built-ins: add object.subset() builtin

This implements the new object.subset() builtin. Based on my benchmarking, this offers a 2.77x speedup compared to implementing the same thing in pure Rego, and is also easier to read. Fixes #4358 Signed-off-by: Charles Daniels <charles@styra.com>
open-policy-agent · Jun 9, 2022 · f2fd8f5 · f2fd8f5
1 parent f137da2
commit f2fd8f5
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Showing 6 changed files with 825 additions and 9 deletions.
diff --git a/ast/builtins.go b/ast/builtins.go
@@ -161,6 +161,7 @@ var DefaultBuiltins = [...]*Builtin{
 	ObjectRemove,
 	ObjectFilter,
 	ObjectGet,
+	ObjectSubset,
 
 	// JSON Object Manipulation
 	JSONFilter,
@@ -1425,18 +1426,36 @@ var JSONPatch = &Builtin{
 	Categories: objectCat,
 }
 
-var ObjectGet = &Builtin{
-	Name: "object.get",
-	Description: "Returns value of an object's key if present, otherwise a default. " +
-		"If the supplied `key` is an `array`, then `object.get` will search through a nested object or array using each key in turn. " +
-		"For example: `object.get({\"a\": [{ \"b\": true }]}, [\"a\", 0, \"b\"], false)` results in `true`.",
+var ObjectSubset = &Builtin{
+	Name: "object.subset",
+	Description: "Determines if an object `sub` is a subset of another object `super`." +
+		"Object `sub` is a subset of object `super` if and only if every key in `sub` is also in `super`, " +
+		"**and** for all keys which `sub` and `super` share, they have the same value. " +
+		"This function works with objects, sets, and arrays. " +
+		"If both arguments are objects, then the operation is recursive, e.g. " +
+		"`{\"c\": {\"x\": {10, 15, 20}}` is a subset of `{\"a\": \"b\", \"c\": {\"x\": {10, 15, 20, 25}, \"y\": \"z\"}`. " +
+		"If both arguments are sets, then this function checks if every element of `sub` is a member of `super`, " +
+		"but does not attempt to recurse. If both arguments are arrays, " +
+		"then this function checks if `sub` appears contiguously in order within `super`, " +
+		"and also does not attempt to recurse.",
 	Decl: types.NewFunction(
 		types.Args(
-			types.Named("object", types.NewObject(nil, types.NewDynamicProperty(types.A, types.A))).Description("object to get `key` from"),
-			types.Named("key", types.A).Description("key to lookup in `object`"),
-			types.Named("default", types.A).Description("default to use when lookup fails"),
+			types.Named("super", types.NewAny(types.NewObject(
+				nil,
+				types.NewDynamicProperty(types.A, types.A),
+			),
+				types.NewSet(types.A),
+				types.NewArray(nil, types.A),
+			)).Description("object to test if sub is a subset of"),
+			types.Named("sub", types.NewAny(types.NewObject(
+				nil,
+				types.NewDynamicProperty(types.A, types.A),
+			),
+				types.NewSet(types.A),
+				types.NewArray(nil, types.A),
+			)).Description("object to test if super is a superset of"),
 		),
-		types.Named("value", types.A).Description("`object[key]` if present, otherwise `default`"),
+		types.Named("result", types.A).Description("`true` if `sub` is a subset of `super`"),
 	),
 }
 
@@ -1513,6 +1532,21 @@ var ObjectFilter = &Builtin{
 	),
 }
 
+var ObjectGet = &Builtin{
+	Name: "object.get",
+	Description: "Returns value of an object's key if present, otherwise a default. " +
+		"If the supplied `key` is an `array`, then `object.get` will search through a nested object or array using each key in turn. " +
+		"For example: `object.get({\"a\": [{ \"b\": true }]}, [\"a\", 0, \"b\"], false)` results in `true`.",
+	Decl: types.NewFunction(
+		types.Args(
+			types.Named("object", types.NewObject(nil, types.NewDynamicProperty(types.A, types.A))).Description("object to get `key` from"),
+			types.Named("key", types.A).Description("key to lookup in `object`"),
+			types.Named("default", types.A).Description("default to use when lookup fails"),
+		),
+		types.Named("value", types.A).Description("`object[key]` if present, otherwise `default`"),
+	),
+}
+
 /*
  *  Encoding
  */

diff --git a/builtin_metadata.json b/builtin_metadata.json
@@ -118,6 +118,7 @@
       "object.filter",
       "object.get",
       "object.remove",
+      "object.subset",
       "object.union",
       "object.union_n"
     ],
@@ -8394,6 +8395,31 @@
     },
     "wasm": true
   },
+  "object.subset": {
+    "args": [
+      {
+        "description": "object to test if sub is a subset of",
+        "name": "super",
+        "type": "any\u003carray[any], object[any: any], set[any]\u003e"
+      },
+      {
+        "description": "object to test if super is a superset of",
+        "name": "sub",
+        "type": "any\u003carray[any], object[any: any], set[any]\u003e"
+      }
+    ],
+    "available": [
+      "edge"
+    ],
+    "description": "Determines if an object `sub` is a subset of another object `super`.Object `sub` is a subset of object `super` if and only if every key in `sub` is also in `super`, **and** for all keys which `sub` and `super` share, they have the same value. This function works with objects, sets, and arrays. If both arguments are objects, then the operation is recursive, e.g. `{\"c\": {\"x\": {10, 15, 20}}` is a subset of `{\"a\": \"b\", \"c\": {\"x\": {10, 15, 20, 25}, \"y\": \"z\"}`. If both arguments are sets, then this function checks if every element of `sub` is a member of `super`, but does not attempt to recurse. If both arguments are arrays, then this function checks if `sub` appears contiguously in order within `super`, and also does not attempt to recurse.",
+    "introduced": "edge",
+    "result": {
+      "description": "`true` if `sub` is a subset of `super`",
+      "name": "result",
+      "type": "any"
+    },
+    "wasm": false
+  },
   "object.union": {
     "args": [
       {

diff --git a/capabilities.json b/capabilities.json
@@ -2671,6 +2671,73 @@
         "type": "function"
       }
     },
+    {
+      "name": "object.subset",
+      "decl": {
+        "args": [
+          {
+            "of": [
+              {
+                "dynamic": {
+                  "type": "any"
+                },
+                "type": "array"
+              },
+              {
+                "dynamic": {
+                  "key": {
+                    "type": "any"
+                  },
+                  "value": {
+                    "type": "any"
+                  }
+                },
+                "type": "object"
+              },
+              {
+                "of": {
+                  "type": "any"
+                },
+                "type": "set"
+              }
+            ],
+            "type": "any"
+          },
+          {
+            "of": [
+              {
+                "dynamic": {
+                  "type": "any"
+                },
+                "type": "array"
+              },
+              {
+                "dynamic": {
+                  "key": {
+                    "type": "any"
+                  },
+                  "value": {
+                    "type": "any"
+                  }
+                },
+                "type": "object"
+              },
+              {
+                "of": {
+                  "type": "any"
+                },
+                "type": "set"
+              }
+            ],
+            "type": "any"
+          }
+        ],
+        "result": {
+          "type": "any"
+        },
+        "type": "function"
+      }
+    },
     {
       "name": "object.union",
       "decl": {