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authorwolfbeast <mcwerewolf@wolfbeast.com>2019-05-19 23:11:17 +0200
committerwolfbeast <mcwerewolf@wolfbeast.com>2019-05-19 23:11:17 +0200
commit162e22a7de3026b676156a2aad29909fe3795dba (patch)
tree5f289528d555a2b7f2906c72591773814d6e0ea4 /js/src/builtin
parentc72afc3c8c3f1df53d241c45dd21aa1b2a6c8e50 (diff)
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Implement array.flat and array.flatMap
Self-hosted implementation that adds both functions and adds them to @@unscopables as specced in ES2019. Resolves #1095
Diffstat (limited to 'js/src/builtin')
-rw-r--r--js/src/builtin/Array.js108
1 files changed, 108 insertions, 0 deletions
diff --git a/js/src/builtin/Array.js b/js/src/builtin/Array.js
index 30e6fb35f..05fc41bc1 100644
--- a/js/src/builtin/Array.js
+++ b/js/src/builtin/Array.js
@@ -1073,6 +1073,114 @@ function ArrayConcat(arg1) {
return A;
}
+// https://tc39.github.io/proposal-flatMap/
+// January 4, 2019
+function ArrayFlatMap(mapperFunction/*, thisArg*/) {
+ // Step 1.
+ var O = ToObject(this);
+
+ // Step 2.
+ var sourceLen = ToLength(O.length);
+
+ // Step 3.
+ if (!IsCallable(mapperFunction))
+ ThrowTypeError(JSMSG_NOT_FUNCTION, DecompileArg(0, mapperFunction));
+
+ // Step 4.
+ var T = arguments.length > 1 ? arguments[1] : undefined;
+
+ // Step 5.
+ var A = ArraySpeciesCreate(O, 0);
+
+ // Step 6.
+ FlattenIntoArray(A, O, sourceLen, 0, 1, mapperFunction, T);
+
+ // Step 7.
+ return A;
+}
+
+// https://tc39.github.io/proposal-flatMap/
+// January 4, 2019
+function ArrayFlat(/* depth */) {
+ // Step 1.
+ var O = ToObject(this);
+
+ // Step 2.
+ var sourceLen = ToLength(O.length);
+
+ // Step 3.
+ var depthNum = 1;
+
+ // Step 4.
+ if (arguments.length > 0 && arguments[0] !== undefined)
+ depthNum = ToInteger(arguments[0]);
+
+ // Step 5.
+ var A = ArraySpeciesCreate(O, 0);
+
+ // Step 6.
+ FlattenIntoArray(A, O, sourceLen, 0, depthNum);
+
+ // Step 7.
+ return A;
+}
+
+// https://tc39.github.io/proposal-flatMap/
+// January 4, 2019
+function FlattenIntoArray(target, source, sourceLen, start, depth, mapperFunction, thisArg) {
+ // Step 1.
+ var targetIndex = start;
+
+ // Steps 2-3.
+ for (var sourceIndex = 0; sourceIndex < sourceLen; sourceIndex++) {
+ // Steps 3.a-c.
+ if (sourceIndex in source) {
+ // Step 3.c.i.
+ var element = source[sourceIndex];
+
+ if (mapperFunction) {
+ // Step 3.c.ii.1.
+ assert(arguments.length === 7, "thisArg is present");
+
+ // Step 3.c.ii.2.
+ element = callContentFunction(mapperFunction, thisArg, element, sourceIndex, source);
+ }
+
+ // Step 3.c.iii.
+ var shouldFlatten = false;
+
+ // Step 3.c.iv.
+ if (depth > 0) {
+ // Step 3.c.iv.1.
+ shouldFlatten = IsArray(element);
+ }
+
+ // Step 3.c.v.
+ if (shouldFlatten) {
+ // Step 3.c.v.1.
+ var elementLen = ToLength(element.length);
+
+ // Step 3.c.v.2.
+ // Recursive call to walk the depth.
+ targetIndex = FlattenIntoArray(target, element, elementLen, targetIndex, depth - 1);
+ } else {
+ // Step 3.c.vi.1.
+ if (targetIndex >= MAX_NUMERIC_INDEX)
+ ThrowTypeError(JSMSG_TOO_LONG_ARRAY);
+
+ // Step 3.c.vi.2.
+ _DefineDataProperty(target, targetIndex, element);
+
+ // Step 3.c.vi.3.
+ targetIndex++;
+ }
+ }
+ }
+
+ // Step 4.
+ return targetIndex;
+}
+
function ArrayStaticConcat(arr, arg1) {
if (arguments.length < 1)
ThrowTypeError(JSMSG_MISSING_FUN_ARG, 0, 'Array.concat');