Lazy load meta schemas

This defers meta schema initialization until they're actually used.
People will probably only use one or two meta schemas so this should
save some load time.

Author: davishmcclurg

README.md

@@ -117,13 +117,13 @@ JSONSchemer.schema(
 
   # meta schema to use for vocabularies (keyword behavior) and schema validation
   # String/JSONSchemer::Schema
-  # 'https://json-schema.org/draft/2020-12/schema': JSONSchemer::DRAFT202012
-  # 'https://json-schema.org/draft/2019-09/schema': JSONSchemer::DRAFT201909
-  # 'http://json-schema.org/draft-07/schema#': JSONSchemer::DRAFT7
-  # 'http://json-schema.org/draft-06/schema#': JSONSchemer::DRAFT6
-  # 'http://json-schema.org/draft-04/schema#': JSONSchemer::DRAFT4
-  # 'http://json-schema.org/schema#': JSONSchemer::DRAFT4
-  # default: JSONSchemer::DRAFT202012
+  # 'https://json-schema.org/draft/2020-12/schema': JSONSchemer.draft202012
+  # 'https://json-schema.org/draft/2019-09/schema': JSONSchemer.draft201909
+  # 'http://json-schema.org/draft-07/schema#': JSONSchemer.draft7
+  # 'http://json-schema.org/draft-06/schema#': JSONSchemer.draft6
+  # 'http://json-schema.org/draft-04/schema#': JSONSchemer.draft4
+  # 'http://json-schema.org/schema#': JSONSchemer.draft4
+  # default: JSONSchemer.draft202012
   meta_schema: 'https://json-schema.org/draft/2020-12/schema',
 
   # validate `format` (https://json-schema.org/draft/2020-12/json-schema-validation.html#section-7)

lib/json_schemer.rb

@@ -87,47 +87,6 @@ class InvalidEcmaRegexp < StandardError; end
   }
   VOCABULARY_ORDER = VOCABULARIES.transform_values.with_index { |_vocabulary, index| index }
 
-  DRAFT202012 = Schema.new(
-    Draft202012::SCHEMA,
-    :base_uri => Draft202012::BASE_URI,
-    :ref_resolver => Draft202012::Meta::SCHEMAS.to_proc,
-    :regexp_resolver => 'ecma'
-  )
-
-  DRAFT201909 = Schema.new(
-    Draft201909::SCHEMA,
-    :base_uri => Draft201909::BASE_URI,
-    :ref_resolver => Draft201909::Meta::SCHEMAS.to_proc,
-    :regexp_resolver => 'ecma'
-  )
-
-  DRAFT7 = Schema.new(
-    Draft7::SCHEMA,
-    :vocabulary => { 'json-schemer://draft7' => true },
-    :base_uri => Draft7::BASE_URI,
-    :regexp_resolver => 'ecma'
-  )
-
-  DRAFT6 = Schema.new(
-    Draft6::SCHEMA,
-    :vocabulary => { 'json-schemer://draft6' => true },
-    :base_uri => Draft6::BASE_URI,
-    :regexp_resolver => 'ecma'
-  )
-
-  DRAFT4 = Schema.new(
-    Draft4::SCHEMA,
-    :vocabulary => { 'json-schemer://draft4' => true },
-    :base_uri => Draft4::BASE_URI,
-    :regexp_resolver => 'ecma'
-  )
-
-  META_SCHEMAS_BY_BASE_URI_STR = [DRAFT202012, DRAFT201909, DRAFT7, DRAFT6, DRAFT4].each_with_object({}) do |meta_schema, out|
-    out[meta_schema.base_uri.to_s] = meta_schema
-  end
-  META_SCHEMAS_BY_BASE_URI_STR['http://json-schema.org/schema#'] = DRAFT4 # version-less $schema deprecated after Draft 4
-  META_SCHEMAS_BY_BASE_URI_STR.freeze
-
   WINDOWS_URI_PATH_REGEX = /\A\/[a-z]:/i
 
