19 files changed, 126 insertions, 48 deletions
diff --git a/lib/syntax_suggest/api.rb b/lib/syntax_suggest/api.rb
index 74e53c2563..65660ec5e5 100644
--- a/lib/syntax_suggest/api.rb
+++ b/lib/syntax_suggest/api.rb
@@ -5,9 +5,28 @@ require_relative "version"
 require "tmpdir"
 require "stringio"
 require "pathname"
-require "ripper"
 require "timeout"
 
+# We need Ripper loaded for `Prism.lex_compat` even if we're using Prism
+# for lexing and parsing
+require "ripper"
+
+# Prism is the new parser, replacing Ripper
+#
+# We need to "dual boot" both for now because syntax_suggest
+# supports older rubies that do not ship with syntax suggest.
+#
+# We also need the ability to control loading of this library
+# so we can test that both modes work correctly in CI.
+if (value = ENV["SYNTAX_SUGGEST_DISABLE_PRISM"])
+  warn "Skipping loading prism due to SYNTAX_SUGGEST_DISABLE_PRISM=#{value}"
+else
+  begin
+    require "prism"
+  rescue LoadError
+  end
+end
+
 module SyntaxSuggest
   # Used to indicate a default value that cannot
   # be confused with another input.
@@ -16,6 +35,14 @@ module SyntaxSuggest
   class Error < StandardError; end
   TIMEOUT_DEFAULT = ENV.fetch("SYNTAX_SUGGEST_TIMEOUT", 1).to_i
 
+  # SyntaxSuggest.use_prism_parser? [Private]
+  #
+  # Tells us if the prism parser is available for use
+  # or if we should fallback to `Ripper`
+  def self.use_prism_parser?
+    defined?(Prism)
+  end
+
   # SyntaxSuggest.handle_error [Public]
   #
   # Takes a `SyntaxError` exception, uses the
@@ -129,11 +156,20 @@ module SyntaxSuggest
   # SyntaxSuggest.invalid? [Private]
   #
   # Opposite of `SyntaxSuggest.valid?`
-  def self.invalid?(source)
-    source = source.join if source.is_a?(Array)
-    source = source.to_s
+  if defined?(Prism)
+    def self.invalid?(source)
+      source = source.join if source.is_a?(Array)
+      source = source.to_s
 
-    Ripper.new(source).tap(&:parse).error?
+      Prism.parse(source).failure?
+    end
+  else
+    def self.invalid?(source)
+      source = source.join if source.is_a?(Array)
+      source = source.to_s
+
+      Ripper.new(source).tap(&:parse).error?
+    end
   end
 
   # SyntaxSuggest.valid? [Private]
@@ -191,7 +227,6 @@ require_relative "lex_all"
 require_relative "code_line"
 require_relative "code_block"
 require_relative "block_expand"
-require_relative "ripper_errors"
 require_relative "priority_queue"
 require_relative "unvisited_lines"
 require_relative "around_block_scan"
diff --git a/lib/syntax_suggest/around_block_scan.rb b/lib/syntax_suggest/around_block_scan.rb
index ce00431b3a..dd9af729c5 100644
--- a/lib/syntax_suggest/around_block_scan.rb
+++ b/lib/syntax_suggest/around_block_scan.rb
@@ -118,7 +118,7 @@ module SyntaxSuggest
     end
 
     # Scanning is intentionally conservative because
-    # we have no way of rolling back an agressive block (at this time)
+    # we have no way of rolling back an aggressive block (at this time)
     #
     # If a block was stopped for some trivial reason, (like an empty line)
     # but the next line would have caused it to be balanced then we
@@ -224,7 +224,7 @@ module SyntaxSuggest
       @scanner.lines
     end
 
-    # Managable rspec errors
+    # Manageable rspec errors
     def inspect
       "#<#{self.class}:0x0000123843lol >"
     end
diff --git a/lib/syntax_suggest/block_expand.rb b/lib/syntax_suggest/block_expand.rb
index e9b486c720..2751ae2a64 100644
--- a/lib/syntax_suggest/block_expand.rb
+++ b/lib/syntax_suggest/block_expand.rb
@@ -157,7 +157,7 @@ module SyntaxSuggest
       end
     end
 
