From d8017615c75ec62be48d09fa53bbb58e93656c9c Mon Sep 17 00:00:00 2001
From: Kim Alvefur <zash@zash.se>
Date: Wed, 29 Dec 2021 16:52:09 +0100
Subject: util.jsonpointer: Resolve JSON Pointers per RFC 6901

---
 teal-src/util/jsonpointer.tl | 46 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 teal-src/util/jsonpointer.tl

(limited to 'teal-src/util/jsonpointer.tl')

diff --git a/teal-src/util/jsonpointer.tl b/teal-src/util/jsonpointer.tl
new file mode 100644
index 00000000..7b9db760
--- /dev/null
+++ b/teal-src/util/jsonpointer.tl
@@ -0,0 +1,46 @@
+
+local enum ptr_error
+	"invalid-table"
+	"invalid-path"
+end
+
+local function unescape_token(escaped_token : string) : string
+	local unescaped = escaped_token:gsub("~1", "/"):gsub("~0", "~")
+	return unescaped
+end
+
+local function resolve_json_pointer(ref : table, path : string) : any, ptr_error
+	local ptr_len = #path+1
+	for part, pos in path:gmatch("/([^/]*)()") do
+		local token = unescape_token(part)
+		if not ref is table then
+			return nil
+		end
+		local idx = next(ref)
+		local new_ref : any
+
+		if idx is string then
+			new_ref = ref[token]
+		elseif idx is 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 as integer == ptr_len then
+			return new_ref
+		elseif new_ref is table then
+			ref = new_ref
+		elseif not ref is table then
+			return nil, "invalid-path"
+		end
+
+	end
+	return ref
+end
+
+return {
+	resolve = resolve_json_pointer,
+}
-- 
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