Add delimiters' and related predicates for RegexpNode` (#41)

As suggested by @bbatsov in rubocop/rubocop#8138 (comment)

CHANGELOG.md

@@ -10,6 +10,7 @@
 * [#20](https://github.com/rubocop-hq/rubocop-ast/pull/20): Add option predicates for `RegexpNode`. ([@owst][])
 * [#11](https://github.com/rubocop-hq/rubocop-ast/issues/11): Add `argument_type?` method to make it easy to recognize argument nodes. ([@tejasbubane][])
 * [#31](https://github.com/rubocop-hq/rubocop-ast/pull/31): Use `param === node` to match params, which allows Regexp, Proc, Set, etc. ([@marcandre][])
+* [#41](https://github.com/rubocop-hq/rubocop-ast/pull/41): Add `delimiters` and related predicates for `RegexpNode`. ([@owst][])
 
 ## 0.0.3 (2020-05-15)
 

lib/rubocop/ast/node/regexp_node.rb

@@ -32,6 +32,26 @@ def content
         children.select(&:str_type?).map(&:str_content).join
       end
 
+      # @return [Bool] if the regexp is a /.../ literal
+      def slash_literal?
+        loc.begin.source == '/'
+      end
+
+      # @return [Bool] if the regexp is a %r{...} literal (using any delimiters)
+      def percent_r_literal?
+        !slash_literal?
+      end
+
+      # @return [String] the regexp delimiters (without %r)
+      def delimiters
+        [loc.begin.source[-1], loc.end.source[0]]
+      end
+
+      # @return [Bool] if char is one of the delimiters
+      def delimiter?(char)
+        delimiters.include?(char)
+      end
+
       # @return [Bool] if regexp contains interpolation
       def interpolation?
         children.any?(&:begin_type?)

spec/rubocop/ast/regexp_node_spec.rb

@@ -141,6 +141,194 @@
     end
   end
 
+  describe '#slash_literal?' do
+    context 'with /-delimiters' do
+      let(:source) { '/abc/' }
+
+      it { expect(regexp_node.slash_literal?).to eq(true) }
+    end
+
+    context 'with %r/-delimiters' do
+      let(:source) { '%r/abc/' }
+
+      it { expect(regexp_node.slash_literal?).to eq(false) }
+    end
+
+    context 'with %r{-delimiters' do
+      let(:source) { '%r{abc}' }
+
+      it { expect(regexp_node.slash_literal?).to eq(false) }
+    end
+
+    context 'with multi-line %r{-delimiters' do
+      let(:source) do
+        <<~SRC
+          %r{
+            abc
+          }x
+        SRC
+      end
+
+      it { expect(regexp_node.slash_literal?).to eq(false) }
+    end
+
+    context 'with %r<-delimiters' do
+      let(:source) { '%r<abc>x' }
+
+      it { expect(regexp_node.slash_literal?).to eq(false) }
+    end
+  end
+
+  describe '#percent_r_literal?' do
+    context 'with /-delimiters' do
+      let(:source) { '/abc/' }
+
+      it { expect(regexp_node.percent_r_literal?).to eq(false) }
+    end
+
+    context 'with %r/-delimiters' do
+      let(:source) { '%r/abc/' }
+
+      it { expect(regexp_node.percent_r_literal?).to eq(true) }
+    end
+
+    context 'with %r{-delimiters' do
+      let(:source) { '%r{abc}' }
+
+      it { expect(regexp_node.percent_r_literal?).to eq(true) }
+    end
+
+    context 'with multi-line %r{-delimiters' do
+      let(:source) do
+        <<~SRC
+          %r{
+            abc
+          }x
+        SRC
+      end
+
+      it { expect(regexp_node.percent_r_literal?).to eq(true) }
+    end
+
+    context 'with %r<-delimiters' do
+      let(:source) { '%r<abc>x' }
+
+      it { expect(regexp_node.percent_r_literal?).to eq(true) }
+    end
+  end
+
+  describe '#delimiters' do
+    context 'with /-delimiters' do
+      let(:source) { '/abc/' }
+
+      it { expect(regexp_node.delimiters).to eq(['/', '/']) }
+    end
+
+    context 'with %r/-delimiters' do
+      let(:source) { '%r/abc/' }
+
+      it { expect(regexp_node.delimiters).to eq(['/', '/']) }
+    end
+
+    context 'with %r{-delimiters' do
+      let(:source) { '%r{abc}' }
+
+      it { expect(regexp_node.delimiters).to eq(['{', '}']) }
+    end
+
+    context 'with multi-line %r{-delimiters' do
+      let(:source) do
+        <<~SRC
+          %r{
+            abc
+          }x
+        SRC
+      end
+
+      it { expect(regexp_node.delimiters).to eq(['{', '}']) }
+    end
+
+    context 'with %r<-delimiters' do
+      let(:source) { '%r<abc>x' }
+
+      it { expect(regexp_node.delimiters).to eq(['<', '>']) }
+    end
+  end
+
+  describe '#delimiter?' do
+    context 'with /-delimiters' do
+      let(:source) { '/abc/' }
+
+      it { expect(regexp_node.delimiter?('/')).to eq(true) }
+
+      it { expect(regexp_node.delimiter?('{')).to eq(false) }
+    end
+
+    context 'with %r/-delimiters' do
+      let(:source) { '%r/abc/' }
+
+      it { expect(regexp_node.delimiter?('/')).to eq(true) }
+
+      it { expect(regexp_node.delimiter?('{')).to eq(false) }
+      it { expect(regexp_node.delimiter?('}')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%')).to eq(false) }
+      it { expect(regexp_node.delimiter?('r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r/')).to eq(false) }
+    end
+
+    context 'with %r{-delimiters' do
+      let(:source) { '%r{abc}' }
+
+      it { expect(regexp_node.delimiter?('{')).to eq(true) }
+      it { expect(regexp_node.delimiter?('}')).to eq(true) }
+
+      it { expect(regexp_node.delimiter?('/')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%')).to eq(false) }
+      it { expect(regexp_node.delimiter?('r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r/')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r{')).to eq(false) }
+    end
+
+    context 'with multi-line %r{-delimiters' do
+      let(:source) do
+        <<~SRC
+          %r{
+            abc
+          }x
+        SRC
+      end
+
+      it { expect(regexp_node.delimiter?('{')).to eq(true) }
+      it { expect(regexp_node.delimiter?('}')).to eq(true) }
+
+      it { expect(regexp_node.delimiter?('/')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%')).to eq(false) }
+      it { expect(regexp_node.delimiter?('r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r/')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r{')).to eq(false) }
+    end
+
+    context 'with %r<-delimiters' do
+      let(:source) { '%r<abc>x' }
+
+      it { expect(regexp_node.delimiter?('<')).to eq(true) }
+      it { expect(regexp_node.delimiter?('>')).to eq(true) }
+
+      it { expect(regexp_node.delimiter?('{')).to eq(false) }
+      it { expect(regexp_node.delimiter?('}')).to eq(false) }
+      it { expect(regexp_node.delimiter?('/')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%')).to eq(false) }
+      it { expect(regexp_node.delimiter?('r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r/')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r{')).to eq(false) }
+      it { expect(regexp_node.delimiter?('%r<')).to eq(false) }
+    end
+  end
+
   describe '#interpolation?' do
     context 'with direct variable interpoation' do
       let(:source) { '/\n\n#{foo}(abc)+/' }