-    # Managable rspec errors
+    # Manageable rspec errors
     def inspect
       "#<SyntaxSuggest::CodeBlock:0x0000123843lol >"
     end
diff --git a/lib/syntax_suggest/capture_code_context.rb b/lib/syntax_suggest/capture_code_context.rb
index 6dc7047176..1f232cfae3 100644
--- a/lib/syntax_suggest/capture_code_context.rb
+++ b/lib/syntax_suggest/capture_code_context.rb
@@ -26,7 +26,7 @@ module SyntaxSuggest
   # they can't add extra data that's not present.
   #
   # In the case of known ambiguious cases, this class adds context
-  # back to the ambiguitiy so the programmer has full information.
+  # back to the ambiguity so the programmer has full information.
   #
   # Beyond handling these ambiguities, it also captures surrounding
   # code context information:
diff --git a/lib/syntax_suggest/clean_document.rb b/lib/syntax_suggest/clean_document.rb
index 2c26061bfc..2790ccae86 100644
--- a/lib/syntax_suggest/clean_document.rb
+++ b/lib/syntax_suggest/clean_document.rb
@@ -47,9 +47,9 @@ module SyntaxSuggest
   # ## Heredocs
   #
   # A heredoc is an way of defining a multi-line string. They can cause many
-  # problems. If left as a single line, Ripper would try to parse the contents
+  # problems. If left as a single line, the parser would try to parse the contents
   # as ruby code rather than as a string. Even without this problem, we still
-  # hit an issue with indentation
+  # hit an issue with indentation:
   #
   #    1 foo = <<~HEREDOC
   #    2  "Be yourself; everyone else is already taken.""
@@ -224,7 +224,7 @@ module SyntaxSuggest
     #
     def join_consecutive!
       consecutive_groups = @document.select(&:ignore_newline_not_beg?).map do |code_line|
-        take_while_including(code_line.index..-1) do |line|
+        take_while_including(code_line.index..) do |line|
           line.ignore_newline_not_beg?
         end
       end
@@ -245,7 +245,7 @@ module SyntaxSuggest
     #     expect(lines[1].to_s).to eq("")
     def join_trailing_slash!
       trailing_groups = @document.select(&:trailing_slash?).map do |code_line|
-        take_while_including(code_line.index..-1) { |x| x.trailing_slash? }
+        take_while_including(code_line.index..) { |x| x.trailing_slash? }
       end
       join_groups(trailing_groups)
       self
@@ -267,7 +267,7 @@ module SyntaxSuggest
       groups.each do |lines|
         line = lines.first
 
-        # Handle the case of multiple groups in a a row
+        # Handle the case of multiple groups in a row
         # if one is already replaced, move on
         next if @document[line.index].empty?
 
@@ -279,7 +279,7 @@ module SyntaxSuggest
         )
 
         # Hide the rest of the lines
-        lines[1..-1].each do |line|
+        lines[1..].each do |line|
           # The above lines already have newlines in them, if add more
           # then there will be double newline, use an empty line instead
           @document[line.index] = CodeLine.new(line: "", index: line.index, lex: [])
@@ -293,7 +293,7 @@ module SyntaxSuggest
     # Like `take_while` except when it stops
     # iterating, it also returns the line
     # that caused it to stop
-    def take_while_including(range = 0..-1)
+    def take_while_including(range = 0..)
       take_next_and_stop = false
       @document[range].take_while do |line|
         next if take_next_and_stop
diff --git a/lib/syntax_suggest/code_block.rb b/lib/syntax_suggest/code_block.rb
index 61e7986da4..d842890300 100644
--- a/lib/syntax_suggest/code_block.rb
+++ b/lib/syntax_suggest/code_block.rb
@@ -81,7 +81,7 @@ module SyntaxSuggest
         # lines then the result cannot be invalid
         #
         # That means there's no reason to re-check all
-        # lines with ripper (which is expensive).
+        # lines with the parser (which is expensive).
         # Benchmark in commit message
         @valid = if lines.all? { |l| l.hidden? || l.empty? }
           true
diff --git a/lib/syntax_suggest/code_frontier.rb b/lib/syntax_suggest/code_frontier.rb
index 8e93b32514..0f870d0df0 100644
--- a/lib/syntax_suggest/code_frontier.rb
+++ b/lib/syntax_suggest/code_frontier.rb
@@ -117,7 +117,7 @@ module SyntaxSuggest
 
