[WIP] Support Prism

Gemfile

@@ -7,6 +7,7 @@ gemspec
 gem "bundler", ">= 1.15"
 gem "debug", ">= 1.0.0"
 gem "guard-rspec", "~> 4.0"
+gem "prism", "~> 1.2"
 gem "rake", "~> 13.0"
 gem "rspec", "~> 3.0"
 gem "rspec_junit_formatter", "~> 0.6.0"

lib/rufo.rb

@@ -14,7 +14,13 @@ def initialize(message, lineno)
   end
 
   def self.format(code, **options)
-    Formatter.format(code, **options)
+    engine = options.delete(:engine)
+    case engine
+    when :prism
+      PrismFormatter.format(code, **options)
+    else
+      Formatter.format(code, **options)
+    end
   end
 end
 
@@ -25,6 +31,7 @@ def self.format(code, **options)
 require_relative "rufo/parser"
 require_relative "rufo/formatter"
 require_relative "rufo/erb_formatter"
+require_relative "rufo/prism_formatter"
 require_relative "rufo/version"
 require_relative "rufo/file_list"
 require_relative "rufo/file_finder"

lib/rufo/prism_formatter.rb

@@ -0,0 +1,182 @@
+# frozen_string_literal: true
+
+require "prism"
+
+class Rufo::PrismFormatter
+  include Rufo::Settings
+
+  DEBUG = true
+
+  def self.format(code, **options)
+    formatter = new(code, **options)
+    formatter.format
+    formatter.result
+  end
+
+  def initialize(code, **options)
+    @code = code
+    @parse_result = Prism.parse(code)
+    unless @parse_result.errors.empty?
+      error = @parse_result.errors.first
+      raise Rufo::SyntaxError.new(error.message, error.location.start_line)
+    end
+
+    init_settings(options)
+  end
+
+  def format
+    debug_log @parse_result
+    visitor = FormatVisitor.new(@code)
+    @parse_result.value.accept(visitor)
+    @output = visitor.output
+
+    @output.chomp! if @output.end_with?("\n\n")
+    @output.lstrip!
+    @output << "\n" unless @output.end_with?("\n")
+  end
+
+  def result
+    @output
+  end
+
+  def debug_log(object)
+    if DEBUG
+      p [:debug, object]
+    end
+  end
+
+  class FormatVisitor < Prism::Visitor
+    attr_reader :output
+
+    def initialize(code)
+      super()
+      @code = code
+      @output = +""
+    end
+
+    def visit_nil_node(_node)
+      write("nil")
+    end
+
+    def visit_true_node(_node)
+      write("true")
+    end
+
+    def visit_false_node(_node)
+      write("false")
+    end
+
+    def visit_integer_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_float_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_rational_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_imaginary_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_symbol_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_interpolated_symbol_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_string_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_class_variable_read_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_global_variable_read_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_numbered_reference_read_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_local_variable_read_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_local_variable_write_node(node)
+      write(node.name.to_s)
+      write(" = ")
+      node.value.accept(self)
+    end
+
+    def visit_hash_node(node)
+      write_code_at(node.location)
+    end
+
+    def visit_instance_variable_read_node(node)
+      write(node.name.to_s)
+    end
+
+    def visit_undef_node(node)
+      write("undef ")
+      node.names.each_with_index do |name, i|
+        if i > 0
+          write ", "
+        end
+        name.accept(self)
+      end
+    end
+
+    def visit_parentheses_node(node)
+      write_code_at(node.opening_loc)
+      node.body.accept(self)
+      write_code_at(node.closing_loc)
+    end
+
+    def visit_call_node(node)
+      write(node.message)
+      if node.receiver
+        node.receiver.accept(self)
+      end
+    end
+
+    def visit_statements_node(node)
+      previous = nil
+      node.body.each do |child|
+        if previous&.newline?
+          write "\n"
+        end
+
+        child.accept(self)
+        previous = child
+      end
+    end
+
+    private
+
+    def write(value)
+      @output << value
+    end
+
+    def write_code_at(location)
+      write(code_at(location))
+    end
+
+    def code_at(location)
+      @code[location.start_offset...location.end_offset]
+    end
+
+    def debug_log(object)
+      if Rufo::PrismFormatter::DEBUG
+        p [:debug, object]
+      end
+    end
+  end
+end

