Merge pull request #1 from jmespath-community/feature/function-let

JEP-11 Lexical Scoping - Function `let()`

Author: springcomp

tests/function_let.json

@@ -0,0 +1,170 @@
+[
+  {
+    "given": {
+      "search_for": "foo",
+      "people": [
+        {
+          "name": "a"
+        },
+        {
+          "name": "b"
+        },
+        {
+          "name": "c"
+        },
+        {
+          "name": "foo"
+        },
+        {
+          "name": "bar"
+        },
+        {
+          "name": "baz"
+        },
+        {
+          "name": "qux"
+        },
+        {
+          "name": "x"
+        },
+        {
+          "name": "y"
+        },
+        {
+          "name": "z"
+        }
+      ]
+    },
+    "cases": [
+      {
+        "description": "Let function with filters",
+        "expression": "let({search_for: search_for}, &people[?name==search_for].name | [0])",
+        "result": "foo"
+      }
+    ]
+  },
+  {
+    "given": {
+      "a": {
+        "mylist": [
+          {
+            "l1": "1",
+            "result": "foo"
+          },
+          {
+            "l2": "2",
+            "result": "bar"
+          },
+          {
+            "l1": "8",
+            "l2": "9"
+          },
+          {
+            "l1": "8",
+            "l2": "9"
+          }
+        ],
+        "level2": "2"
+      },
+      "level1": "1",
+      "nested": {
+        "a": {
+          "b": {
+            "c": {
+              "fourth": "fourth"
+            },
+            "third": "third"
+          },
+          "second": "second"
+        },
+        "first": "first"
+      },
+      "precedence": {
+        "a": {
+          "b": {
+            "c": {
+              "variable": "fourth"
+            },
+            "variable": "third",
+            "other": "y"
+          },
+          "variable": "second",
+          "other": "x"
+        },
+        "variable": "first",
+        "other": "w"
+      }
+    },
+    "cases": [
+      {
+        "description": "Basic let from scope",
+        "expression": "let({level1: level1}, &a.[level2, level1])",
+        "result": [
+          "2",
+          "1"
+        ]
+      },
+      {
+        "description": "Current object has precedence",
+        "expression": "let({level1: `\"other\"`}, &level1)",
+        "result": "1"
+      },
+      {
+        "description": "No scope specified using literal hash",
+        "expression": "let(`{}`, &a.level2)",
+        "result": "2"
+      },
+      {
+        "description": "Arbitrary variable added",
+        "expression": "let({foo: `\"anything\"`}, &[level1, foo])",
+        "result": [
+          "1",
+          "anything"
+        ]
+      },
+      {
+        "description": "Basic let from current object",
+        "expression": "let({other: level1}, &level1)",
+        "result": "1"
+      },
+      {
+        "description": "Nested let function with filters",
+        "expression": "let({level1: level1}, &a.[mylist[?l1==level1].result, let({level2: level2}, &mylist[?l2==level2].result)])[]",
+        "result": [
+          "foo",
+          "bar"
+        ]
+      },
+      {
+        "description": "Nested let function with filters with literal scope binding",
+        "expression": "let(`{\"level1\": \"1\"}`, &a.[mylist[?l1==level1].result, let({level2: level2}, &mylist[?l2==level2].result)])[]",
+        "result": [
+          "foo",
+          "bar"
+        ]
+      },
+      {
+        "description": "Nested let functions",
+        "expression": "nested.let({level1: first}, &a.let({level2: second}, &b.let({level3: third}, &c.{first: level1, second: level2, third: level3, fourth: fourth})))",
+        "result": {
+          "first": "first",
+          "second": "second",
+          "third": "third",
+          "fourth": "fourth"
+        }
+      },
+      {
+        "description": "Precedence of lexical vars from scope object",
+        "expression": "precedence.let({other: other}, &a.let({other: other}, &b.let({other: other}, &c.{other: other})))",
+        "result": {
+          "other": "y"
+        }
+      },
+      {
+        "description": "Precedence of lexical vars from current object",
+        "expression": "precedence.let({variable: variable}, &a.let({variable: variable}, &b.let({variable: variable}, &c.let({variable: `\"override\"`}, &variable))))",
+        "result": "fourth"
+      }
+    ]
+  }
+]