       if ENV["SYNTAX_SUGGEST_DEBUG"]
         puts "```"
-        puts @queue.peek.to_s
+        puts @queue.peek
         puts "```"
         puts "  @frontier indent:  #{frontier_indent}"
         puts "  @unvisited indent: #{unvisited_indent}"
diff --git a/lib/syntax_suggest/code_line.rb b/lib/syntax_suggest/code_line.rb
index a20f34afa4..58197e95d0 100644
--- a/lib/syntax_suggest/code_line.rb
+++ b/lib/syntax_suggest/code_line.rb
@@ -180,12 +180,19 @@ module SyntaxSuggest
     #     EOM
     #     expect(lines.first.trailing_slash?).to eq(true)
     #
-    def trailing_slash?
-      last = @lex.last
-      return false unless last
-      return false unless last.type == :on_sp
+    if SyntaxSuggest.use_prism_parser?
+      def trailing_slash?
+        last = @lex.last
+        last&.type == :on_tstring_end
+      end
+    else
+      def trailing_slash?
+        last = @lex.last
+        return false unless last
+        return false unless last.type == :on_sp
 
-      last.token == TRAILING_SLASH
+        last.token == TRAILING_SLASH
+      end
     end
 
     # Endless method detection
diff --git a/lib/syntax_suggest/code_search.rb b/lib/syntax_suggest/code_search.rb
index 2a86dfea90..7628dcd131 100644
--- a/lib/syntax_suggest/code_search.rb
+++ b/lib/syntax_suggest/code_search.rb
@@ -43,7 +43,7 @@ module SyntaxSuggest
 
     def initialize(source, record_dir: DEFAULT_VALUE)
       record_dir = if record_dir == DEFAULT_VALUE
-        ENV["SYNTAX_SUGGEST_RECORD_DIR"] || ENV["SYNTAX_SUGGEST_DEBUG"] ? "tmp" : nil
+        (ENV["SYNTAX_SUGGEST_RECORD_DIR"] || ENV["SYNTAX_SUGGEST_DEBUG"]) ? "tmp" : nil
       else
         record_dir
       end
@@ -73,7 +73,7 @@ module SyntaxSuggest
       if ENV["SYNTAX_SUGGEST_DEBUG"]
         puts "\n\n==== #{filename} ===="
         puts "\n```#{block.starts_at}..#{block.ends_at}"
-        puts block.to_s
+        puts block
         puts "```"
         puts "  block indent:      #{block.current_indent}"
       end
diff --git a/lib/syntax_suggest/core_ext.rb b/lib/syntax_suggest/core_ext.rb
index e0fd62b81c..c299627bb7 100644
--- a/lib/syntax_suggest/core_ext.rb
+++ b/lib/syntax_suggest/core_ext.rb
@@ -21,7 +21,7 @@ if SyntaxError.method_defined?(:detailed_message)
       attr_reader :string
     end
 
-    # SyntaxSuggest.record_dir [Private]
+    # SyntaxSuggest.module_for_detailed_message [Private]
     #
     # Used to monkeypatch SyntaxError via Module.prepend
     def self.module_for_detailed_message
diff --git a/lib/syntax_suggest/display_invalid_blocks.rb b/lib/syntax_suggest/display_invalid_blocks.rb
index 32ec0021a3..5e79b3a262 100644
--- a/lib/syntax_suggest/display_invalid_blocks.rb
+++ b/lib/syntax_suggest/display_invalid_blocks.rb
@@ -14,7 +14,7 @@ module SyntaxSuggest
       @filename = filename
       @code_lines = code_lines
 