spec/lib/rufo/prism_formatter_source_specs/booleans.rb.spec

@@ -0,0 +1,13 @@
+#~# ORIGINAL false
+
+false
+
+#~# EXPECTED
+false
+
+#~# ORIGINAL true
+
+true
+
+#~# EXPECTED
+true

spec/lib/rufo/prism_formatter_source_specs/chars.rb.spec

@@ -0,0 +1,6 @@
+#~# ORIGINAL char
+
+?a
+
+#~# EXPECTED
+?a

spec/lib/rufo/prism_formatter_source_specs/class_variables.rb.spec

@@ -0,0 +1,6 @@
+#~# ORIGINAL
+
+@@foo
+
+#~# EXPECTED
+@@foo

spec/lib/rufo/prism_formatter_source_specs/floats.rb.spec

@@ -0,0 +1,13 @@
+#~# ORIGINAL
+
+12.34
+
+#~# EXPECTED
+12.34
+
+#~# ORIGINAL
+
+12.34e-10
+
+#~# EXPECTED
+12.34e-10

spec/lib/rufo/prism_formatter_source_specs/imaginaries.rb.spec

@@ -0,0 +1,6 @@
+#~# ORIGINAL
+
+3.141592i
+
+#~# EXPECTED
+3.141592i

spec/lib/rufo/prism_formatter_source_specs/integers.rb.spec

@@ -0,0 +1,6 @@
+#~# ORIGINAL 123
+
+123
+
+#~# EXPECTED
+123

spec/lib/rufo/prism_formatter_source_specs/leading_newlines.rb.spec

@@ -0,0 +1,9 @@
+#~# ORIGINAL
+
+
+
+
+a = 1
+
+#~# EXPECTED
+a = 1

spec/lib/rufo/prism_formatter_source_specs/nil.rb.spec

@@ -0,0 +1,6 @@
+#~# ORIGINAL nil
+
+nil
+
+#~# EXPECTED
+nil

spec/lib/rufo/prism_formatter_source_specs/rationals.rb.spec

@@ -0,0 +1,6 @@
+#~# ORIGINAL
+
+3.141592r
+
+#~# EXPECTED
+3.141592r

spec/lib/rufo/prism_formatter_source_specs/spaces_inside_hash_brace.rb.spec

@@ -0,0 +1,7 @@
+#~# ORIGINAL
+
+{ 1 => 2 }
+
+#~# EXPECTED
+{ 1 => 2 }
+

spec/lib/rufo/prism_formatter_source_specs/special_global_variables.rb.spec

@@ -0,0 +1,27 @@
+#~# ORIGINAL
+
+$~
+
+#~# EXPECTED
+$~
+
+#~# ORIGINAL
+
+$1
+
+#~# EXPECTED
+$1
+
+#~# ORIGINAL
+
+$!
+
+#~# EXPECTED
+$!
+
+#~# ORIGINAL
+
+$@
+
+#~# EXPECTED
+$@

spec/lib/rufo/prism_formatter_source_specs/symbol_literals.rb.spec

@@ -0,0 +1,27 @@
+#~# ORIGINAL
+
+:foo
+
+#~# EXPECTED
+:foo
+
+#~# ORIGINAL
+
+:"foo"
+
+#~# EXPECTED
+:"foo"
+
+#~# ORIGINAL
+
+:"foo#{1}"
+
+#~# EXPECTED
+:"foo#{1}"
+
+#~# ORIGINAL
+
+:*
+
+#~# EXPECTED
+:*

spec/lib/rufo/prism_formatter_source_specs/unary_operators.rb.spec

@@ -0,0 +1,34 @@
+#~# ORIGINAL
+
+- x
+
+#~# EXPECTED
+-x
+
+#~# ORIGINAL
+
++ x
+
+#~# EXPECTED
++x
+
+#~# ORIGINAL
+
++x
+
+#~# EXPECTED
++x
+
+#~# ORIGINAL
+
++(x)
+
+#~# EXPECTED
++(x)
+
+#~# ORIGINAL
+
++ (x)
+
+#~# EXPECTED
++(x)