   FILE_URI_REF_RESOLVER = proc do |uri|
@@ -139,7 +98,7 @@ class InvalidEcmaRegexp < StandardError; end
   end
 
   class << self
-    def schema(schema, meta_schema: DRAFT202012, **options)
+    def schema(schema, meta_schema: draft202012, **options)
       case schema
       when String
         schema = JSON.parse(schema)
@@ -167,5 +126,65 @@ def valid_schema?(schema, **options)
     def validate_schema(schema, **options)
       schema(schema, **options).validate_schema
     end
+
+    def draft202012
+      @draft202012 ||= Schema.new(
+        Draft202012::SCHEMA,
+        :base_uri => Draft202012::BASE_URI,
+        :ref_resolver => Draft202012::Meta::SCHEMAS.to_proc,
+        :regexp_resolver => 'ecma'
+      )
+    end
+
+    def draft201909
+      @draft201909 ||= Schema.new(
+        Draft201909::SCHEMA,
+        :base_uri => Draft201909::BASE_URI,
+        :ref_resolver => Draft201909::Meta::SCHEMAS.to_proc,
+        :regexp_resolver => 'ecma'
+      )
+    end
+
+    def draft7
+      @draft7 ||= Schema.new(
+        Draft7::SCHEMA,
+        :vocabulary => { 'json-schemer://draft7' => true },
+        :base_uri => Draft7::BASE_URI,
+        :regexp_resolver => 'ecma'
+      )
+    end
+
+    def draft6
+      @draft6 ||= Schema.new(
+        Draft6::SCHEMA,
+        :vocabulary => { 'json-schemer://draft6' => true },
+        :base_uri => Draft6::BASE_URI,
+        :regexp_resolver => 'ecma'
+      )
+    end
+
+    def draft4
+      @draft4 ||= Schema.new(
+        Draft4::SCHEMA,
+        :vocabulary => { 'json-schemer://draft4' => true },
+        :base_uri => Draft4::BASE_URI,
+        :regexp_resolver => 'ecma'
+      )
+    end
+  end
+
+  META_SCHEMA_CALLABLES_BY_BASE_URI_STR = {
+    Draft202012::BASE_URI.to_s => method(:draft202012),
+    Draft201909::BASE_URI.to_s => method(:draft201909),
+    Draft7::BASE_URI.to_s => method(:draft7),
+    Draft6::BASE_URI.to_s => method(:draft6),
+    Draft4::BASE_URI.to_s => method(:draft4),
+    # version-less $schema deprecated after Draft 4
+    'http://json-schema.org/schema#' => method(:draft4)
+  }.freeze
+
+  META_SCHEMAS_BY_BASE_URI_STR = Hash.new do |hash, base_uri_str|
+    next unless META_SCHEMA_CALLABLES_BY_BASE_URI_STR.key?(base_uri_str)
+    hash[base_uri_str] = META_SCHEMA_CALLABLES_BY_BASE_URI_STR.fetch(base_uri_str).call
   end
 end

lib/json_schemer/draft202012/vocab/core.rb

@@ -8,9 +8,7 @@ def parse
             schema.meta_schema = if value == schema.base_uri.to_s
               schema
             else
-              JSONSchemer::META_SCHEMAS_BY_BASE_URI_STR.fetch(value) do
-                root.resolve_ref(URI(value))
-              end
+              META_SCHEMAS_BY_BASE_URI_STR[value] || root.resolve_ref(URI(value))
             end
             value
           end

test/json_schema_test_suite_test.rb

@@ -16,13 +16,13 @@ class JSONSchemaTestSuiteTest < Minitest::Test
   end
 
   OUTPUT_DRAFTS = {
-    'draft2020-12' => JSONSchemer::DRAFT202012,
-    'draft2019-09' => JSONSchemer::DRAFT201909
+    'draft2020-12' => JSONSchemer.draft202012,
+    'draft2019-09' => JSONSchemer.draft201909
   }
   DRAFTS = OUTPUT_DRAFTS.merge(
-    'draft7' => JSONSchemer::DRAFT7,
-    'draft6' => JSONSchemer::DRAFT6,
-    'draft4' => JSONSchemer::DRAFT4
+    'draft7' => JSONSchemer.draft7,
+    'draft6' => JSONSchemer.draft6,
+    'draft4' => JSONSchemer.draft4
   )
 
