Add compact_hash plugin

Author: ryanb

README.md

@@ -711,6 +711,7 @@ To register plugins, define a file somewhere in your load path named `syntax_tre
 * `plugin/single_quotes` - This will change all of your string literals to use single quotes instead of the default double quotes.
 * `plugin/trailing_comma` - This will put trailing commas into multiline array literals, hash literals, and method calls that can support trailing commas.
 * `plugin/disable_auto_ternary` - This will prevent the automatic conversion of `if ... else` to ternary expressions.
+* `plugin/strip_hash` - This will remove the spaces at the beginning and end of hashes.
 
 If you're using Syntax Tree as a library, you can require those files directly or manually pass those options to the formatter initializer through the `SyntaxTree::Formatter::Options` class.
 

lib/syntax_tree/formatter.rb

@@ -24,13 +24,15 @@ class Options
       attr_reader :quote,
                   :trailing_comma,
                   :disable_auto_ternary,
-                  :target_ruby_version
+                  :target_ruby_version,
+                  :strip_hash
 
       def initialize(
         quote: :default,
         trailing_comma: :default,
         disable_auto_ternary: :default,
-        target_ruby_version: :default
+        target_ruby_version: :default,
+        strip_hash: :default
       )
         @quote =
           if quote == :default
@@ -74,6 +76,14 @@ def initialize(
           else
             target_ruby_version
           end
+
+        @strip_hash =
+          if strip_hash == :default
+            # This plugin removes the spaces at the beginning and end of hashes.
+            defined?(STRIP_HASH)
+          else
+            strip_hash
+          end
       end
     end
 
@@ -87,10 +97,12 @@ def initialize(
     attr_reader :quote,
                 :trailing_comma,
                 :disable_auto_ternary,
-                :target_ruby_version
+                :target_ruby_version,
+                :strip_hash
 
     alias trailing_comma? trailing_comma
     alias disable_auto_ternary? disable_auto_ternary
+    alias strip_hash? strip_hash
 
     def initialize(source, *args, options: Options.new)
       super(*args)
@@ -103,6 +115,7 @@ def initialize(source, *args, options: Options.new)
       @trailing_comma = options.trailing_comma
       @disable_auto_ternary = options.disable_auto_ternary
       @target_ruby_version = options.target_ruby_version
+      @strip_hash = options.strip_hash
     end
 
     def self.format(source, node, base_indentation = 0)

lib/syntax_tree/node.rb

@@ -5751,11 +5751,11 @@ def format_contents(q)
         q.breakable_empty
       else
         q.indent do
-          q.breakable_space
+          q.strip_hash? ? q.breakable_empty : q.breakable_space
           q.seplist(assocs) { |assoc| q.format(assoc) }
           q.if_break { q.text(",") } if q.trailing_comma?
         end
-        q.breakable_space
+        q.strip_hash? ? q.breakable_empty : q.breakable_space
       end
 
       q.text("}")

lib/syntax_tree/plugin/strip_hash.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module SyntaxTree
+  class Formatter
+    STRIP_HASH = true
+  end
+end

test/plugin/strip_hash_test.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module SyntaxTree
+  class StripHashTest < Minitest::Test
+    def test_single_hash
+      assert_format("{foo: 1}\n")
+    end
+
+    def test_multi_line_hash
+      assert_format(<<~EXPECTED)
+        {
+          fooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo: 1,
+          baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: 2
+        }
+      EXPECTED
+    end
+
+    private
+
+    def assert_format(expected, source = expected)
+      options = Formatter::Options.new(strip_hash: true)
+      formatter = Formatter.new(source, [], options: options)
+      SyntaxTree.parse(source).format(formatter)
+
+      formatter.flush
+      assert_equal(expected, formatter.output.join)
+    end
+  end
+end