Add StrNode#single_quoted?, StrNode#double_quoted? and StrNode#pe…

…rcent_literal?` to simplify checking for string delimiters

changelog/change_add_strnodepercent_literal_to_simplify.md

@@ -0,0 +1 @@
+* [#343](https://github.com/rubocop/rubocop-ast/pull/343): Add `StrNode#single_quoted?`, `StrNode#double_quoted?` and StrNode#percent_literal?` to simplify checking for string delimiters. ([@dvandersluis][])

lib/rubocop/ast/node/str_node.rb

@@ -8,13 +8,56 @@ module AST
     class StrNode < Node
       include BasicLiteralNode
 
+      PERCENT_LITERAL_TYPES = {
+        :% => /^%(?![qQ])/,
+        :q => /^%q/,
+        :Q => /^%Q/
+      }.freeze
+
+      def single_quoted?
+        opening_delimiter&.is?("'")
+      end
+
+      def double_quoted?
+        opening_delimiter&.is?('"')
+      end
+
       def character_literal?
-        loc.respond_to?(:begin) && loc.begin&.is?('?')
+        opening_delimiter&.is?('?')
       end
 
       def heredoc?
         loc.is_a?(Parser::Source::Map::Heredoc)
       end
+
+      # Checks whether the string literal is delimited by percent brackets.
+      #
+      # @overload percent_literal?
+      #   Check for any string percent literal.
+      #
+      # @overload percent_literal?(type)
+      #   Check for a string percent literal of type `type`.
+      #
+      # @param type [Symbol] an optional percent literal type
+      #
+      # @return [Boolean] whether the string is enclosed in percent brackets
+      def percent_literal?(type = nil)
+        return false unless opening_delimiter
+
+        if type
+          opening_delimiter.source =~ PERCENT_LITERAL_TYPES[type]
+        else
+          opening_delimiter.source.start_with?('%')
+        end
+      end
+
+      private
+
+      def opening_delimiter
+        return unless loc.respond_to?(:begin)
+
+        loc.begin
+      end
     end
   end
 end

spec/rubocop/ast/dstr_node_spec.rb

@@ -35,4 +35,73 @@
       it { is_expected.to eq('foo bar baz') }
     end
   end
+
+  describe '#single_quoted?' do
+    context 'with a double-quoted string' do
+      let(:source) { '"#{foo}"' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+
+    context 'with a %() delimited string' do
+      let(:source) { '%(#{foo})' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+
+    context 'with a %Q() delimited string' do
+      let(:source) { '%Q(#{foo})' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+  end
+
+  describe '#double_quoted?' do
+    context 'with a double-quoted string' do
+      let(:source) { '"#{foo}"' }
+
+      it { is_expected.to be_double_quoted }
+    end
+
+    context 'with a %() delimited string' do
+      let(:source) { '%(#{foo})' }
+
+      it { is_expected.not_to be_double_quoted }
+    end
+
+    context 'with a %Q() delimited string' do
+      let(:source) { '%Q(#{foo})' }
+
+      it { is_expected.not_to be_double_quoted }
+    end
+  end
+
+  describe '#percent_literal?' do
+    context 'with a quoted string' do
+      let(:source) { '"#{foo}"' }
+
+      it { is_expected.not_to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+
+    context 'with a %() delimited string' do
+      let(:source) { '%(#{foo})' }
+
+      it { is_expected.to be_percent_literal }
+      it { is_expected.to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+
+    context 'with a %Q() delimited string' do
+      let(:source) { '%Q(#{foo})' }
+
+      it { is_expected.to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.to be_percent_literal(:Q) }
+    end
+  end
 end

spec/rubocop/ast/str_node_spec.rb

@@ -1,7 +1,9 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::AST::StrNode do
-  subject(:str_node) { parse_source(source).ast }
+  subject(:str_node) { parsed_source.ast }
+
+  let(:parsed_source) { parse_source(source) }
 
   describe '.new' do
     context 'with a normal string' do
@@ -30,6 +32,86 @@
     end
   end
 
+  describe '#single_quoted?' do
+    context 'with a single-quoted string' do
+      let(:source) { "'foo'" }
+
+      it { is_expected.to be_single_quoted }
+    end
+
+    context 'with a double-quoted string' do
+      let(:source) { '"foo"' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+
+    context 'with a %() delimited string' do
+      let(:source) { '%(foo)' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+
+    context 'with a %q() delimited string' do
+      let(:source) { '%q(foo)' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+
+    context 'with a %Q() delimited string' do
+      let(:source) { '%Q(foo)' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+
+    context 'with an undelimited string within another node' do
+      subject(:str_node) { parsed_source.ast.child_nodes.first }
+
+      let(:source) { '/string/' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+  end
+
+  describe '#double_quoted?' do
+    context 'with a single-quoted string' do
+      let(:source) { "'foo'" }
+
+      it { is_expected.not_to be_double_quoted }
+    end
+
+    context 'with a double-quoted string' do
+      let(:source) { '"foo"' }
+
+      it { is_expected.to be_double_quoted }
+    end
+
+    context 'with a %() delimited string' do
+      let(:source) { '%(foo)' }
+
+      it { is_expected.not_to be_double_quoted }
+    end
+
+    context 'with a %q() delimited string' do
+      let(:source) { '%q(foo)' }
+
+      it { is_expected.not_to be_double_quoted }
+    end
+
+    context 'with a %Q() delimited string' do
+      let(:source) { '%Q(foo)' }
+
+      it { is_expected.not_to be_double_quoted }
+    end
+
+    context 'with an undelimited string within another node' do
+      subject(:str_node) { parsed_source.ast.child_nodes.first }
+
+      let(:source) { '/string/' }
+
+      it { is_expected.not_to be_single_quoted }
+    end
+  end
+
   describe '#character_literal?' do
     context 'with a character literal' do
       let(:source) { '?\n' }
@@ -83,4 +165,62 @@
       it { is_expected.to be_heredoc }
     end
   end
+
+  describe '#percent_literal?' do
+    context 'with a single-quoted string' do
+      let(:source) { "'foo'" }
+
+      it { is_expected.not_to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+
+    context 'with a double-quoted string' do
+      let(:source) { '"foo"' }
+
+      it { is_expected.not_to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+
+    context 'with a %() delimited string' do
+      let(:source) { '%(foo)' }
+
+      it { is_expected.to be_percent_literal }
+      it { is_expected.to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+
+    context 'with a %q() delimited string' do
+      let(:source) { '%q(foo)' }
+
+      it { is_expected.to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+
+    context 'with a %Q() delimited string' do
+      let(:source) { '%Q(foo)' }
+
+      it { is_expected.to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.to be_percent_literal(:Q) }
+    end
+
+    context 'with an undelimited string within another node' do
+      subject(:str_node) { parsed_source.ast.child_nodes.first }
+
+      let(:source) { '/string/' }
+
+      it { is_expected.not_to be_percent_literal }
+      it { is_expected.not_to be_percent_literal(:%) }
+      it { is_expected.not_to be_percent_literal(:q) }
+      it { is_expected.not_to be_percent_literal(:Q) }
+    end
+  end
 end