Broken site based impl

lib/stdlib/array.js

@@ -0,0 +1,153 @@
+// Arrays. The compiler gives only `a[i]`, `a[i] = x` and `a.length`, which can
+// also be written. Every method here is built on those
+//
+// Not as the spec says:
+// - A method takes one value where the spec takes any number (`push(x)`,
+//   `unshift(x)`, `concat(other)`), because more need rest params
+// - A callback gets the element and its index, not the array too
+// - Holes are not skipped: a callback sees undefined for a hole
+
+// `Array(n)` and `new Array(n)` make an array of `n` holes
+function Array(n) {
+    const a = [];
+    if (n !== undefined) a.length = n;
+    return a;
+}
+
+Array.prototype = {
+    // ── Change the array ──
+    push(x) {
+        this[this.length] = x;
+        return this.length;
+    },
+    pop() {
+        if (this.length === 0) return undefined;
+        const x = this[this.length - 1];
+        this.length = this.length - 1;
+        return x;
+    },
+    shift() {
+        if (this.length === 0) return undefined;
+        const x = this[0];
+        for (let i = 1; i < this.length; i++) this[i - 1] = this[i];
+        this.length = this.length - 1;
+        return x;
+    },
+    unshift(x) {
+        for (let i = this.length; i > 0; i--) this[i] = this[i - 1];
+        this[0] = x;
+        return this.length;
+    },
+    reverse() {
+        for (let i = 0, j = this.length - 1; i < j; i++, j--) {
+            const x = this[i];
+            this[i] = this[j];
+            this[j] = x;
+        }
+        return this;
+    },
+    fill(x, start, end) {
+        const len = this.length;
+        const s = relativeIndex(start === undefined ? 0 : start, len);
+        const e = relativeIndex(end === undefined ? len : end, len);
+        for (let i = s; i < e; i++) this[i] = x;
+        return this;
+    },
+
+    // ── Read ──
+    at(i) {
+        if (i < 0) i += this.length;
+        return this[i];
+    },
+    indexOf(x, from) {
+        for (let i = from === undefined ? 0 : relativeIndex(from, this.length); i < this.length; i++) {
+            if (this[i] === x) return i;
+        }
+        return -1;
+    },
+    lastIndexOf(x) {
+        for (let i = this.length - 1; i >= 0; i--) {
+            if (this[i] === x) return i;
+        }
+        return -1;
+    },
+    includes(x) {
+        return this.indexOf(x) !== -1;
+    },
+    join(sep) {
+        const s = sep === undefined ? "," : sep;
+        let out = "";
+        for (let i = 0; i < this.length; i++) {
+            if (i > 0) out = out + s;
+            const x = this[i];
+            if (x !== undefined && x !== null) out = out + String(x);
+        }
+        return out;
+    },
+    toString() {
+        return this.join(",");
+    },
+
+    // ── Make a new array ──
+    slice(start, end) {
+        const len = this.length;
+        const s = relativeIndex(start === undefined ? 0 : start, len);
+        const e = relativeIndex(end === undefined ? len : end, len);
+        const out = [];
+        for (let i = s; i < e; i++) out[i - s] = this[i];
+        return out;
+    },
+    concat(other) {
+        const out = this.slice();
+        for (let i = 0; i < other.length; i++) out[out.length] = other[i];
+        return out;
+    },
+
+    // ── With a callback ──
+    forEach(f) {
+        for (let i = 0; i < this.length; i++) f(this[i], i);
+    },
+    map(f) {
+        const out = [];
+        for (let i = 0; i < this.length; i++) out[i] = f(this[i], i);
+        return out;
+    },
+    filter(f) {
+        const out = [];
+        for (let i = 0; i < this.length; i++) {
+            if (f(this[i], i)) out[out.length] = this[i];
+        }
+        return out;
+    },
+    reduce(f, init) {
+        let acc = init;
+        for (let i = 0; i < this.length; i++) acc = f(acc, this[i], i);
+        return acc;
+    },
+    find(f) {
+        for (let i = 0; i < this.length; i++) {
+            if (f(this[i], i)) return this[i];
+        }
+        return undefined;
+    },
+    findIndex(f) {
+        for (let i = 0; i < this.length; i++) {
+            if (f(this[i], i)) return i;
+        }
+        return -1;
+    },
+    some(f) {
+        for (let i = 0; i < this.length; i++) {
+            if (f(this[i], i)) return true;
+        }
+        return false;
+    },
+    every(f) {
+        for (let i = 0; i < this.length; i++) {
+            if (!f(this[i], i)) return false;
+        }
+        return true;
+    },
+};
+
+__link_proto_array(Array.prototype);