From 84025c2ce09f377e7ae2919a3157705bdf2435bb Mon Sep 17 00:00:00 2001
From: Brian Sperlongano <zelonewolf@gmail.com>
Date: Thu, 12 Jan 2023 21:38:39 -0500
Subject: [PATCH] Add split/join

---
 build/generate-style-spec.ts                  |  2 ++
 .../expression/definitions/index.ts           | 10 ++++++++
 src/style-spec/reference/v8.json              | 18 +++++++++++++++
 .../expression/tests/join/basic/test.json     | 13 +++++++++++
 .../expression/tests/join/coercion/test.json  | 23 +++++++++++++++++++
 .../expression/tests/split/basic/test.json    | 13 +++++++++++
 .../expression/tests/split/coercion/test.json | 23 +++++++++++++++++++
 7 files changed, 102 insertions(+)
 create mode 100644 test/integration/expression/tests/join/basic/test.json
 create mode 100644 test/integration/expression/tests/join/coercion/test.json
 create mode 100644 test/integration/expression/tests/split/basic/test.json
 create mode 100644 test/integration/expression/tests/split/coercion/test.json

diff --git a/build/generate-style-spec.ts b/build/generate-style-spec.ts
index 2d0ed9a0b71..d2a3ccd6cff 100644
--- a/build/generate-style-spec.ts
+++ b/build/generate-style-spec.ts
@@ -211,7 +211,9 @@ export type ExpressionSpecification =
     | ['concat', ...(ExpressionInputType | ExpressionSpecification)[]] // at least two inputs required -> string
     | ['downcase', string | ExpressionSpecification] // string
     | ['is-supported-script', string | ExpressionSpecification] // boolean
+    | ['join', string, (string | ExpressionSpecification)[]] // string
     | ['resolved-locale', CollatorExpressionSpecification] // string
+    | ['split', string, string | ExpressionSpecification] // string[]
     | ['upcase', string | ExpressionSpecification] // string
     // Color
     | ['rgb', number | ExpressionSpecification, number | ExpressionSpecification, number | ExpressionSpecification] // color
diff --git a/src/style-spec/expression/definitions/index.ts b/src/style-spec/expression/definitions/index.ts
index 3767fd9069b..cefd48b7306 100644
--- a/src/style-spec/expression/definitions/index.ts
+++ b/src/style-spec/expression/definitions/index.ts
@@ -554,6 +554,16 @@ CompoundExpression.register(expressions, {
         varargs(ValueType),
         (ctx, args) => args.map(arg => valueToString(arg.evaluate(ctx))).join('')
     ],
+    'split': [
+        array(StringType),
+        [StringType, StringType],
+        (ctx, [delim, s]) => s.evaluate(ctx).split(delim.evaluate(ctx))
+    ],
+    'join': [
+        StringType,
+        [StringType, array(StringType)],
+        (ctx, [delim, arr]) => arr.evaluate(ctx).join(delim.evaluate(ctx))
+    ],
     'resolved-locale': [
         StringType,
         [CollatorType],
diff --git a/src/style-spec/reference/v8.json b/src/style-spec/reference/v8.json
index 6cfa6349690..e308064aa9d 100644
--- a/src/style-spec/reference/v8.json
+++ b/src/style-spec/reference/v8.json
@@ -3711,6 +3711,24 @@
             "macos": "0.9.0"
           }
         }
+      },
+      "split": {
+        "doc": "Returns an array of strings split by the specified delimiter string",
+        "group": "String",
+        "sdk-support": {
+          "basic functionality": {
+            "js": "3.0.0"
+          }
+        }
+      },
+      "join": {
+        "doc": "Returns a string formed from joining the elements of an array with a specified delimiter in between",
+        "group": "String",
+        "sdk-support": {
+          "basic functionality": {
+            "js": "3.0.0"
+          }
+        }
       }
     }
   },
diff --git a/test/integration/expression/tests/join/basic/test.json b/test/integration/expression/tests/join/basic/test.json
new file mode 100644
index 00000000000..23440266024
--- /dev/null
+++ b/test/integration/expression/tests/join/basic/test.json
@@ -0,0 +1,13 @@
+{
+  "expression": ["join", ";", ["literal", ["a", "b", "c"]]],
+  "inputs": [[{}, {}]],
+  "expected": {
+    "compiled": {
+      "result": "success",
+      "isFeatureConstant": true,
+      "isZoomConstant": true,
+      "type": "string"
+    },
+    "outputs": ["a;b;c"]
+  }
+}
diff --git a/test/integration/expression/tests/join/coercion/test.json b/test/integration/expression/tests/join/coercion/test.json
new file mode 100644
index 00000000000..5ed85aa5adc
--- /dev/null
+++ b/test/integration/expression/tests/join/coercion/test.json
@@ -0,0 +1,23 @@
+{
+  "expression": ["join", "/", ["get", "a"]],
+  "inputs": [
+    [{}, {"properties": {"a": ["a", "b", "c"]}}],
+    [{}, {"properties": {"a": ["a", "b"]}}],
+    [{}, {"properties": {"a": ["a"]}}],
+    [{}, {"properties": {"a": [""]}}]
+  ],
+  "expected": {
+    "compiled": {
+      "result": "success",
+      "isFeatureConstant": false,
+      "isZoomConstant": true,
+      "type": "string"
+    },
+    "outputs": [
+      "a/b/c",
+      "a/b",
+      "a",
+      ""
+    ]
+  }
+}
diff --git a/test/integration/expression/tests/split/basic/test.json b/test/integration/expression/tests/split/basic/test.json
new file mode 100644
index 00000000000..938015e6c62
--- /dev/null
+++ b/test/integration/expression/tests/split/basic/test.json
@@ -0,0 +1,13 @@
+{
+  "expression": ["split", ";", "a;b;c"],
+  "inputs": [[{}, {}, {}]],
+  "expected": {
+    "compiled": {
+      "result": "success",
+      "isFeatureConstant": true,
+      "isZoomConstant": true,
+      "type": "array<string>"
+    },
+    "outputs": [["a", "b", "c"]]
+  }
+}
diff --git a/test/integration/expression/tests/split/coercion/test.json b/test/integration/expression/tests/split/coercion/test.json
new file mode 100644
index 00000000000..19b0723a6ef
--- /dev/null
+++ b/test/integration/expression/tests/split/coercion/test.json
@@ -0,0 +1,23 @@
+{
+  "expression": ["split", "/", ["get", "s"]],
+  "inputs": [
+    [{}, {"properties": {"s": "a/b/c"}}],
+    [{}, {"properties": {"s": "a/b"}}],
+    [{}, {"properties": {"s": "a"}}],
+    [{}, {"properties": {"s": ""}}]
+  ],
+  "expected": {
+    "compiled": {
+      "result": "success",
+      "isFeatureConstant": false,
+      "isZoomConstant": true,
+      "type": "array<string>"
+    },
+    "outputs": [
+      ["a", "b", "c"],
+      ["a", "b"],
+      ["a"],
+      [""]
+    ]
+  }
+}