Implement support of spread operator

src/jsonata.js

@@ -558,6 +558,10 @@ var jsonata = (function() {
                 result = await evaluateGroupExpression(expr, input, environment);
                 break;
 
+            case '...':
+                result = await evaluate(expr.expression, input, environment);
+                break;
+
         }
         return result;
     }
@@ -915,8 +919,29 @@ var jsonata = (function() {
             for(var pairIndex = 0; pairIndex < expr.lhs.length; pairIndex++) {
                 var pair = expr.lhs[pairIndex];
                 var key = await evaluate(pair[0], reduce ? item['@'] : item, env);
+                if(key === undefined) {
+                    continue;
+                }
+                // handle spread operator
+                if (pair[0].value === '...') {
+                    if(typeof key !== 'object' || key === null || Array.isArray(key)) {
+                        throw {
+                            code: "T2015",
+                            stack: (new Error()).stack,
+                            position: expr.position,
+                            value: key
+                        }
+                    }
+                    for (const [_key, _value] of Object.entries(key)) {
+                        groups[_key] = {
+                            data: _value,
+                            exprIndex: pairIndex,
+                            canOverride: true
+                        };
+                    }
+                }
                 // key has to be a string
-                if (typeof  key !== 'string' && key !== undefined) {
+                else if (typeof key !== 'string') {
                     throw {
                         code: "T1003",
                         stack: (new Error()).stack,
@@ -925,9 +950,9 @@ var jsonata = (function() {
                     };
                 }
 
-                if (key !== undefined) {
+                else {
                     var entry = {data: item, exprIndex: pairIndex};
-                    if (groups.hasOwnProperty(key)) {
+                    if (groups.hasOwnProperty(key) && !groups[key].canOverride) {
                         // a value already exists in this slot
                         if(groups[key].exprIndex !== pairIndex) {
                             // this key has been generated by another expression in this group
@@ -2005,6 +2030,7 @@ var jsonata = (function() {
         "T2012": "The delete clause of the transform expression must evaluate to a string or array of strings: {{value}}",
         "T2013": "The transform expression clones the input object using the $clone() function.  This has been overridden in the current scope by a non-function.",
         "D2014": "The size of the sequence allocated by the range operator (..) must not exceed 1e6.  Attempted to allocate {{value}}.",
+        "T2015": "The right side of the spread operator must evaluate to an object: {{value}}",
         "D3001": "Attempting to invoke string function on Infinity or NaN",
         "D3010": "Second argument of replace function cannot be an empty string",
         "D3011": "Fourth argument of replace function must evaluate to a positive number",

src/parser.js

@@ -35,6 +35,7 @@ const parser = (() => {
         '^': 40,
         '**': 60,
         '..': 20,
+        '...': 50,
         ':=': 10,
         '!=': 40,
         '<=': 40,
@@ -164,6 +165,11 @@ const parser = (() => {
             }
             // handle double-char operators
             if (currentChar === '.' && path.charAt(position + 1) === '.') {
+                // triple-dot ... spread operator
+                if (path.charAt(position + 2) === '.') {
+                    position += 3;
+                    return create('operator', '...');
+                }
                 // double-dot .. range operator
                 position += 2;
                 return create('operator', '..');
@@ -565,6 +571,7 @@ const parser = (() => {
         terminal("in"); //
         prefix("-"); // unary numeric negation
         infix("~>"); // function application
+        prefix("..."); // spread operator
 
         infixr("(error)", 10, function (left) {
             this.lhs = left;
@@ -759,9 +766,13 @@ const parser = (() => {
             if (node.id !== "}") {
                 for (; ;) {
                     var n = expression(0);
-                    advance(":");
-                    var v = expression(0);
-                    a.push([n, v]); // holds an array of name/value expression pairs
+                    if (n.id === '...') { // Spread operator
+                        a.push([n, {type: 'variable', value: ''}]); // the value is an identity expression
+                    } else {
+                        advance(":");
+                        var v = expression(0);
+                        a.push([n, v]); // holds an array of name/value expression pairs
+                    }
                     if (node.id !== ",") {
                         break;
                     }

test/test-suite/groups/spread/case000.json

@@ -0,0 +1,11 @@
+{
+    "expr": "{...Address, \"hello\":\"world\"}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "result": {
+        "Street": "Hursley Park",
+        "City": "Winchester",
+        "Postcode": "SO21 2JN",
+        "hello": "world"
+    }
+}

test/test-suite/groups/spread/case001.json

@@ -0,0 +1,10 @@
+{
+    "expr": "{...Address, \"Street\":\"world\"}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "result": {
+        "City": "Winchester",
+        "Postcode": "SO21 2JN",
+        "Street": "world"
+    }
+}

test/test-suite/groups/spread/case002.json

@@ -0,0 +1,10 @@
+{
+    "expr": "{\"Street\": \"test\", ...Address}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "result": {
+        "Street": "Hursley Park",
+        "City": "Winchester",
+        "Postcode": "SO21 2JN"
+    }
+}

test/test-suite/groups/spread/case003.json

@@ -0,0 +1,11 @@
+{
+    "expr": "{...Address, \"Test\": FirstName}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "result": {
+        "Street": "Hursley Park",
+        "City": "Winchester",
+        "Postcode": "SO21 2JN",
+        "Test": "Fred"
+    }
+}

test/test-suite/groups/spread/case004.json

@@ -0,0 +1,11 @@
+{
+    "expr": "['yo', ...foo.blah.baz.fud, 'whats up']",
+    "dataset": "dataset0",
+    "bindings": {},
+    "result": [
+        "yo",
+        "hello",
+        "world",
+        "whats up"
+    ]
+}

test/test-suite/groups/spread/case005.json

@@ -0,0 +1,8 @@
+{
+    "expr": "{...Wrong.Address, \"hello\":\"world\"}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "result": {
+        "hello": "world"
+    }
+}

test/test-suite/groups/spread/case006.json

@@ -0,0 +1,6 @@
+{
+    "expr": "{...null, \"hello\":\"world\"}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "code": "T2015"
+}

test/test-suite/groups/spread/case007.json

@@ -0,0 +1,6 @@
+{
+    "expr": "{...Phone, \"hello\":\"world\"}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "code": "T2015"
+}

test/test-suite/groups/spread/case008.json

@@ -0,0 +1,6 @@
+{
+    "expr": "{...Surname, \"hello\":\"world\"}",
+    "dataset": "dataset1",
+    "bindings": {},
+    "code": "T2015"
+}