[ruby/prism] Prism.parse_success?(source)

A lot of tools use Ripper/RubyVM::AbstractSyntaxTree to determine
if a source is valid. These tools both create an AST instead of
providing an API that will return a boolean only.

This new API only creates the C structs, but doesn't bother
reifying them into Ruby/the serialization API. Instead it only
returns true/false, which is significantly more efficient.

https://github.com/ruby/prism/commit/7014740118

2 files changed, 30 insertions, 1 deletions

diff --git a/lib/prism.rb b/lib/prism.rb
index 909b71d66d..b9e615df6c 100644
--- a/lib/prism.rb
+++ b/lib/prism.rb
@@ -64,6 +64,22 @@ module Prism
   def self.load(source, serialized)
     Serialize.load(source, serialized)
   end
+
+  # :call-seq:
+  #   Prism::parse_failure?(source, **options) -> bool
+  #
+  # Returns true if the source is invalid Ruby code.
+  def self.parse_failure?(source, **options)
+    !parse_success?(source, **options)
+  end
+
+  # :call-seq:
+  #   Prism::parse_file_failure?(filepath, **options) -> bool
+  #
+  # Returns true if the file at filepath is invalid Ruby code.
+  def self.parse_file_failure?(filepath, **options)
+    !parse_file_success?(filepath, **options)
+  end
 end
 
 require_relative "prism/node"
diff --git a/lib/prism/ffi.rb b/lib/prism/ffi.rb
index 36f1c398de..8324f722a7 100644
--- a/lib/prism/ffi.rb
+++ b/lib/prism/ffi.rb
@@ -72,7 +72,8 @@ module Prism
       "pm_serialize_parse",
       "pm_serialize_parse_comments",
       "pm_serialize_lex",
-      "pm_serialize_parse_lex"
+      "pm_serialize_parse_lex",
+      "pm_parse_success_p"
     )
 
     load_exported_functions_from(
@@ -268,6 +269,18 @@ module Prism
       end
     end
 
+    # Mirror the Prism.parse_success? API by using the serialization API.
+    def parse_success?(code, **options)
+      LibRubyParser.pm_parse_success_p(code, code.bytesize, dump_options(options))
+    end
+
+    # Mirror the Prism.parse_file_success? API by using the serialization API.
+    def parse_file_success?(filepath, **options)
+      LibRubyParser::PrismString.with(filepath) do |string|
+        parse_success?(string.read, **options, filepath: filepath)
+      end
+    end
+
     private
 
     # Convert the given options into a serialized options string.