initial commit

LICENSE

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+Copyright (c) 2019 Christine Dodrill <me@christine.website>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.

objpatch.nimble

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+# Package
+
+version       = "0.1.0"
+author        = "Christine Dodrill"
+description   = "Store JSON objects and patches to them, then query the aggregate object"
+license       = "0BSD"
+srcDir        = "src"
+bin           = @["objpatch"]
+
+
+
+# Dependencies
+
+requires "nim >= 0.20.2"

src/objpatch.nim

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+import hashes, json, strformat, tables
+
+proc diff(old, new: JsonNode): JsonNode =
+  ## return the json fields that are different between the two objects
+  result = newJObject()
+
+  var
+    oldFields = old.getFields
+    newFields = new.getFields
+    oldHashes = newOrderedTable[string, Hash]()
+    newHashes = newOrderedTable[string, Hash]()
+
+  for k, v in old.getFields.pairs:
+    oldHashes[k] = v.hash
+
+  for k, v in new.getFields.pairs:
+    newHashes[k] = v.hash
+
+    if not old.contains(k):
+      result.add k, v
+
+  for k, v in oldHashes.pairs:
+    if newHashes.contains(k) and newHashes[k] != v:
+      if oldFields[k].kind == JObject:
+        result.add k, diff(oldFields[k], newFields[k])
+      else:
+        result.add k, newFields[k]
+
+proc combine(old, patch: JsonNode): JsonNode =
+  ## Applies the patch on top of the old data to get the resulting aggregate
+  ## object.
+  result = newJObject()
+  var
+    oldFields = old.getFields
+    newFields = patch.getFields
+
+  for k, v in oldFields.pairs:
+    result.add k, v
+
+  for k, v in newFields.pairs:
+    if v.kind == JObject:
+      result.add k, combine(oldFields[k], newFields[k])
+    else:
+      result.add k, v
+
+when isMainModule:
+  let
+    old = """{"foo": "bar", "shouldnt": "change", "obj": {"is": "fine", "too": false}}""".parseJson
+    new = """{"foo": "baz", "bar": "boz", "new": "data", "with_an_array": ["foo", "bar", "baz"], "obj": {"hi": "mom"}}""".parseJson
+    patch = old.diff new
+    res = old.combine patch
+
+  echo fmt"old: {old.pretty}"
+  echo fmt"new: {new.pretty}"
+  echo fmt"patch: {patch.pretty}"
+  echo fmt"result: {res.pretty}"