@ -150,7 +150,7 @@ The following fields are given when relevant to nodes in the source code:
 
 |lvar|Local variable access|One child, the variable name|foo|N/A
 
-|lvasgn|Local variable assignment|Two children: The variable name (symbol) and the expression.|a = some_thing|N/A
+|lvasgn|Local variable assignment|Two children: The variable name (symbol) and the expression.|a = some_thing|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/AsgnNode[AsgnNode]
 
 |masgn|Multiple assigment.|First set of children are all `mlhs` nodes, and the rest of the children must be expression nodes corresponding to the values in the `mlhs` nodes.|a, b, = [1, 2]|N/A
 
@@ -166,13 +166,13 @@ The following fields are given when relevant to nodes in the source code:
 
 |numblock|Block that has numbered arguments (`_1`) referenced inside it.|Three children. First child is a `send`/`csend` node representing the way the block is created, second child is an `int` (the number of numeric arguments) and the third child is a body statement.|proc { _1 + _3 }|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/BlockNode[BlockNode]
 
-|op_asgn|Operator-assignment - perform an operation and assign the value.|Three children. First child must be an assignment node, second child is the operator (e.g. `:+`) and the third child is the expression node.|a += b|N/A
+|op_asgn|Operator-assignment - perform an operation and assign the value.|Three children. First child must be an assignment node, second child is the operator (e.g. `:+`) and the third child is the expression node.|a += b|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/OpAsgnNode[OpAsgnNode]
 
 |optarg|Optional positional argument. Must come inside an `args`.|One child - a symbol, representing the argument name.|def foo(bar=1)|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/ArgNode[ArgNode]
 
 |or|Or operator|Two children are both expression nodes representing the operands.|a or b|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/OrNode[OrNode]
 
-|or_asgn|Or-assignment (OR the receiver with the argument and assign it back to receiver).|Two children. First child must be an assignment node, second child is the expression node.|a \|\|= b|N/A
+|or_asgn|Or-assignment (OR the receiver with the argument and assign it back to receiver).|Two children. First child must be an assignment node, second child is the expression node.|a \|\|= b|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/OrAsgnNode[OrAsgnNode]
 
 |pair|One entry in a hash. |Two children, the key and value nodes.|1 => 2|https://rubydoc.info/github/rubocop/rubocop-ast/RuboCop/AST/PairNode[PairNode]
 

lib/rubocop/ast.rb

@@ -39,10 +39,12 @@
 require_relative 'ast/node/arg_node'
 require_relative 'ast/node/args_node'
 require_relative 'ast/node/array_node'
+require_relative 'ast/node/asgn_node'
 require_relative 'ast/node/block_node'
 require_relative 'ast/node/break_node'
 require_relative 'ast/node/case_match_node'
 require_relative 'ast/node/case_node'
+require_relative 'ast/node/casgn_node'
 require_relative 'ast/node/class_node'
 require_relative 'ast/node/const_node'
 require_relative 'ast/node/def_node'
@@ -61,6 +63,9 @@
 require_relative 'ast/node/lambda_node'
 require_relative 'ast/node/module_node'
 require_relative 'ast/node/next_node'
+require_relative 'ast/node/op_asgn_node'
+require_relative 'ast/node/and_asgn_node'
+require_relative 'ast/node/or_asgn_node'
 require_relative 'ast/node/or_node'
 require_relative 'ast/node/pair_node'
 require_relative 'ast/node/procarg0_node'

lib/rubocop/ast/builder.rb

@@ -20,6 +20,7 @@ class Builder < Parser::Builders::Default
       # @api private
       NODE_MAP = {
         and:          AndNode,
+        and_asgn:     AndAsgnNode,
         alias:        AliasNode,
         arg:          ArgNode,
         blockarg:     ArgNode,
@@ -32,10 +33,15 @@ class Builder < Parser::Builders::Default
         shadowarg:    ArgNode,
         args:         ArgsNode,
         array:        ArrayNode,
+        lvasgn:       AsgnNode,
+        ivasgn:       AsgnNode,
+        cvasgn:       AsgnNode,
+        gvasgn:       AsgnNode,
         block:        BlockNode,
         numblock:     BlockNode,
         break:        BreakNode,
         case_match:   CaseMatchNode,
+        casgn:        CasgnNode,
         case:         CaseNode,
         class:        ClassNode,
         const:        ConstNode,
@@ -60,6 +66,8 @@ class Builder < Parser::Builders::Default
         lambda:       LambdaNode,
         module:       ModuleNode,
         next:         NextNode,
+        op_asgn:      OpAsgnNode,
+        or_asgn:      OrAsgnNode,
         or:           OrNode,
         pair:         PairNode,
         procarg0:     Procarg0Node,

lib/rubocop/ast/node/and_asgn_node.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `op_asgn` nodes.
+    # This will be used in place of a plain node when the builder constructs
+    # the AST, making its methods available to all assignment nodes within RuboCop.
+    class AndAsgnNode < OpAsgnNode
+      # The operator being used for assignment as a symbol.
+      #
+      # @return [Symbol] the assignment operator
+      def operator
+        :'&&'
+      end
+    end
+  end
+end

lib/rubocop/ast/node/asgn_node.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `lvasgn`, `ivasgn`, `cvasgn`, and `gvasgn` nodes.
+    # This will be used in place of a plain node when the builder constructs
+    # the AST, making its methods available to all assignment nodes within RuboCop.
+    class AsgnNode < Node
+      # The name of the variable being assigned as a symbol.
+      #
+      # @return [Symbol] the name of the variable being assigned
+      def name
+        node_parts[0]
+      end
+
+      # The expression being assigned to the variable.
+      #
+      # @return [Node] the expression being assigned.
+      def expression
+        node_parts[1]
+      end
+    end
+  end
+end