-      @terminal = terminal == DEFAULT_VALUE ? io.isatty : terminal
+      @terminal = (terminal == DEFAULT_VALUE) ? io.isatty : terminal
     end
 
     def document_ok?
diff --git a/lib/syntax_suggest/explain_syntax.rb b/lib/syntax_suggest/explain_syntax.rb
index 142ed2e269..0d80c4d869 100644
--- a/lib/syntax_suggest/explain_syntax.rb
+++ b/lib/syntax_suggest/explain_syntax.rb
@@ -2,7 +2,21 @@
 
 require_relative "left_right_lex_count"
 
+if !SyntaxSuggest.use_prism_parser?
+  require_relative "ripper_errors"
+end
+
 module SyntaxSuggest
+  class GetParseErrors
+    def self.errors(source)
+      if SyntaxSuggest.use_prism_parser?
+        Prism.parse(source).errors.map(&:message)
+      else
+        RipperErrors.new(source).call.errors
+      end
+    end
+  end
+
   # Explains syntax errors based on their source
   #
   # example:
@@ -15,8 +29,8 @@ module SyntaxSuggest
   #   # => "Unmatched keyword, missing `end' ?"
   #
   # When the error cannot be determined by lexical counting
-  # then ripper is run against the input and the raw ripper
-  # errors returned.
+  # then the parser is run against the input and the raw
+  # errors are returned.
   #
   # Example:
   #
@@ -91,10 +105,10 @@ module SyntaxSuggest
     # Returns an array of syntax error messages
     #
     # If no missing pairs are found it falls back
-    # on the original ripper error messages
+    # on the original error messages
     def errors
       if missing.empty?
-        return RipperErrors.new(@code_lines.map(&:original).join).call.errors
+        return GetParseErrors.errors(@code_lines.map(&:original).join).uniq
       end
 
       missing.map { |miss| why(miss) }
diff --git a/lib/syntax_suggest/lex_all.rb b/lib/syntax_suggest/lex_all.rb
index 132cba9f5d..c16fbb52d3 100644
--- a/lib/syntax_suggest/lex_all.rb
+++ b/lib/syntax_suggest/lex_all.rb
@@ -3,34 +3,53 @@
 module SyntaxSuggest
   # Ripper.lex is not guaranteed to lex the entire source document
   #
-  # lex = LexAll.new(source: source)
-  # lex.each do |value|
-  #   puts value.line
-  # end
+  # This class guarantees the whole document is lex-ed by iteratively
+  # lexing the document where ripper stopped.
+  #
+  # Prism likely doesn't have the same problem. Once ripper support is removed
+  # we can likely reduce the complexity here if not remove the whole concept.
+  #
+  # Example usage:
+  #
+  #   lex = LexAll.new(source: source)
+  #   lex.each do |value|
+  #     puts value.line
+  #   end
   class LexAll
     include Enumerable
 
     def initialize(source:, source_lines: nil)
-      @lex = Ripper::Lexer.new(source, "-", 1).parse.sort_by(&:pos)
-      lineno = @lex.last.pos.first + 1
+      @lex = self.class.lex(source, 1)
+      lineno = @lex.last[0][0] + 1
       source_lines ||= source.lines
       last_lineno = source_lines.length
 
       until lineno >= last_lineno
-        lines = source_lines[lineno..-1]
+        lines = source_lines[lineno..]
 
