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-rw-r--r--util/jsonpointer.lua40
1 files changed, 40 insertions, 0 deletions
diff --git a/util/jsonpointer.lua b/util/jsonpointer.lua
new file mode 100644
index 00000000..7c657266
--- /dev/null
+++ b/util/jsonpointer.lua
@@ -0,0 +1,40 @@
+local function unescape_token(escaped_token)
+ local unescaped = escaped_token:gsub("~1", "/"):gsub("~0", "~")
+ return unescaped
+end
+
+local function resolve_json_pointer(ref, path)
+ local ptr_len = #path + 1
+ for part, pos in path:gmatch("/([^/]*)()") do
+ local token = unescape_token(part)
+ if not (type(ref) == "table") then
+ return nil
+ end
+ local idx = next(ref)
+ local new_ref
+
+ if type(idx) == "string" then
+ new_ref = ref[token]
+ elseif math.type(idx) == "integer" then
+ local i = tonumber(token)
+ if token == "-" then
+ i = #ref + 1
+ end
+ new_ref = ref[i]
+ else
+ return nil, "invalid-table"
+ end
+
+ if pos == ptr_len then
+ return new_ref
+ elseif type(new_ref) == "table" then
+ ref = new_ref
+ elseif not (type(ref) == "table") then
+ return nil, "invalid-path"
+ end
+
+ end
+ return ref
+end
+
+return { resolve = resolve_json_pointer }