   OUTPUT_SCHEMAS = OUTPUT_DRAFTS.each_with_object({}) do |(draft, _meta_schema), out|
@@ -151,7 +151,7 @@ def test_json_schema_test_suite_output
   end
 
   def test_meta_schemas
-    JSONSchemer::META_SCHEMAS_BY_BASE_URI_STR.each do |_base_uri_str, schemer|
+    JSONSchemer::META_SCHEMA_CALLABLES_BY_BASE_URI_STR.transform_values(&:call).each_value do |schemer|
       assert(schemer.valid_schema?)
       assert(JSONSchemer.valid_schema?(schemer.value))
     end

test/json_schemer_test.rb

@@ -266,11 +266,11 @@ def test_it_raises_for_unsupported_meta_schema
   end
 
   def test_string_meta_schema
-    assert_equal(JSONSchemer::DRAFT6, JSONSchemer.schema({}, :meta_schema => JSONSchemer::Draft6::BASE_URI.to_s).meta_schema)
+    assert_equal(JSONSchemer.draft6, JSONSchemer.schema({}, :meta_schema => JSONSchemer::Draft6::BASE_URI.to_s).meta_schema)
   end
 
   def test_default_meta_schema
-    assert_equal(JSONSchemer::DRAFT202012, JSONSchemer::Schema.new({}).meta_schema)
+    assert_equal(JSONSchemer.draft202012, JSONSchemer::Schema.new({}).meta_schema)
   end
 
   def test_draft4_default_id
@@ -306,8 +306,8 @@ def test_it_allows_validating_schemas
       'details' => { 'missing_keys' => ['maximum'] }
     }
 
-    draft7_meta_schema = JSONSchemer::DRAFT7
-    draft4_meta_schema = JSONSchemer::DRAFT4
+    draft7_meta_schema = JSONSchemer.draft7
+    draft4_meta_schema = JSONSchemer.draft4
 
     assert(JSONSchemer.valid_schema?(valid_draft7_schema, :meta_schema => draft7_meta_schema))
     refute(JSONSchemer.valid_schema?(invalid_draft7_schema, :meta_schema => draft7_meta_schema))

test/performance/benchmark_json_schema_test_suite.rb

@@ -19,7 +19,7 @@
   gem 'json_schemer', :path => '.'
 end
 
-$meta_schema = JSONSchemer::DRAFT4
+$meta_schema = JSONSchemer.draft4
 $ref_uris = Dir["JSON-Schema-Test-Suite/remotes/**/*.json"].each_with_object({}) do |file, out|
   uri = URI("http://localhost:1234#{file.delete_prefix('JSON-Schema-Test-Suite/remotes')}")
   out[uri] = JSON.parse(File.read(file))

test/performance/profile.rb

@@ -8,13 +8,13 @@
 end
 
 OUTPUT_DRAFTS = {
-  'draft2020-12' => JSONSchemer::DRAFT202012,
-  'draft2019-09' => JSONSchemer::DRAFT201909
+  'draft2020-12' => JSONSchemer.draft202012,
+  'draft2019-09' => JSONSchemer.draft201909
 }
 DRAFTS = OUTPUT_DRAFTS.merge(
-  'draft7' => JSONSchemer::DRAFT7,
-  'draft6' => JSONSchemer::DRAFT6,
-  'draft4' => JSONSchemer::DRAFT4
+  'draft7' => JSONSchemer.draft7,
+  'draft6' => JSONSchemer.draft6,
+  'draft4' => JSONSchemer.draft4
 )
 
 OUTPUT_SCHEMAS = OUTPUT_DRAFTS.each_with_object({}) do |(draft, _meta_schema), out|