lib/rubocop/ast/node/casgn_node.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `casgn` nodes.
+    # This will be used in place of a plain node when the builder constructs
+    # the AST, making its methods available to all assignment nodes within RuboCop.
+    class CasgnNode < Node
+      # The namespace of the constant being assigned.
+      #
+      # @return [Node, nil] the node associated with the scope (e.g. cbase, const, ...)
+      def namespace
+        node_parts[0]
+      end
+
+      # The name of the variable being assigned as a symbol.
+      #
+      # @return [Symbol] the name of the variable being assigned
+      def name
+        node_parts[1]
+      end
+
+      # The expression being assigned to the variable.
+      #
+      # @return [Node] the expression being assigned.
+      def expression
+        node_parts[2]
+      end
+    end
+  end
+end

lib/rubocop/ast/node/op_asgn_node.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `op_asgn` nodes.
+    # This will be used in place of a plain node when the builder constructs
+    # the AST, making its methods available to all assignment nodes within RuboCop.
+    class OpAsgnNode < Node
+      # @return [AsgnNode] the assignment node
+      def assignment_node
+        node_parts[0]
+      end
+
+      # The name of the variable being assigned as a symbol.
+      #
+      # @return [Symbol] the name of the variable being assigned
+      def name
+        assignment_node.name
+      end
+
+      # The operator being used for assignment as a symbol.
+      #
+      # @return [Symbol] the assignment operator
+      def operator
+        node_parts[1]
+      end
+
+      # The expression being assigned to the variable.
+      #
+      # @return [Node] the expression being assigned.
+      def expression
+        node_parts.last
+      end
+    end
+  end
+end

lib/rubocop/ast/node/or_asgn_node.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module AST
+    # A node extension for `op_asgn` nodes.
+    # This will be used in place of a plain node when the builder constructs
+    # the AST, making its methods available to all assignment nodes within RuboCop.
+    class OrAsgnNode < OpAsgnNode
+      # The operator being used for assignment as a symbol.
+      #
+      # @return [Symbol] the assignment operator
+      def operator
+        :'||'
+      end
+    end
+  end
+end

spec/rubocop/ast/and_asgn_node_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::AST::AndAsgnNode do
+  let(:or_asgn_node) { parse_source(source).ast }
+  let(:source) { 'var &&= value' }
+
+  describe '.new' do
+    it { expect(or_asgn_node).to be_a(described_class) }
+  end
+
+  describe '#assignment_node' do
+    subject { or_asgn_node.assignment_node }
+
+    it { is_expected.to be_a(RuboCop::AST::AsgnNode) }
+  end
+
+  describe '#name' do
+    subject { or_asgn_node.name }
+
+    it { is_expected.to eq(:var) }
+  end
+
+  describe '#operator' do
+    subject { or_asgn_node.operator }
+
+    it { is_expected.to eq(:'&&') }
+  end
+
+  describe '#expression' do
+    include AST::Sexp
+
+    subject { or_asgn_node.expression }
+
+    it { is_expected.to eq(s(:send, nil, :value)) }
+  end
+end

spec/rubocop/ast/asgn_node_spec.rb

@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::AST::AsgnNode do
+  let(:asgn_node) { parse_source(source).ast }
+
+  describe '.new' do
+    context 'with a `lvasgn` node' do
+      let(:source) { 'var = value' }
+
+      it { expect(asgn_node).to be_a(described_class) }
+    end
+
+    context 'with a `ivasgn` node' do
+      let(:source) { '@var = value' }
+
+      it { expect(asgn_node).to be_a(described_class) }
+    end
+
+    context 'with a `cvasgn` node' do
+      let(:source) { '@@var = value' }
+
+      it { expect(asgn_node).to be_a(described_class) }
+    end
+
+    context 'with a `gvasgn` node' do
+      let(:source) { '$var = value' }
+
+      it { expect(asgn_node).to be_a(described_class) }
+    end
+  end
+
+  describe '#name' do
+    subject { asgn_node.name }
+
+    context 'with a `lvasgn` node' do
+      let(:source) { 'var = value' }
+
+      it { is_expected.to eq(:var) }
+    end
+
+    context 'with a `ivasgn` node' do
+      let(:source) { '@var = value' }
+
+      it { is_expected.to eq(:@var) }
+    end
+
+    context 'with a `cvasgn` node' do
+      let(:source) { '@@var = value' }
+
+      it { is_expected.to eq(:@@var) }
+    end
+
+    context 'with a `gvasgn` node' do
+      let(:source) { '$var = value' }
+
+      it { is_expected.to eq(:$var) }
+    end
+  end
+
+  describe '#expression' do
+    include AST::Sexp
+
+    subject { asgn_node.expression }
+
+    context 'with a `lvasgn` node' do
+      let(:source) { 'var = value' }
+
+      it { is_expected.to eq(s(:send, nil, :value)) }
+    end
+
+    context 'with a `ivasgn` node' do
+      let(:source) { '@var = value' }
+
+      it { is_expected.to eq(s(:send, nil, :value)) }
+    end
+
+    context 'with a `cvasgn` node' do
+      let(:source) { '@@var = value' }
+
+      it { is_expected.to eq(s(:send, nil, :value)) }
+    end
+
+    context 'with a `gvasgn` node' do
+      let(:source) { '$var = value' }
+
+      it { is_expected.to eq(s(:send, nil, :value)) }
+    end
+  end
+end