         @lex.concat(
-          Ripper::Lexer.new(lines.join, "-", lineno + 1).parse.sort_by(&:pos)
+          self.class.lex(lines.join, lineno + 1)
         )
-        lineno = @lex.last.pos.first + 1
+
+        lineno = @lex.last[0].first + 1
       end
 
       last_lex = nil
       @lex.map! { |elem|
-        last_lex = LexValue.new(elem.pos.first, elem.event, elem.tok, elem.state, last_lex)
+        last_lex = LexValue.new(elem[0].first, elem[1], elem[2], elem[3], last_lex)
       }
     end
 
+    if SyntaxSuggest.use_prism_parser?
+      def self.lex(source, line_number)
+        Prism.lex_compat(source, line: line_number).value.sort_by { |values| values[0] }
+      end
+    else
+      def self.lex(source, line_number)
+        Ripper::Lexer.new(source, "-", line_number).parse.sort_by(&:pos)
+      end
+    end
+
     def to_a
       @lex
     end
diff --git a/lib/syntax_suggest/parse_blocks_from_indent_line.rb b/lib/syntax_suggest/parse_blocks_from_indent_line.rb
index 241ed6acb4..39dfca55d2 100644
--- a/lib/syntax_suggest/parse_blocks_from_indent_line.rb
+++ b/lib/syntax_suggest/parse_blocks_from_indent_line.rb
@@ -8,7 +8,7 @@ module SyntaxSuggest
   # grabbing one that contains only an "end". In this example:
   #
   #   def dog
-  #     begonn # mispelled `begin`
+  #     begonn # misspelled `begin`
   #     puts "bark"
   #     end
   #   end
diff --git a/lib/syntax_suggest/pathname_from_message.rb b/lib/syntax_suggest/pathname_from_message.rb
index b6fe1617be..ab90227427 100644
--- a/lib/syntax_suggest/pathname_from_message.rb
+++ b/lib/syntax_suggest/pathname_from_message.rb
@@ -13,7 +13,7 @@ module SyntaxSuggest
   #    # => "/tmp/scratch.rb"
   #
   class PathnameFromMessage
-    EVAL_RE = /^\(eval\):\d+/
+    EVAL_RE = /^\(eval.*\):\d+/
     STREAMING_RE = /^-:\d+/
     attr_reader :name
 
diff --git a/lib/syntax_suggest/ripper_errors.rb b/lib/syntax_suggest/ripper_errors.rb
index 48eb206e48..4e2bc90948 100644
--- a/lib/syntax_suggest/ripper_errors.rb
+++ b/lib/syntax_suggest/ripper_errors.rb
@@ -1,7 +1,10 @@
 # frozen_string_literal: true
 
 module SyntaxSuggest
-  # Capture parse errors from ripper
+  # Capture parse errors from Ripper
+  #
+  # Prism returns the errors with their messages, but Ripper
+  # does not. To get them we must make a custom subclass.
   #
   # Example:
   #
diff --git a/lib/syntax_suggest/scan_history.rb b/lib/syntax_suggest/scan_history.rb
index d15597c440..dc36e6ba2e 100644
--- a/lib/syntax_suggest/scan_history.rb
+++ b/lib/syntax_suggest/scan_history.rb
@@ -118,7 +118,7 @@ module SyntaxSuggest
     # Returns an array of all the CodeLines that exist after
     # the currently scanned block
     private def after_lines
-      @code_lines[@after_index.next..-1] || []
+      @code_lines[@after_index.next..] || []
     end
 
     private def current
diff --git a/lib/syntax_suggest/syntax_suggest.gemspec b/lib/syntax_suggest/syntax_suggest.gemspec
index 0e611c13d0..756a85bf63 100644
--- a/lib/syntax_suggest/syntax_suggest.gemspec
+++ b/lib/syntax_suggest/syntax_suggest.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |spec|
   spec.description = 'When you get an "unexpected end" in your syntax this gem helps you find it'
   spec.homepage = "https://github.com/ruby/syntax_suggest.git"
   spec.license = "MIT"
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.5.0")
+  spec.required_ruby_version = Gem::Requirement.new(">= 3.0.0")
 
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = "https://github.com/ruby/syntax_suggest.git"
diff --git a/lib/syntax_suggest/version.rb b/lib/syntax_suggest/version.rb
index ac8c2f62e5..4320adb218 100644
--- a/lib/syntax_suggest/version.rb
+++ b/lib/syntax_suggest/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module SyntaxSuggest
-  VERSION = "1.1.0"
+  VERSION = "2.0.0"
 end