feat: support $ref without full URI (#31)

Author: spacewander

lib/jsonschema/store.lua

@@ -36,7 +36,7 @@ local function urlunescape(fragment)
   return fragment:gsub('%%(%x%x)', percent_unescape):gsub('~[01]', tilde_unescape)
 end
 
--- attempt to translate a URI fragemnt part to a valid table index:
+-- attempt to translate a URI fragment part to a valid table index:
 -- * if the part can be converted to number, that number+1 is returned to
 --   compensate with Lua 1-based indices
 -- * otherwise, the part is returned URL-escaped
@@ -192,6 +192,16 @@ function store_mt:insert(schema)
   local map = {}
 
   local function walk(s, p)
+    -- handle '$id' keyword
+    if s['$id'] then
+        local u = url.parse(s['$id'])
+        if u.schema ~= nil or u.fragment == nil then
+            error("Only location independent id is supported. Unsupported $id: " .. s['$id'])
+        end
+
+        map[u.fragment] = self:ref(s).schema
+    end
+
     local id = s.id
     if id and s ~= schema and is_schema(p) then
       -- there is an id, but it is not over: we have 2 different cases (!)

t/draft7.lua

@@ -35,6 +35,11 @@ local blacklist = {
   ['contains keyword validation'] = {
     ['not array is valid'] = true
   },
+  -- not support: an external resolver is required
+  ['remote ref, containing refs itself'] = true,
+  ['Recursive references between schemas'] = true,
+  ['Location-independent identifier with absolute URI'] = true,
+  ['Location-independent identifier with base URI change in subschema'] = true,
 }
 
 local supported = {
@@ -88,9 +93,10 @@ local supported = {
   'spec/JSON-Schema-Test-Suite/tests/draft7/const.json',
   'spec/JSON-Schema-Test-Suite/tests/draft7/contains.json',
 
+  -- ref
+  'spec/JSON-Schema-Test-Suite/tests/draft7/ref.json',
   -- not support: an external resolver is required
   -- 'spec/JSON-Schema-Test-Suite/tests/draft7/refRemote.json',
-  -- 'spec/JSON-Schema-Test-Suite/tests/draft7/ref.json',
   -- 'spec/JSON-Schema-Test-Suite/tests/draft7/definitions.json',
 
   -- not support: todo
@@ -114,9 +120,12 @@ for _, descriptor in ipairs(supported) do
   for _, suite in decode_descriptor(descriptor) do
     local skipped = blacklist[suite.description] or {}
     if skipped ~= true then
-      local validator = jsonschema.generate_validator(suite.schema, {
+      local ok, validator = pcall(jsonschema.generate_validator, suite.schema, {
         name = suite.description,
       })
+      if not ok then
+        error("failed to generate validator for case " .. suite.description .. ", err: " .. validator)
+      end
       for _, case in ipairs(suite.tests) do
         if skipped[case.description] then
           print("skip suite case: [" .. suite.description .. "] -> [" .. case.description .. "]")